Paranoia About Fats Is Driven by Junk Science
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.
With the exception of palmitic acid, a saturated fat with 16 carbons, most fats we eat have 18 carbons. With no double bonds, an 18-carbon fat molecule is called stearic acid, a saturated fatty acid. Add one double bond and you’ve got oleic acid. With two double bonds, it becomes linoleic acid (LA), and with three double bonds, it’s alpha-linolenic acid (ALA). (Allport recommends remembering these two similarly named fats by remembering that the molecule with the extra double bond – linolenic – has the name with an extra letter in it.)
Omega-6 vs. Omega-3: It’s the Ratio, Stupid
What makes a fat classified as an omega-3, omega-6 or even omega-9? The placement of the double bond closest to the end of the molecule. LA, with its last double bond six spots from the end, is an omega-6. ALA, with its last bond three spots from the end, is an omega-3. And oleic acid, with its last and only bond nine spots from the end, is an omega-9. Omega is the last letter of the Greek alphabet, so the name “omega-3” denotes the double bond is three away from the omega end, the tail end, of the molecule.
Our bodies can make fat, we can add carbons to fat molecules, and we can even add double bonds to fat molecules. However, we cannot add double bonds any closer than nine spots from the end. If you eat an omega-3, it remains an omega-3. If you eat an omega-6, it remains an omega-6.
Here’s the catch: we usually eat fat molecules with 18-carbons, but we need longer chain fatty acids for important purposes in our bodies. After we eat LA (an omega-6) and ALA (an omega-3), the two compete for the same set of enzymes to elongate and desaturate them into arachadonic acid (ARA, an omega-6), eicosapentaenoic acid (EPA, an omega-3), and docosahexaenoic acid (DHA, an omega-3).
Omega-3s are stronger competitors to gain use of these enzymes, but they can’t compete if we flood our bodies with omega-6s. And that’s what we do.
A healthy omega-6 to omega-3 ratio is somewhere around 4:1, and some scientists think it could be even closer to 2:1. Americans average something more like 10:1.
The Systematic Flooding of Our Food System With Omega-6s
How did we get where we are today? Consider our food system: lots of shelf-stable packaged foods, plenty of cheap, grain-fed animal products, and a consumer base convinced that saturated fats are bad and polyunsaturated fats are good. Each of these factors adds up to more omega-6s and less omega-3s.
Omega-3s are often found in leafy greens. You might not think of spinach as a fatty food – and it isn’t – but within the tiny bit of fat in raw spinach, you’ll find five times more omega-3s than omega-6s. Seeds, on the other hand, tend to have more omega-6s than omega-3s. Out of the world’s most popular vegetable seed oils (soy, sunflower, rapeseed, peanut, cottonseed, olive, sesame, corn, and safflower), only rapeseed (canola) has a favorable ratio of omega-6s to omega-3s.
Consider your average supermarket. How much space is devoted to seeds and their oils compared to leafy greens? Check out any packaged food on the market. Odds are you’ll find corn and soy… both seeds. What did the animals that produced the meat, milk, and eggs eat? Probably a lot of corn and soy. Even factory farmed cattle, which still eat some grass, eat more seeds (again, mostly corn and soy) than their ancestors did a century ago.
Omega-6s are more shelf-stable than omega-3s. Flax oil, high in omega-3s, must be stored in dark bottles in the fridge, and even still it must be consumed quickly before it goes rancid. And seeds, full of omega-6s, are higher in calories than leafy greens, so factory farms prefer them as a quick way to fatten livestock. And, as Americans learned from “experts” that saturated fat is bad and polyunsaturated fat is good, the food industry gave us what we asked for – but usually in the form of shelf-stable omega-6s.
Another factor comes from our ability to produce vegetable seed oils. Using a simple mechanical process one can extract olive oil and avocado oil. To extract other oils, like soybean oil, chemical solvents are used. Until about a century ago, all soybean oil extraction was done mechanically (and not very efficiently), but soybean oil was hardly the major food source it is today.
Extracting soybean oil with hexane, a toxic chemical that can cause nerve damage, was just one innovation that made soybean oil ubiquitous in our food supply. As factory farming increased – and with it the demand for soybean meal – the result was an increase of its byproduct, soybean oil. Also important: making soybean oil more palatable to consumers. That requires the oil to be degummed, refined, bleached, and deodorized. Partial hydrogenation also allowed vegetable oils to stand in where we previously used saturated fats (i.e. margarine instead of butter).
The advent of these technologies made an unprecedented amount of vegetable seed oils – and omega-6s – available in our food supply. By 1986, a whopping 81.7 percent of the vegetable oil Americans ate came from soybeans. The tide turned a bit over the next decade, as canola oil gained a reputation as a healthy oil – but more than three-quarters of the vegetable oil in the U.S. still came from soybeans.
A study found that the single largest source of omega-6s (58 percent) in the U.S. food was soybean oil – more than meat, fish, eggs, milk, cheese, lard, and other vegetable oils combined. Soybean oil does not have the worst ratio of omega-6 to omega-3 – other oils like cottonseed, sunflower, safflower, and corn are all far worse. But since it is so prevalent in our food, it’s the biggest culprit all the same.
The Science Revisited
The title of a recent piece by omega-3 pioneer Ralph Holman is telling: “The Slow Discovery of the Importance of Omega-3 Essential Fatty Acids in Human Health.” While we were tripping over ourselves to rid our diets of all fats, or saturated fats, or animal fats, or trans-fats, as one trend gave way to the next, scientists like Holman were carefully piecing together the importance of omega-3s in reducing inflammation and heart disease. Sadly, as they were figuring out the importance of the ratio of omega-6 to omega-3s, the nation’s ratio kept tipping in the wrong direction.
Artemis Simopoulos, author of The Omega Diet, is one of the scientists who made great contributions to understanding the importance of omega-3s. A physician and the president of the Center for Genetics, Nutrition, and Health, she went back and looked at the raw data from Ancel Keys’ famous Seven Countries Study.
Undertaken in the late 1950s, the study examined diet and heart disease in Yugoslavia, Finland, Italy, the Netherlands, Greece, Japan, and the U.S. It “clearly showed that the people who had the lowest rate of heart disease and cancer and who lived the longest were the people who lived on the island of Crete, in Greece,” she explains. Simopoulos recognized Keys’ mistakes in interpreting the data. He neglected to distinguish between omega-6s and omega-3s.
As a Greek, Simopoulos certainly knew something about the traditional Greek diet. “When I was looking at the traditional diet of Crete,” she recalls, “I became very much aware that the people in Greece at the time – and I’m talking prior to 1960 – they ate a lot of wild plants. And so I studied the wild plants and the composition of the wild plants and I found that wild plants have more antioxidants, more vitamin C, more vitamin E, and more omega-3s,” in the form of ALA. “And purslane,” a common edible weed in the Mediterranean, “has more omega-3s than any other plant.”
One day she was visiting her parents in Greece and she saw the chickens eating purslane. “I questioned whether that egg would be different in composition than the egg you buy in the supermarket where the chickens are fed corn and other grains.” Analyzing the eggs, she found they contained equal amounts of omega-6 and omega-3s, whereas a typical egg in U.S. supermarkets has a ratio of 20:1.
The difference was not just the purslane that the Greek chickens ate. “They eat grass, they eat bugs, and they eat worms,” notes Simopoulos – adding that bugs and worms are high in ALA, EPA and DHA. “What’s fascinating is that the amount of DHA in egg yolk [from her chickens] is equivalent to mother’s milk at one month of age.”
Other top sources of omega-3s are fish, particularly wild-caught fish, and seaweed. Like the bugs, worms and wild plants eaten by the Greek chickens, wild-caught fish and seaweed are not cultivated by humans.
The Bottom Line: Eat Less Omega-6s
While we usually consume omega-3s as ALA, our bodies require EPA and DHA. EPA is commonly used in our membranes, whereas DHA is important in our brains and eyes. And with a few exceptions (for example, premature babies and people with hypertension), humans can turn ALA into EPA and DHA. But, remember, that only happens if you do not consume so much omega-6s that they monopolize the enzymes needed.
According to Simopoulos, traditionally only 2% of energy came from omega-6 and 1% came from omega-3s. “The ratio was either balanced or it was 2:1,” she says. And we won’t achieve that ratio unless we dramatically bring down the amount of omega-6s we eat.
How do we do this? The people of Greece have a good idea: use olive oil. A healthy, monounsaturated fat, it does not play into the omega-6 vs. omega-3 ratio. Eat your fish and eat your greens (even seaweed) to get omega-3s, but boot the omega-6s from your diet.