Despite rapidly accumulating data on human nutrition, there has been great confusion as to what diet benefits human longevity most. To address this issue properly, we need to look to evolutionary biology. Like other species, we are originally programmed to benefit from specific foods and a specific eating cycle – these factors are inherent to our biology and certainly affect our health and life span.
So, to what food and eating cycles are you biologically aligned?
Based on fossil evidence, physical anthropology points to several features that distinguished the evolution of humans from other apes. These evolutionary features give us a great indication as to what our original diet was. And they tell us what makes our diet different from that of other apes.
It has been largely agreed that human bipedalism (walking on two legs) is an evolutionary trait that took place before the early Pleistocene period (1.75 million years ago). With it came a substantial increase in brain size and a decrease in anterior teeth and jaw size.
The evolution of the human jaw and teeth seems to comprise a functional purpose: adaptation to a specific diet.
According to Clifford J. Jolly, author of The Seed Eaters, you have not evolved to eat plant shoots or animal flesh as your primary staple foods. Human molars and jaw actions are clearly not adapted to mincing grass blades; nor are they adapted to tearing meat apart. Our teeth and jaws are structured to break up small, hard, solid objects that are more or less spherical in shape. This is done by a combination of crushing and rolling such as is employed in milling machines.
Jolly argues that out of potential foods that fit that description, only those that were widespread enough in open country (which was the main human habitat) could serve as the original staple food of humans. These are the seeds of grasses and annual herbs. That’s the premise of Jolly’s hypothesis. However, the idea that the early human’s main staple food was seeds alone is highly arguable.
Since early humans’ main habitat also included woodlands, it’s more plausible that the early human diet consisted of both grassland seeds and tree nuts. The mixed seeds and nuts diet yields a superior protein composition and a higher biological value than a diet based on seeds alone. Hence, a mixed seed-nut diet could have supported human survival better than a seed diet alone.
But there are also logistic reasons why mixed seeds and nuts constituted our original diet.
Seeds and nuts offer a larger variety of rancidity-resilient items as compared to seeds alone or animal foods alone. Tree nuts, and seeds of tubers and bulbs, are quite resilient to rancidity and could therefore be stored and used all year round. That’s unlike meat, sprouted grass grains, or sprouted legume seeds, which are much more perishable and therefore could not be stored and used all year round.
Seeds and nuts seem to define the character of the early human diet. This means that our original diet was primarily low-glycemic, high in fat, and fibrous. This is not to say that other food resources such as dairy, fish, or meat were not exploited when available. What it indicates is that the early human diet was centered on seeds and nuts. The seed-nut diet has kept humans alive in times when animal food was not accessible, providing sufficient protein, essential nutrients, and fuel calories to sustain life. Our adaptation to seed-nut chewing is mostly reflected in the flat wear-plane of our cheek teeth. We’re the only mammal predator that possesses this unique chewing feature.
Put simply, you are primarily a seed and nut eater, and you’re also capable of eating animal food. And note that the human diet differs from the chimpanzees’ diet, which is mostly based on fruit, and the gorillas’ diet, which is largely based on herbage. So what does that tell us?
You can eat animal flesh, but you can’t depend on it as a main staple food. Meat is not essential to us, but plant foods are. You can’t live on meat alone, and you can’t live on fruits alone. But you can live on a seed-nut vegetarian diet, and you can further improve that diet by adding animal food to the mix. The human body is apparently more vegetarian than carnivorous.
You get most of your vital nutrients, vitamins, and antioxidants from plant sources. And unlike other predators such as canines and felines, you’re capable of enzymatically utilizing essential oils from plants. You have enzymes (desaturase) that convert plants’ long-chain polyunsaturated essential fatty acids into their bioactive forms, EPA, DHA, and GLA.
All that said, our early ancestors were partly carnivorous, and meat cutting was done with tools instead of teeth. You can certainly benefit from animal and marine foods as quality protein sources. Whey protein, cheese, eggs, fish, seafood, and meat have a higher amino acid score than plant food. Animal-flesh and marine foods provide unique muscle-supportive compounds, such as beta-alanine and carnosine that are not found in plant foods. And in this respect they provide superior nourishment to the muscle.
The combination of seeds and nuts with animal or marine food yields ideal nourishment and seems to be a primal fit for our gatherer-hunter nature.
Seeds, nuts, and animal or marine foods are complementary food sources that enhance each other’s biological value.
Animal and marine foods provide quality protein whereas seeds and nuts provide additional protein, essential nutrients, and fuel calories. Combinations of meat, fish, or dairy with seeds or nuts have been used by traditional cuisines around the world, including Mediterranean, Middle Eastern, Indian, and Chinese.
Note that certain varieties of seeds, nuts, animal foods, and marine foods may cause allergic reactions in some people. Make sure that your food selection doesn’t include items you’re sensitive to. Before finalizing this topic, I need to address two more issues.
There is a high likelihood that early humans consumed sprouted grains (starch-seeds), which were abundant in open grassland. Nonetheless, grains could not have been the early humans’ main staple food for two reasons.
First, unless sprouted, grains are virtually inedible in their raw state. The biological value of grains actually increases upon roasting or baking, and these methods were not used during the early Pleistocene, when the first recognizably human-like evidence appears in the fossil record.
Second, preagricultural grass grains could not provide sufficient protein to support human survival as a main staple food. About five thousand years ago (the beginning of the agricultural era) there was a notable shift in the human diet toward grains. Since then our ancestors have been continuously shifting away from our original low-glycemic diet of nuts and seeds toward a diet based on high-glycemic refined carbohydrates, which you are not evolutionary adapted to.
Legumes were available seasonally in open grassland. Grindstones with adherent legume-seed starch appear in the African fossil record. Legumes have the highest protein content among seeds, and that trait could have potentially made them suitable to serve as a main staple food for early humans. Nonetheless, unless sprouted, soaked, or cooked, legumes contain inhibitors and digestion-disrupting elements that render them problematic for human consumption.
It’s plausible that humans were gathering young pea pods and sprouted beans seasonally, but the earliest record of legume usage as a main human food appears at about the same time as that of grains. It has been largely agreed that our early ancestors ate every nontoxic seed present in the environment. Whether legume seeds belong to this category remains open to speculation.
But food is only one determining factor in your diet. Other factors are your calorie intake and your meal frequency. Let’s take a look at how these dietary factors affect your health and longevity.
The relation between calorie intake and human longevity has been a subject of great scientific interest. Based on animal studies, the most proven approach to counteracting aging is calorie restriction. Aside from genetic manipulation, calorie restriction represents the only proven record for prolonging life in animals. And that’s not its only benefit.
Tests conducted on laboratory animals have shown that calorie restriction can lower the risk of cancer, diabetes, and cardiovascular disease. It had also been shown to stave off age-related neurodegeneration.
In practice, calorie restriction means lowering normal calorie intake by about 40 to 60 percent. But you still maintain a healthy diet rich in vitamins, minerals, and antioxidants. A growing number of people are now living by this regimen. Many of them are scholars and researchers, passionate in their belief that the methodical restriction of their calorie intake can extend their lives.
It certainly seems so, but it’s still too early to predict. And even if calorie restriction extends life, at what price does it come?
One notable side effect of chronic calorie restriction is the lowering of your body’s temperature and metabolic rate. That side effect is essentially an energy-preservation mechanism, and it kicks in when your body’s energy intake is chronically low. The consequences of that may include hormonal decline, with decreased thyroid activity and a decline in sex hormones. Metabolic declines of this type have been also associated with loss of muscle strength and libido. Again, it’s still too early to predict, but even if calorie restriction enables people to live longer, it may come at the cost of some of the most important things that make life worth living.
Is there anything else that can be done to trigger your longevity genes, apart from chronically restricting your calorie intake? Apparently there is one dietary option: intermittent fasting.
Recent studies have indicated that lowering your meal frequency to one meal per day or every other day may actually provide you with the same benefits as calorie restriction without restricting your calories.
The initial studies were done on mice. The mice had to go through a special feeding cycle called intermittent fasting. That feeding cycle consisted of a fasting day followed by an overfeeding day in which the mice were allowed to consume twice their normal calorie intake. The results revealed astonishing longevity benefits. Mice on intermittent fasting have been shown to improve their insulin sensitivity, rejuvenate their brain cells, and substantially increase their life span. Most importantly, the studies’ findings supported the hypothesis that humans and animals evolved to better survive when there’s a large gap between meals (at times twenty-four or even forty-eight hours).
According to Dr. Mark Mattson, professor of neurosciences at Johns Hopkins University, humans adapted early on to intermittent fasting as an evolutionary favorite feeding cycle. Mattson, who conducted the initial studies on intermittent fasting, argues that primordial conditions of food scarcity and a hunter-gatherer lifestyle created the necessity to adapt to one meal per day or even every other day.
One of the greatest advantages of intermittent fasting is the rejuvenating impact on your brain and muscle. It literally forces your body to recycle and rejuvenate brain and muscle tissues.
Fasting increases the expression of brain-derived neurotrophic factor (BDNF) in your brain and muscle. This neurotrophic growth factor has been shown to catalyze conversion of brain stem cells and muscle satellite cells into new neurons and new muscle cells, respectively. BDNF has profound neuro-protective properties. It plays important roles in brain cognitive function and long-term memory and protects against dementia, Alzheimer’s disease, Parkinson’s disease, and brain aging. The rejuvenating effect of fasting on your brain and muscle tissues is more profound than was initially thought.
In your muscle, fasting triggers the removal and recycling of broken proteins and damaged cells. This recycling process is done by the ubiquitin enzymes (cellular recycling enzymatic system), which detect and digest broken proteins and damaged cells. The nitrogen amino by-products are then recycled and used for synthesis of new proteins and generation of new cells.
Note that this tissue-rejuvenating process is triggered by the catabolic process of protein breakdown such as that due to injury, fasting, or exercise. During the overfeeding phase, your body shifts from a catabolic recycling mode into an anabolic tissue-building mode. Overfeeding may yield additional benefits. When done properly, it boosts your thyroid and sex hormones along with your body’s metabolic rate. And note that if you add a viable exercise protocol to this regimen, it may yield an even stronger impact on your body composition, tissue integrity, and biological age.
The notion that calorie restriction and intermittent fasting can increase life span has been controversial and arguable. Can our society accept the idea that hunger and “near starvation” is healthy?
We habitually like eating lots of foods all day long, and most of us will fail to restrict calorie intake or follow periodical fasting even if trying to. So here we are today desperate for something else – perhaps a pill that can extend life and requires no calorie restriction and no hustle.
But there is no such pill.
Longevity is inherent to your body and it’s essentially triggered by how you eat, exercise, and live. There is no pill in the world that will ever change that. No pill will ever substitute the effects of exercise, fasting, and good nutrition on your genes.
When your longevity genes are triggered, they activate mechanisms that improve your energy efficiency, recycle old damaged cells, destroy tumors, and regenerate tissues. Your body not only retains its youthful appearance, it also gets stronger and healthier. But you need to make a choice – adjust your diet and lifestyle to stay physically young or keep a “normal” routine and be ready to accept the consequences on your biological age.