Is there a diet we are 'supposed' to follow?
We eat food to provide our body with the nutrients required to perform its many functions. Our body is built from these nutrients and we cannot achieve proper health and wellness without considering nutrition.
We don’t just eat for nutrition and health. There is a great sense of reward and satisfaction that comes from eating food. But some foods we eat actually don’t leave us feeling that great. Think of sugar peaks and troughs, hangovers after only one wine, and fast food that leaves us hungrier than before. These foods – the ones that really don’t serve us well – are the result of the industrialisation of food. Instead, wherever possible, we should be nourishing our bodies with natural ingredients grown and gathered in our local communities.
Eating is essential to human survival, so it is extraordinary that we have become so confused about what to eat. How is it that we have lost the knowledge or ability to consume foods that nourish our bodies, as well as our minds and spirit? As a species, we have survived for over 2 million years… but where has all of our instinctive knowledge about food gone?
In his book Sapiens, Yuval Noah Harari mounts a compelling argument that the domestication of a small number of grains during the Neolithic period was the turning point for our dietary patterns and food knowledge.
There are many cultures worldwide that have maintained knowledge of plants for food and medicine.
Traditional cultures and societies – such as indigenous Australians, who settled Australia over 45,000 years ago – have a robust knowledge of how native plants can nourish the mind, body and spirit, both for medicine and nutrition. We don’t find this information online or in textbooks, because it has rarely been recorded in written form. Instead, it is passed down through stories from generation to generation. Read more about sharing stories to discover the link between your family health history and your own here.
Could the disconnection between our food source and nature be the root cause of poor health? In Australia, 1 in 2 of us have self-reported to suffer from a chronic disease (2014-15 National Health Survey). One of the great losses that occurs when foods are processed and sprayed with pesticides is the microorganisms that live symbiotically with plants and animals. These microorganisms are essential to the health of the plant, animals and, of course, humans. It is suggested that a loss of microbial diversity could be at the root of many modern diseases. If this is the case, can we go back and reintroduce the bugs we need by eating foods that our ancestors ate? And, in doing so, can we boost our health?
Evolution of our genes and our ancestral diet
Diet has two definitions: firstly, the kind of foods that a person regularly eats; and a special course of food that a person restricts themselves to, often for medical or health reasons. Let’s focus on the former definition and explore the idea of whether there is a diet we are ‘supposed’ to eat based on our genetics as Homo sapiens and, if so, what it looks like.
The genus Homo started its evolutionary journey to becoming the modern human around 2.5 million years ago. Modern humans – those that share similar physical features to us – evolved around 200,000 years ago. Homo sapiens continued to move around the world during a time when other Homo species (erectus and neanderthanlensis) became extinct, but not before interbreeding with Homo sapiens, leaving a legacy of DNA that can be seen in our genes today.
The quest to understand what life looked like back then is ongoing. The field is filled with theories that contradict one another and there is no single theory that is universally accepted by scientists. This leaves us all with an incomplete picture of our evolution and makes identifying the diet of our ancestors difficult.
When looking at the diet of any species, we need to look at the range of foods that could have been consumed based on chemical and mechanical characteristics, such as how they chewed, how their digestion worked, how they were able to move and think, what the chemical contents of the foods were, and what could have been found within their given environment. This involves understanding whether food was abundant and whether obtaining the food was profitable to the species (a cost: benefit ratio; that is, how much energy was required to get the food versus how much energy could have been gained by eating the food).
Three main methods of gathering our food have been identified and investigated: hunting, scavenging and underground storage (e.g. root vegetables). Extreme views focus on the likely diet if humans predominately used only one of these approaches to gather food. A more balanced approach is a combination of these 3 techniques, that varied by availability and was influenced by season and environment, but always aligned with our unique physiology.
Humans are omnivorous species, meaning we can process and metabolise animal and plant materials. Estimates based on recent research of our ancestors’ diet suggest that fats and carbohydrates each contributed around 35% of dietary energy, and protein contributed around 30%. Saturated fats are said to have made up approximately 7.5% of total energy, with small amounts of trans fatty acids (the fats found in vegetable oils that are used in most processed foods), and a 2:1 ratio of polyunsaturated fats omega 6 and omega 3. Cholesterol consumption was high at around 480mg/day. Carbohydrates came from fruits and vegetables, not grains, and dairy intake is said to have been limited.
While the jury might always be out on what we ‘should’ eat, it is pretty clear what we shouldn’t be eating – that is, foods that are highly processed, full of artificial additives and made in laboratories. We need to be eating foods that are provided by nature. These foods satisfy us on all levels: they meet our nutritional requirements; the foods are delicious and ‘guilt’ free; and they come without the plastic wrapping that is proven to be destroying our environment.
• Eaton SB (2006) The ancestral human diet: what was it and should it be a paradigm for contemporary nutrition? Proceedings of the Nutrition Society 65(1): 1-6
• Green RE, et al (55 other authors) A draft sequence of the Neandertal Genome (2010) Science 328(5979): 710-722
• Sayers K, Lovejoy CO (2014) Blood, bulbs and bunodonts: on evolutionary ecology and the diets of Ardipithecus, Australopithecus, and early Homo. Q Rev Biol 89(4): 319-357
• Yuval Noah Harari, ‘Sapiens’