Major changes in human diet and nutrition have occurred over the last 1,000 years. The nutritional environment that individuals are exposed to today is far different from the environment that humans are predisposed to live in. Human nutrition has moved from a hunter-gatherer dietary pattern compromising of freshly foraged fruits, vegetables, seeds, and nuts to a modern day diet characterised by high intakes of processed carbohydrates such as cereals and grains, saturated fats, salt and refined sugars. This change in diet has resulted in large spikes in illnesses directly linked to poor diet such as obesity, diabetes, cardiovascular disease, and cancer.

The human race has existed for over two million years and in this time there have been three separate food revolutions. The first revolution was the discovery of fire and the ability to cook foraged plants and captured wild animal meat. Fire aided with digestion and helped eliminate toxins in food sources.

The second revolution, 11,000 years ago was the introduction of agriculture, including cereal grains such as oats, barley and wheat and fatty animals such as cows and sheep which were raised solely for food purposes. Both grains and animal food sources were very different to the pre-agricultural diet of humankind. Researchers suggest that the human genetic makeup may not be able to fully adapt to the high levels of grain and animal protein consumption commonly found in the modern diet.

The third food revolution that began 250 years ago was the industrial era. Where novel food sources such as salt, dairy, fatty and processed meats, cereals, vegetable oils and refined sugars became staples in the diet. This once again dramatically altered the nutritional characteristics of what we were eating. Replacing native plant sources of hunter and gatherer times with these novel foods has resulted in negatively affecting the nutritional makeup of most foods that we consume so they appear almost nothing like the foods they originate from. This change in diet has been said to have occurred too recently on an evolutionary scale for human genetics to adjust. Fatty meats and refined grains as a staple food is a recent addition to the human diet and a dramatic departure from the food sources we are genetically adapted to eating. This discord between human genetic dietary needs and present day dietary patterns could be responsible for the increase in modern lifestyle diseases such as obesity, type 2 diabetes, cardiovascular disease, cancer. More recent evidence also suggests a link between dietary patterns and mental health issues such as depression and anxiety.

Research being undertaken in Australia on dietary patterns defines an unhealthy dietary pattern as having a  high consumption of refined foods, red and processed meats, fried foods, salt, eggs from caged birds, dairy products from grain fed animals, refined grains, artificially sweetened foods and a high intake of sugary snacks, drinks and alcoholic beverages. This dietary pattern is low in fruit, vegetables, wholegrains, legumes and water. Foods within an unhealthy dietary pattern are usually made in factories and put through processes that strip them of essential vitamins and minerals, added sugar, salt, preservatives and chemicals that are often un-identifiable as food sources. Unfortunately unhealthy dietary patterns have also been labelled ‘Western’ dietary patterns as this is the most common way of eating in Western countries such as Australia and the United States.

Healthy dietary patterns, on the other hand, are characterised by a diet rich in fresh fruit, vegetables, wholegrains, nuts, seeds, beans, legumes and water. With a moderate consumption of olive oil, dark chocolate and red wine. A healthy dietary pattern also includes low or no red meat, processed, refined and sugary snacks and drinks. Not surprisingly, a healthy dietary pattern contain foods as close as possible to their natural state, as nature intended them. This way of eating is very popular in the Mediterranean and Japan where physical and mental health diseases are much lower than in Western countries.

Evidence suggests that eating a healthy dietary pattern could not only reduce the risk of lifestyle related diseases such as diabetes and heart disease but is also implicated in decreasing mental health disease such as depression and anxiety. A recent clinical trial in Australia took 56 people who reported having symptoms of depression and split them into two groups. The first group was given nutritional information sessions for 12 weeks and asked to stick to a diet that represented a healthy dietary pattern. The second group attended social support groups for 12 weeks but remained on their current Western style diet. After the 12 weeks the individual’s in the healthy diet group reported less depressive symptoms than those in the social group with 32% of the group having scores so low that they no longer met the criteria for depression.

The costs that are associated with treating physical and mental disease in Australia are immense. Emerging evidence that we could use diet to prevent and treat a wide range of physical and mental health issues is revolutionary. The solution could be as simple as switching from a diet high in processed and sugary foods to one rich in fresh whole foods closer to their natural state. As Hippocrates said “Let food be thy medicine and let medicine be thy food”.

Written by Megan Lee

Email: megan.lee@scu.edu.au

Instagram @meganlovingmeagain

Twitter @MeganLeePhD