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| Sunday, 27 January 2002 |
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Features |  |
| News Business Features Editorial
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Health Environmental chemicals and sex hormones A visiting professor in toxicology from New Zealand, Dr. Ravi Gooneratne who has just completed a postgraduate course in Applied Environmental Toxicology at Postgraduate Institute of Science, University of Peradeniya says that the link between disease and exposure to environmental chemicals and/or oestrogenic plants is far from conclusive. It is true to say that our society is hooked on chemicals. We use many chemicals in our daily life. The soaps, creams, detergents (washing powders, dish washing liquids), fly sprays, and weed killers, all contain chemicals. These chemicals are an essential component of the lifestyle enjoyed by the Sri Lankans. Although even inert materials like plastics are thought to be involved in this controversy, chemicals like DDT, polychlorinated biphenyls (PCBs), and dioxins are cited as the major culprits. Pesticides, the toxicities due to these in Sri Lanka are one of the highest in the world, are singled out. But evidence is far form conclusive. It is true that many of these nasty chemicals are now banned in Sri Lanka but they have been used in this country for many years and because they do not easily breakdown they still persist in the environment. There is now conclusive evidence that these chemicals act like, or interfere with, the actions of sex hormones. Sex hormones are important for: * formation of sex organs in the foetus, * development of sex characteristics at puberty, * control of menstrual cycle in women, * control of sperm production in men, * sexual behaviour after puberty. Males also produce a small amount of oestrogen and females produce small amounts of testosterone in the adrenal gland (found close to the kidneys). The roles of oestrogen in men and testosterone in women are poorly understood. However, it is known that too much oestrogen in males can have a feminising effect, while too much testosterone in females can have a masculinizing effect. Chemicals and sex hormones The idea that chemicals can alter hormone production is not new. Over the years, many drugs have been developed for treating hormone imbalances in humans: * Drugs can increase hormone activity by binding to the hormone receptor, turning on the response. Such drugs are called mimics or agonists. Certain other drugs can increase hormone activity by stopping the breakdown of the hormone in the body prolonging its effect. Ethinyloestradiol is a synthetic oestrogen mimic that is widely prescribed in birth control pills. * Drugs can decrease hormone activity by inhibiting production of the hormone or by increasing the rate of breakdown of the hormone. Other drugs, called antagonists bind to the hormone receptor, but like a rusty key cannot turn on the ignition. Instead, by occupying the receptor, antagonists block the natural hormone from binding and thereby block hormone activity. Tamoxifen, a drug widely used in breast cancer, is an example of an oestrogen receptor antagonist that blocks the action of oestrogen. Oestrogenic chemicals Scientists have known for sometime that the pesticide DDT that has been used in Sri Lanka for a long time to control the malaria mosquito had high oestrogen like activity when fed or injected to rats. Since then many chemicals which have been used or still used in this country, including a variety of pesticides (methoxychlor,kepone), industrial chemicals like some PCBs, and some dioxins and industrial effluents, some surfactants and some spermicides have all been reported to produce oestrogenic like effects in laboratory experimental animals. However compared to the natural oestrogen produced by the body, most of these chemicals have very weak oestrogenic activity. Therefore, some scientists believe the chemicals that exhibit weak oestrogenic activity can in fact have an opposite effect (that is, anti-oestrogenic activity) because they block the effects of highly potent oestrogenic compounds produced by the body. There is also a number of dietary and environmental compounds which themselves have no oestrogenic activity, but can exhibit anti-oestrogenic activity. Some polyaromatic hydrocarbons such as the by-products of combustion of organic compounds in cigarettes (during smoking) and foods (during barbecuing), can contribute significantly to the average daily intake of anti-oestrogens. Many naturally occurring chemicals found in a variety of plants can also alter hormone activity when eaten. Phyto-opestrogens are plant-derived chemical that bind to oestrogen receptors. They are found in soya beans, broccoli, clovers, Lucerne, to name a few. The potency of these phyto-oestrogens is usually weak compared to the activity of the natural hormone and oestrogen drugs. Environmental chemicals and reproductive health In male adults, unless testosterone production is suppressed, any possible feminising effect of extra oestrogen is likely to be overridden by the much greater influence of testosterone. In contrast, small amounts of chemical dioxin given to pregnant rates have been shown to result in smaller sex organs, delayed sexual maturity, reduced sperm production and change in sexual behaviour of the male offspring. Because DDT, PCBs and dioxins accumulate in body fat, these can pass via breast milk from mother to the baby. The levels of these chemicals in the breast milk of women in Sri Lanka are not known but it is possible that the levels in women in urban and industrialised areas may be high. Two reports from Denmark have shown that men on organic diets had higher sperm counts. A recent study carried out in New Zealand did not find a difference in sperm count between men on organic diets and other diets, but men on organic diets had a significantly lower percent of abnormal sperms (72%) compared to the rest. But evidence is far from conclusive because studies in laboratory animals have shown that exposure to some chemicals like dioxin results in reduced sperm production, whereas exposure to other chemicals such as dioxin can increase sperm production. There is a need to assess the overall risk of exposure to the spectrum
of chemicals we come across in daily life. We are exposed to a whole range
of chemicals but with our current understanding of chemicals and plants,
each showing both oestrogenic and anti-oestrogenic activity, it is
difficult to estimate what the overall effect of exposure might be. The Miracle Soya Bean by Dr. D.P. Atukorale It is said that the soya bean is a gift to all generations of mankind from the sages and wise rulers of China. When the soya reached the West at the end of the 18th century, the soya oil, which was commercially made, was used for manufacture of soap and the remains of the bean were fed to the cattle. Soya meat and soya milk are very familiar to most Sri Lankans and it is low in calories and being a plant product, soya does not contain cholesterol. Soya milk is the ideal substitute for dairy milk if you are allergic to lactose or if you are a pure vegetarian who wants to get the benefits of a diet free of animal products. I believe that today, expanding of soya industry should be encouraged by the government of Sri Lanka as it makes good economic sense when compared to the very high cost involved in meat production. A cup of soya beans (172g) contains 15.43g of fat of which 3.41g is monounsaturated, 8.71g of fibre, 1.27 RE of vit A, 2.92mg of vit C, 0.27mg of thiamine, 0.49mg of riboflavin, 0.69mg of nicotinic acid, 0.09mg of biotin, 0.31mg of pantothenic acid, 0.40mg of thiamine 92.5mg of folic acid, 177.44mg of calcium, 8.84mg of iron and 1.98mg of zinc. A word of caution Soya and some of the other beans contain a substance known as trypsin inhibitor. Trypsin is an enzyme secreted by the pancreas and trypsin helps to digest proteins. As heating destroys trypsin inhibitor, all soya products have to be heated before eating. Soya milk, Tofu and TVP are heated during the manufacture. Therefore in actual practice, soya sprouts is the only one that should be boiled before consuming. Tofu Tofu which is a fermented product like bean curd but is a dried form. Tofu contains 100% soya bean and has a higher percentage of protein than any other natural food in existence and is entirely cholesterol free. Tofu has been the staple food for millions of people in Asia for centuries. Eating tofu reduces the risk of cancer according to several decades of large scale research in Japan. Eating tofu cuts the risk of stomach cancer and tofu has anti-carcinogenic properties. Does Tempeh, which is a fermented soya bean product, contain vitamin B 12. The answer is both "yes" and "no". Recent tempeh samples purchased from various markets in Jarkarata reveals that a high amount of vit. B 12 is present. However commercially prepared western tempeh does not contain any B12. Soya sauce: This is an ancient and traditional seasoning which has achieved prominence and acceptance the world over. It is a dark rich sauce with a savoury salty taste as well. Very little is required within a dish or serving. Soyaflour: This is made of ground dried soya bean and producing a dense rich flour. It may be mixed with wheat flour, with a view to increase the protein content of your bread. TVP is made from soya bean processed into high protein low fat food. TVP is made to resemble the look and texture of meat products. TVP is a valuable, safe and inexpensive source of proteins and content of 40% protein is very much more than in fish, meat, poultry and dhall. Omega - 3 fatty acids isoflavones, saponins and phenolc acids found in soya are effective against cancer. Soya beans reduce the blood cholesterol level especially the LDL (bad
cholesterol) level and also raises HDL (good cholesterol) level and
prevents ischaemic heart disease. Drumstick for a healthy life Eat drumstick curries and lead a healthy life! The drumstick is valued mainly for its tender pods, which are relished as vegetable but all its parts - bark, root, fruit, flowers, leaves, seeds and even gum - are of medicinal value. They are used in the treatment of ascites, rheumatism and venomous bites as antiseptic and as cardiac and circulatory stimulants. Fresh root of the young tree (as also the root bark) is used as rebufacient and vesicant. Internally, it is a stimulant, diuretic and antilithic. Externally, it is applied as a plaster or poultice to inflammatory swellings. The root, in prescribed doses, is given in intermittent fevers, paralytic affections, epilepsy and hysteria and externally in palsy, chronic rheumatism enlargement of spleen, dyspepsia and also in bites by rabid animals. A compound spirit made of the roots and orange peel with a little bruised nutmeg is useful in fainting fits, giddiness, nervous debility, spasmodic affections of the bowels, hysteria and flatulence. (Courtesy India Perspectives). |
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