Dear Dr. Roach: Are there any benefits to taking omega-3?
Dear B.H.: Yes, there are, but it’s not clear just how big those benefits are. Although there has been some evidence that omega-3 fatty acids may be of benefit in slowing dementia, treating depression and helping asthma, the consensus on these topics is that omega-3 supplements are unlikely to have a large benefit.
However, most of the interest in omega-3 fatty acids is in cardiovascular health. There have been many studies looking at the effect of fish-derived omega-3 fatty acids on heart outcomes. Certainly, they reduce triglycerides and slightly increase HDL levels. They slightly cut blood pressure and heart rate. Like other cholesterol-lowering agents, such as niacin and statins, they slightly increase blood sugar levels, though to a lesser extent than other agents.
In large clinical trials looking at outcomes that matter, such as heart attack and overall risk of dying, study results are mixed. Earlier studies tend to show a large benefit, while more recent studies show a small benefit.
However, no studies have suggested significant harm, and my view after reviewing the available studies is that omega-3 supplementation is likely to have a modest heart benefit. The greater the risk of heart disease for a given individual, the more benefit he or she is likely to get.
The amount of omega-3 needed to benefit is small, about 250 mg per day of EPA plus DHA (the two different forms). This can be obtained by a supplement, or by eating about two servings of fatty fish per week.
Dear Dr. Roach: I’ve been diagnosed with midstage prostate cancer. I understand that sugars feed cancer, but what about sugar alcohols?
Dear D.P.: Cancers are very good at using whatever energy supply they can get, including sugar. However, even if you eat no sugar, your body will make sugar, which is necessary for your brain. There is no way to diet so effectively that it can prevent a cancer, of any type, from using sugar to grow.
However, excess sugar isn’t good for anyone, especially someone fighting off cancer, and particularly so in someone being treated with radiation, chemotherapy or recovering from surgery. So, most cancer experts recommend a diet high in fruits and vegetables and low in refined grains and simple sugars. The natural sugars found in fruits will not adversely affect your cancer treatment.
You asked also about sugar alcohols. Sugar alcohols, like xylitol and sorbitol, are poorly absorbed sweeteners. They almost certainly are less harmful than plain sugar, but many people can be very sensitive to their laxative effects. While they will not cause problems with your cancer treatment, foods that have these products are generally less nutritious than the diet above.
Email questions to ToYourGoodHealth@med.cornell.edu.