I make no secret of the fact that I’m a believer in the concept that our diets should, for the most part, emulate those of our ancient ancestors. The diet we ate for long periods of our evolution is likely the diet we are best adapted to and is the best for us. There’s abundant scientific evidence to support this concept, by the way, and most agree that it makes sense too.
The thing is, do we actually know what our ancient ancestors ate? There is evidence that prior to about 10,000 years ago, our ancestors were hunter-gatherers. For the vast majority of our evolution our diet was devoid of many modern-day foodstuffs including bread, pasta, breakfast cereals, milk, refined vegetable oils and refined sugar. ‘New’ foods eaten in the last 10,000 years make up about 75 per cent of the typical calories consumed in a ‘standard Western diet’.
Until recently, in evolutionary terms, the human diet was ostensibly made up of ‘primal’ foods such as meat, fish, shellfish, eggs, fruits, vegetables and nuts. However, it stands to reason too that the relative proportions of these foods in the diet would have varied considerably as a result of availability and necessity.
Our ancestors evolving away near the equator would, likely, have decent access to plant-based foods including fruit and vegetable matter. But the further away we get from the equator towards the poles, the less plant matter there is, and the more reliant on hunting for meat and fish our ancestors would have been.
One way of getting some insight into the details of our evolutionary diet is to examine the diet of modern hunter-gatherers. Probably the best source of relevant data here is known as the Ethnographic Atlas. Within it can be found dietary information from 229 contemporary hunter-gatherer societies. This data was recently analysed by two German researchers in an effort to gain insight about the carbohydrate content of primitive, hunter-gatherer diets [1].
The percentage of calories contributed by carbohydrate varied from about 3 per cent to around 50 per cent. It will come as no surprise that they discovered that percentage of the diet coming from carbohydrate was higher in populations close to the equator than those further away. The most common percentage among all the groups came in at around 20 per cent.
Official recommendations are normally that about 60 per cent of the calories we consume should come from carbohydrate. That’s actually higher than the most carbohydrate-rich hunter-gatherer diet of all, and about three times the average carbohydrate percentage in such diets. The authors of this study conclude, ‘…the range of energy intake from carbohydrates in the diets of most hunter-gatherer societies was markedly different (lower) from the amounts currently recommended for healthy humans.’
It’s perhaps worth mentioning too that not only has the quantity of carbohydrate changed in percentage terms, but its quality too. Long gone are the days when our carbohydrate mainly came in the form of fruits and vegetables including tubers. Now, we consume much more in the way of grain-based products, many of which have been refined, refined sugar and fruit that has been cultivated to be sweeter than fruit found in the wild.
Evolution allows some adaptation over time, of course, but there are limits. Adaptation is generally slow to come, and many of us run the risk of consuming carbohydrate beyond what is good for us in terms of both quality and quantity.
There problems with such a diet are manifold, I think. We can have the blood sugar disruption and surges of insulin to start with. Peaks of blood sugar encourage damage in the body through a variety of processes including inflammation and glycation (binding of sugar to tissues). Highs of blood sugar can lead some time later to lows which can trigger all manner of symptoms such as hunger, food cravings, mental fatigue, mood change and waking in the night.
The surges of insulin that comes in response to gluts of blood sugar can predispose us to problems such as weight gain, heart disease and type 2 diabetes.
Of course one way out of this would be to reject conventional nutritional advice on carbohydrate consumption, and keep the diet as ‘primal’ as possible.
References:
1. Ströhle A, et al. Diets of modern hunter-gatherers vary substantially in their carbohydrate content depending on ecoenvironments: results from an ethnographic analysis. Nutr Res 2011;31(6):429-35.
