Benefits — and risks — of flaxseed oil
Dear Dr. Blonz: You wrote about flax recently, and I bought some, ground it in my coffee grinder, and have been adding it to my diet on a daily basis. I have two questions. First, what is the recommended daily amount? I have found anything from 1-3 tablespoons as a guideline. I want to take enough to get the benefits, without taking too much. Secondly, and more importantly: A physician quoted online said that men should avoid flaxseed based on a study by the University of Virginia School of Medicine, which found that the oil “may promote the growth of prostate tumors in someone with prostate cancer.” Is this a valid concern? Does it apply to ground flaxseed? Is the risk worth the health benefits? — P.P., San Jose, California
Dear P.P.: Fats and oils represent nature’s most concentrated sources of energy. Fat is the storage material of choice in the plant world, ideal when there is a need to pack a lot of energy in a small space. Seeds tend to be light in weight and small in size, yet contain sufficient energy to fuel a plant’s initial growth until the sprout can poke out of the soil, into the sunshine, and begin to make energy on its own. Seeds need protections for this purpose. The primary defense is the seed coat, but also important are the phytochemical substances that protect the fat from various environmental, insect or microbiological elements.
Flaxseed oil is highly unsaturated: About 60 percent of the fatty acids in flax are polyunsaturates. Of concern with prostate cancer is alpha-linolenic acid (ALA), an omega-3 polyunsaturated fatty acid that is plentiful in flax. Research has reported a significant relationship between the intake of ALA and the risk of various aspects of prostate cancer.
A key point here is the fact that when flaxseed oil is removed from the seed and separated from its phytochemical bodyguards, the chances of the oil breaking down and causing health problems may increase. With whole flaxseed, you get the entire package of fats, fiber and the variety of phytochemical compounds and antioxidants, known as lignans, naturally present in flax. These are not normally present in flaxseed oil. You can, however, find flaxseed oil products that include these compounds along with the oil.
Whole flaxseed has not been associated with an increased risk of cancer. In fact, there is evidence that this whole food has cancer-fighting abilities.
The message is that we need to make sure that the fats we eat are well protected by having them as a part of a whole food. Eating whole greens, vegetables, fruits and certain seeds allows those foods to bring along their full variety of healthful components.
When eating flaxseed, cracking or grinding the seeds makes sense, as the fibrous protective coats of intact seeds tend to pass through undigested. One tablespoon of ground flaxseed contains about 1.6 grams of omega-3 fatty acids, which is in the range recommended for adults by the Institute of Medicine. (If not used immediately, ground flax should be refrigerated in a tightly sealed container.)
Readers may email questions to questions@blonz.com.