Genes Boost Fish Oils' Effect Against Breast Cancer
Fri Sep 24, 2004 7:03 PM ET
FRIDAY, Sept. 24 (HealthDayNews) -- Women with certain genes get an extra protective boost when they take fish oils called marine n-3 fatty acids that may reduce the risk of breast cancer.
That's the conclusion of a study by researchers at the University of Southern California and the National University of Singapore.
The study found that women whose bodies do a poor job of eliminating the fish oils' byproducts seem to derive the most benefit from taking them. It's believed the fish oils' byproducts provide the cancer-fighting properties.
"In this study, we found that women with certain common DNA patterns experienced more breast cancer protection from marine n-3 fatty acids than women with other common patterns," study author Dr. Manuela Gago-Dominguez, an assistant professor of preventive medicine at USC's Keck School of Medicine, said in a prepared statement.
Researchers examined data from the Singapore Chinese Health Study of diet and cancer risk in more than 63,000 Chinese women and men who live in Singapore.
The findings could help scientists better understand how fish oils may protect against cancer.
The study appeared in the Sept. 21 online issue of Carcinogenesis.
Potential Side Effects of Fish Oil Capsules
General: Fishy odor, gastrointestinal upset
Coagulation: Increased bleeding time may result in nosebleeds, easy bruising
Metabolism: Can increase cholesterol in those with combined hyperlipidemia
Can increase calorie intake and hence weight gain
Some preparations have added cholesterol
Some lack vitamin E (alpha tocopherol); concern for oxidation
Immune response: Various parameters are decreased (uncertain significance)
Toxicity: Vitamin A and D toxicity with some preparations
Some fish oils (not highly refined) may contain pesticide
Concerns regarding effects on immune response
Cost: Expensive compared with dietary fish intake
Omega-3 Fatty Acids Improve Systemic Arterial Compliance
Laurie Barclay, MD
Medscape Medical News 2002. © 2002 Medscape
July 26, 2002 — Two omega-3 fatty acids contained in fish, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), significantly improve systemic arterial compliance, according to the results of a double-blind, placebo-controlled trial reported in the August issue of the American Journal of Clinical Nutrition. As a result, systolic and pulse pressure and total vascular resistance tended to decrease, while triglyceride levels dropped significantly.
"Substantial epidemiologic and other evidence shows that eating fish may benefit people at high risk for ischemic heart disease (IHD), [and] sudden cardiac deaths occur less frequently in individuals who habitually [eat] fish," write Paul Nestel, from Baker Medical Research Institute in Melbourne, Australia, and colleagues. "Because of increasing evidence linking heightened pulse pressure, a reflection of increased arterial stiffness, to increased coronary risk, interventions that improve arterial compliance are thought likely to reduce risk for IHD."
During a seven-week dietary intervention, 38 middle-aged men and women with elevated plasma total cholesterol were randomized to treatment with an EPA supplement (3 g/day), a DHA supplement (3 g/day), or placebo.
Systemic arterial compliance was unchanged in the placebo group, rose 36% in the EPA group and 27% in the DHA group (P=.043), and there was a trend toward reduced systolic and pulse pressure in the omega-3 fatty acid groups. Plasma total and very low density lipoprotein triacylglycerol concentrations were significantly lower in the treatment groups than in the placebo group (P=.026 and .006, respectively).
"EPA and DHA increase systemic arterial compliance and tend to reduce pulse pressure and total vascular resistance, effects that may reduce the risk of adverse cardiovascular events," the authors write.
Am J Clin Nutr. 2002;76:326-330
Reviewed by Gary D. Vogin, MD
Laurie Barclay, MD, is a staff writer with WebMD.
Medscape Medical News is edited by Deborah Flapan, an associate editor at Medscape. Please send press releases and comments to news@webmd.net.
Fish Oil Reduces Body Fat Mass
Obesity is not only widespread in world populations, but has been designated by the World Health Organization as an important risk factor for heart disease, diabetes, certain cancers and a number of other disorders. As a result, many scientists are currently focusing on ways to combat this growing problem. New research, as reported in the March 1998 issue of PUFA Newsletter, suggests that omega-3 fatty acid supplementation may reduce body fat mass.
Data from animal studies has indicated that omega-3 fatty acids, which are found in fish and fish oil, may modulate the balance between the proportion of fat that is burned up as energy and the amount that is stored. For example, feeding rodents fish oil reduces weight gain and the deposit of body fat.
In a recent study at Bretonneau Hospital, Tours, in France, a group of six healthy volunteers (five men and one woman) were given tests with two types of diet. First, they spent three weeks on a conventional French diet, with no restrictions on quantity, eating meals prepared by a dietitian and comprising 52 per cent carbohydrates, 16 per cent protein and 32 per cent fat. Then, between 10 and 12 weeks later, the volunteers ate the same diet for a further three weeks except that 6 g of fat (such as butter, olive oil and sunflower oil) was replaced by 6 g of fish oil each day.
The latter was administered as capsules containing 1.8 g per day of fish oil, which, depending on the species, is equivalent to between 100 and 200 g of fish. At various times the researchers measured energy intake, physical activity, weight, metabolic rate, and other indicators including body composition.
Substituting fish oil for the same amount of visible fat appeared to stimulate the resting metabolic rate by some four per cent, reports Dr C. Couet, who led the investigation. Over the three weeks, subjects eating the control diet showed a 0.30 kg reduction in body fat. However, while eating the fish oil diet the decrease in body fat almost tripled to 0.88 kg, even though there was no change in weight. The absence of weight loss may have been due to the very short period of the tests.
The number of participants in the study was too small to draw conclusions about the usefulness of fish oil supplements in management of obesity, the investigators noted. However, further research with larger numbers and including obese patients is now envisaged.
Both Fish Oil and Vitamin E Improve ALT (liver function test) in Study
Jules Levin, NATAP
VITAMIN E OR OMEGA-3 FATTY ACID CONCENTRATE (OMACOR‚) AS SUPPRESSIVE TREATMENT FOR PATIENTS WITH CHRONIC HEPATITIS C.
John B Gross, Laurie A Czaplewski, David J Brandhagen, Albert J Czaja, John J Poterucha, Terry M Therneau, Mayo Clin, Rochester, MN
For patients with chronic hepatitis C who are not candidates for interferon-based treatment, an alternative might be suppressive treatment with a well-tolerated agent that reduces inflammation and might therefore slow progression of fibrosis. Vitamin E has previously been shown to reduce ALT levels among a small group of patients with chronic hepatitis C. Omega-3 fatty acid (O3FA) concentrate (Omacor‚) has been shown to reduce disease activity in chronic conditions such as arthritis and IBD. AIM: to determine whether short-term treatment with vit E or O3FA reduces serum ALT levels among patients with chronic hepatitis C.
METHODS: Patients had histological evidence of chronic hepatitis, detectable serum HCV RNA, and ALT at least 2X normal. They had received no antiviral, herbal, or vitamin treatment within 30 days of entry. In random order, they were given vit E 400 IU BID x 12 wk, then O3FA 2 g BID x 12 wk, or vice versa, with 12-wk observation after each. Blood tests were monitored at 0, 2, 4, 8, and 12 wk of treatment, and at 12 wk after treatment.
RESULTS: 20 patients were enrolled, most having failed interferon; 13 have completed treatment and follow-up on vit E, and 10 on O3FA. On vit E, median ALT was ~60% of baseline, starting at 2 wk; 11 of 13 patients had a reduction in ALT. On O3FA, median ALT gradually declined to ~60% of baseline at 12 wk; 7 of 10 had reduced ALT. Median ALT relapsed toward baseline after each treatment. Median ALT (% of baseline): see table. Among 7 patients on vit E with paired PCR results available thus far (Chiron bDNA assay), we found no significant changes in RNA levels on treatment compared to baseline.
CONCLUSIONS: 1) Both vitamin E and O3FA (Omacor‚) can reduce ALT levels among patients with chronic hepatitis C. 2) The progressive decline in ALT over 12 weeks on O3FA suggests that longer treatment might be beneficial. 3) These agents warrant further study as alternative suppressive treatments for patients who are not candidates for conventional therapy. Grant support was received from Mayo Foundation and from Pronova a.s. (NorwayFISH OIL FOR ARRYTHMIAS
Previous studies have suggested that fish oil supplements may reduce the risk of an additional heart attack or stroke in patients who have recently experienced a heart attack. Now new study findings reveal that the supplement may also reduce the risk of sudden death. The findings show that this reduced risk was evident after as few as 3 months, which seems to support the hypothesis that adding n-3 polyunsaturated fatty acids (PUFAs)--commonly found in fish and fish oil--to a healthy diet may lower the risk of fatal arrhythmia, an irregular heartbeat that in severe cases can lead to cardiac arrest, the authors report. "Reduction of sudden death appeared early after start of treatment," lead study author Dr. Roberto Marchioli, of Consorzio Mario Negri Sud in Italy, told Reuters Health. This "seems to support the idea that (the benefits of PUFAs) could be due to an anti-arryhythmia effect," he added. The study included 11,323 patients who had suffered a heart attack within the previous 3 months. All of the patients received the same preventive care and ate Mediterranean-style diets rich in fruits, vegetables, olive oil and fish. But some patients also consumed 1 gram of the fish oil supplements per day. During the 3.5-year follow-up period, 1,031 individuals died, Marchioli and his colleagues report in the April issue of the Circulation: Journal of the American Heart Association. Patients who took the fish oil supplements appeared to be at a 41% lower risk of death from any cause after only 3 months of treatment, study findings indicate. After 4 months of treatment, these patients also appeared to be at a significantly reduced risk of sudden cardiac death. And by the end of the study period, patients treated with fish oil supplements were 45% less likely to die suddenly from a heart-related cause, Marchioli and his colleagues report. In light of the findings, Marchioli said that the benefit of fish oil supplements "seems to be additive to the benefit that can be obtained by standard preventive treatment." "One capsule of a fish oil concentrate daily for 3.5 years resulted in a very significant reduction in sudden cardiac death. Thus, a simple and safe change in diet can potentially produce a large public health benefit," editorialist Dr. Alexander Leaf of Harvard Medical School in Boston, Massachusetts, told Reuters Health. "Individuals who have known coronary heart disease or a family history of coronary heart disease among immediate relatives would be prudent to heed the recent advice of the American Heart Association to eat two or more meals of oily fish per week or take a daily supplement of fish oil capsules," Leaf added.
Eating oily fish cuts heart attacks
Studies suggest fatty oils can reduce risk o
f cardiac deaths up to 30 percent.By David Brown / Washington Post
HEART RHYTHM AND FISH OIL
BOSTON -- Two new studies show that both men and women who eat substantial amounts of oily fish are greatly protected from fatally abnormal heart rhythms.
The studies -- which both draw their conclusions from long-term observation of tens of thousands of people -- greatly bolster the evidence that eating fish regularly can have major health benefits.
While most of earlier studies involve only men, one of the new studies demonstrates fish's benefit in women.
Although ocean-living, cold-water oily fish such as salmon, swordfish and tuna offer the largest easily accessible source of beneficial n-3 fatty acids, there are others. Flax seed oil, canola oil, and English walnuts all contain significant amounts of the oils.
Scientists in both studies said that while eating fish is good advice, people shouldn't jump to the conclusion that fish-oil supplements are an equivalent or a substitute.
One Brigham and Women's Hospital study, which appears in today's Journal of the American Medical Association, found that the more frequently a woman ate fish, the less likely she was to suffer a heart attack or die of any cardiac cause.
Specifically, those who ate fish three times a month had a 30 percent lower risk of heart attack or death as those who never ate fish. Eating fish five times a week was only slightly more beneficial; those women had a 34 percent lower risk. Similar trends were seen in estimations of n-4 fatty acids in the diet.
The study was based on the experience of 85,000 women nurses, beginning in 1976.
Each year, about 220,000 Americans experience sudden death, collapsing and dying within an hour, often before they get to a hospital. In most cases, an abnormal heart rhythm arising from existing heart disease is believed to be the cause. In about 50 percent of cases, however, the sufferer is unaware he or she has heart disease. There's no chest pain or previous heart attack. Instead, sudden death is the first symptom of their problem.
"Prevention is really the only way to impact the rate and mortality from sudden death," said Christine Albert, a cardiologist at Brigham and Women's Hospital in Boston, who headed a second study. "One way you could do it in a population that's healthy is through diet and lifestyle."
In Albert's study, published in this week's New England Journal of Medicine, researchers looked at the experience of about 22,000 male doctors who enrolled in the Physicians' Health Study in 1982. They were all free of heart disease at the time, and about 15,000 also volunteered a blood sample.
Over the next 17 years, 94 of the men who'd given blood samples and who hadn't subsequently been diagnosed with heart disease died suddenly. The researchers chose about 180 surviving members of the study and compared them with those victims. In particular, they compared the bloodstream concentrations of substances called n-3 fatty acids, found primarily in fish oils.
On average, the men who died had lower amounts of n-3 fatty acids than the ones who hadn't died suddenly. When the researchers divided all the men into four groups based on the concentration of n-3 fatty acids in the blood, the men in the highest quarter had only one-fifth the risk of sudden death as those in the lowest quarter.
The researchers used dietary information gathered in five interviews between 1980 and 1994 to estimate fish intake. They also calculated the approximate amount of n-3 fatty acid consumed, based on the type of fish the women listed in their diet questionnaires.
The nurses' study also showed that the primary effect was in reducing sudden death, although the risk of having a heart attack was also lower in fish-eaters.
Terry Jacobson, a physician at Emory University who has studied the effects of fish oils on heart disease, said he believes the new studies "have large public health implications." He added, however, that before fish-oil can be used as preventive medicine in healthy people, a study needs to be done in which people are randomly assigned to either get the oils or a placebo.
He said he plans to propose such a study to the National Institutes of Health in the near future. He said at least 6,000 people would need to be enrolled and observed for at least three or four years.
A European study published in 1999 showed that fish-oil supplements reduced the risk of sudden death in people who'd already suffered a heart attack. The n-3 fatty acids appear to have a specific antiarrhythmic effect, possibly by stabilizing membranes of heart muscle cells.
The oils also have a blood-thinning effect similar to aspirin. In some observational studies, fish consumption has been associated with a lower risk of stroke. There have been anecdotal observations that fish-oil supplements may have anti-depressant effects, as well.
