Over the years I’ve written numerous articles about nutrition. I’ve talked at length about carbohydrates, fats, and proteins, discussed how various foods and nutrients affect gene expression, inflammatory processes, and microbiota composition, and I’ve examined how the characteristics of the human diet have changed throughout our evolution. Many of the articles I’ve put out over the years, both here on the blog and on other sites I write for, are long and complex and contain quite a bit of scientific lingo.
I suspect that some people feel they are too long and complex and have trouble making sense of the research. The may not care that much about the science behind it all; they just want to know what they should eat. I can completely understand that. This is part of the reason why I occasionally put up concise posts here on the blog that summarize things I’ve been talking about in my long and detailed articles on nutrition. Today, I felt it was time to put up another one of these summary posts. What I’ve done is to pull out the most important takeaway points from the articles I’ve written on diet and health and create a list that summarizes what I consider to be the main characteristics of a healthy diet.
My belief is that a healthy diet is a diet that is rooted in the original human dietary template. I think a fairly strict Paleo diet can work very well for a lot (probably most) people. That said, factors such as lifestyle, activity levels, and health status have to be considered when a person’s diet is to be designed. The list below is built up of general principles, it’s obviously not a plan that fits hand in glove for each and every individual out there.
Okay, with that said, let’s get to it…
1) It’s low in highly processed foods
Highly processed, modern foods such as chocolate, pizza, and ice cream have several unfavorable nutritional characteristics that make them unfit for human consumption. Among other things, they are high in sugar, salt, and/or refined fat and low in protein, omega-3, and fiber. These foods adversely affect gene expression, microbiota composition, immunity, and hormonal status (1, 2, 3).
2) Its foundation is built up of animal source foods and vegetables
Vegetables of various sorts have been a staple component of the human diet for millions of years. The same is true for animal source foods, which have been an important part of the human diet for at least 2.5 million years (4, 5, 6). These foods are nutritious and healthy and should be at part of virtually every meal. It’s advisable to not just eat white fish and lean muscle meats, but also some organ meats and fatty, wild-caught seafood, which are a good source of long-chain fatty acids and fat-soluble vitamins.
3) It’s low in salt, saturated fat, and omega-6
The modern man is taking in a lot more salt and omega-6 than his primal ancestors, which is unfortunate, as these nutrients have been shown to cause a range of negative health effects when they are consumed in excess (1, 7, 8, 9). The same is true for saturated fats, which unlike what some people seem to believe, did not make up a large part of the ancestral diets that supported the development of Homo sapiens.
4) It’s low in dairy foods and cereal grains
Dairy foods and cereal grains only entered into the human diet quite recently. Some of our preagricultural ancestors may have occasionally consumed certain types of cereal grains, but not in large quantities. Both cereal grains and dairy foods have several unfavorable nutritional characteristics that make them less than ideal choices as staple foods. Among other things, cereal grains have a very high carbohydrate density, contain a myriad of potentially problematic antinutrients, and are high in potentially gut-irritating, insoluble fiber (10, 11, 12). Moreover, they have a low nutrient density when compared with fruits and vegetables and are low in high-quality protein (10).
The milk of each species on this planet was “designed” by evolutionary forces to support the growth and development of the young of that species. It was obviously not designed to support the health or physical development of members of another species. Cow’s milk is an evolutionarily novel component of the human diet that doesn’t seem to agree well with the human physiology. It’s contains a range of compounds (e.g., lactose, hormones, casein) that may adversely affect our health (13, 14, 15). Some of these compounds are either partially or fully removed during fermentation; however, others remain fully intact.
5) It contains moderate-high amounts of protein (>20% of total calories), low-moderate amounts of carbohydrate (20-40% of calories works well for most people), and moderate amounts of fat
Many of the nutrition articles I’ve written over the years have been devoted to the question of what constitutes an “optimal” ratio of protein to carbohydrate to fat. The key takeaway from those articles is that the macronutrient breakdown described above works well for the vast majority of people. This recommendation is based on a combination of modern scientific research, the evolutionary evidence, and the experience and knowledge I’ve gained from coaching clients and experimenting with different macronutrient ratios.
6) It’s high in fiber and omega-3
Ancestral human diets were markedly higher in fiber and omega-3 than most modern diets (7, 8, 9). Fermentable fibers pass undigested through the small intestine and end up on the dinner plate of the microbes that dwell in the colon. They are then broken down and converted to a variety of other compounds, including Short-Chain Fatty Acids (SCFAs). Some of these SCFAs remain in the colon, where they are used as energy by the cells lining the intestine, whereas others pass into systemic circulation, where they do a variety of good stuff, such as triggering the production of anti-inflammatory cytokines and fueling the liver. Omega-3 can also help suppress inflammation, although via different mechanisms. It’s also very important for brain health.
7) It’s built up of fresh, high-quality foods
Much of the food that’s available at modern supermarkets is not of high-quality. It has been produced in an unnatural way, is on the verge of spoiling, and/or contains residues of antibiotics, pesticides, or other man-made chemicals. The first priority for someone who’s looking to eat healthy is to locate real, unprocessed food. The next priority is to find food that is as fresh as possible and has been produced and handled in a sustainable and healthy way.
All organisms that are present on this planet are a product of evolutionary processes. Just like humans, plants and animals have changed over time in response to changes in their environment. They are all adapted to different conditions. This is something we humans often forget. Many domesticated animals have been put into an environment they are poorly adapted for: they are given food that doesn’t agree with their biology, they live in unsanitary, confined conditions, and they rarely move around. Fruits, vegetables, and other plant foods are also typically produced in a milieu that is poorly matched with their genome. These evolutionary mismatches produce novel phenotypic characteristics and ill health.
All of this is to say that it’s a good idea to seek out the highest quality food you can find. Grass-fed meat, wild seafood, and organic vegetables and fruits may not have been produced under ideal conditions, but they tend to be superior to their conventionally produced counterparts in several respects. Obviously, choosing organic and/or grass-fed may not always an option. If it isn’t, it’s perfectly okay to buy conventionally produced food. It’s not going to kill you.
Regardless of whether you buy organically or conventionally produced produce, it’s advisable to always choose the freshest food you can find. This is particularly true in the context of animal source foods. Even if a piece of meat or fish is fine to eat according to the expiration date, microbes attached to the product may have started producing various toxins if the product has been stored for a long time.
8) It’s low in compounds that possess antimicrobial properties
Some foods, such as raw onions and certain types of spices, contain compounds that possess antimicrobial properties. These substances may destabilize the microbiota if they are consumed in moderate-large quantities. One of the most important moments in human evolution took place when our ancestors learned how to control fire and cook food. This ability allowed them kill food-borne pathogens and expand their diet to include foods that are hard to digest in their raw form. Cooking not only releases nutrients that otherwise can’t be reached by human digestive enzymes, but it also neutralizes many antinutrients and other potentially problematic compounds, such as allicin, an antimicrobial substance found in garlic.
9) It contains fresh, raw plant foods derived from a trusted source
Fresh, raw plant foods were an essential part of our Paleolithic ancestors’ diet. Just like humans, plants are colonized by large numbers of microorganisms. Some of these organisms have the potential to do us harm; however, others may actually do us good (16). Some of the food-borne microbes that pass into your digestive system when you eat raw, minimally washed vegetables or fruits may get through the acidic barrier in your stomach and take up residence deep in your gut. If the microbes are of the friendly kind, this is a good thing, as they may contribute new and useful genetic functions to your microbiota.
It’s important to note that no two plants carry an identical microbiota. The microbiota of a plant is shaped by the its environment. The microbiota of a fresh lettuce collected from a healthy backyard garden obviously differs from that of the microbiota of a lettuce that has been produced in unhealthy soil, sprayed with pesticides, and/or stored in a plastic wrapping for weeks.
10) It contains a diversity of different foods, but it’s quite stable in its composition over time
The weight of the evidence suggests that humans evolved on a fairly diverse diet (5, 6, 8). In general, it’s not good to eat a very limited diversity of foods. If your whole diet is based around just a couple of different food items, you’ll not only be susceptible to developing nutritional deficiencies and imbalances, but your gut microbiota will probably not be able to attain solid footing.
Different microbes have different dietary preferences. Some produce enzymes that degrade inulin, a type of carbohydrate found in foods such as onion and Jerusalem artichoke; others have specialized in breaking down lactose, the sugar found in milk; and yet others do their best work when they get a generous supply of oligosaccharides. If you eat a very limited number of foods, some microbes in your gut get a lot for dinner, whereas others get little or nothing. The former proliferate, whereas the latter fade and perhaps even disappear completely from the gut. In other words, a very restricted diet may select for a microbiota that lacks diversity and resilience and is dominated by a small number of organisms that have specialized in breaking down the limited set of nutrients that pass into the lower gut (17, 18).
I know some people have made the case that a very restricted diet doesn’t necessarily inhibit microbial diversity, but I haven’t been convinced by their arguments. With that being said, it’s not wise to take things to the extreme. One of the worst things you can do for your microbiota is to constantly change your diet, eating new foods and dishes all the time. If you do this, your microbiota will never have a chance to fully adapt to the diet you’re eating and you will probably experience a range of health problems, ranging from bloating to fatigue to mood swings. Instead of making major changes in your diet on a daily or weekly basis, it’s much better to change it gradually by the seasons.
Okay, that’s it. I hope you found some useful tips! Let me know in the comment section if you have any questions or thoughts on the article.