Omega-3 in human evolution
The first observations to spark interest in omega-3s came from looking at the diet of the Greenland Inuit who ate huge volumes of marine animal fat, with few other options available to them. Although not considered the healthiest of diets, the high consumption of omega-3 fats appeared to offer benefits for cardiovascular health. These discoveries proved to be the launch pad for a plethora of research into omega-3s that continues to this day. Despite the considerable body of research supporting the significant health-enhancing roles of omega-3s, the amount we consume as individuals is troublingly low. Omega-3 fats are an essential component of any nutritional approach to maintaining and promoting long-term health.
Omega-3 in human evolution: Growth of the brain
One of the most important events in human evolution was the growth of the brain. Man’s very early ancestors had small brains and, as such, were simple creatures, eating a plant-based diet and leading a non-diverse life. Archaeological sites in East Africa dating back over two and a half million years show the first signs of human consumption of animals; the animals consumed were ‘opportunistic’ choices and easily come by without the need to risk interaction with ferocious predators. These would have included small birds, eggs, small land mammals and several species of water-dwelling creatures, including fish and reptiles. It is thought that the combination of eating small animals and marine creatures, of all varieties, was the catalyst for human brain development.
The human brain is nearly 60% fat. Fatty acids are crucial molecules that determine your brain’s integrity and ability to perform. Beyond their role in building the brain structure, fats like EPA and DHA act as messengers – key players in the production of neurotransmitters, with neuroprotective effects against diseases like dementia.
The brain is a huge organ, with very high energy requirements and thus the capture, consumption and later cooking of animals would have allowed a much greater intake of energy compared with plants foods alone. The greater supply of energy made available by eating animals supported the growth of a much larger brain. Certain anthropological researchers believe that it is no accident that the brain grew rapidly about two million years ago when, according to evidence from numerous archaeological sites, humans began to consume marine animals in high quantities.
A large proportion of the brain is composed of fat. The long-chain omega-3 fats eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are fundamental to the structure and function of the brain and are abundant in marine animals, alongside the important structural fat, arachidonic acid (AA). According to Dr Stephen Cunnane, a metabolic physiologist at the University of Sherbrooke, Quebec, “it was this rich and secure shore-based diet that fueled and provided the essential nutrients to make our brains what they are today.” As humans became more advanced and the brain developed further, they became expert hunters and relied heavily on fat-rich large animal meats, in combination with foraged local plant foods, to provide the nutrient-rich diet that allowed for ongoing adaptation.
Some debate persists over the extent to which stone tool making and marine life consumption contributed to the development of the human brain, yet it is undoubted that the amount of omega fats consumed was very consistent. A balance of 1-2:1 of omega-6 to omega-3 fats would have been provided from a variety of wild, natural and seasonal local plant foods, wild animals and marine creatures. This balance of omega fats (despite new sources of food, better hunting techniques and movement to new landmasses), stayed with us and formed the basis of the development of the intricate and tightly regulated systems of the body over the next 990,000 years.
Agriculture and the shift in Omega-6 & Omega-3 balance
The birth of agriculture ten thousand years ago (a mere blink of an eye in time compared with how long humans have roamed the earth) changed everything. The first signs of agriculture actually date back about another 10,000 years previous and much of the change in the way humans sourced their food was a result of climate change. Over this time, life on earth faced numerous and prolonged periods of extreme cold (ice ages) and glacial formation, which wiped out many of the large mammals and plant foods that humans had previously relied on. Humans had to turn to smaller wild game and foraging for grains and nuts such as corn, barley and acorns, which were able to survive these harsh conditions. The reliance on this type of food intensified and resulted, approximately ten thousand years ago, in the full domestication of cereal grains and the animals we commonly find on our plates today. It is thought that, despite the intense labor required to farm crops and livestock, humans considered farming a much more reliable supply of food, such that agriculture likely fueled the rapid growth of the human population.
With the dramatic change in the way we sourced our food came a huge shift in the nutrients we consumed. Though the new plants that were consumed were a good source of omega-6 fats, they lacked vital omega-3s and the delicate balance we had evolved to thrive on began to tip in favor of omega-6. The continuing rise in the population led to an increased demand for food, as well as increased land requirements to farm and feed livestock. Thus, grains were seen as an energy-efficient food source, resulting in an increased reliance on them to feed both humans and livestock.
Grass-fed organic meat is by far the healthiest option of all but most cattle are now fed on omega-6 rich grains, which is detrimental to the nutrient profile of meat
Animals were confined to smaller and smaller spaces as their grain intake meant that they required less ‘pasture’. No longer consuming high amounts of omega-3 rich grass, foraged plants and insects, animals converted lower amounts of long-chain omega-3s to pass onto humans in meat products. The nutrient profile of the animals we consumed had changed dramatically. As the population continued to rise and technologies developed, humans began to move further away from rivers and seas, meaning fish and marine foods – the richest source of omega-3s in our diet – no longer regularly featured on the menu.
Over the last one hundred years, the refining of grains, the heavy use of manufactured vegetable oils and public health messages to reduce our fat intake, have escalated the problem to epic proportions. As such, the last ten thousand years have witnessed humans shifting from eating a 100% natural diet, with an optimal omega-6 to omega-3 ratio of 1-2:1, to consuming a largely artificial and omega-6 rich grain-based diet in many Western countries, such that our ratio of these essential fats has escalated to in excess of 15:1 in favor of omega-6.
To make matters worse, high consumption of artificial, processed and refined modern foods, together with intense farming, depletes our food sources of vital vitamins and minerals needed to support all the biochemical processes that make our bodies work. One such process is the metabolism of omega-3 long-chain fats from short-chain fats found in plant foods. This process is enzyme-dependent, and these enzymes are reliant upon sufficient intake of micronutrients in the form of vitamins and minerals. Modern western civilizations therefore not only eat considerably (>15x) less omega-3 compared to omega-6, but now also have a reduced capacity to make important long-chain omega-3s from the omega-3 plant fats we do eat. Quite simply, most of us are deficient in the required enzymes to make these necessary conversions – a key one being delta-6-desaturase (D6D).
We’d like to point out here that switching to grass-fed and pastured meats can dramatically improve your fatty acid profile. A study published in the British Journal of Nutrition in 2011 put individuals on a grass-fed or grain-fed (fortified blend of grains and soy) red meat diet and compared their omega-6 to omega-3 ratio after four weeks. Individuals who ate the grass-fed meat had a significantly improved plasma omega-6 to omega-3 ratio (it went from 9:1 to 6:1) compared with those on a diet of red meat from animals that had been grain fed (which actually increased from 8:1 to 13:1). In the UK there are several suppliers of grass-fed meat online who deliver nationwide.
The imbalanced Omega-3 to Omega-6 ratio and its impact on health
Why is our fatty acid profile so important? As mentioned previously, the delicate balance of omega-6 to omega-3 has shaped our evolution for nearly two million years. Every single cell in the body functions optimally with a specific ratio of fats making up its structure. The heart, brain, immune system and hormones all rely on this balance in order to function correctly and keep us healthy. Shifting this balance therefore has huge health implications and studies consistently find that the omega-6 to omega-3 ratio plays a vital role in the severity and spread of modern health epidemics such as cardiovascular disease (CVD), depression, dementia and arthritis. Pre-agriculture, these conditions did not exist and today even children are being diagnosed with CVD, obesity and diabetes, as well as severe neurodevelopmental and mental health disorders.
Omega-3 health benefits are widely researched
Since the very first observation studies published in the 1980s suggested that omega-3 fats are important for health and longevity, there has been constant interest in their role in health and disease. Over 1000 studies are published each year investigating the omega-3 fats.
Low levels of omega-3 along with high omega-6 intake (throughout growth and development in childhood and later in adult life), unfortunately characteristic of modern diets, correlates with increased risk of cardiovascular disease, Alzheimer’s and dementia, depression, allergy, autoimmunity, multiple sclerosis, schizophrenia, autism, ADHD, eczema and psoriasis, arthritis, osteoporosis, poor stress coping mechanisms, fatigue and inflammatory illness.
The long-chain omega-3s EPA and DHA, specifically, are now understood to be fundamental to the proper function of the heart and blood vessels, the immune system and inflammatory process, brain and central nervous system structure and function, infant development, mood regulation, joint and bone structure and skin health.