It’s common to hear about single dietary elements causing various chronic diseases (eg salt causes high blood pressure – which it can -, and that saturated fat causes heart disease); however, the accumulation of evidence over the last decades indicates that the majority of the “diseases of civilization” have multifactorial dietary elements underlying their etiology, in combination with environmental agents and genetic susceptibility. This little series of posts aims to provide a brief summary of how the new conditions of life collides with our ancient genome. Here’s the first part.
In the US (and also elsewhere), between 1909 to 1999, there was a remarkable rise in the consumption of oils (salad and cooking oils +130%, shortening +136%, margarine +410%). Why?
The entrance of the mechanized oil-seed industry. In the past, most oils that were extracted seems to have been used for nonfood purposes, such as medicine and illumination. In addition, at that time the oils came from sesame, flax, walnuts, etc.
Now, margarine contains trans fatty acids from the hydrogenation process, which were practically never found in conventional foods.
-> Added oils through the industrial revolution seriously upped the fat content of the standard diet.
Today, alcohol, as most other things we consume, are available all year round. While some wine here and there has been found to be even healthy, it’s interesting to think of how, before the Neolithic period, the consumption of such beverages must have been extremely limited due to several factors, for example: 1) Fruit availability fluctuated with the seasons, 2) Those people couldn’t store very much.
About 75% of the daily salt intake in Western populations is obtained through processed foods, in which the salt did not occur naturally, but was added by the producer. 15% comes from cooking and table salt use, and the remaining 10% occurs naturally in foods. This means that 90% of our sodium intake comes from manufactured salt that is added to our diets.
The current collection of evidence suggests that our salt consumption has minimal or no evolutionary precedent in humans before the Neolithic period.
In the past, all animal foods that were consumed came from wild animals, the fat content of which depended on the species body mass (larger species generally have more fat), age, sex, and the cyclic waxing and waning of the seasons, which brought changes in the availability of food. Thus, the peak body fat % in wild animals are maintained only during a short period of the year, and the majority of fatty acids that is stored in the depots of wild animals are saturated fatty acids; these stores are depleted during most of the year in wild animals. The fat that is stored in muscles and organs are unsaturated fatty acids, and these are also the dominant fats in the edible carcass.
As we introduced animal husbandry, it became possible to interfere with the seasonal changes in body fat of the animals (mainly preventing the seasonal decline), and to slaughter the animal at peak body fat percentage. Advances in food-processing allowed us to store concentrated forms of saturated animal fats in the form of cheese, butter, tallow, and salted fatty meats for later consumption. When we developed farming and transport practices concerning grains, it spawned the practice of feeding grains to cattle kept in feedlots. Before 1850, practically all cattle were free range/pasture fed and slaughtered ar around 5 years of age. By 1855, we could have a steer ready for slaughter in 2 years through rapidly fattening them in feedlots, producing “marbled” meat (a result of excessive triacylglycerol accumulation in muscle interfascicular adipocytes, but that might be too much information). That kind of meat has a much greater saturated fatty acid content, less omega 3, and more omega 6 (which is what we don’t want).
Today, we can have a steer ready in ONE year, at which point it’s characteristically obese. 99% of all beef consumed in the US is produced like this; from grain-fed, feedlot cattle. 200 years ago, that percentage was virtually 0.
The introduction of the foods that I’ve mentioned in this and the previous post adversely affected several dietary indicators: 1) glycemic load, 2) fatty acid composition, 3) macronutrient composition, 4) micronutrient density, 5) acid-base balance (our bodies are extremely sensitive to disruptions in pH), 6) sodium-potassium ratio (these two little substances are crucial for the functioning of our bodies), and 7) fiber content.
The last post in this little series will further discuss the health ramifications of these foods and the following alterations that I just mentioned.