Omega-3 versus omega-6 vetzuren in de voeding.*
Een Amerikaanse onderzoekster/publiciste heeft alles aan medische en wetenschappelijke onderzoeken omtrent omega-vetzuren van de laatste twintig jaar op een rijtje gezet in een boek. Zij concludeert dat wellicht door de extra aandacht de laatste twintig jaar op de grote voordelen van onverzadigde vetzuren versus verzadigde de balans wel heel erg doorgeslagen is naar alleen de onverzadigde omega-6 vetzuren ten koste van de onverzadigde omega-3 vetzuren. Zo worden dieren gevoerd met maïs en soja met het gevolg dat ook hun weefsel vol omega-6 vetzuren zit. Een ander voorbeeld eieren van kippen, die veel maïs te eten krijgen, hebben nog slechts 10% omega-3 vetzuren in vergelijking met eieren van kippen die vrij kunnen rondlopen. Omega-6 vetzuren zijn zeker essentieel voor het lichaam maar de hoeveelheden die mensen tegenwoordig met hun voeding binnen krijgen geven weer aanleiding tot allerlei chronische ziektes. Omdat omega-6 en omega-3 vetzuren met elkaar concurreren in het lichaam heeft alleen extra omega-3 inname weinig zin als niet tegelijkertijd de hoeveelheid omega-6 sterk verminderd wordt. We zullen dus iets moeten doen aan een betere verhouding in onze voeding, veel minder omega-6 en meer omega-3 vetzuren.
How
Omega-6s Usurped Omega-3s In US Diet
Has
a little-known family of polyunsaturated fatty acids called Omega-6s, which has
quietly permeated the Western diet in recent decades, nullified the impact of
heart disease-fighting omega-3s? According to a new book, The Queen of Fats,
Americans now have so many omega-6s in our bodies that eating fish to bolster
our omega-3s may not do any good. Why? Because these two families of fats
compete in our body's metabolism.
Or, as Susan Allport, the author of this new landmark book about the history,
science and economics of omega-3s, published by the University of California
Press (September, 2006), puts it: “It is not the fish we are NOT eating that
is our problem, but the oils we ARE eating.”
How have omega-6s saturated the Western diet so completely and quietly? Ms.
Allport's heavily researched, fact filled book says that most of our cooking
oils are heavily laden with omega-6s (much used corn oil, for example, has a 46
to 1 ratio of omega-6s to omega-3s; lesser used canola oil's ratio, however, is
only 2 to 1), and that whatever omega-3s there are in oils are eliminated if
those oils are hydrogenated or partially hydrogenated to extend the shelf life
of foods, as occurs in most food manufacturing.
Also, when farmers feed corn and soybeans (instead of grass) to the animals we
eat, their tissues become full of omega-6s at the expense of omega-3s. Eggs from
chickens fed corn, for instance, have one-tenth the omega-3s in them as eggs
from free-range chickens that eat greens and bugs.
According to Ms. Allport's research, the out-of-kilter balance between these two
families of fats, one of which is derived from the fats in green leaves
(omega-3s) and the other from seeds (omega-6s), is as much a culprit as
cholesterol, saturated and trans fats for our country's epidemics of heart
disease, obesity and other chronic health problems. Omega-6s are not bad, she
cautions; in fact they are absolutely essential for health. We just have too
many of them.
Ms. Allport writes at a lively pace about how scientists, in just the past two
decades, have discovered how omega-3s are essential for our eyes to see and our
brains to function, and she also focuses on policy changes that are needed. For
example, most people are unaware of the omega-6/omega-3 problem because the
USDA's dietary guidelines do not mention it. The American Heart Association does
not distinguish between these two families of fats.
Short of overhauling some aspects of the food processing and vegetable oil
industries, which she feels ultimately are necessary, Ms. Allport suggests we
should consume oils and fats that have a healthier balance of omega-3s and
omega-6s and eat foods that are rich in omega-3s, including greens, flax seed,
fish, and free range (or omega-3 enriched) meat, dairy products, and eggs. She
has a handy time line of the important omega-3 discoveries (from their use in
brain function to prevention of arrhythmia), 30 pages of medical and science
journal citations, interviews with researchers and a handy glossary of terms.
(Sept.
2006) (Opm. Meer over vetzuren.)