Protein Powders: Benefits, Types, Dosing, and Side Effects

Table of Contents

• Overview
• Forms and Bioavailability
• Evidence for Benefits
• Recommended Dosing
• Safety and Side Effects
• Drug Interactions
• Dietary Sources
• References

Overview

Protein is an essential macronutrient required to build, maintain, and repair muscle tissue, and it plays a central role in virtually every metabolic process in the human body. Protein powders offer a concentrated source of protein without the significant saturated fat, cholesterol, or excess carbohydrates that can accompany whole-food protein sources such as meats and dairy [1]. However, protein powders are ultra-processed foods, and the whole foods from which they are derived provide important nutrients beyond protein — including vitamins, minerals, healthful fats, complex carbohydrates, and fiber — that powders typically lack [1].

The Academy of Nutrition and Dietetics (AND) recognizes a daily protein requirement of approximately 0.40 g/lb (0.8 g/kg) of body weight for sedentary individuals, 0.55–0.65 g/lb for endurance athletes, and 0.65–0.80 g/lb for strength athletes [1][2]. For a 150 lb (68 kg) person, this translates to approximately 60 g for sedentary individuals, 90 g for endurance athletes, and 109 g for strength athletes. The AND also states that the maximum usable daily protein intake for adults is approximately 1 g/lb (2.2 g/kg) of body weight, and that the usable amount from a single meal for muscle synthesis is roughly 30 g [1].

Many older adults fail to meet even basic protein requirements. Analysis of NHANES data (2005–2014) found that among men, 31% of 51–60 year-olds, 37% of 61–70 year-olds, and 42% of those over 70 did not consume the minimum 0.36 g/lb recommended. For women, the figures were even higher: 45%, 48%, and 50% respectively (Krok-Schoen, J Nutr Health Aging, 2019) [3]. There is evidence that protein intake in older adults may need to be 25–50% above current recommendations — approximately 0.45 to 0.55 g/lb — to better stimulate muscle creation and reduce muscle loss (Deutz, Clin Nutr, 2014) [4]. A study among people aged 60+ in South Florida found that those with the lowest average protein intakes were African Americans (0.29 g/lb), followed by European Americans (0.38 g/lb), while Hispanic Americans had the highest protein intakes (0.44 g/lb) (Gropper, J Nutr Geron Geriat, 2019) [5].

Protein powders typically come in canisters or packets ready to be mixed with water, milk, juice, or other beverages. They are marketed as dieting aids, meal replacements, endurance and recovery products, and concentrated protein sources — primarily for athletes seeking to build muscle and strength [1]. The global protein powder market was valued at approximately USD 24.6 billion in 2024 and is projected to reach USD 46.2 billion by 2034 [6].

Forms and Bioavailability

Not all protein powders are equivalent. The protein source, processing method, and form determine amino acid profile, bioavailability (how efficiently protein is absorbed and utilized), digestibility, and tolerance. Understanding these differences is critical to selecting the right protein for a given purpose.

Animal-Based Proteins

Whey Protein

Whey is the most widely used protein source in commercial protein powders. It is derived from the liquid portion of milk during cheese production and is a complete protein containing all nine essential amino acids. Whey has the highest branched-chain amino acid (BCAA) content found in nature — the BCAAs valine, leucine, and isoleucine become depleted following exercise and are needed for muscle tissue maintenance [1][7]. Whey protein is digested faster than casein and more completely than soy protein, with an absorption time of approximately 1–2 hours [7][8].

Forms of whey protein:

• Whey concentrate — Contains 25–80% protein by weight, with residual lactose, fat, and cholesterol. If concentrated without heat ("cold process"), it may retain immunostimulant immunoglobulins [1].
• Whey isolate — Lower in lactose, fat, and cholesterol than concentrate. Typically over 90% protein by weight. Suitable for lactose-intolerant individuals as it contains minimal lactose (Kalman, Foods, 2014) [1][9].
• Whey hydrolysate — Pre-digested protein that is assimilated more quickly than non-hydrolyzed forms. Well suited for post-exercise recovery due to increased bioavailability and reduced digestive energy requirements [1].
• Ion-exchange purified whey — The purest form, but may have reduced immunostimulant properties due to chemical processing [1].

Isolates, hydrolysates, and other purified forms are typically more expensive than standard concentrates due to additional processing [1].

Any whey protein product will contain cysteine, which — along with glycine and glutamic acid — can be converted to glutathione, a key antioxidant (Tsutsumi, Austin J Nutri Food Sci, 2014) [10]. One trial found that a standard whey protein was actually more effective as a glutathione precursor than a patented "immunoenhancing" whey product (Micke, Eur J Clinical Investigation, 2001) [11].

Whey protein may contain trace amounts of estrogens from cow's milk, but amounts are extremely small and likely inconsequential — estradiol is bound to fat in milk and there is little fat in whey protein powders (Pape-Zambito, J Dairy Sci, 2010) [12]. Due to soy in cattle feed, whey powders may also contain very small amounts of soy isoflavones. Analysis of a whey protein supplement found less than 1 mg each of daidzein and genistein per 26.3 g serving (Haun, Sci Rep, 2018) [13].

A laboratory-produced form of whey protein (Perfect Day), made via fermentation by the fungus Trichoderma reesei, is marketed as non-animal whey protein. It has a similar amino acid profile to cow-derived whey, including 5 g of BCAAs per 32 g serving, and is considered suitable for vegans, lactose-free, and cholesterol-free. However, it contains at least 90% beta-lactoglobulin — a major milk allergen — and products must bear the allergen statement "Contains Milk Protein" (FDA, GRAS Notice No. 863) [1][14].

Casein Protein

Casein is the other major milk protein (milk protein is 80% casein and 20% whey). It is also a complete protein, extremely high in the amino acid glutamine — the predominant amino acid in muscles. However, casein has a lower biological value than whey, meaning a lower percentage of consumed protein is absorbed and utilized [1]. Casein forms gel-like micellar structures in the stomach, enabling slow digestion over 6–8 hours [7][8]. This sustained amino acid release makes casein theoretically beneficial for overnight muscle maintenance.

A study among healthy, active young men in a resistance training program found that after 3 months, average increases in muscle strength and lean mass were similar whether 35 g of casein was consumed at bedtime or earlier in the day (at least 6 hours before bedtime). Both groups also consumed 25 g of whey protein immediately after resistance training. Increases in lean mass (approximately 5 lbs) and muscle soreness were similar (Joy, J Int Soc Sports Nutr, 2018) [15].

A study funded by Immunotec found that among sedentary older adults (average age 71) who began resistance exercise 3 times per week, taking 20 g of a patented whey isolate (Immunocal) or 20 g of casein daily for 4.5 months produced modest increases in lean mass and strength in both groups, with lower body strength increases approximately 10% greater with the whey isolate (Karelis, J Nutr Health Aging, 2015) [16]. However, given casein's lower bioavailability, the comparison is not particularly impressive.

Forms of casein:

• Micellar casein — Natural, un-denatured form; more slowly absorbed [1].
• Caseinates (e.g., calcium caseinate) — Chemically treated forms that are more readily absorbed and provide a good source of calcium [1].

Prostate cancer concern: Because casein is the main protein in milk and dairy, and the National Cancer Institute notes that "a diet high in dairy foods and calcium may cause a small increase in the risk of prostate cancer," there is some concern. A laboratory study showed that casein protein promoted growth of certain prostate cancer cells (but not breast cancer cells) (Park, World J Mens Health, 2014) [17]. An observational study of 500,000 men from ten European countries found a 17% increased risk of prostate cancer among those consuming the most yogurt (median 57 g/day) compared to the least (median 15 g/day), though there was no increased risk from milk or cheese in general (Allen, Br J Cancer, 2008) [18]. However, other dairy components such as fat content may play a role. Among men with localized prostate cancer, highest versus lowest whole milk intake doubled the risk of progression to lethal prostate cancer, while highest low-fat dairy intake showed the opposite effect (Pettersson, Cancer Epidemiol Biomarkers Prev, 2012) [19]. At this point it is not possible to know whether casein protein itself increases prostate cancer risk in men, but it would seem best to use it in moderation.

Alpha-s1 casein hydrolysate (Lactium) for anxiety and sleep: Preliminary evidence suggested calming effects via GABA receptor modulation (Messaoudi, Eur J Nutr, 2005; Kim, Eur J Clin Nutr, 2007) [20][21]. However, more recent studies found little benefit. A placebo-controlled study in 43 adults (average age 49) with mild-to-moderate sleep difficulty found that 300 mg Lactium taken one hour before bedtime for one month was no better than placebo for subjective or objective sleep measures (Kim, Nutrients, 2019) [22]. A study in 36 adults with chronic insomnia using 600 mg Lactium (reduced to 300 mg after two weeks) found only a 7.7-minute decrease in sleep onset latency — not reaching the clinically meaningful threshold of 8 minutes, and similar to the placebo group's 6.1-minute decrease (Chang, Clin Nutr, 2024) [23].

Egg White Protein

Egg white (albumen) protein powder is a complete protein. Although sometimes promoted for very high biological value, this applies only at lower intake levels (approximately 14 g/day) (Srikantia, FAO, 1981) [1]. There is a lack of clinical studies comparing egg white protein with other types. A small 8-week study in female athletes (ages 18–22) taking 15 g of egg white protein before exercise found no significant increase in muscle strength compared to a carbohydrate control (Hida, Nutrients, 2012) [24].

Collagen Protein

Collagen protein, extracted from animal bones, skin, and connective tissues, supports joint and skin health but has an incomplete amino acid profile — lacking sufficient tryptophan and methionine — limiting its use as a sole protein source for muscle building [7]. A study among 22 women aged 60–80 who performed resistance exercise showed whey protein to be much more effective at building muscle than collagen protein (Oikawa, Am J Clin Nutr, 2019) [25]. Collagen should not be expected to provide the muscular benefits of a complete protein powder, though it may provide modest benefits for wrinkles and osteoarthritis.

Bone Broth Protein

Bone broth protein supplements consist of dehydrated broth typically from chicken bones. Chicken bones contain all essential amino acids and primarily consist of glycine, proline, and hydroxyproline, along with type I and type II collagen (Losso, J Food Biochem, 2013; Dong, Food Chem, 2014) [26][27]. However, there is little information about the amino acid profile of bone broth preparations — which varies based on preparation method, simmering duration, and bones used — and there appear to be no published clinical studies on bone broth protein supplementation. One small laboratory study found that traditional chicken soup (including vegetables) inhibited neutrophil movement, suggesting a possible anti-inflammatory effect rather than the "immune boosting" effect often marketed (Bo, Chest, 2000) [28]. There is evidence that chicken bone broth can contain significant lead contamination (7 mcg/L in "organic" broth), likely due to lead accumulation in bones, with cartilage and skin broth containing 35% more lead than meat-only broth (Monro, Med Hypotheses, 2013) [29].

Cricket Protein

Cricket powder (made from washed, dried, and ground crickets) is approximately 60% protein, rich in vitamin B-12, and considered a more environmentally friendly animal protein source. About 20–25% of the powder is fat (some saturated), with minimal carbohydrate (mainly fiber) and no sugar [1]. A European Food Safety Authority safety review (2018) noted bioaccumulation of heavy metals — particularly cadmium, arsenic, lead, and tin — as a concern of "considerable" importance [30]. Additional concerns include high bacterial counts, spore-forming bacteria survival after thermal processing, and allergenicity (people allergic to insects or shellfish may react) [30].

Plant-Based Proteins

Plant-based proteins typically contain a lower ratio of total essential amino acids to total protein compared to animal-based proteins (26% vs. 37%). To obtain the 10.9 g of essential amino acids found in 25 g of whey protein, a person would need approximately: 30 g potato protein, 34 g corn protein, 37 g pea protein, 39 g rice protein, 40 g soy protein, 48 g hemp protein, 49 g wheat protein, or 51 g oat-based protein (Gorissen, Amino Acids, 2018) [31].

Individual plant proteins can be low in specific essential amino acids. Key limitations and recommended companion proteins include:

Plant Protein	Limitations	Companion Protein(s)
Corn	Low lysine	Pea, potato, soy
Hemp	Low total EAAs, low leucine, low lysine	Pea, potato, soy
Oat	Low total EAAs, low leucine, low lysine, low methionine	Potato; pea or soy + rice
Pea	Low methionine	Corn, hemp, potato, rice
Potato	None	Any
Rice	Low lysine	Pea, potato, soy
Soy	Low methionine	Corn, hemp, potato, rice
Wheat	Low total EAAs, low lysine, low methionine	Potato; pea or soy + rice

Sources: Craig, J Am Diet Assoc, 2009; Marsh, Med J Aust, 2013; Gorissen, Amino Acids, 2018 [31][32][33].

Despite these limitations, studies show that soy, rice, pea protein, and mycoprotein can be just as effective as whey protein for maintaining or building muscle mass when combined with routine resistance exercise [1].

Soy Protein

Soy protein is a complete protein acceptable to vegetarians and vegans, containing little fat or cholesterol, particularly in isolate form. Soy protein is considered equivalent to human protein, though it contains little of the sulfur-containing amino acid methionine — a deficiency that is not a problem in normal adult nutrition (Gorissen, Amino Acids, 2018) [31]. In 1999, the FDA authorized the health claim that eating 25 g of soy protein daily, combined with a low-fat, low-cholesterol diet, can reduce heart disease risk [1]. However, in October 2017, the FDA proposed revoking this claim due to inconsistent findings since 1999 regarding whether soy protein lowers LDL cholesterol [1].

A study among 38 men (average age 26) compared soy protein supplementation with a plant-based diet and whey protein supplementation with a mixed diet, combined with resistance exercise twice weekly for 12 weeks. Both groups achieved similar, modest increases in lean muscle mass. The total daily protein intake for all participants was standardized at 1.6 g/kg body weight (Hevia-Larrain, Sports Med, 2021) [34].

Soy protein contains isoflavones with weak estrogen-like effects, but concentrations are much lower than in soy flour (approximately 200 mg aglycone isoflavones per 100 g). Soy protein concentrate contains only 12 mg per 100 g if produced by alcohol extraction, or approximately 100 mg if produced by water extraction [1]. Analysis of a supplement containing 80% soy protein concentrate found 14 mg daidzein and 18 mg genistein per 39 g serving, and consuming two servings daily for 3 months had no effect on blood estradiol levels in healthy college-aged men (Haun, Sci Rep, 2018) [13]. Other clinical studies show no impact on estrogen levels or gynecomastia risk among men taking up to 150 mg of isoflavones daily (Messina, Nutrients, 2016) [35]. Although animal research has linked excessive soy intake with reduced fertility, a study among women found that higher intake of soy or soy isoflavones was not associated with having fewer eggs [1].

Thyroid concern: Anyone with thyroid disease or predisposition to thyroid dysfunction should limit soy protein intake. Isoflavones in soy can affect thyroid hormone levels. A study in adults with normal thyroid function found that 15 g of soy protein containing approximately 33 mg aglycone isoflavones daily increased TSH and rT3 and decreased fT4 after 3 months — though levels returned to normal by 6 months (Sathyapalan, Front Endocrinol, 2018) [36]. Soy isoflavones may also inhibit absorption of thyroid hormone medication (Messina, Thyroid, 2006) [37].

Prostate cancer and soy: Results are mixed. Higher soy intake (as in Asian countries) has been associated with lower prostate cancer risk, but a protective effect is not established. A study following over 76,000 men for 11.5 years found no association between soy isoflavone intake and total prostate cancer risk, but those with the highest dietary intake (0.75–2.03 mg/day) had a 91% increased risk of advanced prostate cancer compared to those with the lowest intake (Reger, Int J Cancer, 2018) [38]. In men at high risk for prostate cancer recurrence, consumption of approximately 20 g soy protein isolate daily showed no difference in recurrence after 2 years compared to placebo. The researchers noted that soy may be protective when consumption begins early in life but not later when cancer is already present (Bosland, JAMA, 2013) [39].

Rice Protein

Rice protein is obtained by enzymatic separation from rice seed. While it contains all essential amino acids, analysis shows that whey protein isolate contains 39% more essential amino acids and 33% more BCAAs than rice protein isolate (Kalman, Foods, 2014) [9]. Rice protein has a relatively low amount of lysine (Gorissen, Amino Acids, 2018) [31]. Nevertheless, a study in healthy young men found that 48 g of either rice protein isolate or whey protein isolate taken 3 days/week immediately after resistance training for 2 months resulted in similar increases in lean muscle mass and strength (Joy, Nutr J, 2013) [40]. Rice protein is considered hypoallergenic and well absorbed.

Pea Protein

Pea protein is a complete protein, rich in BCAAs. A study comparing pea protein isolate to casein concluded that pea protein is "high quality" and meets all amino acid requirements, though certain BCAAs (leucine, valine) and amino acids (lysine, phenylalanine) are somewhat less digestible from pea than casein, and the estimated proportion of amino acids eventually converted into body proteins was somewhat lower with pea (Guillin, Am J Clin Nutr, 2021) [41]. Like soy, pea protein is low in methionine [31].

A placebo-controlled study comparing pea protein isolate to whey protein found nearly equivalent increases in strength and muscle thickness across all groups. Among men weakest at baseline, muscle thickness increase was significantly greater for pea protein compared to placebo, with no statistical difference between whey and pea or whey and placebo. The 12-week study involved healthy young men performing strength training 3 times weekly, consuming 25 g protein each morning and after workouts (Babault, J Int Soc Sports Nutr, 2015) [42]. A study among exercise-trained adults (average age 38) found similar strength increases with pea and whey protein over 2 months (Banaszek, Sports, 2019) [43]. Interestingly, neither of these studies prove an overall benefit from protein supplementation per se, but both demonstrate a benefit from strength training.

Phytate concern: Pea protein powder may contain high concentrations of the antinutrient phytate, which can bind minerals (iron, zinc, calcium) in the gastrointestinal tract and form insoluble complexes that cannot be absorbed. A laboratory study found one pea protein preparation was 2% phytate by weight — a 33 g serving would contain 660 mg of phytate (Naczk, J Food Sci, 1986) [44]. Phytate levels were somewhat lower in soy protein isolate (1.69%) and concentrate (1.17%), and much lower in wheat gluten (0.27%). However, amounts vary widely; NOW Foods reports their pea protein contains only 0.61% phytate, comparable to dried peas (2.2–12.2 mg/g) (Schlemmer, Mol Nutr Food Res, 2009) [45]. The average daily phytate intake in the US is estimated at 750 mg, with significantly higher intakes among vegetarians (1,250–1,550 mg) [45]. Consuming pea protein 2–3 hours apart from mineral-rich meals or supplements can reduce phytate effects.

Kidney stone risk: A preliminary study found that consuming 60 g of pea protein daily for 5 days increased calcium phosphate supersaturation and urinary oxalate levels, potentially concerning for those at risk for calcium phosphate or calcium oxalate kidney stones (the most common type), though taking it with calcium might reduce calcium oxalate stone risk. However, pea protein (and soy protein) lowered uric acid supersaturation and increased urine pH, which may help those prone to uric acid or cystine stones. Whey protein did not produce these effects. The study was short-term and did not include participants with a history of kidney stones (Wong, Urology, 2025) [46].

Hemp Protein

Hemp protein is derived from industrial Cannabis sativa L. and has no psychoactive properties. One of its main proteins is albumen, containing all essential amino acids and BCAAs. On a percentage basis, hemp contains lower amounts of BCAAs and essential amino acids than whey or soy, though more BCAAs than rice or egg white. It is exceptionally high in arginine but relatively low in leucine and lysine (Callaway, Euphytica, 2004; Gorissen, Amino Acids, 2018) [31][47]. Hemp protein also provides beneficial omega-3 fatty acids, delivering approximately 15 g protein per serving (Rodriguez-Leyva, Nutr Metab, 2010) [48]. However, there is little published research on hemp protein for muscle building or sports recovery.

Peanut Protein

Peanut protein powders naturally contain carbohydrates (half of which is fiber), some sugar, and unsaturated oil — most of the oil in raw peanuts is removed during processing. Each 20 g of peanut protein powder provides approximately 150 calories — roughly 50–90% more than comparable servings of whey, casein, or pea protein. Peanut protein contains all essential amino acids but is low in methionine (Gorissen, Amino Acids, 2018) [31].

Mycoprotein (Quorn)

Mycoprotein is protein derived from the fungus Fusarium venenatum. By dry weight, it is approximately 25% fiber (about two-thirds as beta-glucans) and 45% protein, with essential amino acids comprising approximately 44% of total protein (Monteyne, Am J Clin Nutr, 2020; Denny, Nutr Bull, 2008) [49].

A 10-week study found that mycoprotein supplementation plus resistance training was as beneficial for increasing muscle mass and strength as milk-based protein. In the study, 22 young adults participated in resistance exercise 5 times weekly. Those on a vegan diet supplemented with mycoprotein (15.3 g post-exercise, 30.7 g before sleep) and those on an omnivorous diet supplemented with equivalent milk-based protein both increased lean mass by approximately 6.8 lbs and showed significantly increased strength for deadlift, squat, and bench press (Monteyne, J Nutr, 2023) [50]. However, the lack of a no-supplement control group means the protein's specific contribution cannot be confirmed.

Mycoprotein may cause gastrointestinal distress due to high fiber content. Other reported adverse reactions include vomiting, nausea, diarrhea, hives, and breathing difficulties. Two deaths from anaphylactic reactions have occurred among people with asthma who consumed mycoprotein-based products (Finnigan, Curr Dev Nutr, 2019) [51]. Note that many Quorn products are not vegan because they also contain egg albumin as a binding ingredient [51].

Protein Purity and Essential Amino Acid Content

Protein powders typically consist of 70–90% protein by weight, with concentrates around 70–80% and isolates over 90% [7]. A standard 25–30 g serving of whey protein provides approximately 100–150 calories, 20–30 g of protein, and 1–5 g each of carbohydrates and fats [7].

Plant-based powders, such as pea, soy, or rice, often provide similar protein content per serving (20–25 g) but may include higher fiber (2–5 g) and generally lower BCAA levels compared to whey unless blended [7].

To assess protein quality, calculate: (grams of protein per serving / total grams per serving) x 100. Whey isolates often exceed 80–90% protein; concentrates typically range from 70–80%; values below 60–70% may suggest significant fillers [7].

Amino acid spiking is a deceptive practice in which manufacturers add cheap free-form amino acids like glycine or taurine to inflate measured protein content via nitrogen analysis without providing a complete protein profile. Products with separately listed amino acids or unusually high glycine/taurine in the amino acid profile may be spiked [7].

Evidence for Benefits

Building and Maintaining Muscle Mass

Combined with regular resistance exercise, protein supplementation can help increase muscle mass and strength gains — although the evidence is more consistent in younger adults than in older adults.

Meta-analyses and systematic reviews:

A review of 49 studies found that increasing total daily protein intake up to 0.73 g/lb (1.6 g/kg) of body weight significantly enhanced changes in muscle strength and size during prolonged resistance exercise training in both younger and older adults. Consuming more than this amount provided no additional benefit. All sources of protein were beneficial — including whey, soy, casein, pea supplements, and whole foods such as beef, yogurt, and eggs (Morton, Br J Sports Med, 2017) [52].

However, a review of 38 RCTs among older adults (age 50+) found that while resistance training produced muscular benefits, combining protein supplementation with training did not show greater effects on muscle mass, strength, or physical performance than resistance training alone (Tian, J Nutr, 2025) [53].

A review of 22 studies in both young and older individuals found that after training 2–5 times per week for 6–24 weeks, subjects receiving supplemental protein gained an additional 1.5 lbs of muscle and could leg press an additional 30 lbs compared to those not getting extra protein. Most studies involved whey protein given immediately before, during, or after exercise (Cermak, Am J Clin Nutr, 2012) [54].

When dietary protein is already adequate:

A study of older men consuming approximately 93 g of protein daily found that 12 weeks of resistance exercise plus supplementary protein (21 g post-exercise and before sleep) did not improve muscle strength or size compared to exercise with a non-protein placebo (Holweda, Nutr Physiol Metab, 2018) [55].

Similarly, among untrained postmenopausal women (average age 58), 12 weeks of resistance training plus 0.77 g/lb protein including a whey protein supplement, plus an additional 30 g whey protein following each training session, did not significantly improve strength or body composition compared to resistance training with regular protein intake (0.41 g/lb, which is close to amounts considered adequate for older adults). Both groups showed significant improvements in muscle mass and strength compared to a non-training control (Ioannidou, J Nutr Health Aging, 2024) [56].

A 10-week study among Pilates-trained women (average age 31) found that approximately 18 g of whey protein twice daily in addition to approximately 80 g dietary protein/day (about 0.6 g/lb, within requirements for endurance athletes) did not significantly improve body weight, BMI, muscle mass, hip or waist circumference, core endurance, or flexibility compared to placebo plus Pilates — though both groups improved compared to baseline (Karpouzi, J Int Soc Sports Nutr, 2025) [57].

A study in Canada found that neither whey nor casein supplementation (10 g per meal, 3 times daily) led to greater improvements in muscle quality or function than no supplementation in 60 elderly men already consuming adequate protein (0.61 g/lb) who underwent 12 weeks of mixed power training. All three groups benefited equally from the training (Dulac, Br J Nutr, 2020) [58].

A study at Tufts University raised protein intake among older adults from 0.85 to 1.5 g/kg/day (about a 44 g increase for a 150 lb adult) using whey protein isolate for 24 weeks with no significant improvement in muscle strength, power, physical function, or mass compared to placebo. Adding potassium bicarbonate to reduce potential protein-induced acidity was also not helpful (Ceglia, Am J Clin Nutr, 2026) [59].

A study among 116 older adults (average age 73) found that increasing protein to 0.72 g/lb versus 0.45 g/lb during 8 weeks of resistance training did not enhance muscle strength, aerobic endurance, walking speed, flexibility, or mobility, but the high-protein group showed a modestly greater increase in muscle mass (1.12 vs. 0.49 lbs) and slightly greater decrease in body fat (1.03 lb decrease vs. 1.3 lb increase) (Unterberger, Clin Nutr, 2022) [60].

Importantly, simply eating extra protein without exercise does not help build muscle or increase strength, as demonstrated in several clinical studies (Bhasin, JAMA Int Med, 2018; Mori, Geriatr Gerontol Int, 2018; Zhu, J Nutr, 2015) [61][62][63].

Protein without exercise for maintenance:

A study in 123 older adults (average age 70), nearly 40% of whom consumed less than the recommended daily protein, found that 16 g daily of whey, soy, or whey-soy blend while maintaining regular activity helped maintain lean mass and physical performance over 6 months compared to a control group that lost 1% of muscle mass and had slight declines in gait speed. The protein was taken as 8 g servings with breakfast and dinner. The type of protein did not make a difference (Li, J Acad Nutr Diet, 2021) [64].

Older Adults and Sarcopenia

Resistance exercise and protein supplementation are particularly beneficial for older adults at risk for sarcopenia — progressive loss of skeletal muscle mass and strength that increases fall risk (Clynes, Calcif Tissue Int, 2015) [65].

A 3-month study among older women (average age 67) who regularly performed resistance exercise (approximately 3 days/week) found that 35 g of hydrolyzed whey protein (providing 27.1 g protein) consumed immediately after exercise modestly increased lean soft tissue (3.8% vs. 2% for placebo) and muscle strength as measured by volume load (45.4% vs. 35.4%). Women consuming whey also had a greater reduction in the total cholesterol to HDL ratio (-11.8% vs. -2.9%). There was no significant change in body fat in either group (Fernandes, Exp Gerontol, 2018) [66].

The same researchers found that taking protein immediately before exercise also increased lean tissue and improved cholesterol, but only when protein was taken after exercise did it significantly improve metabolic health (based on fasting blood glucose and cholesterol levels) and reduce body fat (Nabuco, Nutr Metab Cardio Dis, 2018) [67].

A study among 72 older adults (average age 74) with slow walking speed due to knee osteoarthritis and sarcopenia showed that those supplementing with approximately 24 g of blended protein (50% whey, 30% casein, 20% soy) twice daily while participating in resistance training achieved normal walking speed after only 14 weeks compared to 25 weeks for exercise-only. Baseline dietary protein intake was low (0.37 g/lb). Exercise was supervised moderate-to-high intensity 3 times weekly for 2 weeks, then at-home resistance exercise daily for 10 weeks (Liao, Nutrients, 2023) [68].

A 12-month study of 218 older adults (ages 75–96, mostly women) with sarcopenia who were already consuming adequate protein (0.45 g/lb) found only a slight, non-statistically-significant performance benefit from supplementing with 20 g protein twice daily from a whey-enriched beverage versus low-protein or protein-rich food snacks. All participants performed light resistance exercises and received 20 mcg (800 IU) vitamin D daily (Bjorkman, JAMDA, 2019) [69].

Bed Rest and Hospitalization

A study of 20 healthy older adults (ages 60–80) assigned to 7 days of bed rest found that those receiving whey protein isolate (replacing some mixed protein sources) tended to retain more leg muscle while losing more body fat, and recovered leg strength faster during rehabilitation — though differences did not reach statistical significance. Both groups experienced a 20% reduction in knee strength. The apparent benefit may relate to whey's high leucine content (Arentson-Lantz, J Gerontol Biol Sci Med Sci, 2019) [70].

Among 622 hospitalized older adults (average age 78) with moderate or severe malnutrition, consuming an oral nutritional supplement providing 20 g protein (from milk, soy, caseinate, and whey), 350 calories, 11 g fat, 44 g carbohydrate, 1.5 g HMB, 160 IU vitamin D, and other micronutrients twice daily during hospitalization and for 90 days after discharge did not reduce length of stay or readmission rate, but improved nutritional status and reduced the risk of dying by 51% compared to placebo (Deutz, Clin Nutr, 2016) [71].

Weight Loss and Body Composition

Caloric restriction with exercise: A study among obese young men found that during 4 weeks of dieting (40% caloric restriction) and intense exercise (6 days/week), those receiving extra whey protein (approximately 34 extra grams per drink, 3–4 drinks/day, with less fat to offset calories) lost more fat (2.9 lbs more) and gained more muscle (2.4 lbs more) than controls, though increases in strength were the same between groups — a finding that surprised the researchers (Longland, AJCN, 2016) [72].

A 3-month trial among 26 older women (average age 69) with sarcopenic obesity found that 35 g hydrolyzed whey protein after whole-body resistance training 3 times weekly produced greater decreases in total fat (-3.3% vs. -0.3%) and greater increases in arm and leg muscle (6% vs. 2.5%) compared to placebo, with no change in total energy intake in either group (Nabuco, Clin Nutr ESPEN, 2019) [73].

A 12-week study of 133 overweight adults (average age 37) following a reduced-calorie diet (500 kcal/day below energy needs) and exercising 2.5 hours/week found that a protein and fiber shake (17 g protein from whey and pea, 6 g fiber) consumed 30 minutes before breakfast and lunch produced more weight loss than a calorie-matched placebo (-7.3 lbs vs. -4 lbs), though body fat reduction was similar (both approximately 1%) (Glynn, J Nutr, 2022) [74].

Without dieting or exercise: A study of obese men found that a drink containing 30 g whey protein slowed stomach emptying but did not reduce feelings of hunger or food consumption at a meal 3 hours later (Oberoi, Nutr Diabetes, 2020) [75].

Post-bariatric surgery: A study among 78 adults (average age 41) after mini gastric bypass found that 15 g whey protein powder providing 11.3 g protein twice daily for 3 months resulted in significantly less fat-free mass loss (-5.95% vs. -9.54%) and muscle mass loss (-5.93% vs. -9.05%) compared to placebo, but did not result in significantly greater total weight loss, lower BMI, or greater reduction in body fat, visceral fat, or trunk fat (Sabooni, Clin Nutr ESPEN, 2025) [76].

Bone health during weight loss: A study of 187 obese/overweight older adults (average age 71) participating in a 6-month weight loss program (reduced calorie diet plus aerobic exercise 3 times weekly) found that 25 g whey protein twice daily increased hip bone strength — a measure of bone's ability to withstand impact — by 3.8% compared to 0.5% without protein supplementation. However, protein did not increase bone mineral density in the hip and did not result in greater weight loss (approximately 17 lbs in both groups) (Weaver, Osteoporos Int, 2026) [77].

Protein distribution and weight loss: A study of overweight-to-obese older adults on a physical activity and dieting regimen found that transition to more even protein intake across meals was associated with a greater decline in BMI and abdominal subcutaneous fat (Farsijani, J Nutr Health Aging, 2020) [78].

Blood Sugar, Insulin Response, and Diabetes

Protein supplementation appears to aid blood sugar control and may benefit diabetes management.

A study among centrally obese, insulin-resistant men found that consuming 20 g of whey protein 15 minutes before or during a meal significantly reduced post-meal blood sugar increase compared to not consuming protein or consuming it 15 minutes after the meal (Allerton, Br J Nutr, 2018) [79].

In 15 people with well-controlled type 2 diabetes (on sulfonylurea or metformin), drinking 50 g whey protein (in 250 mL water) before a high glycemic meal resulted in 28% lower glucose levels, 96% higher early insulin response, and 105% higher overall insulin response over 3 hours compared to placebo. In addition to increasing insulin secretion, whey protein slows gastric emptying (Jakubowicz, Diabetologia, 2014; Ma, Diabetes Care, 2009) [80][81].

A study among 18 adults with poorly controlled type 2 diabetes (average HbA1c 7.3%) showed that 15 g whey protein 10 minutes before breakfast reduced post-meal blood sugar by 16% over 4 hours, attributed to a 40% increase in beta-cell function and 22% reduction in post-meal insulin clearance (Smith, J Clin Endocrinol Metab, 2023) [82].

Protein type matters: A study in 9 healthy men (average age 30) found that whey protein elicited a greater insulin increase over 3 hours than equal amounts of rice or potato protein isolates (approximately 45.5 g protein in 8.5 oz low-sugar orange juice), with potato having the least effect. At 1 hour, this caused a temporary dip in blood sugar with whey, while blood sugar was steadier with plant proteins. The researchers suggested that differences in BCAA absorption rates may explain the varying impacts (Lorinczova, Nutrients, 2021) [83].

Diabetes reversal: A study of 30 people with type 2 diabetes in the UK found that following a very low calorie diet — 3 daily protein shakes providing 624 kcal/day (43% carbohydrate, 34% protein, 19.5% fat) plus up to 240 g non-starchy vegetables — for 8 weeks, followed by gradual transition to solid foods, reversed diabetes in 40% of patients (87% if diabetic for less than 4 years). Fasting glucose fell below 7 mmol/L. Average weight loss was 31 lbs during the first 8 weeks, with reversal sustained for 6 months. Participants were taken off all antidiabetic medication and received weekly counseling (Steven, Diabetes Care, 2016) [84].

Dialysis and Kidney Disease

Dialysis may decrease serum albumin, and levels below 4.0 g/dL are associated with increased mortality (Owen, N Engl J Med, 1993) [85]. Protein supplementation of dialysis patients with serum albumin ≤ 3.5 g/dL was associated with a 69% reduction in mortality compared to non-supplemented patients. Protein was given orally as either Novasource Renal (21.6 g protein per 237 mL) or Liquacel (16 g protein per 30 mL) (Benner, J Renal Nutr, 2018) [86]. However, it is not necessary to supplement all dialysis patients — a study of 10,043 dialysis patients showed no difference in mortality between universal protein supplementation versus albumin-guided supplementation (Weiner, ASN Kidney Week, 2020) [87].

Cardiovascular Effects

A study among 99 individuals in their late 60s and early 70s found that 12 weeks of 50 g daily whey protein isolate versus 50 g maltodextrin produced a modest but statistically significant reduction in aortic stiffness, though there was no effect on blood flow to the brain or cognitive function. The study was dairy-industry funded (Lefferts, Nutrients, 2020) [88].

Higher protein intake along with adequate calcium from foods may reduce fracture and fall risk in elderly adults. A study involving 7,195 elderly adults (average age 85) in 60 long-term care facilities found that facilities providing additional milk, yogurt, and cheese (total 1,152 mg calcium and 69 g protein/day vs. usual 700 mg calcium and 58 g protein) had 11% lower fall risk at 3 months, 33% lower overall fracture risk, and 46% lower hip fracture risk at 5 months (Juliano, BMJ, 2021) [89].

Cancer and Chemotherapy

In malnourished advanced cancer patients in Italy undergoing chemotherapy, 3 months of daily supplementation with 20 g whey protein isolate (actual intake averaged 12 g due to incomplete compliance) resulted in improved body composition, muscle strength, body weight, and 9.8% reduced chemotherapy toxicity compared to nutritional counseling alone. Both groups had access to an energy-dense liquid formula. However, self-reported quality of life was not significantly different between groups (Cereda, Cancer Med, 2019) [90].

Skin and Wrinkles

Unlike collagen (a protein uniquely containing hydroxyproline), there does not appear to be any clinical evidence in humans that other proteins such as whey reduce wrinkles. The closest evidence comes from a mouse study in which whey peptides fed twice daily for 17 weeks during chronic UVB radiation exposure resulted in smaller increases in skin thickness (inflammation) and less reduction in skin elasticity compared to controls (Kimura, J Nutr, 2014) [91].

HIIT Training

Combining protein supplementation with high-intensity interval training (HIIT) does not appear to provide additional benefit in younger adults. An 8-week study among 47 adults (average age 31) found that 40 g whey protein after low-volume HIIT (14–24 minutes on a stationary bicycle, 3 times weekly) did not improve fat mass, skeletal muscle mass, blood pressure, power output, or cardiovascular fitness compared to a non-protein maltodextrin placebo — both groups showed reductions in blood pressure and increases in power output and VO2 max (Reljic, Nutrients, 2022) [92].

Recommended Dosing

Daily Protein Requirements

Population	Protein (g/lb body weight)	Protein (g/kg body weight)	Example (150 lb person)
Sedentary adults	0.40	0.8	60 g/day
Older adults (50+)	0.45–0.55	1.0–1.2	68–83 g/day
Endurance athletes	0.55–0.65	1.2–1.4	83–98 g/day
Strength athletes	0.65–0.80	1.4–1.8	98–120 g/day
Maximum usable daily intake	1.0	2.2	150 g/day

Sources: AND; Deutz, Clin Nutr, 2014; Morton, Br J Sports Med, 2017 [1][4][52].

Per-Meal Protein

The usable amount of protein from a single meal for muscle synthesis is approximately 30 g [1]. A post-workout dose of 20–40 g of high-quality protein, ideally within 30–60 minutes after exercise, is recommended for optimal muscle protein synthesis [7][52]. It is best to divide daily protein intake across at least 3 meals to optimally stimulate muscle growth (Paddon-Jones, Curr Opin Clin Nutr Metab Care, 2009) [93].

To reach theoretical maximal protein stimulation at each meal, a study in England showed that people in all age groups would need to consume more protein at breakfast, and older people (in their 70s and 80s) would also need to increase protein intake at lunch — when they tend to consume significantly less protein than younger people (Smeunix, Front Nutr, 2020) [94].

Timing

A review of 34 clinical trials found that consuming protein supplements with meals, rather than between meals, resulted in a slightly greater percentage of people experiencing muscle increases (94% vs. 90%) and substantially more experiencing fat reductions (87% vs. 59%). The researchers speculated that supplementing between meals may be akin to snacking, while protein at mealtime may displace some energy otherwise consumed (Hudson, Nutr Rev, 2018) [95]. Taking protein after exercise, as part of a meal, appears to be optimal for both muscle building and metabolic improvement [67][95].

A study in 24 healthy elderly adults (average age 70) found that consuming protein evenly throughout the day resulted in higher blood amino acid levels and greater protein synthesis-to-breakdown ratio compared to consuming protein mainly in the evening (Agergaard, Clin Nutr, 2023) [96]. However, a study in young healthy untrained men (average age 21) found that distributing total daily protein (including 25 g whey) across meals did not increase gains in muscle mass or strength compared to skewing intake toward evening during 6 weeks of resistance training (Chen, Nutrients, 2022) [97].

For blood sugar control, consuming 20 g whey protein 15 minutes before or during a meal is effective (Allerton, Br J Nutr, 2018) [79].

Plant-Based Protein Adjustments

Due to generally lower digestibility and lower essential amino acid ratios in plant-based proteins, slightly higher doses may be required to achieve equivalent amino acid absorption compared to animal-derived sources. Combining complementary plant proteins (e.g., pea + rice) can create a more complete amino acid profile approximating whey [7][31].

Protein Powder as Part of MicroVitamin+ Powder

Dr Brad Stanfield's MicroVitamin+ Powder includes 12.5 g of collagen peptides and 5 g of creatine monohydrate alongside 25 core micronutrient ingredients. Combining creatine with protein supports enhanced strength gains and muscle recovery [7]. While the collagen in MicroVitamin+ Powder supports skin elasticity and joint health rather than being a primary muscle-building protein, the creatine component provides an evidence-based complement to dietary protein intake for adults seeking to maintain muscle mass and physical performance.

Mixing and Preparation

Protein powders can be mixed into hot food or beverages without reducing protein's nutritional benefit. Whey and casein appear stable up to approximately 150°F, but may begin to denature and clump at 167°F (freshly brewed coffee temperature). Amino acids from denatured protein can still be used by the body (Milan, Am J Clin Nutr, 2024) [98]. To reduce clumping, mix protein into cool or room temperature liquid before adding to hot beverages (Li, Front Nutr, 2021; Giroux, Int Dairy J, 2020; Qian, Korean J Food Sci Anim Resour, 2017) [99][100][101].

Storage

Protein powder is quite stable in dry form with a shelf life of 9–18 months (up to 2 years) at room temperature (Tunick, J Dairy Sci, 2016; Sithole, J Dairy Sci, 2005) [102]. Store in a closed container at room temperature, away from light. Fats and oils in protein powders can form volatile compounds over time; exposure to ambient light can worsen off-flavors in pea protein, leading to rancid and sulfurous odor as well as color changes (Fischer, Molecules, 2022) [103]. Similar degradation occurs in whey protein stored at high temperatures (113°F) (Javidipour, Dairy Sci Technol, 2008) [104]. Proteins stored at very high temperatures (140°F) may not mix as well due to protein clumping (Paul, J Food Eng, 2022) [105]. Refrigeration is not necessary and may cause moisture accumulation from condensation. To reduce moisture exposure in humid climates, store in several small containers rather than one large one [1].

Safety and Side Effects

Digestive Issues

Whey protein contains lactose, which can cause bloating, gas, cramps, and diarrhea in lactose-intolerant individuals. Whey concentrates contain up to 5% lactose, while isolates contain minimal lactose and are generally well tolerated (Kalman, Foods, 2014) [9][1]. Plant-based protein powders may contain anti-nutrients like phytic acid, which can bind minerals (iron, zinc, calcium) and reduce their absorption when consumed in large amounts [44][45].

Kidney Strain

High protein doses exceeding 2 g/kg body weight daily have been associated with increased kidney strain, including hyperfiltration and potential damage, particularly in individuals with pre-existing kidney conditions [7]. In chronic kidney disease (CKD stages 3–5 not on dialysis), intake should be limited to approximately 0.6–0.8 g/kg body weight daily [7]. Excessive cricket protein intake may also not be advisable for people with impaired kidney function [30].

Heavy Metal Contamination

Independent testing by the Clean Label Project (2023–2024 study of 160 products) revealed that plant-based protein powders often contain higher levels of heavy metals — cadmium (five times higher on average than whey-based) and lead. Chocolate flavors had notably higher cadmium (up to 110 times more than vanilla). Organic labeling did not guarantee lower contamination and sometimes correlated with higher levels [7].

Acne

Long-term whey protein use has been linked to acne exacerbation due to elevated levels of insulin-like growth factor 1 (IGF-1), which stimulates oil production and skin inflammation [7].

Allergic Reactions

Dairy-based powders can trigger reactions in those with milk allergies (hives, vomiting, anaphylaxis). Soy-based options may cause similar symptoms in soy-sensitive individuals [7]. People allergic to insects or shellfish may react to cricket protein [30]. Mycoprotein (Quorn) has caused anaphylactic reactions, including two deaths in people with asthma [51].

Blood Pressure in Older Adults

Some older adults may temporarily experience low blood pressure 2–3 hours after consuming whey protein [1].

Unexpected Ingredients

Some products — particularly those promoted for "energy" — contain caffeine-containing ingredients such as coffee extract, guarana, mate, or cocoa. Many powders are also fortified with vitamins and minerals. Products should be carefully evaluated before use by children, pregnant or nursing women, or people with diabetes [1].

Drug Interactions

Protein-Drug Interactions

Drug	Interaction	Recommendation
Tetracycline antibiotics	Whey protein may decrease absorption	Take antibiotics 2 hours before or 4–6 hours after whey protein [7]
Renal medications	Increased nitrogen load from excess protein can strain kidneys	Caution in patients with compromised renal health [7]
Levodopa	High protein intake may compete with absorption	Space protein intake away from medication doses

Interactions with Other Supplements

• Creatine: Combining protein powder with creatine is generally safe and may provide complementary benefits for muscle performance and recovery [7].
• Calcium: High protein intake can increase urinary calcium excretion, though it may also enhance intestinal calcium absorption [7].
• Magnesium: Athletes may take magnesium supplements (200–400 mg) alongside protein powder to support muscle function, though evidence for magnesium's role in preventing cramps is limited [7].
• Iron, zinc, calcium: Phytate-rich plant proteins (especially pea) may reduce absorption of these minerals when consumed together [44][45].

Conditions Requiring Caution

• Chronic kidney disease (stages 3–5, not on dialysis): High-dose protein is contraindicated. Limit to approximately 0.6–0.8 g/kg body weight daily [7].
• Phenylketonuria (PKU): Standard protein powders containing phenylalanine are contraindicated due to inability to metabolize this amino acid. Phe-free protein substitutes are required [7].
• Thyroid disease: Soy protein may affect thyroid hormone levels and inhibit thyroid medication absorption (Messina, Thyroid, 2006) [37].
• Milk allergy: All whey and casein products should be avoided. Laboratory-produced whey (Perfect Day) still contains the major milk allergen beta-lactoglobulin [14].
• Soy allergy: Soy protein isolates and concentrates should be avoided [1].
• Gout/uric acid kidney stones: Whey protein does not appear to affect uric acid levels, but pea and soy protein may lower uric acid supersaturation [46].

Dietary Sources

Protein is found in a wide range of whole foods. Meeting daily requirements through diet alone is achievable for most people, and protein powders are most useful when dietary intake falls short or when rapid post-exercise absorption is prioritized.

High-Protein Foods

Food	Serving	Protein (g)	Calories
Chicken breast, cooked	3 oz (85g)	26	140
Lean beef, cooked	3 oz (85g)	26	180
Salmon, cooked	3 oz (85g)	22	175
Greek yogurt, plain	1 cup (245g)	20	130
Cottage cheese, low-fat	1 cup (226g)	28	185
Eggs	2 large	12	140
Lentils, cooked	1 cup (198g)	18	230
Black beans, cooked	1 cup (172g)	15	227
Tofu, firm	1/2 cup (126g)	10	88
Almonds	1 oz (28g)	6	164
Milk, 2%	1 cup (244g)	8	122

Source: USDA FoodData Central.

Practical Notes on Dietary Protein

• Whole foods provide nutrients beyond protein. Protein powders lack many vitamins, minerals, fiber, and phytonutrients found in whole-food protein sources [1].
• Protein from food is sufficient for most people. If daily intake from diet meets requirements (including during exercise), additional protein powder does not provide measurable benefit [52][55][57][58].
• All protein sources are effective. Studies consistently show that whey, soy, casein, pea, rice, and mycoprotein can all support muscle maintenance and growth when combined with resistance exercise [1][52].
• For plant-based diets: Combining complementary plant proteins (e.g., pea + rice, soy + corn) ensures a complete amino acid profile [31][32].
• Protein distribution matters. Distributing protein across at least 3 meals may be more effective for muscle synthesis than consuming the majority at one meal [93][96].

Nutrient Content of Common Liquids Mixed with Protein Powder (per 1 cup / 8 fl oz)

Liquid	Calories	Carbohydrate	Fat	Protein
Whole milk	146	11 g	8 g	8 g
Skim milk	86	12 g	0 g	8 g
Chocolate milk (reduced fat)	190	30 g	5 g	7 g
Orange juice	110	25 g	1 g	2 g
Apple juice	117	29 g	0 g	0 g

Source: USDA Nutrient Database [1].

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