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Friday 2 October 2015

Could So-Called 'Healthy' Vegetable And Seed Oils Be Making Us Fat And Sick?

Although reported to the point of no longer being newsworthy, it is still shocking that fully one-third of U.S. adults are overweight with another more than one-third (35.7%) being obese. The current level of obesity is particularly striking when one considers the startling trajectory; from 1960 to 2010, the percentage of obese Americans nearly tripled overall, and more than tripled among men.Moreover, the percentage of extremely obese Americans—essentially zero in 1960—totaled >6% of the population in 2010. Trend lines seem only to point upward. And along with expanding waistlines, there has been corresponding rises in related conditions likediabetes, unhealthy blood cholesterol and heart disease.

Experts have advanced several dietary culprits as possible explanations for these alarming trends. But one interesting possibility has received little attention: some of the oils we were advised to eat.

The transition from solid fats to liquid fats

With late 20th-century concerns about saturated fats in diets and their relationship to heart disease, several dietary recommendations called for replacing saturated fats with unsaturated fats. As a result, liquid fats (various oils) replaced solid fats (like butter)

Over the last several decades, the consumption of vegetable and seed oils like those from soybean cottonseed, corn, canola, safflower and

sunflower increased substantially. For instance, from 1970 to 2000 the average consumption of soybean oil went from around 4 lbs. per person per year to around 26 lbs.

All the other oils mentioned above, including soybean oil, are all rich sources of unsaturated fatty acids. In particular, many of these oils are rich sources of linoleic acid.

We may now be consuming more linoleic acid than our bodies evolved to handle

Today, linoleic acid alone provides up to 8% of our total daily calories, whereas for pre-agricultural humans, linoleic acid would have contributed only about 1-3% of total daily calories. In other words, we may now be consuming anywhere from 2.5 to 8 times as much linoleic acid as our bodies might have evolved to handle in the hundreds of thousands of years before the relatively recent advent of agriculture (and the even more recent advent of industrial food processing).



Linda said...

Interesting. So many things have changed in our food supply. I don't think it's even possible to eat like great-grandma ate.

chris c said...

Yes agreed, I've seen many sources that say the same thing. Not just the high carbs but the low fat seems to be a major factor in breaking the metabolism in the first place, especially when the majority of the fat is Omega 6.

ISTR there were some early studies on Omega 6 oils that made them appear quite toxic compared to saturated and other fats, up until some dietary threshold quantity was reached. The only trials that make them appear to have benefits have an overdose of O6 in both trial and control groups.