FOCUS ON NUTRITION ED BLONZ
Be careful when choosing and using flax seed

April 2, 2008

QUESTION: I have been using flaxseed as a source for omega-3 fatty acids, sprinkling some on my cereal or using it in baking. I recently read that raw flaxseed is toxic until it is heated, but flaxseed oil is not toxic. Should I be baking my ground flaxseed in muffins, breads, etc., instead of eating it raw? Should I stick to flaxseed oil?



ANSWER: Let's check out some of the basic flax. The fatty acids in flaxseed are highly unsaturated, more so than most other vegetable oils. This makes flax seeds more susceptible to oxidation, a reaction that destroys the nutritive value of an oil and turns it rancid. This doesn't make the oil toxic, but rancid fats are not what you want in your food or in your body. The key is exposure to air (oxygen), and heat can speed up the process.

The intact flaxseed has a protective coat that keeps the oil safe inside. The seed coat is so strong that most intact flaxseeds tend to pass right through our digestive systems.

Inside flaxseeds are a number of antioxidants, which are nature's way of helping assure the viability of the seeds once they are planted. The healthful components of the flaxseeds become available to us once the seeds are cracked or ground, but the process also increases the susceptibility to oxidation. This is why ground flaxseed should be stored in airtight containers and kept in the refrigerator once opened.

One other aspect that relates to toxicity is the fact that flaxseed contains cyanogenic (cyanide producing) compounds. Their mere presence does not make flaxseed dangerous; it all comes down to the dose and the nutritional status of the consumer.

Cyanogenic compounds are present in a number of other foods, and they cause problems primarily in individuals who are malnourished, particularly those who have an inadequate intake of protein. The cyanogenic compounds in flaxseed are more a concern for livestock, which may consume very large amounts. Heat or processing provides a remedy because it helps to break down the compounds into harmless substances.

Note that if you were to take a purified flaxseed oil, you would get the omega-3s but not the fiber or phytochemicals naturally present in flax. You would avoid the cyanogenic compounds, but the risk of rancidity would remain.

If you are interested in using flaxseed oil, look for a brand that contains all the beneficial compounds found in the intact seed. These include the phytochemicals known as lignans.

Flaxseed oils should be stored in the refrigerator or freezer.

Is there a health difference between steel-cut oatmeal and longer cooking oatmeal? Does the preparation make a health difference, too? I prepare mine by putting both oatmeal and water in at the same time and then cooking. Thank you.

O.M.

ANSWER: There is no health or nutritional difference between steel-cut and traditional long-cooking oatmeal. The same goes for quick-cook oats. It is the cut of the oats and the speed with which they cook, not the oats themselves, that are different.

One-half cup (40 grams) of the dry oats in any of those cuts contains about 3 grams of fat, 5 grams of protein, 27 grams of carbohydrate, 4 grams of fiber and no sodium. Your method of preparation sounds fine.

Ed Blonz, Ph.D., is a nutritional scientist based in Northern California. General-interest questions about nutrition can be mailed to: Ed Blonz, Focus on Nutrition, P.O. Box 120191, San Diego, CA 92112-0191, or sent via e-mail to [email protected].