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Life Extension Magazine

Life Extension Magazine April 2010
Nutraceutical Update

Lignans
Important Phytonutrients for Robust Health


By Dale Kiefer
Cardiovascular Protection

Cardiovascular Protection

Diets including plenty of whole grains, nuts, seeds, legumes, fruits, and vegetables are loaded with lignans, and such diets have been consistently associated with a reduced risk of cardiovascular disease. Of course, such diets also contain a host of other phytonutrients, so this cardioprotective effect would not necessarily be owed solely to the high lignan content. But studies that have investigated this question appear to confirm an important role for lignans in cardiovascular protection.32,34-37,65

In 1998, for example, Canadian researchers addressed the issue by examining the effects of two different types of flaxseed on markers of atherosclerosis in rabbits. One group received flaxseed high in both lignans and the omega-3 fatty acid, alpha-linolenic acid (ALA). A second group received a type of flaxseed, called Type II, which is high in lignans but virtually devoid of fatty acids. Both types of flaxseed reduced atherosclerosis. Type II flaxseed reduced the development of atherosclerosis by 69%. Researchers concluded that the reduction in atherosclerosis by the low-omega-3 flaxseed was due to a decrease in serum total cholesterol and LDL. “In conclusion,” they wrote, “[the atherosclerosis-reducing] activity of Type II flaxseed is not due to alpha-linolenic acid.”36

Several clinical trials have reported a link between flaxseed consumption and modest, but significant, reductions in LDL levels. Subjects experienced from 8 to 14% reductions in levels of this “bad” lipid.34,35,65 Of course, the importance of lowering LDL for optimal heart health is widely documented. More recently, US scientists conducted a randomized, placebo-controlled, double-blind study of the relationship between flaxseed consumption and cardiovascular disease risk factors in adults with high cholesterol.

Subjects consumed 40 grams ground flaxseed per day, or placebo, for 10 weeks. Compared to placebo (wheat), flax significantly reduced LDL levels at five weeks. Average reductions were 13%. By 10 weeks, reductions were approximately 7%. “Ground flaxseed has a modest but short lived LDL-cholesterol lowering effect,” researchers concluded. Additionally, levels of lipoprotein (a) were significantly reduced, by about 14%, and insulin sensitivity was significantly increased.30 High levels of lipoprotein (a) are associated with an increased risk of atherosclerosis, which is a root cause of most heart disease.66

Bolstering Bone Health

Osteoporosis threatens the health of both aging men and women, but it is especially troublesome for elderly women. In the United States, approximately 10 million Americans are affected by osteoporosis, and the financial impact of the disease is estimated to be at least $17.9 billion per year.52 Characterized by a progressive loss of bone mass through a process known as demineralization, osteoporosis increases bone fragility, thus increasing the risk of fracture.10 Among women, estrogen deficiency following menopause plays an enormous role in the development of bone fragility.67 Observational studies have shown that populations with a high intake of soy isoflavones experience a lower incidence of osteoporosis-related fractures compared to Western populations.49

Bolstering Bone Health

Researchers examined data from more than 70 studies for a 2003 review of the evidence regarding phytoestrogens (including lignans) and bone health. These included studies involving bone cells grown in the laboratory, investigations using animal models of human postmenopausal osteoporosis, and human observational/epidemiologic and human dietary intervention studies. “On balance,” wrote the authors of the review, “the collective data suggest that diets rich in phytoestrogens have bone-sparing effects in the long term…”50 More recently, Chinese researchers conducted a meta-analysis, in which data from numerous clinical trials is combined and statistically analyzed. After examining data from ten trials, involving more than 600 subjects, they wrote: “The spine bone mineral density in subjects who consumed isoflavones increased significantly…in comparison to that in subjects who did not consume isoflavones.”51

These investigators concluded: “Isoflavone intervention significantly attenuates bone loss of the spine in menopausal women. These favorable effects become more significant when more than 90 mg/day of isoflavones are consumed.” Furthermore, wrote the Beijing-based scientists, “…Soy isoflavone consumption for six months can be enough to exert beneficial effects on bone in menopausal women.”51 Thus it is possible to protect bone health even later in life, by increasing phytoestrogen intake.

While many of these studies have considered the bone-sparing effects of isoflavone phytoestrogens, rather than lignans in particular, there is strong evidence that lignans are equally effective at protecting against osteoporosis. For example, Japanese researchers conducted an experiment on female rats, removing their ovaries to simulate the effects of menopause on women. The bones of test animals that received the lignan, isotaxiresinol, for six weeks were compared to the bones of rats that did not receive the lignan. Both bone mineral content and bone mineral density were increased in test animals as compared to control rats, and decreases of three bone strength indexes, induced by the removal of the animals’ ovaries, were prevented. “Biochemical markers for bone remodeling revealed that isotaxiresinol slightly increased bone formation and significantly inhibited bone resorption [bone loss] without side effect on uterine tissue,” wrote the scientists.53

Summary

Lignans may not often make headlines, but chances are they’ve been protecting you from a variety of degenerative conditions for as long as you have been consuming whole grains, legumes, vegetables, soy and/or flaxseed. Life Extension® members consume potent lignan concentrates in the supplements they use every day. A plethora of evidence shows that these important phytochemicals work in a variety of ways to prevent cancer, protect the cardiovascular system, ward off viral infection, and maintain bone health.

If you have any questions on the scientific content of this article, please call a Life Extension® Health Advisor at 1-866-864-3027.

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