Can You Fight Heart Disease With Fish?

Although the use of highly active antiretroviral therapy (HAART) has many benefits, it can have a dark side -- side effects. Some HAART-related side effects are grouped under the label HIV-lipodystrophy syndrome, or, more simply, lipodystrophy. The main features of this syndrome include the following:

• loss of fat under the skin (subcutaneous fat), particularly in the face, arms and legs
• fat gain in the abdomen, shoulders and breasts (mostly in women)

In addition to these physical changes, other aspects of the lipodystrophy syndrome may involve changes in the levels of certain substances in the blood as follows:

• increased levels of sugar (glucose)
• increased levels of the hormone insulin
• increased levels of fatty substances such as triglycerides
• increased levels of "bad" LDL cholesterol
• decreased levels of "good" HDL cholesterol

These changes can increase the risk of cardiovascular disease and diabetes. In addition to changes to the diet and implementing an exercise program, drug therapies and supplements are available to help manage these complications. For more information on these, please see CATIE's "Practical Guide to HIV Drug Side Effects," available at www.catie.ca/sideeffects_e.nsf.

We now bring you a report on a short-term study about the use of fish and borage seed oils to help alter lipid -- cholesterol and triglyceride -- levels in the blood. Although the subjects in this study were healthy and HIV negative, the results may be useful for researchers planning studies in people with HIV.

Why Fish Oil?

For the past two decades, researchers have been testing substances called omega-3 fatty acids -- EPA and DHA -- found in fatty fish such as:

• anchovies
• cod
• halibut
• sardines
• salmon
• tuna

In high doses, EPA and DHA can lower triglyceride levels in the blood of people. Unfortunately, these supplements do not usually lower levels of "bad" LDL cholesterol or raise levels of "good" HDL cholesterol. Oils from certain plant sources such as evening primrose or borage seeds contain a substance called GLA, which may also have an impact on lipid levels in people.

To find out about the effect of fish and plant oils on lipid levels, researchers at the University of Guelph, Ontario, conducted a study using healthy middle-aged subjects. The researchers found that a mixture of the two oils was able reduce triglyceride levels and raise levels of "good" HDL cholesterol.

Study Details

Researchers recruited 32 healthy women, then divided them into four groups where they received different combinations of EPA, DHA and GLA. The study lasted for four weeks.

Results

The most interesting results were from the group that received 4 grams/day of EPA and DHA and 2 grams/day of GLA. In this group, triglyceride levels fell by 35%. Levels of "bad" LDL cholesterol fell by 11%. These changes were statistically significant; that is, not likely due to chance alone.

Reducing the Risk of Heart Disease

The researchers used an established risk "calculator" called PROCAM (available at www.chd-taskforce.de/calculator/calculator.htm) to assess the changes in blood lipid levels and to also take into account other factors such as age, smoking, etc. They found that the group that received 4 grams/day of EPA and DHA and 2 grams/day of GLA had, in theory, a 43% reduced risk of a heart attack.

Longer and well-designed studies for testing these oils in HIV positive people on HAART are also required. Although the results of this study are promising, a disadvantage with this "natural" approach is the large amount of capsules -- in some cases as many as 10 -- of fish and borage seed oil that need to be consumed on a daily basis. This may affect adherence to fish oil therapy over the long term. And taking such a large dose of fatty acids may also require "preservatives" to prevent them from going rancid or oxidizing in the body. Examples of preservatives or antioxidants that can dissolve in fat include vitamin E, co-enzyme Q10 and alpha-lipoic acid.

Notes

The omega-3 fatty acids used in this study were:

• EPA: eicosapentaenoic acid
• DHA: docosahexaenoic acid
• GLA: gamma-linolenic acid

The fish oil used in the study had higher-than-normal levels of EPA and DHA and was supplied by Croda Chemicals Ltd., in Goole, UK. The oils and fatty acids used in the study were placed into capsules by Bioriginal Food and Science Corporation in Saskatoon, Canada. Not mentioned in the study is that high doses of fish oils can prolong the time taken for blood to clot. Over the short length of the Guelph study, this did not appear to be a problem. Eating three servings of fatty fish each week is also a good way of obtaining EPA and DHA.

References

1. Simpoulos AP. Omega-3 fatty acids in inflammation and autoimmune diseases. Journal of the American College of Nutrition 2002;21(6):495-505.
2. Laidlaw M and Holub BJ. Effects of supplementation with fish-oil-derived n-3 fatty acids and ã- linolenic acid on circulating plasma lipids and fatty acid profiles in women. American Journal of Clinical Nutrition 2003;77:37-42.