Omega and Liver Inflammation
From: Andy Soos, ENN.com
Omega-3 fatty acids are
fats commonly found in marine and plant oils. Research at Oregon State
University has found that one particular omega-3 fatty acid has a powerful
effect in preventing liver inflammation and fibrosis — common problems that are
steadily rising along with the number of Americans who are overweight.
Some of
the other potential health benefits of omega-3 fatty acids supplementation
remain controversial. They are considered essential fatty acids, meaning that
they cannot be synthesized by the human body but are vital for normal
metabolism.
The study, published
online in the Journal of Nutrition, was one of the first to directly compare
the effects of two of the omega-3 fatty acids often cited for their nutritional
value, DHA and EPA.
In research with
laboratory animals, it found that EPA had comparatively little effect on
preventing the fibrosis, or scarring, that’s associated with NASH. However, DHA
supplementation reduced the proteins involved in liver fibrosis by more than 65
percent.
"A reduction of
that magnitude in the actual scarring and damage to the liver is very
important," said Donald Jump, a principal investigator with the Linus
Pauling Institute at OSU and a professor in the College of Public Health and
Human Sciences.
Jump said:
"Our studies may represent the first to specifically compare the capacity
of EPA versus DHA to prevent NASH. It appears that DHA, which can also be
converted to EPA in the human body, is one of the most valuable for this
purpose."
NASH is a progressive
form of liver disease that is associated with chronic inflammation and
oxidative stress, resulting from excess fat storage in the liver. Chronic
inflammation can eventually lead to fibrosis, cirrhosis, or even liver cancer.
While management of lifestyle, including weight loss and exercise, is one
approach to control the onset and progression of fatty liver disease, other
approaches are needed to prevent and treat it.
The levels of omega-3
oils needed vary with the health concern, officials say.
"Omega-3 fatty
acids are typically recommended for the prevention of cardiovascular
disease," Jump said. "Recommended intake levels of omega-3 fatty
acids in humans for disease prevention are around 200-500 milligrams of
combined DHA and EPA per day."
Omega-3 fatty acids have
mild antihypertensive effects. When subjects consumed omega-3 fatty acids from
oily fish on a regular basis, their systolic blood pressure was lowered by
about 3.5—5.5 mmHg. Eating a diet high in fish that contain long chain
omega-3 fatty acids does appear to decrease the risk of stroke. However
evidence does not support a beneficial role for omega-3 fatty acid
supplementation in preventing cardiovascular disease (including myocardial infarction
and sudden cardiac death) or stroke.
Levels used in therapy
to lower blood triglycerides, also a risk factor for cardiovascular disease,
are higher, about 2-4 grams of combined EPA and DHA per day. The OSU studies
with mice used DHA at levels comparable to the triglyceride therapies.
"DHA was more
effective than EPA at attenuating inflammation, oxidative stress, fibrosis and
hepatic damage," the researchers wrote in their conclusion. "Based on
these results, DHA may be a more attractive dietary supplement than EPA for the
prevention and potential treatment of NASH in obese humans."
Not all is good
though. In a letter published October 31, 2000, the United States Food
and Drug Administration Center for Food Safety and Applied Nutrition noted that
known or suspected risks of EPA and DHA consumed in excess of 3 grams per day
may include risk from potential increased bleeding and oxidation of omega-3
fatty acids, forming biologically active oxidation products.
For further information
see Omega.
