Tuesday, December 27, 2011

Environmental Factors Associated with Breast Cancer

A recent report says that "Lifestyle Changes Prevent One-Third of Cancers", and that fewer than 10 percent of breast cancer cases are inherited (33rd Annual San Antonio Breast Cancer Symposium, 12/7/2011).

Anything that increases a woman's exposure to estrogen also increases her risk for breast cancer, a disease that affects one in eight women:

• being overweight: Full fat cells make estrogen, so overweight women have more estrogen
• not exercising: lack of exercise increases risk for obesity
• drinking alcohol
• taking birth control pills
• taking estrogen and progesterone pills at any age
• starting periods before age 11
• starting menopause after age 55
• never being pregnant (thus more menstrual cycles)
• never breast feeding

Radiation from too many medical tests also increases breast cancer risk. Three abdominal CT scans give as much radiation as atomic bomb survivors received. Possible, but unproven, causes of breast cancer include: smoking, second-hand smoke, nighttime shift work, exposure to benzene and other chemicals, or to BPA and certain other plastics ingredients.

There is no evidence that breast cancer is caused by hair dyes or by radiation from cellphones, microwaves or other electronic gadgets.

WHY DOCTORS PRESCRIBE PROGESTERONE: Taking progesterone and estrogen markedly increases breast cancer risk. Estrogen stimulates the inner lining of the uterus to grow, and uncontrolled growth is cancer. Taking estrogen can cause uterine cancer, while progesterone stops estrogen from stimulating the uterus. So, to prevent uterine cancer, doctors usually prescribe progesterone with estrogen to any woman who still has a uterus. However, taking both estrogen and progesterone increases breast cancer risk. Many doctors now recommend no hormone therapy for women at menopause.

Friday, December 09, 2011

Why Three out of Four Athletes Take Caffeine Before Competition

In January 2004, the World Anti-Doping Agency removed caffeine from its prohibited drug list to allow athletes to take coffee, tea, chocolate, cocoa, guarana, cola drinks, energy drinks and so forth. Researchers have now measured the caffeine concentration in 20,686 urine samples obtained for doping control from 2004 to 2008. They found that 75 percent of athletes in official national and international competitions had consumed caffeine before or during competition (Appl Physiol Nutr Metab, Aug 2011;36(4):555-61). As expected, athletes in endurance sports (triathlon, cycling, and rowing) had the highest urine concentrations of caffeine. Gymnasts had the lowest urine caffeine concentration. Athletes older than 30 had higher levels of caffeine in their urine than those younger than 20. Males and females had the same urine concentrations.

HOW CAFFEINE INCREASES ENDURANCE: The limiting factor to how fast you can move during a race is the amount of oxygen that you can take in and use. Since sugar requires less oxygen than fat to power your muscles, you want to get sugar into your muscles as quickly as possible. Anything that increases the amount of sugar that can be absorbed from your intestines into your bloodstream will help you ride or run faster and longer.

When you exercise, caffeine can increase endurance by increasing the absorption of sugar from your intestines (Medicine & Science in Sports & Exercise, July, 2010) and by increasing the uptake of sugar by your exercising muscles by as much as 26 percent (Journal of Applied Physiology, June 2006).

Caffeine helps athletes run faster in both short and long-distance races. In short races, it makes athletes faster by causing the brain to send messages along nerves to cause a greater percentage of muscle fibers to contract at the same time. In longer races, it delays fatigue by preserving stored muscle sugar. Muscles get their energy from sugar and fat in the bloodstream, and from sugar, fat and protein stored in the muscles. When muscles run out of their stored sugar, they hurt and become more difficult to coordinate. Caffeine causes muscles to burn more fat, thus sparing stored muscle sugar to delay fatigue.

HOW MUCH DO YOU NEED? Most research shows that it doesn't take much more than one or two soft drinks to increase endurance. Caffeine loses its beneficial effects with repeated exposure, so athletes who want to gain maximum advantage from caffeine during competition should avoid drinking caffeinated beverages when they are not competing.

HOW MUCH IS SAFE? Nobody really knows how much caffeine you can take in without harming yourself. At rest, caffeine is a diuretic, but during exercise it does not increase urination. Caffeine is a potent stimulant that can cause irregular heartbeats and raise blood pressure.

RESTRICT CAFFEINE WHEN NOT COMPETING: Caffeine increases sugar absorption from the gut. Taking caffeine when you eat carbohydrate-containing foods can double your rise in blood sugar (Journal of Caffeine Research, April 16, 2011). Since more than 35 percent of North Americans will become diabetic and have high rises in blood sugar levels after meals, most people should not take caffeinated drinks with meals that contain carbohydrates: bread, spaghetti, or sugared foods and drinks. If you are already diabetic, your blood sugar levels rise even higher and you suffer cell damage. This cell damage causes all of the horrible side effects of diabetes: blindness, deafness, heart attacks, strokes and so forth.