Soy Intake And Its Impacts On Health Essay
The consumption of soy products has become a subject of debate since their recent introduction in the Western diet. Although soy consumption has tremendously increased due to the evidence provided by recent campaigns on its health benefits, there is a brewing controversy affecting soy intake. Some critics argue that some studies suggest that taking soy products has certain adverse effects to health. Consumption of large quantities of soy products has been linked to early puberty in girls, as well as decrease in sexual energy, especially in men.
This paper seeks to determine if these are facts or myths by examining soy intake and some of its impacts on health. Soy (or Soya) is a term commonly used to represent products derived from soy beans. Soy beans are obtained from the soy bean plant, which is a legume plant originally cultivated in ancient Asia. It was not until the first century AD when soybeans were introduced to other countries. Contrary to popular belief, soy was never a staple in Asia. It was used to supplement other foods and only used to a large extent during food shortage cases.
The legume became popular in North America and Europe during World War II and it has received so much liking ever since that it is currently the leading crop in the United States. Soy products have numerous and uses, ranging from popular foods such as tofu, tempeh, soy milk, to industrial products such as soap and cosmetics. In the United States, soybean oil accounts for 80% of domestic bio-diesel production. But it is soy’s impacts on health that has become a controversial issue, with many people linking soy to infertility, thyroid cancer, breast cancer and hypothyroidism and other numerous disorders.
Some of these may be myths, half-truths and others may be plain lies. So as to appropriately determine the impacts of soy on health, it is of paramount importance to first explore the nutrient composition of soy. Various soybean products such as whole bean, soy flour, soy concentrate, and soy isolate, soy milk and tofu have varying essential amino acid composition. Among other amino acids, Phenylalanine & Tyrosine, a non essential amino acid that helps regulate mood and also stimulating the nervous system is found in big amounts.
For instance, tofu has 83 mg/100g protein, with other products such as whole bean, soy flour and soymilk having 87mg/100g and 80mg/100g of protein respectively. Other vital amino acids found in large amounts are Leucine, Lysine and Isoleucine, among other amino acids such as Threonine, Tryptohan and Valine, which have a significant contribution as well, although Tryptohan is only available in products such as soy flour, soy concentrate and soy isolate in small amounts of 14mg, 16mg and 14mg/100g protein respectively. Tofu, soymilk and whole bean have negligible amounts of the amino acids (Los Angeles Chinese learning center, 2000)
One of the key issues affecting soy intake is whether it lowers cholesterol. Cholesterol, a waxy alcohol found in the blood plasma and required by all animals for normal cellular function is vital for life, though in small quantities. Cholesterol needs to be taken in very small amounts because consumption of foods rich in cholesterol leads to its accumulation in the body tissues which has been associated with atherosclerosis, a disease which causes chronic inflation in the arteries. Many foods have been identified as favorites to lowering cholesterol levels in the body tissues.
Among the major ones are: oat for soluble fiber, fish for Omega 3 Fatty Acids, nuts for healthy fats, foods fortified with plant sterols and last but not least, soy products. It is important to note however that these are only the major foods. Researchers have recommended the intake of other foods such as sugar cane (natural extract) and discouraged industrial processed sugar which is linked to high blood pressure levels . Green tea and turmeric extract, among other related foods have also been recommended because they all have a significant role in lowering cholesterol.
Clinical evidence has shown that although soy may not lower cholesterol to a large extent, soy products should not be avoided altogether. Since soy products contain high level of polyunsaturated fats, fiber, vitamins, minerals and low levels of saturated fat, they are considered a healthy replacement for meats and other foods high in saturated fat and total fat. (Health Castle, 2006) Cholesterol campaigns are conducted every day to especially discourage people from processed foods and instead consume raw, fresh products.
This campaign has attracted media interest in recent years as many diseases and health complications affecting people are cholesterol linked, caused by overweight cases. A case study on soy consumption and cholesterol reduction was made in the department of biochemistry, the University of Western Ontario, Canada, to support that soy products indeed lower cholesterol in much high levels, compared to animal proteins. The study revealed that animal proteins such as casein are more hypercholesterolemic than soy protein or other plant proteins when fed to rabbits in low fat, cholesterol free, semi purified diets.
Soy protein gave a lower level of serum cholesterol in rabbits than did a soy protein-amino acid mixture, suggesting the presence of factors in soy protein that counteract the effects of hypercholesterolemic amino acids. More evidence favoring soy protein revealed that soy protein is also less hypercholesterolemic than casein in other animal species, particularly when the diet contains cholesterol, and substitution of soy protein for animal protein in the diet reduces the concentration of serum cholesterol in humans.
With the threat of inflamed arteries caused by atherosclerosis due to accumulated cholesterol in human bodies which results to large amounts of money in diagnosing and treating the disease, and greater risks of surgical intervention in sever cases, any dietary measures to prevent this disease need not to be taken lightly. And with the proof gained from various scholarly articles, soy intake indeed lowers cholesterol. Another field which has received a lot of attention globally is the effect soy has on cancer.
A lot of money is being spent everyday in laboratories, government offices and research stations in an effort to look for better ways to curb this class of diseases. With cancer causing more than 10% of all deaths in the world and the death rate increasing everyday, there is definitely a cause for alarm. So as to best understand the effects of soy on cancer, it would be important to study its effects to specific classifications of cancer. Soy has a significant effect on all cancer classifications.
There are numerous types of cancer: breast cancer, prostate cancer, lung cancer, colorectal cancer, bladder cancer, endometrial cancer, pancreatic cancer and many other Leukemia linked occurrences affecting children. Although prostate cancer is ranked as the third most common type of cancer due to the fact that it can only occur in men, it poses a greater risk to men over fifty years old. There are so many known causes of deaths resulting from prostate cancer such that in the United States, where it is most common, staggering amounts of money are spent every year for its diagnosis, treatment and prevention.
The good news is that soy products have been found to prevent occurrences of prostate cancer. Most of the data collected has revealed that soy has a greater effect on prostate cancer than even in breast cancer, contrary to popular belief. During the late 80s, it was recorded that Japanese men in Hawaii who ate tofu at least 5 times per week had 65% less chance of developing prostate cancer than those who ate tofu only once a week or less. Men who drank soy milk at least once a day had 70% less chance of developing prostate cancer than those who never drank soy milk at all, according to researchers in 1998.
More studies show that soy products slow the progression of prostate cancer in many animal and in vitro studies. Health centers have recommended the intake of soy foods such a tofu, tempeh, soy milk and edamame in diets, which has a better effect than taking soy isolate supplements. This can be attributed to a study published in Urology in September 2004 where Australian researchers found that men consuming a soy-enriched diet has a statistically significant drop of 12. % in prostate-specific antigen (PSA) levels, compared to the control group whose PSA levels rose 40% (Healthcastle. com, 2005)
Adding foods such as tofu, tempeh and soy milk in the diet are not the only ways of helping prevent occurrences of prostate cancer. To those who may not afford to purchase such processed foods, fermented soy beans, commonly referred to as ‘natto’, is their answer. Although some critics may discourage people from eating natto due to its strong cheese like smell, and its slimy texture, its many medicinal reasons are far much worth including it in the diet.
Apart from significantly lowering the rate of the prostate cancer in men, it has numerous other benefits such as lowering rates of broken bones, improving digestion(due to its high fiber content), helping curb the accumulation of body fat by raising the activity of the thyroid gland, which in turn reduces obesity rates by assisting in the burning of fats. The long fermentation process in the preparation of natto has been attributed to creating natural probiotics which assist the digestive system. Other health benefits related to the fermenting process are such as the fact that isoflavones are reduced to healthy levels fit for body intake.
However, recent news showed that natto should be consumed in low quantities since if isoflavones are taken in higher levels than is necessary, they pose a dangerous risk of interfering with the action of estrogen production. Many researchers are of the idea that fermented and fresh foods are safer and more beneficial to the body since they help avoid heart related complications often brought about by the additives processed foods are exposed to during preparation, processing, and preservation. The most common cancer in women, breast cancer, has also received tremendous attention and interest from enthusiastic researchers and scientists alike.
Controversy has also affected the breast cancer and soy impact field, with some researchers claiming that genistein only protects against development of breast cancer if taken during puberty. More controversy is brewing with a few studies showing that estrogen like effects in isoflavones may be harmful for women with breast cancer. Most researchers have avoided making recommendations regarding the subject. Reliable information gained after numerous experiments is that phytoestrogens in soy foods are anti-estrogens, that is, they may block estrogen from reaching the receptors, hence potentially protecting women from developing breast cancer.
Since the natural estrogen levels in pre-menopausal women are high, eating soy products may be beneficial. Genetically modified soybean, along with other 42 types of crops are approved by Health Canada for food use in Canada and 44 crops are approved in the United States. This soy and breast cancer controversy has led to many health professionals agreeing that a healthy balanced diet that includes soy is healthy, along with plenty of whole grains and fruits and vegetables. (Healthcastle. com 2005) Other cancer types, such as lung cancer; colorectal cancer and bladder cancer, which is common in men, are also affected by soy products.
Lung cancer, for instance, the highest cause of deaths in both men and women and the second most common in both as well, after prostate cancer in men and breast cancer in women, has a lower risk in people who take diets higher in plant derived phytoestrogens. A research was conducted regarding the possibility that slightly “estrogenic” foods could prevent lung cancer and the information obtained suggested that study participants who ate diets containing high amounts of these phytoestrogens had a lower incidence of lung cancer in both smokers and in non-smokers.
What was more interesting is that women who consumed heir phytoestrogens from fruits and vegetables lowered their risk by 41% while men who ate soy lowered their lung cancer risk by 72%. Mathew Schabath, Ph. D. , a postdoctoral researcher in the department of Epidemiology, said that although such studies which rely on a person’s recall of the food they have eaten months before, have known limitations and require more investigations, the research findings were enough to support a growing body of evidence that suggests estrogen-like compounds in food may help protect against development of lung cancer and other cancers as well.
This information is further proof that cancer, in general, is affected by soy, since, as aforementioned, soy products especially fermented and unprocessed products, lower obesity cases, a key cancer risk factor. It is recommended to at least include small amounts of soy regularly in the diet. Substituting grilled meat with soy can also greatly reduce the risk of stomach cancer, colon cancer, pancreatic cancer and breast cancer, which are all have a link with consumption of grilled meat.
Soy, therefore, if consumed wisely can help greatly reduce cancer cases, which has cost the society billions of dollars a year in eradication campaigns and research. Soy has numerous health benefits. This is the reason why soy products such as soy flour, concentrates, isolates and textured soy protein have been used for several decades as a functional ingredient by US and industries in Europe. Clinical evidence has shown that both concentrated and isolated soy proteins are easily digested by humans, and research has also shown that soy products have an equal protein quality in milk, meat as well as in eggs.
More evidence shows that these proteins are acceptable in almost all diets containing virtually no cholesterol and being lactose-free. These are some of the qualities and properties which make soy proteins favorable, in addition to health benefits such as reducing cholesterol levels, menopause and reduction in the risk of several diseases, such as cancer, heart diseases, osteoporosis and several others. Moreover, soy protein is known to supply all the nine essential amino acids and providing many functional benefits to the food processors.
The uses that soy has in infant formula cannot be underestimated. Many parents use soy formula since soy provides complete protein that is not as allergenic as cow’s milk protein. Soy formula has been used for decades and is still continuing to be used to treat infant diarrheas. Case studies on rats fed on high levels of soy protein reveal that such rats develop normally and there are no harmful effects but numerous beneficial health effects.
Studies have shown that more than 60% of American women breast feed during their infant’s first weeks of life, but after six months, the figure drops to 30 percent. Although many causes can be attributed to this drop, cases of women preferring soy formula are increasing every day. Soy formula, which is a rich source of dietary protein, has received favor from especially Western countries in the past years due to the high quality of its protein content as well as the low cost.
Many health benefits have been linked to soy products, and nutrients such as phytoestogens, which can bind to estrogen receptors in the body although with low affinity and have biological activities in the body that often times mimic that of estrogen. Soy products have daidzein; genistein and glycitein, the three most common phytoestrogens found in soy products. In addition to their phytoesterogenic activities, deidrein and genistein are also known to have powerful in vivo antioxidant effects that may be physiologically important.
Ultimately, the content of daidzein, genistein, and glycitein present in a food appears to determine the extent of health protection received by consumers of a traditional Asian diet. (Wilson T & Temple N. J. , 2001, 75) Consuming large quantities of soy is harmful as is the case with other foods. A stern warning is especially directed to cancer survivors as they may be more vulnerable to a relapse. There is also the risk of potential tumor growth with taking soy products in women with current or past breast cancer.
High consumption of soy can be dangerous to men with prostate cancer, since phyto-oestrogens may imitate the male hormone androgen. Consumption of tofu in large quantities has also been seen to be harmful for the brain. The men with high tofu consumption were studied to experience more strokes than men with lower intake; which is believed to have accelerated brain ageing. The same study also showed that high levels of midlife tofu consumption were directly linked to poor cognitive test performance, enlargement of ventricles and low brain weight. (Descheemaeker K & Debrugne L. 000, 134)
Although some critics have argued that soy should not be consumed due to claims such as soy may interfere with zinc absorption, and the claim that low cholesterol equates to both a low libido, which can be attributed to infertility in especially men, and a decreased ability to cope with stress, researchers have discredited these claims due to their lack of sufficient evidence. Others claim that of all the beans, the soy bean has the highest levels of phytic acid, which blocks the uptake of essential minerals such as iron, calcium, magnesium and zinc.
This has been dealt with by researchers who came up with methods of improving this, the simplest being soaking the beans prior to cooking, which neutralizes the acid. Very many people have allergies to dairy hence they have opted for soy. In all the legumes, the soy plant has been found to have the largest quantities of proteins, which has made the soy plant a favorite. This and many other vital health benefits of soy, such as helping control cancer occurrences, lowering cholesterol levels in the blood, and assisting the digestive system are enough to confidently say that including soy in a diet has invaluable benefits.