Naturally_Speaking_L_N_Shevyrdyaeva (Л.Н. Шевырдяева - Naturally Speaking & Listening), страница 19

Over the last 30 years, the number of twin births has nearly trebled. This rise seems to have followed the introduction of in vitro fertilization and a preference for having children later in life. But in the mid-1990s, doctors began limiting the number of embryos transferred in the course of in vitro fertilization and still the proportion of twin births rose. Now new research seems to show that bovine growth hormone in the food supply may be responsible.

Using data obtained from mothers by way of questionnaire, physician Gary Steinman of the Long Island Jewish Medical Center and his colleagues compared the number of twin births from moms who consumed meat and/or milk and those who consumed no animal products at all. They found that the omnivores and vegetarians were five times more likely to have fraternal twins than the vegans. In a report published in the current issue of the Journal of Reproductive Medicine, Steinman argues that insulin-like growth factor, a protein released by the liver in response to growth hormone, may be the reason. Studies have shown that the protein increases ovulation and that it persists in the body after entering via digested food, particularly milk. Drinking a glass of milk a day over a 12-week period raised levels of the protein in the body by 10 percent. Vegan women, it turns out, have 13 percent lower concentrations of it in their blood.

Steinman observed in the May 6 issue of The Lancet that although the twinning rate in the U.K.--where bovine growth hormone is banned--rose by 16 percent between 1992 and 2001, it increased by 32 percent in the U.S., where the substance is not banned. Of the new work he says: "This study shows for the first time that the chance of having twins is affected both by heredity and environment or, in other words, by both nature and nurture." (From Scientific American Online, May 22, 2006)

Text B. Diet May Cut Cholesterol As Much As Drugs Do

By Sarah Graham

Eating a diet similar to that of our simian relatives can have as much of an effect on cholesterol levels as modern medicine does, a new study suggests. Results published today in the Journal of the American Medical Association indicate that a strict, low-fat vegetarian diet high in specific plant products can lower levels of bad cholesterol as much as widely prescribed statin drugs can.

A number of foods, soy protein and oats among them, have known cholesterol-lowering effects. David J. A. Jenkins of the University of Toronto and his colleagues tested a specific vegetarian diet that combined many of these food groups into one menu that contained high amounts of plant sterols, fiber, nuts and soy protein. Of the 46 patients with high cholesterol levels that the team studied, 16 ate this diet for a month. A second group of 16 ate a regular low-fat vegetarian diet and 14 participants consumed the low-fat diet and took 20 milligrams of lovastatin, a standard cholesterol-reducing drug. At the end of the study period, those patients who ate the special diet lowered their levels of LDL cholesterol (the "bad" type associated with clogging coronary arteries) by 29 percent whereas the patients taking lovastatin reduced their LDL levels by 31 percent. The low-fat dieters, in contrast, showed just an 8 percent decrease in the amount of LDL present. "As we age, we tend to get raised cholesterol, which in turn increases our risk of heart disease," Jenkins explains. "This study shows that people now have a dietary alternative to drugs to control their cholesterol, at least initially."

The results are still preliminary, however. Writing in an accompanying commentary, James W. Anderson of the University of Kentucky notes that if the findings are confirmed by larger and more rigorous studies, they could have far-reaching implications for many patients suffering from cholesterol problems. He notes "those who are motivated to adopt prudent diets might achieve meaningful lipid reductions without pharmacotherapy." (From Scientific American Online, July 23, 2003)

Text C. Additive Might Fight Fast-Food Fat

By Sarah Graham   

In recent years fast food has been linked to the country's rising obesity rates and the increased incidence of diabetes. Findings presented yesterday at the annual meeting of the American Chemical Society in San Diego may provide a means of tempering the cuisine's ill effects: an additive that can slow the absorption of fat to a healthier rate.

Wallace H. Yokoyama of the United States Department of Agriculture and his colleagues fed a group of hamsters a diet with a fat content similar to that of typical American fast food--that is, with about 38 percent of its calories derived from fat--for four weeks. A second group of animals ate a low-fat diet with 11 percent of the total calories coming from fat. At the end of the study period, the high-fat eaters developed insulin resistance--a precursor to diabetes--whereas the control animals did not. The initial results corroborated previous findings in similar studies. But when the scientists repeated the experiment with the addition of a cellulose derivative known as hydroxypropylmethylcellulose (HPMC) to the high-fat food, the animals on that diet did not develop insulin resistance.

HPMC is already used as a food additive to modify the texture of items such as fillings, sauces and glazes. To achieve similar fat-fighting results in humans, much larger amounts (about five grams per serving) would be required, the scientists propose. The mechanism for HPMC's beneficial effects remains unclear, although Yokoyama posits that the compound works to slow down the absorption of fat by the digestive system. The results, which are preliminary, are not a panacea for fast-food devotees, however. "Obviously, the less fat you eat, the better off you are," Yokoyama says. "But if you're going to eat high-fat foods, then adding HPMC to it might help limit the damage." (From Scientific American Online, March 16, 2005)

Exercise 9. Summarize all the information about the role of diet discussed in this unit and speak on the effects of food on human organism.

Section 3. Recommended Report and Presentation Topics

1. “Out of Africa” migration theory.

2. Hutchinson syndrome.

3. Alzheimer’s disease.

4. Parkinson’s disease.

5. Why do people in the Caucasus traditionally live longer?

6. Age-related transformations in the organism.

7. Anti-age industry.

8. Impaired vision.

9. Wrinkles.

10. Pheromones.

11. The evolutionary role of sexual reproduction.

12. Hermaphrodites.

13. Parthenogenesis.

14. Eating disorders – bulimia, anorexia.

15. Why does fast food taste so good?

16. Health effects of fast food.

17. Dieting.

18. Vegetarians and vegans.

19. Internal organs transformation and alcoholism.

20. Prohibition and legal control of drugs.

1 Note. Causes of seizures:

1. for neonates (less than 1 month old) include perinatal hypoxia and ischemia, intracranial hemorrhage and trauma, acute CNS infection, metabolic disturbances (hypoglycemia, hypocalcemia, hypomagnesemia, pyridoxine deficiency), drug withdrawal, developmental disorders, genetic disorders;

2. for infants and children (up to 12 years of age) the causes are febrile seizures, genetic disorders (metabolic, degenerative, primary epilepsy syndromes), CNS infection, developmental disorders, trauma, idiopathic;

3. for adolescents (12–18 years) – trauma, genetic disorders, infection, brain tumor, illicit drug use, idiopathic;

4. for young adults (18–35 years) – trauma, alcohol withdrawal, illicit drug use, brain tumor, idiopathic.

2 The measure of life expectancy at birth is a statistic that represents the expected duration of life for babies born during a given time period, usually one calendar year. Calculated from death rates observed at every age, it is based on the critical assumption that the age-specific risks of death observed during a given year will prevail for all babies born in that year, for the remainder of their lives. In contrast, life span is the theoretical upper limit to life that would be observed if everyone in the population adopted ideal lifestyles from birth to death and if external threats to life were eliminated. Some researchers believe that there is no biologically determined life span per se, but rather a series of time-dependent physiological declines that may eventually be subject to modification (Encyclopedia of Bioethics, 2004, p.98)

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