What it is, how it happened, and how to fix it … in brief, cut back on vegetable oils and foods high in them, and get ample omega-3s from seafood and supplements
Many scientists familiar with food-borne fats' impacts on human health express deep concern over Americans' relatively recent shift to diets that promote disease.
This unhealthful shift included a rapid rise in consumption of vegetable oils – and packaged or prepared foods made with them – which produced a big, unprecedented, imbalance in Americans' intake of omega-3 and omega-6 fats.
As Columbia University Professor Mehmet Oz, M.D., said, "Maintaining the right balance between omega-3 and omega-6 fats is absolutely vital for your health.”
(HUFA is the acronym for highly unsaturated fatty acids. In human cells, the dominant and only essential HUFAs are long-chain omega-3 and omega-6 fatty acids.)
Professor William E. Lands – who's one of the world's most respected and rigorous fatty acids researchers – co-authored that research, and makes the broader societal case for optimizing people's omega-3/omega-6 balance:
"Physicians, health insurers, and policymakers could revolutionize preventive health care, and reduce related costs and suffering, by monitoring Americans' proportions of omega-3 and omega-6 blood fatty acids, and encouraging dietary choices that improve that balance.” – William E. Lands, Ph.D.
A sickening rise in omega-6s … and decline in omega-3s
The available evidence indicates that people will thrive best – and reduce their risk of most major diseases – on diets providing about three parts omega-6 fats to one part omega-3 fats.
But Americans' relative intakes of omega-6s to omega-3s shifted dramatically in favor of omega-6 fats over the past 100 years … a trend that accelerates sharply starting in the late 1960's.
As a consequence, the average American's diet now provides 20 or more parts omega-6s to one part omega-3s … a whopping seven times or more higher than the three-to-one intake ratio shown to deter major diseases and promote optimal health.
This radical dietary shift resulted partly from a decline in Americans' consumption of omega-3 fatty acids … but mostly from a radically higher intake of omega-6 fatty acids.
Omega-6 fats predominate in the cheap vegetable oils that started replacing butter and lard in the 1960's – with the as yet unrealized goal of reducing heart disease risks – mostly corn, soy, cottonseed, sunflower, and safflower oils.
But ample and fast-growing evidence shows that America's relatively recent turn to oils high in omega-6 fats – and the great majority packaged and takeout foods made with them – has had unanticipated, seriously unhealthful consequences.
America's severe omega imbalance drives major diseases
That article summarizes a rigorous evidence review refuting the American Heart Association's 2009 finding that Americans' very high, historically unprecedented intake of omega-6 fats poses no heart risks.
In short, the AHA's 2009 report didn't distinguish between clinical trials that raised people's omega-6 intake only vs. those in which omega-3 intake also rose … a truly astonishing scientific error that perpetuates the deadly mistake that Americans' extremely high omega-6 intakes don't matter.
Other ill effects of America's omega-imbalance include higher risks for depression and major cancers. To read summaries of recent – and rather alarming – research in this realm, visit the "Omega-3 / Omega-6 Balance
” section of our news archive.
How the omega imbalance harms human health Hundreds of studies link the higher disease risks linked to America's omega-imbalance largely to omega-6 fatty acids' comparatively stronger and generally pro-inflammatory influences on hormone-like immune system agents called eicosanoids (eye-coss-uh-noyds).
Omega-3s exert weaker, generally anti-inflammatory influences on these hormone-like agents … and their influence is easily overwhelmed by an excess of dietary omega-6 fats.
Critically, omega-3 and omega-6 fats compete for absorption into our cells, and an excess of dietary omega-6s will result in too few omega-3s being incorporated into cell membranes, from where they exert their essential, indirectly hormone-like effects.
Adding to this problem, many of the omega-3s in American's diets consist of the "short-chain” omega-3 called ALA, which occurs in a few plant foods … beans, dark leafy greens, flax seeds and oil, canola oil, and walnuts.
Omega-3 ALA has to be converted into the long-chain forms the body actually needs to survive and thrive, called EPA and DHA.
And the rate at which this conversion occurs – which is already very inefficient (only one to 10 percent of ALA gets converted to EPA and DHA), is further reduced when your diet is awash in competing omega-6 fats … especially the short-chain omega-6 fat called LA.
Omega-6 LA predominates in most vegetable oils … except olive, macadamia nut, and "hi-oleic” sunflower oils.
Seafood is the only food source of the long-chain omega-3s our bodies need, and fatty fish like salmon, sardines, tuna, and sablefish offer the highest levels, by far.
This is why doctors and researchers alike urge people to eat more fatty fish and/or take fish oil supplements, instead of trying to balance their omega-6 intake with plant-source omega-3 ALA … which is the kind typically used to "omega-3-fortify” cereals, yogurt, and other packaged foods.
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Hibbeln JR, Nieminen LR, Blasbalg TL, Riggs JA, Lands WE. Healthy intakes of n-3 and n-6 fatty acids: estimations considering worldwide diversity. Am J Clin Nutr 2006 83: S1483-1493.
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William E. Lands, Ph.D.
The following papers by Professor William E. Lands, Ph.D., and his colleagues explore the omega imbalance from the perspective of this universally respected scientist, who for decades has decried America's unhealthful omega-3/6 imbalance.
Each title is followed by an excerpt(s), edited as needed to clarify technical language, that captures one of that paper's key points ... to read the full paper, click its title.
Note: HUFA is the acronym for highly unsaturated fatty acids. In human cells, the dominant and only essential HUFAs are long-chain omega-3 and omega-6 fatty acids.
"Careful review of molecular events connecting diets to death identifies two modifiable food imbalances that cause major chronic diseases in Americans. They are 1) imbalance between ingestion and expenditure of food energy [calories], and 2) imbalance between omega-3 and omega-6 essential fatty acid levels in ingested foods.”
"Many financial losses will likely be decreased by primary prevention advice to choose foods that increase intakes of omega-3 fats, decrease intakes of omega-6 fats and include fewer calories per meal.”
"Every year, more young people start the slow progressive injury that eventually becomes cardiovascular disease and death.”
"It could be prevented with nutrition education, but medical efforts focus more on treatments for older people than on preventing primary causes of disease in young people. Two avoidable risks [omega-3/6 fat imbalance and oxidative stress] are prevented by simple dietary interventions: (1) Eat more omega-3 and less omega-6 fats … (2) eat less food per meal …”
"The increases in world omega-6 LA consumption over the past century may be considered a very large uncontrolled experiment that may have contributed to increased societal burdens of aggression, depression, and cardiovascular mortality …”
"… a healthy dietary allowance for omega-3 HUFAs for current US diets was estimated at 3.5 grams per day for a 2000-calorie per day diet. This allowance for omega-3 HUFAs can likely be reduced to one-tenth of that amount by consuming fewer omega-6 fats.”
"…diets during the 4–5 million years of hominid [ancestral human] evolution were likely abundant in seafood and other sources of omega-3 HUFAs but had sparingly little contribution of calories from omega-6-rich seed oils.”
"In stark contrast, at the turn of the recent millennium, a single food source, soybean oil, appears to deliver 20% of all calories in the average US diet, with [the result that] about 9% of the average American's calories come from omega-6 linoleic acid (LA) ...”
"The high prevalence in the USA of chronic diseases and disorders mediated by omega-6 eicosanoids prompts the question ‘What proportion of omega-6 HUFA in the tissue phospholipid HUFA is optimal for health?'.”
"Current dietary habits in the USA maintain about 75% of the phopholipid-form highly unsaturated fatty acids [HUFAs] as omega-6 fatty acids (and cardiovascular mortality and arthritic morbidity is severe), whereas the Japanese have traditionally maintained about 50% of cell membraine fatty acids as omega-6s (and cardiovascular mortality and arthritic morbidity are less severe) and Greenlanders had even lower proportions of omega-6s in their cell membranes, with lower incidence of myocardial infarction [heart attack] or arthritis.”