Paranoia About Fats Is Driven by Junk Science
Photo Credit: Kritchanut/ Shutterstock.com
Stay up to date with the latest headlines via email.
You’ve heard about omega-3s. You probably know you need to eat them. You’ve likely heard that they’re found in fish. But odds are, there’s a lot more you need to know about this family of healthy fats.
Over the last century, Americans have become increasingly confused about fats. Travel back to the Little House on the Prairie, and you’d find Americans happily adding lard, cream and butter to their food. In the 20th century, these saturated animal fats went out of vogue, and “healthier” products like margarine graced American tables instead. Today, no healthy eater would touch the trans-fats in margarine – although they might opt for a trans-fat-free margarine made with palm oil instead.
What’s the right answer? And where do omega-3s fit in? As you’ll see, while we need omega-3 rich foods in our diet, the bottom line is that we must eat less of another kind of fat, omega-6s, to get the benefit of the omega-3s.
We Don’t Need Fat…Do We?
To understand Americans’ troubled relationship with fat, one must begin when scientists first identified that food was made from protein, carbohydrates and fat. Our bodies can turn carbs into fat, they figured, so we don’t actually need fat to survive. Wrong! But it wasn’t easy to prove this, at least until modern medicine perfected intravenous feeding (total parenteral nutrition, in hospital-speak).
In a strange twist of fate, scientist Ralph Holman’s mother fell ill and ultimately died after a long period receiving fat-free intravenous nutrition. Holman researched the role of fat in human nutrition and he was convinced that certain fats – essential fatty acids – are needed for humans to survive. But he had not been able to prove it.
“Holman watched helplessly as [his mother] died of the very deficiency that he was working to prevent,” wrote Susan Allport in The Queen of Fats: Why Omega-3s Were Removed From the Western Diet and What We Can Do To Replace Them. Holman lost his mother, but with her death, he proved humans must eat certain fats to survive.
Bad Science Gets Popularized
Careful scientists often assume that there is still plenty we do not know, refraining from making public recommendations until all of the facts are in. (For an example of this, see the recent Michael Pollan article about microbes’ role in human health; he emphasizes that the science is so new there aren’t many concrete recommendations yet.) But every now and again, a charismatic and arrogant scientist will popularize a current working theory, right or wrong.
Such was the case with Ancel Keys, nicknamed “Monsieur Cholesterol” for popularizing the term and pontificating against it. President Eisenhower had a heart attack in 1955, and suddenly the entire nation was interested in cardiovascular health. Keys had the answer: don’t eat fat. He later amended this to an also overly simplified mantra of “saturated fat, bad; unsaturated fat, good.”
An obedient nation swapped out butter and lard for unsaturated vegetable oils, especially soybean oil. (Soybean oil is often labeled “vegetable oil” at the store.) But unsaturated vegetable oils are not all equal. They might be monounsaturated or polyunsaturated. Within the polyunsaturated fats, there are omega-6s and omega-3s. And even within those categories, there are different fats with different properties. (You may have heard of the highly sought-after omega-3s EPA and DHA.)
Fat Chemistry 101
Fats are easier to understand once you have a very basic idea of their chemical structure. To grossly oversimplify, fats are basically long chains of carbons connected mostly by single bonds. Scientists classify fats by the number of carbons in the chain, the number of double bonds between the carbons, and the placement of these double bonds.