Healthnotes Newswire (May 17, 2007)—Tuna oil rich in the essential fatty acid DHA (docosahexaenoic acid) can lower triglycerides and possibly enhance the cholesterol-lowering effects of statin drugs, according to a new study.
“We wanted to know the effects of DHA on people whose triglycerides were elevated in addition to their cholesterol,” said Barbara J. Meyer, PhD, associate professor at the School of Health Sciences, University of Wollongong in Australia, and lead author of the new study. “A high proportion of statin-treated patients still have elevated triglycerides.”
Most fat in food and in the body exists as triglycerides. They’re also present in blood plasma and, in association with cholesterol, form the plasma lipids. Elevated triglycerides are linked to coronary artery disease in some people.
To date, only fish oil supplements rich in the essential fatty acid EPA (eicosapentaenoic acid) have been evaluated in people with combined high cholesterol and triglycerides who are controlling their conditions with statin drugs.
The term “statin” refers to a class of drugs that lower cholesterol levels by inhibiting an enzyme needed for the body to synthesize cholesterol. The 45 patients in this study, all with elevated cholesterol and triglycerides, were taking simvastatin (Zocor), pravastatin (Pravachol), atorvastatin (Lipitor), cerivastatin (Baycol), or fluvastatin (Lescol).
In the double-blind study, the patients were randomly assigned to receive either 4 or 8 grams per day of DHA-rich tuna oil, or else an olive oil placebo, for six months.
After three months, triglycerides were reduced by 27% in people who supplemented their diets with 8 grams per day of tuna oil (providing 2.16 grams per day of DHA), and this level of improvement was seen again at six months. There was also a trend toward lowering total cholesterol levels beyond what had already been achieved by the statin therapy. (The 4-grams-per-day group did not experience these improvements.)
Long-term therapy with some statin drugs has been associated with adverse effects on the liver, kidney, and muscles. Other side effects include musculoskeletal discomfort, constipation, indigestion, stomach pain, skin rashes, and flatulence. Statin therapy also results in unfavorable changes in blood levels of another fatty acid called arachidonic acid. Therefore, natural therapies that could decrease statin use without adverse effects are considered desirable.
“Supplementation with DHA-rich fish oil has the potential to further improve cardiovascular disease risk and potentially reduce medication in people taking statins,” Dr. Meyer said. “Taking fish oil together with a statin may be preferable to combinations of drugs currently prescribed for combined high cholesterol and triglycerides, as there are fewer side effects associated with fish oil supplementation.”
(Lipids 2007;42:109–15)
Jeremy Appleton, ND, CNS, is a licensed naturopathic physician, certified nutrition specialist, and published author. Dr. Appleton was the Nutrition Department Chair at the National College of Naturopathic Medicine, has served on the faculty at Bastyr University of Natural Health Sciences, and is a former Healthnotes Senior Science Editor and a founding contributor to Healthnotes Newswire. He has worked extensively in scientific and regulatory affairs in the supplement industry and is now a consultant through his company Praxis Natural Products Consulting and Wellness Services.
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