by Craig Weatherby
A few days ago, we published Part I
of our review of a great new book, The Queen of Fats
, by Susan Allport: author of several other science-oriented books and a contributor to the The New York Times
In this installment, we address the book’s subtitle: “Why Omega-3s Were Removed from the Western Diet and What We Can Do to Replace Them.”
Here, we’ll address the subjects surrounding the book’s subtitle
—Why Omega-3s Were Removed from the Western Diet and What We Can Do to Replace Them
—and the issue of trans fats.Why did omega-3s disappear
—from modern diets?
We should have known, but were surprised to learn from The Queen of Fats
that omega-3 fatty acids are the most abundant fats on earth, thanks to their presence in virtually every green plant, in which they are essential parts of the membranes of cells (chloroplasts) that perform photosynthesis.
Plants only contain the short-chain omega-3 called ALA, which the human body converts to the long-chain omega-3s
About Susan Allport
She is the author of two other highly praised books—The Primal Feast: Food, Sex, Foraging, and Love, and A Natural History of Parenting —and has appeared on Oprah & Friends Radio and NPR’s "Science Friday" and "The Splendid Table."
We’re sure you’ll find her contributions enlightening pleasures to read!
(EPA and DHA) critical to our cell membrane functions. Otherwise, long-chain omega-3s are found in abundance only in fish, aquatic plants, and algae.
And omega-3s used to be adequately abundant in Western diets, thanks to their presence in green vegetables, pasture-fed livestock, most seed oils, and whole grains.
But omega-3s were removed from the Western diet—even as the amount of competing omega-6 fatty acids rose sharply—thanks to two trends that began in the late 19th century and accelerated greatly during the latter half of the 20th century:1) Mass Migration from Farms to Factories
Americans moved from small, diverse family farms to cities, where they ate less omega-3-rich vegetables and pasture-fed livestock and more omega-6-rich, omega-3-poor packaged foods and commercial meats and poultry.
Commercially produced beef, pork, and poultry were increasingly raised on diets high in grains instead of pasture: a practice that raised the omega-6 content of livestock meat steadily while almost eliminating its omega-3s.2) The Switch from Lard to Hydrogenated Vegetable Oils
The mistaken belief that dietary cholesterol and saturated fats cause heart disease took hold after World War II, and researchers discovered that polyunsaturated fats can lower cholesterol levels.
Dietary cholesterol has very little to do with heart disease—and blood cholesterol profiles are, by themselves, poor predictors of cardiovascular risk—but excessive intake of saturated fats is definitely risky.
Accordingly, over the past 50 years, food manufacturers switched from using highly saturated i.e., (spoilage-resistant) animal fats in baked goods and packaged foods, to using a few mostly-polyunsaturated vegetable oils: corn, safflower, sunflower, canola, soy, and cottonseed.
(Canola and soy oils are higher in omega-3s than the others, but are still dominated by omega-6 fats.)
Vegetable oils used in baked goods and packaged foods are almost always partially hydrogenated, because omega-3s are ten times more susceptible to oxidation, compared with omega-6 fats. Accordingly, omega-3s become rancid fairly rapidly, thereby cutting the “shelf life” of processed and packaged foods very short.
Unfortunately, the vital distinctions between omega-3 and omega-6 essential fatty acids (EFAs)—and the importance of maintaining a balanced intake of both—were overlooked and ignored.
So no one was concerned by the fact that the process of hydrogenating vegetable oils destroys virtually all of their tiny-to-modest amounts of omega-3s, leaving only their omega-6 polyunsaturated fats.
In addition to destroying their omega-3s, the process of partially hydrogenating vegetable oils creates artery-scarring trans fats, while leaving intact an artery-inflaming, heart-unhealthful excess of omega-6 fats.Omega imbalance may outweigh faults of “trans” fats
Trans fats—which are created during partial hydrogenation of vegetable oils—rank high among the heart-attacking food factors targeted by public health campaigners.
But the role that trans fats play in promoting cardiovascular disease may not be as big as that of the omega-6 overload in American’s diets.
Researchers have assumed that it is the trans fats in hydrogenated oils—which can have deleterious cardiovascular effects—that make these chemically altered oils unhealthful.
But as Allport explains in The Queen of Fats
, this assumption overlooks the elephant in the room: that is, the excess of omega-6 fats and deficiency of omega-3 fats in Americans’ diets.
She makes these cogent remarks on the UCAL Press website, “If we come to an understanding of how important it is to have a healthy balance between the two families of essential fats, the omega-3s and omega-6s, we’ll be much better off. If we just tweak the diet, say to remove trans fats but to maintain the current imbalance, we could be in even worse shape.“
The question is: are our health problems due to the presence of trans fats, or to excessive amounts of omega-6s and the absence of omega-3s? There is a great deal of experimental and epidemiological research to support the latter, and much less to implicate trans fats.”
And as Ms. Allport noted during our interview with her, “Studies in trans fats haven’t controlled for omega-6 intake. It would be interesting to take people with good omega-3/omega-6 ratios, put them on high-omega-6 diet, and record the results.”Restoring omega-3s to our diets: Fish versus spinach, flax and company
Susan Allport suggests ways—in addition to eating fish—that Americans can increase their intake of omega-3s. She focuses on upping American’s intake of green, leafy vegetables and decreasing their intake of seeds and seed oils high in omega-6 EFAs (corn, soy, safflower, etc.).
We question Ms. Allport’s prescriptions regarding coo. She recommends soy and canola because they contain more omega-3s, in much higher proportions relative to omega-6s, than do corn, sunflower, olive, or safflower oils.
But we vote for mostly-monounsaturated oils like olive, macadamia, and hi-oleic sunflower instead, for two reasons:
- High omega-6 intake is a big problem, and soy and canola oils contain more omega-6s than the mostly-monounsaturated oils
- Soy and canola contain too many omega-6s to be every day oils in the context of diet overflowing in these fatty acids.
Her prescriptions for upping Americans’ intake of omega-3s focus on redressing their general dietary deficiency of leafy greens, and on omega-3-enriched or fortified foods, like some eggs, “natural” baked goods (e.g., frozen flaxseed waffles), and yogurts.
This seems odd at first blush—as does the photo of eggs, rather than fish, on the book’s cover—since fish are the richest omega-3 sources, by far.
And among foods, only fish contain the long-chain “marine” forms the body actually uses (EPA and DHA), instead of the short-chain form in plants, which it must convert, quite inefficiently, to the marine forms.
Susan Allport told us that she emphasized vegetable sources of omega-3s—and omega-3-fortifed brands of foods like yogurt, cereal, and eggs—for two reasons:
- People already know that fish offer omega-3s, but remain largely unaware that green, leafy vegetables contain small but significant amounts and also offer beneficial fiber and antioxidants.
- In the future, a growing imbalance between seafood demand and supply may make it increasingly hard for people to get all the omega-3s they need from sustainably produced fish and fish oil. And farmed fish are typically much higher in omega-6s, compared with their wild counterparts.
We have considerable sympathy for these points. We would only remind readers that plant foods contain only the short-chain omega-3 called ALA, most of which the body converts, very inefficiently (five to 15 percent of dietary ALA), to the long-chain, “marine” forms (EPA and DHA) needed in our cell membranes and found most abundantly in oily fish such as salmon.
But this is a minor quibble. The Queen of Fats is an excellent book that we hope will have a real impact, and prompt more fortification of foods with omega-3s of all kinds.
Ideally, manufacturers will fortify foods with marine-source DHA and EPA when feasible, but substantial amounts of added plant-form omega-3s would be very welcome as well. (Sadly, many “omega-3-fortified” foods contain only tiny amounts of plant-form omega-3s.)
Omega-3s have yet to reach their rightful prominence in public health policy, but this truly important book should help redress that wrong.
Seasons of Fat... Susan's followup article
In another article by Susan Allport, titled "Seasons of Fat
," she addresses the amazing biochemical properties that make omega-3 DHA indispensable to human health.
As she explained in her chapter titled “The Speed of Life,” the fats we eat govern the speed at which animals—including humans—move, think, and live. The DHA in human cell membranes is fundamental to thinking and moving fast, and the richest dietary source by far is fish.