Plastic Bottles and Containers: New Concerns

A study from Peninsula Medical School in Exeter, U.K. shows that high levels of urinary Bisphenol-A (BPA), a chemical compound commonly used in plastic packaging for food and beverages, is associated with heart attacks, strokes, diabetes and abnormal liver tests (JAMA, Sept 17, 2008). BPA can break down to form female hormones called estrogens that are linked to breast and uterine cancer in women, decreased testosterone levels in men, and may also cause birth defects.

You are exposed to BPA, primarily through food, drinking water, tooth sealants that you may receive in a dentist's office, and exposure through your skin and lungs from household dusts. Ninety percent of Americans have detectable levels of BPA in their urines.

Although the safety of BPA is still uncertain, you would be prudent to limit your exposure. The primary concerns are plastic water bottles and baby bottles. Each bottle is supposed to have a number in a circle stamped on the bottom. Try to avoid the following numbers:
#1 Most single-use water bottles are made from polyethylene terephthalate (PET or PETE).
#7 This is used for many colorful hard plastic lexan bottles made with polycarbonate plastics.
At a minimum, do not re-use bottles or containers with these numbers. Do not freeze or reheat foods or beverages in them.

Plastic products that bear the following numbers appear to be safe:
#2 HDPE, high-density polyethylene, the most widely recyced plastic,
#4 LDPE, low-density polyethylene) and
#5 PP, polypropylene.

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Cancer: More Environmental than Genetic

More than 85 percent of the known causes of cancers are environmental, not genetic. Normal cells undergo apoptosis, a process in which each cell lives only so long and then dies. Cancer means that the DNA in cells cannot do its usual job of telling a cell when to die, so the cells grow forever and can spread to other parts of the body to kill you. Scientists have developed drugs and other treatments to destroy the process that makes cancer cells immortal. However, each cancer cell has hundreds, and even thousands, of different pathways that they can use to make them live forever. Pancreatic cancer cells have an average of 63 mutations (Science, September 4, 2008), and a brain tumor called glioblastoma has at least 47.

So when scientists develop a drug to kill a cancer, the drug acts on one or more pathways and may temporarily inhibit the cancer, but drugs never block all the pathways that can go wrong. Therefore cancer can always come back. That is why doctors often use as many as five different drugs to treat some cancers because they want to block as many of the different pathways as possible.

At this time, I believe that the best approach is to avoid or limit your exposure to known or suspected environmental triggers for cancers, which include:

- meat, particularly beef (eating red meat is associated with increased risk for 17 different cancers)
- barbecued, grilled or deep-fried foods (browning or burning foods, particularly fats or starches, forms carcinogens)
- BPA (Bisphenol A) in some plastics
- PCB's
- lead in any form
- molds such as aflatoxin from rotten peanuts or grains
- arsenic in well water
- asbestos in old buildings
- sexually transmitted diseases such as hepatis C that causes liver cancer or HPV, the human wart virus that causes cervical cancer
- formaldehyde or carbon tetrachloride
- Helicobacter pylori (bacteria that cause stomach burning and ulcers) which can cause stomach cancer
- unnecessary X rays, particularly CAT scans
- heavy exposure to pesticides
- radon from the ground leaking into your house
- tobacco in any form
- second-hand smoke
- alcohol (more than three drinks a day increases cancer risk)
- exposure to uranium
- excessive UV radiation (too much sunlight)
- not enough sunlight (lack of vitamin D)
- night shift work (depresses melatonin, a cancer-preventing hormone)

Other cancer risk factors include lack of exercise, excess weight, lack of fiber in the diet, a diet that is low in vegetables, early puberty in women (before age 12), late menopause (after age 55) or taking estrogen after menopause. In 2008, cancer will take the lives of about 230,000 more Americans than it did in 1971. Try not to be one of them.

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Limit All Sugared Drinks, Not Just HCFS

High-fructose corn syrup (HFCS) contains approximately 59 percent fructose and 41 percent glucose, while fruits juices contain a ratio of 50 percent glucose to 50 percent fructose. There really is no difference. HFCS is no better and no worse than any sugared beverage or fruit juice, it is just cheaper. When manufacturers process corn for oil, the residue is a sugary liquid that used to be thrown away. In the 1950s, soft drink makers discovered that HFCS could be added to sweet drinks at a fraction of the cost of cane sugar. Then scientists noticed that Americans have gotten progressively fatter from the 1950s to the present. This is the same period that HFCS was added to the American diet.

In the following years, many respected scientists tried to link HFCS to the obesity epidemic. However, we now have multiple studies showing that any kind of sugar in liquid form can make you fat (American Journal of Clinical Nutrition, May 2008). When you eat sugar in solid form, such as in a cookie, you eat less of other foods because the solid food fills you up. However, in liquid form, sugar supplies calories without making you feel full. When you drink any liquid containing sugar, you do not reduce your intake of food to compensate. Sugar in liquid form is not recognized by your brain as extra calories and therefore does not suppress appetite.

Today almost all researchers agree that HFCS is no worse than any other liquid sugar. All forms of sugar-water can make you fat. That includes fruit juices, sugar added to your coffee or tea, and any other sugared drinks.
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Burning Feet while Cycling

Many cyclists suffer from "burning foot syndrome", pain on the bottom of the feet, particularly during a long ride. After years of this problem, I tried a simple tip from RoadBikeRider, a free weekly newsletter from some of America's best long distance bicycle riders: Ed Pavelka, Fred Matheny, and Lon Halderman. They suggest moving the cleats back as far as possible toward the arch of the foot. All of the other articles I have read and all of the experts I have consulted recommend that you set your cleats on your shoes so that the ball of your big toe is exactly aligned with the axle of the pedal. Following Lon Haldeman's advice, I moved my cleats back last week and my feet have stopped burning. I also think I am riding faster.

This flies in the face of what other experts claim: the further back your cleat, the less power you get from your calf muscle. That's just not true. More than 90 percent of the pressure on your pedals comes from your thighs, not your lower leg (calf) muscles. The pain is caused by the front part of the foot pressing on the pedals. Moving the cleat backward takes the pressure of the forefoot and relieves the pain. As Haldeman states, you actually can be in better shape when you don't have burning feet, and you can train further and ride faster. (To subscribe to their free newsletter go to http://www.roadbikerider.com)

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Cracked skin on your heels

If you have painful cracks in the skin on your heels, try applying tape across the split skin to limit movement of the cracked edges. Let the tape fall off, as pulling it off may tear the skin even more. Friction irritates the cracks, causing more pain, so avoid loose slip-on shoes, sandals or any other footwear that causes friction. Do not file the skin as this can cause even greater thickening (called the Koebner phenomenon) that leads to cracking.

Your podiatrist can prescribe topical medications, such as urea-based creams or cortisone creams, to help heal the cracks. Cortisone creams should be used with caution since they can cause permanent thinning of the skin. If your symptoms are severe, your doctor may recommend cortisone injections, but again be aware of the side effects of too much cortisone. More

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Exercise benefits: new studies

This month's literature shows that exercise prevents cancers and helps to improve mental function with aging. Researchers from the University of Melbourne in Australia show that adults with memory impairment improve mental function after a six-month exercise program (JAMA, September 3, 2008). Another study, from Tokyo, shows that adults who exercise regularly and are active are less likely to develop a range of cancers (American Journal of Epidemiology, August 2008). The researchers followed 80,000 Japanese adults for up to ten years. Those who were more active had reduced risk for developing any type of cancer, particularly cancers of the colon, liver, pancreas or stomach.

This benefit was greatest in those who were not overweight, showing that exercising enough to control your weight is better than just exercising. Exercise lowers body fat and being overweight is associated with increased cancer risk. Furthermore, exercise can activate immune cells to hep prevent cancer. It also lowers certain sex hormones and insulin-like growth factors that can feed the growth and spread of tumors. Newsletter

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Nitric Oxide May Help Athletes

Should you believe claims that nitric oxide supplements will enlarge muscles and increase endurance? Actually, there are no products that contain nitric oxide because it is too unstable. However, supplements containing arginine (an amino acid) in combination with another blood vessel widener, alpha- ketoglutarate, can stimulate the blood vessels to increase production of nitric oxide. This dilates blood vessels that bring blood to muscles. Several studies show that the nitric oxide releasers may help athletes exercise longer, but the data are weak, sparse and not very impressive. If you take these supplements and do not exercise to your maximum, you are wasting your money. However, if you are already exercising as hard and as fast as you can, taking these supplements may let you do more work, which can make your muscles stronger (Medicine & Science in Sports & Exercise, December 2000).

Promoters of these supplements recommend doses of 6,000-10,000 mg per day and most athletes who use them take far more than that. Half of the athletes who took double the recommended dose suffered adverse side effects, usually nausea, stomach cramps or diarrhea. High doses may drop blood pressure which would harm performance. Blood pressure usually rises with exercise; a person with resting blood pressure of 120/80 can expect it to rise to 200/80 while jogging.

Prescription nitric oxide simulators such as Viagra can benefit men who have difficulty achieving or maintaining erections. Exercise, by itself, raises blood levels of nitric oxide (American Journal of Hypertension, August 2007). So if you want your arteries to make more nitric oxide, go out and exercise.
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