How do we know, truly know, what the best diet is for a longer, healthier life?
Well instead of guessing, we can engineer the best diet from first principles thinking. First principles thinking cuts through the noise by focusing on the most basic truths.
And when we get this right, we can add 7.3 healthy years to our life [1].
In this article, I’ll reveal three foundational principles that make achieving this goal not just possible, but straightforward.
Table of Contents
1. Section 1: Essential Vitamins and Minerals
2. Section 2: Proteins and Amino Acids
3. Section 3: Fiber-Rich Foods
4. Section 4: Putting it Together
5. Section 5: 3 Things to Avoid
6. Reference
Section 1: Essential Vitamins and Minerals
The first foundational principle is this: We need to ensure we’re getting all the essential vitamins and minerals our bodies need. But that’s a lot harder than many realize. And the impact of falling short is more serious than we usually assume.
Let me explain.
There are lots of things our bodies need to maintain health that they can’t make. These include vitamins like A and E and minerals like zinc and iron. Vitamins and minerals perform a range of functions from helping us build new cells to producing hormones. Deficiencies can lead to serious health conditions and even, in extreme cases, death. So whatever else we’re focusing on when it comes to our diet, we need to make sure we’re getting these essential nutrients.
But that’s not easy. And the consequences are significant. Let me give you an example. Potassium has been identified by the U.S. Dietary Guidelines as a nutrient of public health concern [2]. This is for two reasons: One, people aren’t getting enough. And, two, a deficiency causes real problems.
So how much are we supposed to get? And how short are we falling? The recommended daily intake of potassium for adults is 4,700 mg [3]. According to data from 2012, the average American gets about 2,640 mg a day [4]. And 97% of the population wasn’t getting enough [5]. A more recent study found potassium levels have been declining, with rising levels of serious deficiency [6].
And this isn’t just a problem in the U.S. The standard Western diet common all over the world virtually guarantees we won’t get enough potassium.
But why is this a problem? Too little potassium can increase blood pressure, kidney stone risk, and the amount of calcium that ends up in our urine. This can lead to a deficiency in calcium, too.
We know that risks for heart attacks and strokes are directly linked to blood pressure. As pressure goes up, so do deaths [7].
How significant is the impact of potassium? A meta-analysis examined the results of 22 randomized controlled trials. The researchers discovered that increased potassium intake reduced systolic blood pressure by 3.49 mm Hg on average [8]. And look what happened when the potassium intake reached 3,500 to 4,700 mg. The reduction in blood pressure was 7.16 mm Hg [9].
Does that large of a change matter? Yes. A systematic analysis of studies on blood pressure and cardiovascular risk includes some eye-opening numbers. Clinical trials show a reduction of blood pressure by just 10 mm Hg cuts the risk of coronary heart disease by 22% and stroke by a whopping 41% [10].
So we can see that getting enough potassium is crucial but few manage to do so.
Another example is magnesium. U.S. nutritional survey data indicate about half of Americans get less magnesium from their diet than they should [11]. And magnesium deficiency is associated with increased risks for obesity, type 2 diabetes, high blood pressure, and heart disease [12].
And this is why I include both potassium and magnesium in my personal supplement routine. But just because I take a supplement, this in no way means you have to also.
So what are the implications for our diet? We want to prioritize foods that are packed with vitamins and minerals. We especially want to include good sources of potassium, magnesium, and other hard-to-get nutrients.
Which foods fit this description? Fresh fruits, vegetables, and legumes are all-stars when it comes to nutrient density. Spinach and other leafy greens, broccoli, lentils, and chickpeas are all excellent sources of potassium and other essential nutrients.
But those foods are low in other nutrients like iron and Vitamin B12. So does that mean we need animal products in our diet? Before answering that question, we need to talk about proteins.
Section 2: Proteins and Amino Acids
This is the second fundamental principle we can use to engineer the perfect diet. We need to get adequate protein. Here’s why. (And we’ll talk about what counts as adequate in a minute.)
Proteins are our body’s source for getting amino acids. Amino acids are the building blocks of proteins in the body, and proteins are the building blocks of pretty much everything else. We need them to create and repair muscles, skin, bones, and other tissues throughout the body. Amino acids are also necessary for producing hormones, creating neurotransmitters, and maintaining the immune system.
Like essential vitamins and minerals, there are some amino acids — called essential amino acids — the body can’t make. We need to get the 9 essential amino acids from the proteins we eat.
So where can we get protein in our diet? Meat is a particularly dense source of protein, as are eggs and dairy. For example, 100 g of chicken breast contains 32 g of protein. But plants can also be good sources of protein. 100 g of chickpeas, for example, contains 19 g of protein.
But how much protein do we actually need in our diet, and what else do we have to factor in when selecting protein sources for the perfect diet? The baseline recommendation for protein, the Recommended Dietary Allowance (RDA), stands at 0.8 grams per kilogram of body weight, or 0.36 grams per pound [13].
But that’s just the baseline. In other words, that’s the minimum amount we need. But there are good reasons to think more would be helpful. For one thing, high-protein diets help us maintain a healthy weight. They make us feel fuller and stimulate the body to burn more calories [14].
But there’s a second reason a higher protein diet works in our favor.
A growing body of evidence shows that as muscle strength declines, total death rates increase [15]. On average, human muscle mass declines by about 1% per year from the age of 40 [16].
Therefore, to prevent muscle loss, we want to maximize muscle strength in youth, maintain that muscle in middle age, and minimize loss as we get older.
And we know from many lines of evidence that as protein intake increases, so does the response to exercise. This means we gain more muscle from the same amount of exercise if we increase protein intake up to a point.
So what is the perfect level of protein intake to maximize the benefits of exercise? A massive 2018 meta-analysis combining 18 separate randomized controlled trials found that as daily protein intake increased, so, too did the response to exercise training up until 1.6 g of protein intake per kg of lean body weight per day [17]. Protein intake above that level didn’t seem to offer any further benefits for muscle performance.
So far then, we want a diet that allows us to reach our recommended daily intake of vitamins and minerals, with a particular focus on potassium and magnesium, and a diet that’s high in protein to maximize the benefits of exercise.
But where should we get our protein? — from animal or plant sources? An interesting 2020 study found that when people ate more protein, overall death rates went down [18]. This reinforces the idea that a higher-protein diet is best for our health. But that same study found this relationship was even stronger for plant-based proteins [19].
This could be because animal proteins can come along with things we don’t want, like saturated fat. But there’s a good reason to at least consider including fish in our diet. That’s because fish is a source of another essential nutrient: omega 3 fatty acids.
Omega 3s play a crucial role in brain function, heart health, and inflammation regulation. There are 3 types: ALA, EPA, and DHA. The only one found in plants is ALA. Our bodies can convert that to EPA and DHA, but the process is very inefficient. It is hard to get enough this way. It’s much better to get EPA and DHA directly in fish like salmon.
So, to sum up, even if a person chooses to eat a vegetarian diet, the one meat they might consider including is fish for its Omega 3s, as well as its B12 content.
Personally, I prioritize plant sources of protein because they help me avoid saturated fat. But they also help me follow a third key principle of a healthy diet, which we’ll look at next.
Section 3: Fiber-Rich Foods
This third principle is a bit different than the first two. Vitamins, minerals, and protein are all essential. We can’t live without them. But now we’re going to look at something that isn’t essential. Yet the data show us it’s really helpful. And, as we’ll see, prioritizing it makes it a lot easier to satisfy the first two principles as well.
Remember the study we just looked at? The protective effects of high-protein diets were strongest with plant-based proteins. After examining the evidence, the study authors concluded this wasn’t because those eating plant proteins were getting less fat [20]. Something else seems to be going on. Part of the answer likely has to do with fiber.
Fiber is the part of plants that our bodies can't digest. It appears to have beneficial effects on a number of fronts from appetite regulation to gut health. We have multiple lines of evidence that higher-fiber diets reduce a number of serious health risks.
For instance, a massive meta-analysis published in The Lancet links higher fiber intake with a 15-30% decrease in deaths from all causes and from heart disease and strokes [21]. Increased fiber intake can also help with weight loss. For example, researchers found eating an extra 14 grams of fiber a day was associated with a 10% decrease in calories consumed. This in turn led to a weight loss of 1.9 kg (about 4 pounds) over 3.8 months [22].
Looking at available data, it appears that the more fiber a person eats, the more benefits they receive—up to a point, of course. While fiber is generally great, too much can cause digestive issues like constipation or bloating, so it's important to listen to your body. And to add further nuance to this discussion, people with irritable bowel syndrome may need a low-fiber diet. There’s no one-size-fits-all diet, but for the general population a higher-fiber diet is great.
But most of us living in Western countries are getting far too little fiber in our diets. On average, we need to increase our fiber intake by around 50% to hit recommended levels of 30-35 g per day for men and 25-32 g per day for women [23].
And here’s a huge bonus to targeting fiber-rich foods. These tend to be the very same foods that are great sources of plant protein and essential vitamins and minerals.
Section 4: Putting it Together
Here’s a great way to visualize this that will help us apply the three principles to engineer the best diet for a healthy life.
Imagine the three principles we’ve talked about so far as circles. Each circle represents foods that are good sources of what the principle says we should target. So we have foods rich in vitamins and minerals, foods high in lean protein, and foods full of fiber. When these three circles overlap, we’ll find foods that give us all 3 things at once.
So what kinds of things are in that area of overlap? The top options are legumes. This includes lentils, chickpeas, black beans, and edamame. These superfoods are the foundation of the best diet, starting from the fundamentals.
And researchers have even tried to quantify the impact of prioritizing these in our diet. One massive study concluded adding them can add up to two and a half years to our life expectancy [24].
Other great foods in the area of overlap include brussels sprouts, quinoa, avocados, almonds, pistachios, and chia seeds.
Foods in the overlapping area are the best, but there are plenty of great choices that might have two of the things we want to target without having all three. Fish, for instance, has plenty of protein and is also packed with nutrients like vitamin D, calcium, phosphorus, iron, magnesium, and potassium. Any fresh fruit or vegetable is also likely to be a good choice.
Section 5: 3 Things to Avoid
You may have noticed we haven’t talked much about typical topics when it comes to diets: carbs and fats, because aside from Omega-3 fats, neither carbs nor other fats are technically essential. That’s why people sometimes follow a low-fat diet or a low-carb diet such as keto. So how do carbs and fats fit into a healthy diet?
Let’s start with carbs. Are they a problem? No. In fact, the study we just looked at found eating the right kind of carbs is also associated with living a longer life. What’s the right kind? Whole grains [25]. This means things like whole wheat, oats, brown rice, and quinoa.
But what we definitely want to avoid are processed carbs like white flour and especially sugar. Research has found that increased sugar intake is linked to an elevated risk of death from cardiovascular disease [26].
What about fats? The important point here is that the type of fat matters. We know that trans fats and saturated fats have negative health impacts. On the other hand, unsaturated fats have been linked to improved health. For example, one study found higher olive oil intake was associated with risks of death that were 19% lower for heart disease, 17% lower for cancer, and 29% lower for diseases of the brain and nervous system [27].
And while we’re talking about things to avoid, we need to also mention salt. Our bodies need a little, but most of us get way too much. And elevated salt causes our blood pressure to rise.
So if we want to shape our diet according to first principles, it’s simple. Eat these foods:
- Legumes (lentils, chickpeas, beans, edamame)
- Fresh vegetables and fruits
- Whole grains
- Lean proteins including fish or plant-based options
- Fiber-rich foods
Avoid these foods:
- Highly processed foods
- Refined carbs like white bread and sugary snacks
- Foods high in saturated or trans fats
- Foods loaded with salt
References
1. https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1003889
2. https://odphp.health.gov/sites/default/files/2019-09/2015-2020_Dietary_Guidelines.pdf
3. https://www.ncbi.nlm.nih.gov/books/NBK589562/
4. https://www.ncbi.nlm.nih.gov/books/NBK589562/
5. https://pubmed.ncbi.nlm.nih.gov/26962185/
6. https://pubmed.ncbi.nlm.nih.gov/32401639/
7. https://www.ahajournals.org/doi/10.1161/HYPERTENSIONAHA.119.14240
8. https://www.bmj.com/content/346/bmj.f1378.long
9. https://www.bmj.com/content/346/bmj.f1378.long
10. https://www.ahajournals.org/doi/10.1161/HYPERTENSIONAHA.119.14240
11. https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
12. https://pmc.ncbi.nlm.nih.gov/articles/PMC9103223/
13. https://www.health.harvard.edu/blog/how-much-protein-do-you-need-every-day-201506188096
14. https://www.uptodate.com/contents/obesity-in-adults-dietary-therapy
15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5772850/
16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5772850/
17. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5867436/
18. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7374797/
19. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7374797/
20. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7374797/
21. https://pubmed.ncbi.nlm.nih.gov/30638909/
22. https://pubmed.ncbi.nlm.nih.gov/11396693
23. https://pmc.ncbi.nlm.nih.gov/articles/PMC7589116/
24. https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1003889
25. https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1003889
