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Fatty
Acid Imbalance Hurts our Health Throughout most of human
history, our ancestors ate a diet that was nearly perfect in its
balance between two essential fatty acids, omega-3s and omega-6s,
which have crucial, though opposite, roles to play in metabolism. In the last few decades,
however, this delicate balance has been thrown out of whack, with
most of us eating too many omega-6s, which come chiefly from corn
and safflower oils, and far too few omega-3s, found in fatty,
cold-water fish such as salmon and tuna as well as walnuts,
canola, soy and flax seed oil. This nutrient imbalance is believed
to contribute to arthritis, cystic fibrosis, heart attacks and
other diseases. “We are drowning in omega-6
relative to omega-3’s,” says Dr. George L. Blackburn,
associate director of nutrition in the Division of Nutrition at
Harvard Medical School. Throughout
evolution, the ratio of omega-6 to omega-3 was two 6’s to one 3,
he says. “Now it’s about 20 to one. We have wiped out a lot of
sources of omega-3 and have a huge intake of omega-6-heavy
products like corn and safflower oils.” “We need some of both,”
adds Dr. Walter Willett, chair of the department of nutrition at
the Harvard School of Public Health. The goal is to bring back a
balance “by increasing omega-3s, not by decreasing omega-6s.” Omega-6 fatty acids get
converted in the body to substances that rev up the immune system
and inflammatory response – a good thing for fighting
infections, but detrimental in people prone to auto-immune
problems such as arthritis. Omega-6s also boost clotting – a
benefit if you’re bleeding to death, but potentially harmful in
terms of increasing clots that can lead to heart attacks or
strokes. “We have doubled omega-6s in
our food supply in the last 40 years” says Willett. “That’s
one of the most important reasons that heart disease mortality has
declined by 50 percent since the 1950s…Omega-6 lowers
cholesterol and has some benefits on platelets and anti-arrhythmic
effects as well….We need the 6s. We don’t want to reduce
those.” Omega-3s, by contrast, get
converted in the body to substances that decrease the immune
response, a benefit for people with auto-immune problems, and
increase the time it takes for blood to clot, a benefit for people
at risk of heart disease. Omega-3’s also decrease potentially
fatal cardiac arrhythmias and are crucial to the healthy
development of the spinal cord, brain and retina in infants and to
healthy brain functioning in older people as well. Because Americans are
relatively deficient in omega-3s, doctors and scientists are now
scrambling to find ways to increase omega-3s in our diet. Last week, researchers at
Massachusetts General Hospital announced that they had genetically
altered mice to produce omega-3 fatty acids. Scientists from Beth
Israel Deaconess Medical Center and UMass Memorial Medical Center
in Worcester also reported on research that suggests that people
with cystic fibrosis may be helped by increasing omega-3s. Later this month, the
Institute of Medicine, an arm of the National Academy of Sciences,
is expected to issue a report evaluating the methods used to
assess the safety of additives to infant formula, including DHA,
an omega-3 fatty acid, and AA, an omega-6. European countries have
long added DHA and AA to baby formulas; American manufacturers
began doing so two years ago to bring formulas closer to the
composition of breast milk. Because there are now so many
products, particularly dietary supplements, out there in health
food stores, supermarkets and pharmacies, it’s worth taking a
moment to understand the terminology on product labels and ads. There are many kinds of
omega-6 fatty acids, and the one people need to consume in the
diet – that is, the “essential” fatty acid – is linoleic
acid. This gets converted in the body to arachidonic acid (AA)
(which cannot be obtained from the diet) and which boosts the
immune system and clotting by increasing a hormone called
prostaglandin E2. There are also many kinds of
omega-3 fatty acids, the most important of which are DHA (docosahexaenoic
acid) and EPA (eicosapentaenoic acid), both of which are found in
fish. DHA can also be made by the body from its precursor, an
omega-3 called linolenic acid, which comes from soy, canola,
walnut and flaxseed. EPA can also be made from linolenic acid. The
body’s biochemical machinery uses these acids to make
prostaglandin E1, which slows down the immune system and increases
the time it takes for blood to clot. Omega-6 and omega-3 are both
in the family of “PUFAS,” or polyunsaturated fatty acids.
Fatty acids are long chains of carbon atoms hooked to each other
and linked hydrogen bonds. If there are no “double bonds”
between carbons, the fat is said to be saturated.
If there is a “double bond” anywhere in this chain, the
fat is unsaturated. If there are lots of double bonds, the fat is
polyunsaturated. Polyunsaturated fats are
considered “good”
because every double bond causes a 37 degree kink in the chain,
which makes the fat more fluid. That in turn makes it easier for
the fat to do one of its major jobs, slink into the fatty membrane
around cells. Because omega-3 fatty acid
suppresses immune function and increases the time it takes for
blood to clot, one might think that an excess could lead to an
increase in infections and bleeding problems. This does not appear
to be the case. “We’re not even close to those dangers - maybe
the Eskimos are,” says Dr. Ernst Schaefer, chief of the lipid
metabolism laboratory at the Human Nutrition Research Center at
Tufts University. The bottom line? Don’t stop
eating omega-6 oils, but increase omega-3 however you can. This
means eating more fish – yes, even salmon despite the risk of
pollutants such as mercury, dioxin or PCBs. It also means
breastfeeding if you can, or choosing formulas containing DHA and
AA if you can’t. If you hate fish, try taking 1
gram a day of fish oil supplements containing omega-3 fatty acids.
But beware: Fish oil capsules vary greatly in quality. To reduce
the chance that the supplements have the same pollutants as in
fish, it may be wise to stick with well-known national brands.
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