Monday, August 30, 2010

Cholesterol in Foods OK

A review of the world's literature shows that dietary cholesterol itself is not associated with increased risk for suffering a heart attack (Current Atherosclerosis Reports, September 2010). More than 80 percent of the cholesterol in your bloodstream is made by your liver. Less than 20 percent comes from your diet. When you take in more cholesterol, your liver makes less so that your blood cholesterol remains virtually the same. The few people who do increase their blood levels of total cholesterol when they eat cholesterol-rich foods, have an increase in the good HDL cholesterol that prevents heart attacks.

Since the 1960s various organizations have recommended eating no more than 300 mg of cholesterol per day, the amount found in one egg. However, eating three eggs per day does not increase blood cholesterol levels. Poultry, eggs and shellfish, all rich sources of cholesterol, have not been shown to increase heart attack risk. Meat IS associated with increased risk for heart attacks, but I believe that the culprit is not cholesterol. A more likely explanation is the sugar-protein called Neu5GC found in meat from mammals, which may cause inflammation.

Sunday, August 29, 2010

Prolong Life with Methionine Restriction?

Humans live longer when they exercise, eat lots of fruits and vegetables, keep body fat low, and restrict excess calories, meat and protein. The latest research show that restricting a certain protein building block called methionine may be more effective in prolonging life than restricting calories or proteins.

Caloric restriction with adequate intake of nutrients prolongs life in fruit flies, roundworms, and mice by increasing insulin sensitivity and heart function, and decreasing inflammation and the muscle wasting of aging. In humans, calorie restriction helps to prevent diabetes, heart disease and cancer. However, getting all of the nutrients you need while restricting calories is very difficult.

Anything that increases cell growth and increases production of new cells in your body appears to shorten lifespan. Your cells are programmed so that when food is scarce, cells lie dormant in an attempt to conserve energy to help you survive. However, when food is plentiful, extra calories stimulate new cell growth which ultimately shortens lifespan. Researchers have identified a protein in cells called TOR (Target Of Rapamycin) which promotes cell growth. Blocking TOR increases lifespan in yeast, worms, flies and mice (Aging Cell, September 2010). Caloric restriction and a drug called rapamycin block TOR to decrease cell growth and prolong life (Nature, July 8, 2009). However, rapamycin is not safe because it suppresses immunity to increase infections and it also markedly increases blood levels of triglycerides to increase risk of heart attacks.

The most potent dietary activators of TOR are amino acids, the building blocks of protein. Restricting protein lowers TOR and another major promoter of cell growth called Insulin-like Growth Factor-1 (Rejuvenation Research, October 2007). Restricting just one amino acid, methionine, extends the life of flies and mice as much as caloric restriction does (Medical Hypotheses, February 2009). Methionine is found primarily in animal products, and is very low in foods that come from plants. Eating a diet high in fruits and vegetables and low in meat and dairy products markedly restricts intake of methionine. Furthermore, this diet is much easier to follow than one that restricts calories.

Thursday, August 12, 2010

Lack of Vitamin D Weakens and Injures Muscles

Because of injuries in the springtime, I missed six Boston Marathons back in the 1960s. It wasn't until 40 years later that I found the cause: my vitamin D3 blood level was 20 nmol/l (normal is greater than 75 nmol/L, equal to 30 ng/ml). Recently I moved to Florida and have been relatively injury free for the first time in my life. I now know that people genetically susceptible to vitamin D deficiency are the ones most likely to suffer muscle weakness, injuries and poor athletic performance. Many exercisers and even competitive athletes are vitamin D deficient even if they live in the sunbelt. I believe that sunlight offers benefits that cannot be obtained just by taking vitamin D pills.

Vitamin D acts directly on specific receptors in muscles to make them stronger and prevent injury (Scandinavian Journal of Medicine & Science in Sports, April 2010). As people age, they become increasingly susceptible to muscle weakness and falls caused by lack of vitamin D. Muscles are made of thousands of individual fibers that are classified into two types: slow twitch fibers that govern endurance, and fast twitch fibers that govern primarily strength and speed. Vitamin D specifically maintains the function of the fast twitch strength fibers. A review of the world's literature showed that lack of vitamin D is associated with muscle weakness in older people (Molecular Aspects of Medicine, June 2005). With aging, you lose muscle fibers. For example, the vastus medialis muscle in the front of the upper leg has 800,000 fibers in a 20 year old, but only 250,000 in a 60 year old. Vitamin D slows this loss of muscle fibers, preserves muscle strength and helps to prevent falls, while lack of vitamin D increases loss of fibers, muscle weakness and falls (Pediatric Clinics of North America, June 2010).

If you suffer muscle weakness, pain or injuries:
• Check your vitamin D3 level. That is the only available dependable test. If it is below 75 nmol/L (30 ng/ml), you are deficient.
• You can try taking vitamin D3 at a dose of at least 2000 IU/day for a month.
• If that does not bring your D3 level to normal, you can check with your doctor about taking higher doses.
• A certain percentage of people will have their vitamin D3 levels go above a normal 75 nmol/L and still suffer from muscle weakness, fatigue, pain and injuries.
• These people may benefit from exposure to sunlight.
• Since skin cancer is caused by cumulative exposure to sunlight over a lifetime, you should restrict exposure to sunlight on your head, face, top of ears, arms and hands.
• Try exposing your legs and bathing trunk areas. Be careful to avoid sunburn.
• Start at low exposures of less than a couple of minutes and work up gradually. You cannot tell that you have suffered a sunburn until the next day when your skin will burn, itch and perhaps blister.

Wednesday, August 04, 2010

Cold Drinks Improve Sports Performance

Drinking cold fluids lowers body temperature. More than 70 percent of the calories that you use to convert food to energy are lost as heat. So the more intensely you exercise, the more heat you produce. A rise in body temperature slows you down because the heart has to work harder to pump extra blood from your hot muscles to your skin to dissipate the heat. Seven studies show that cold beverages lower body temperature and improve performance by an average of 10 percent (International Journal of Sport Nutrition and Exercise Metabolism, April 2010).
How much water do you need?