Soy and cardiovascular disease PART 2
The process of atherosclerosis also alters the natural vasodilatation in the affected arteries. Feeding monkeys with soy leads to the increase of vasodilator response to acetylcholine of the coronary arteries. In short, replacing animal protein diet with soy protein lowers the process of atherosclerosis in several animals, as well as risk factors for atherosclerosis in humans. These positive results determined the Medicines and Food Administration of the US to recently approve supporting that “daily use of 25 g of soy protein in a diets low in saturated fat and cholesterol, can reduce the risk of heart disease’’.
In the first number of 2001 issue of The Journal of Clinical Endocrinology and Metabolism (vol. 86, p. 14-47), Thomas B. Clarkson and collaborators at the Comparative Medical Research Centre and Public Health Department, Wake Forest University, Winston-Salem, USA published the result of a study conducted on monkeys that were fed for 26 months with an atherogenic diet, containing 42% fats, then being ovariectomized continuing with the same regime for 36 months. Some of these monkeys were given soy protein with fitoestrogenele they contain. Compared to the control animals and those who consumed soy presented:
- a significant decrease in total cholesterol;
- remarkable increase in HDL;
- LDL and triglycerides significant decrease;
- reduction of atherosclerotic lesions in the the common and internal carotid artery.
Details of this work supports the conclusion that soy can inhibit or brake the after menopause atherosclerosis. But what are the soy products effects on menopause-related symptoms? In a study, women who consumed 40 grams of soy protein daily had 45% fewer hot flashes, compared to those who consumed 40 grams of casein daily.
In another study, daily intake for four weeks of 20 g of soy protein with isoflavones that it contains, has obviously diminished the severity of vasomotor symptoms, compared to women receiving a carbohydrates placebo.
Researchers at the University of Texas have found that soy diet lowers the circulating levels of 17-beta estradiol with 25%, and progesterone by 45%. It is said that in Japan there is no word for hot flashes.
A few words about soy and about osteoporosis. The fact that asian women rarely presents osteoporosis, despite the fact that they ingest less calcium and that they use far less the estrogen hormone substitution therapy than women in western hemisphere has intrigued the researchers. We should notice that as the alimentation of Japan is becoming increasingly similar to that of the west, the frequency of osteoporosis is increasing.
It showed that the soy protein prevents loss of bone mass due to the estrogen deficiency at ovariectomized rats.
In women, daily administration for six months of 40 g of soy protein has led to an increase in mineral content and the bone density in the lumbar spine, compared with women that received daily 40 g of casein.
In the Phytochemistry journal (2001; 56 (7): 733-9), Choi and collaborators shows that in tissues cultures, soy increases the bone-forming cell activity, ie osteoblasts.
Finally, the administration of soy for 10 weeks improved the short and long term memory. And at women in menopause, soy administration for six months improved verbal memory, compared to a group that received a placebo.
Studies conducted so far shows that soy can improve the cognitive functions both in men as well as in women, regardless of age. Soy isoflavones acts on the hippocampus and the front crust of the brain.