Monday, March 28, 2011

How Exercise Keeps You Young (and Prolongs Your Life)

Dr. Mark Tarnopolsky, of McMaster University in Hamilton, Ontario, has shown that exercise prevents aging in mice programmed to grow old rapidly (The Proceedings of the National Academy of Sciences, September 22, 2010). The exercising mice did not have the expected shrinkage with aging of their brains, hearts, muscles, skin, hair, ovaries, testicles, spleen, kidneys, and liver. Many other studies show that exercise in later life slows signs of aging such as loss and graying of hair, weaker and smaller muscles, loss of brain function and size, thinning of skin, damage to blood vessels associated with heart attacks and strokes, loss of apoptosis associated with increased cancer risk, and loss of sexuality associated with shrinking of testicles and ovaries.

The explanation for these incredible findings appears to be in the mitochondria that convert food to energy for your body. At all ages, the exercising mice appeared younger and healthier than the non-exercising mice. Mitochondria have a different DNA than other cells in mammals. That means that in the process of evolution, bacteria invaded cells and provided the ability to turn sugar to energy more efficiently than any other process in the body. Aging in humans is associated with loss of function and number of mitochondria which causes decline in tissue functions that causes cancers, arteriosclerosis, diabetes, and Parkinson's and Alzheimer's disease. With aging, genetic mutations cause mitochondria to malfunction and die and you to look older.

As you age, you lose your ability to make AMP-activated protein kinase, also known as AMPK (Cell Metabolism, February 2007). This enzyme functions to increase mitochondria in muscles. Anything that reduces the number or efficiency of mitochondria interferes with your body's ability to burn fat and sugar for energy. As a result, blood sugar, fat and cholesterol levels rise. Most cells in your body contain many mitochondria, small furnaces that burn food for energy. With aging, the number and the efficiency of mitochondria both decrease. This interferes with your body's ability to turn food into energy. The extra calories that are not burned accumulate in your body as fat in your muscles, liver and fat cells. This causes you to gain weight. Extra fat in cells block their ability to take in sugar from the blood stream, so blood sugar levels rise and you are at increased risk for developing diabetes. Extra fat in the liver prevent the liver from removing extra insulin, so insulin levels rise to constrict arteries and cause heart attacks. Insulin also makes you hungry all the time to increase your chances of gaining weight.

AMPK is increased by exercise and by drugs used to treat diabetes, such as metformin or Actos. The best way to increase the number and size of mitochondria in your cells is to exercise. If you do not have a regular exercise program, you are shortening your life. How exercise strengthens mitochondria and prevents aging

The benefits reported in mice appear to apply to humans. For the last two years, Diana and I (ages 69 and 75) have been part of group of tandem bicycle riders, ages 40s to 70s, who race flat out for 25 to 30 miles three times a week and ride more than 100 additional miles in the rest of the week. All look younger, are thinner and more muscular, and are far more active than their same-age contemporaries in The Villages, Florida where we live.

Wednesday, March 09, 2011

Impotence Predicts Heart Attacks, Diabetes

Men who are impotent are at increased risk for heart attacks and diabetes. (Atherosclerosis, February 2011). The two most common causes of impotence are blood vessel disease (arteriosclerosis) or lack of the male hormone, testosterone. When a man lacks testosterone, he usually has little or no sexual desire. On the other hand, if he still has desire, his testosterone is usually normal but his blood vessels are usually damaged and the same damage that occurs in the penis also occurs in the arteries leading to his heart.

Lack of male hormones is strongly associated with increased blood levels of triglycerides and the bad LDL cholesterol that increase risk for metabolic syndrome, obesity, diabetes, high blood pressure and atherosclerosis. Giving testosterone to men deficient in that hormone lowers levels of triglycerides and the bad LDL cholesterol, and helps to slow the progression of blood vessel damage.

All men who have difficulty achieving erections need to get blood tests for diabetes (HBA1C), testosterone, prolactin (a hormone that causes impotence and is produced by a brain tumor), cholesterol and triglycerides, and have their blood pressure checked. Most of these men will have serious blood vessel damage from arteriosclerosis and will need a program that includes *losing weight if overweight, *starting a supervised exercise program, *restricting refined carbohydrates (sugared drinks and foods made from flour), fried foods and red meat, *increasing intake of fruits and vegetables, and *checking their vitamin D3 (should be greater than 75 nmol/L).

Men who need testosterone replacement should not take testosterone pills because they go from the intestines to the liver to lower the good HDL cholesterol and increase risk for heart attacks. They should use a route that bypasses the liver such as testosterone injections or testosterone gel that is rubbed on the skin.

Tuesday, March 08, 2011

Restrict Protein, Not Just Calories, to Prolong Life

Recent research show that protein restriction may be far more effective than calorie restriction in prolonging the lives of humans. Many studies show that restricting calories prolongs the lives of yeast, worms, spiders, flies, insects, rats and probably monkeys. Humans who severely restrict calories have long-life characteristics, such as low cholesterol and blood pressure and hearts that are more than 15 years younger than those of other North Americans their age (Experimental Gerontology, August 2007).

However, most of the test group of humans who restrict calories do not have a drop in a hormone called Insulin-Like Growth Factor-1 (IGF-1) that appears necessary for living a long time. High blood levels of IGF-1 are associated with premature aging and diseases of aging such as diabetes and cancer. IGF-1 levels are lower than normal in worms, flies and mice on restricted-calorie diets, but not in humans. This week a report shows that IGF-1 shortens life by increasing cell DNA genetic damage, and causes cancer by blocking apoptosis that causes cancer cells to kill themselves before they destroy their host (Science Translational Medicine, February 16, 2011).

Luigi Fontana, a professor of medicine at Washington University in St Louis, noticed that most calorie-restricting humans eat high levels of protein, about 1.7 grams per kilogram of body weight/day. This is more than the US government-recommended intake of 0.8 g/kg/day, and even higher than the 1.2 g/kg/day that the average American eats. Dr. Fontana asked humans on calorie restricted diets to reduce their intake of protein to 0.95 g/kg/day. After just three weeks of reduced protein intake, their IGF-1 levels dropped markedly (Aging Cell, September, 2008).

Among the calorie-restricting humans, vegans have lower levels of IGF-1 than meat-eaters (Rejuvenation Research, February 2007). Strict vegans also have significantly lower IGF-1 levels than people who restrict just calories, even if they are heavier and have more body fat. Strict vegans take in about 10 percent of their calories from protein, whereas those on calorie restriction tended to get 24 percent of calories from protein. Other data show that diets lower in protein might protect against some cancers. So restricting protein may be more important than restricting calories.

If fruit flies and rodents are fed special diets that restrict protein, they can eat as many calories as they want and still live longer (Nature, December 2009). This suggests that as long as you are not overweight, you may not need to restrict calories. Instead, restrict only protein which is far easier to do.

Furthermore, you can probably eat all the fruits and vegetables you want and not restrict calories as long as you restrict protein. That's very good news because it is far easier to restrict protein than it is to restrict all foods. The only way that you can restrict calories and still remain healthy is to eat a diet based on vegetables. It now appears that you extend your life far more by reducing protein that you would by restricting just calories.