Seeds can combat cancer, cholesterol, constipation and coronaries

There is a bagel bakery in Chicago that sells “Brainy Bagels.” I kid you not. They’re made with flaxseeds, which have an extremely high content of alpha-linolenic acid, a compound that falls into the category of omega-3 fatty acids. There is some evidence that omega-3 fats (the terminology refers to an aspect of their molecular structure) could be linked to mental acuity, hence the birth of “Brainy Bagels.” Although I might be skeptical about the bagel’s ability to oil our intellectual machinery, I think it’s probably a smart thing to eat flaxseed bagels, muffins or, in fact, flaxseed anything.

I know what you’re thinking. We already have to eat oat bran, soybeans and broccoli for good health. Now flaxseeds, too? I’m afraid so. The plant that gave us linen, linseed oil and linoleum could also give us longevity. You’ve got to be impressed when scientific studies show that flax might aid in the prevention or treatment of many conditions, including heart disease, cancer and diabetes. How could a simple seed do all that? Basically because the chemical make-up of the seed isn’t so simple. There are numerous components, but three in particular look interesting in terms of health benefits.

Aside from its unclear role in brain function, alpha-linolenic acid has some well-documented effects on heart disease. It reduces the risk of blood clot formation, lowers the chance of potentially lethal irregular heartbeats and probably has an anti-inflammatory effect on blood vessels. Several studies have found a link between increased intake of alpha-linolenic acid and a reduced risk of death from heart disease. Alpha¬linolenic acid helps lower blood cholesterol, but there is another component in flaxseed that doesthis even more effectively. That’s soluble fibre. On its journey through the digestive tract, it binds cholesterol and prevents it from being absorbed. It also binds the bile acids, which are needed for digestion, forcing the body to produce more. Since the starting material for the biosynthesis of bile acids is cholesterol, blood levels of cholesterol go down.

So how many flaxseeds do you have to torture yourself with to reduce your cholesterol? About 2 heaping tablespoons (30 mL or 25 to 30 grams) a day should do it. Grind the flaxseed in a coffee grinder; otherwise a lot of it comes out as it went in. You can store the ground seeds in a tightly closed jar in the fridge but not for very long. The flaxseed oil turns rancid pretty quickly. Sprinkle the ground flaxseed on cereal, mix it into yogurt, stir it into juice. The total cholesterol-lowering is usually in the range of 5 to 10 per cent, with LDL, the “bad” cholesterol, dropping by as much as 18 per cent. This is not far from the results seen with medications. And there’s another benefit. Flax, which has insoluble fibre in addition to soluble fibre, can eliminate more than just heart disease. Since fibre isn’t absorbed by the body but goes “right through,” you’ll be visiting the facilities pretty regularly. There’ll be no need for prune juice. The fibre is even effective in regulating blood sugar for diabetics.

Now we come to the most exciting compound in flaxseeds, namely secoisolariciresinol diglycoside (SD). Don’t let the name scare you. This is potentially great stuff. Bacteria in our colon feed on it and then churn out compounds known as lignans. These have a chemical similarity to estrogen, and since they originate from a plant source, they’re termed phytoestrogens, from the Greek “phyto” for plant. These phytoestrogens have anti-cancer properties.

A study in Finland showed that women with breast cancer had lower levels of lignans in the urine than healthy women. By contrast, the highest urinary levels of lignans were found in women living in areas with low breast cancer rates. This actually makes sense if we look at the molecular mechanism of “estrogen-responsive” breast cancer. In this common form of the disease, circulating estrogen interacts with special proteins in cells known as estrogen receptors. The long protein molecules are coiled into a specific shape with inherent cavities into which estrogen molecules fit, like a key fits into a lock. The result of this interaction is the activation of genes in the cell that are responsible for cell proliferation.

In other words, the cells start multiplying rapidly, a situation that can lead to cancer. The more estrogen molecules around, the more cells activated.

Phytoestrogens are chemically similar enough to estrogen to fit into the receptors, but the fit is not perfect. Something like a rusty key being inserted into a lock. It might not open the lock, but it prevents the right key from entering. If some of the locks are occupied by these rusty keys, there is a smaller chance of cell proliferation. But does this fanciful analogy have any practical significance? That’s what Dr. Lilian Thompson at the University of Toronto wanted to find out. So she induced cancer in rats with a known carcinogen and fed some animals varying amounts of flaxseed. Fewer and smaller tumours developed in the flax-fed animals. Even when tumours formed, they progressed more slowly and invaded tissue less vigorously. This finding meshed with the previous observation that feeding flax to female rats lengthened their estrous cycles. Estrogen governs the cycle and if there is less estrogenic stimulation, the cycle is longer. With less stimulation, one would expect a reduced risk of cancer, which was indeed found.

But more flax is not necessarily better, as researchers discovered.

When the rat chow contained 5 per cent flax by weight, there was a delayed onset of puberty; but when the amount of flax was doubled, onsetof puberty came earlier. In males, 5 per cent flax reduced prostate cell proliferation but 10 per cent increased it.

How do we explain this? Actually it’s pretty reasonable. Although rusty keys may not open locks as effectively, if you have enough of them, they will start opening some locks.

Obviously, with flax, as with other physiological interventions, the dose is important. So not only does eating flax affect body chemistry, but it changes the way the body metabolizes natural estrogen. In a study at the University of Minnesota, post-menopausal women were given diets supplemented with flax, and estrogen metabolites in the urine were measured. There was a significant increase in the level of an estrogen metabolite that protects against breast cancer.

Studies in mice have shown effects against other cancers, like melanoma. When melanoma was induced, there was a reduction in tumours with increasing doses of flaxseed. Even more interesting was the fact that the tumours did not metastasize effectively, suggesting that flax might be an effective adjunct to the diet of cancer patients.

At the University of Toronto, a hundred women with newly diagnosed breast cancer have been enrolled in a study where half of them will eat a daily muffin containing 25 grams of flaxseed. But we don’t really have to wait for the outcome of such a study to increase our flax intake. I’m not sure how much flax the “Brainy Bagels” of Chicago have, but it could be a fair bit. After all, when a student interviewed on a TV news program was asked if he felt any different after eating one, he replied, “Yup, I feel smarter.” Maybe he was right. He then ate another flaxseed bagel.

Dr. Joe Schwarcz is director of McGill University’s Office for Chemistry and Society. He can be seen regularly on the Discovery Channel and is heard every Friday from 10:30 a.m. to noon on CJAD radio. His E-mail address is schwarcz@chemistry.mcgill.ca. You can write to him do The Gazette Magazine, 250 St. Antoine St. W., Montreal, PQ, H2Y 3R7.

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