Sunday, November 30, 2008

Lifting Weights Does Not Hamper Children's Growth

Lifting weights before puberty growth does not prevent children from growing to their full potential height. Bones grow from growth centers that are weakest part of bone, but strength training during growth does not damage these growth centers and children who lift weights in programs with experienced supervision do not suffer more injuries than adults. There used to be concern that growing large muscles would make people musclebound and interfere with coordination, but this does not happen. With increased strength comes increased speed and increased coordination in movements requiring strength.

Having large strong muscles makes you a better athlete. Muscle growth is limited by the size of the bones on which they attach, so the larger the bone, the stronger the muscle. Children who start to play tennis before they go into puberty have larger bones in the arm that holds the racquet. They also have larger bones in their tennis arm than those who start to play tennis later in life. The larger and stronger your muscles, the harder you can hit a tennis ball. The best time for future Olympians to start training is while their bones are still growing.

Wednesday, November 26, 2008

Reduce Belly Fat with Intense Exercise

Researchers at the University of Virginia show that intense exercise is far more effective in reducing belly fat than less intense exercise (Medicine & Science in Sports & Exercise, November 2008).

Storing fat primarily in your belly usually means that you have very high insulin levels which increase risk for heart attacks, strokes, diabetes, metabolic syndrome and even some cancers. Insulin causes fat to be deposited in your belly.

Exercise makes muscles more sensitive to insulin so that you need less to do the same job. The more intensely you exercise, the more sensitive muscles become to insulin. You cannot exercise intensely every day because intense exercise damages muscles and you have to allow time for muscles to recover. However, you can check with your doctor to make sure that you do not have a health problem that can make exercise unsafe for you. If you pass, try to exercise intensely at least once a week.
Newsletter

Friday, November 21, 2008

Why Migraines May Reduce Breast Cancer Risk

Few migraine sufferers can see any bright side to their pain, but now we have one study showing that a history of migraines is associated with a lower risk for breast cancer. The report appears in Cancer Epidemiology, Biomarkers & Prevention (November 2008). Researchers pooled data from two studies of postmenopausal women to compare odds ratios among 1900 with breast cancer and 1400 controls. Women who had migraines showed reduced risks for ductal and lobular carcinomas, especially hormone-receptor–positive tumors.

One of the triggers for migraines is a sudden drop in estrogen that causes a drop in brain levels of serotonin, the neurotransmitter that makes you happy and smart. Premenstrual syndrome occurs when the sudden drop in estrogen in the later part of the menstrual cycle causes a drop in serotonin that can make some women sad and depressed. Women who suffer migraines may have lower levels of estrogen, the female hormone that can stimulate breast cancers to grow.

Tuesday, November 18, 2008

Inflammation: More Important than Cholesterol

At the American Heart Association conference in New Orleans, researchers from the Jupiter study reported that statin drugs caused people with normal cholesterol but with high C-reactive protein levels to suffer 54 percent fewer heart attacks, 48 percent fewer strokes, 46 percent fewer angioplasties or bypass operations and 20 percent fewer deaths from any cause than those taking placebos (NEJM, November 9, 2008). The results were so dramatic they made the front page of the New York Times, Washington Post and many other newspapers.

A C-reactive protein test (CRP) measures inflammation. Inflammation is caused by anything that keeps your immunity active such as chronic infections or anything that damages tissue such as smoking, having high cholesterol or high blood pressure. Last week I reported a theory to explain why eating mammal meat causes inflammation and is associated with increased risk for premature death, cancers and heart attacks. Meat contains a molecule called Neu5Gc that humans do not have, so the immune system of humans attacks this protein as if it was an invading germ and eventually attacks the host itself to destroy the blood vessels and increase risk for heart attacks and strokes.

Many scientists feel that inflammation is a stronger predictor of heart attacks than high cholesterol levels. At present, statins are prescribed to treat people with heart disease or high cholesterol. This study shows that they prevent heart attacks in people with high CRP and normal cholesterol levels, presumably because statins reduce inflammation. About 7 million people in the US have normal cholesterol and high CRP. Treating them with a brand-name statin would cost each $116 a month or $9.7 billion a year, and prevent about 28,000 heart attacks, strokes and cardiovascular deaths each year.

Rather than just writing a prescription for statins, I think doctors should ask why a patient's CRP is elevated and try to lower it with lifestyle changes or treatment of any underlying chronic infection.

Friday, November 14, 2008

Still Eating Red Meat? You May Want to Reconsider

Several years ago, Professor Ajit Varki of the University of California, San Diego discovered a molecule called Neu5Gc that appears in the tissues of every mammal except humans (Proceedings of the National Academy of Sciences, September 29, 2003). Now he has put together the pieces of a puzzle that may explain why humans evolved with large brains and why, if we want to live into old age, we should probably avoid eating meat from any other mammals (Science, October 31, 2008).

His theory depends on evolution. Living creatures on earth started as one-celled organisms, progressed to 2 cells, and eventually to fish and birds. A mutation occurred in progressing to mammals, who developed the gene to make Neu5Gc. Mammals progressed to apes and Neanderthals, and as humans evolved, Neu5Gc added a single oxygen atom to become a different molecule called Neu5Ac. So Neu5Gc is found in all mammals and their milks except humans. It is not in fish or birds. Interestingly, the Neu5Ac molecule explains why humans are the only mammal to suffer from malaria. The malaria parasite cannot enter a cell until it grabs onto the Neu5Ac on the surface of human cells.

Many epidemiological studies show that people who eat red meat are at increased risk for heart attacks, strokes, at least 17 different cancers, diabetes, autoimmune diseases, arthritis and asthma. Scientists have blamed saturated fats or burnt fats, but this does not explain why red meat is linked to all of these diseases while poultry, fish or saturated fats from plants are not.

Dr. Varki proposes another theory. When humans ingest the flesh or milk of any mammal, they absorb Neu5Gc and treat it the same way as an invading germ, so they make antibodies against it. This turns on their immunity and keeps it active so it eventually attacks the host itself, the human body. This is called chronic inflammation, which can lead to heart attacks, strokes, cancers and so forth.

Since humans cannot make Neu5Gc, any amount found in human cells come from the mammals that they have eaten. Neu5Gc is found in high levels in tumors, with the highest levels in metastasizing tumors. In our food supply, Dr. Varki found very high levels of Neu5Gc in beef, pork, lamb and goat, and moderately high amounts in milk and cheese. Low levels are found in turkey, duck, chicken and eggs; and negligible amounts occur in plants and seafood.

I stopped eating meat many years ago, and this report makes me even more convinced that it should be avoided. I eat lots of fruits, vegetables, whole grains, beans and nuts, as well as fish and shellfish. Eggs, long thought to be a harmful high- cholesterol food, now appear to be a healthful dietary staple. While poultry appears to be a healthful food according to Dr. Varki's theory, I still do not eat it. I do not drink milk and now plan to limit cheese as well.

Wednesday, November 12, 2008

Side Stitches

Side stitches are caused by a stretching of the ligaments that run downward from the diaphragm to hold up the liver. You breathe once for each two strides. You breathe out when one foot, usually the right, strikes the ground. So, your diaphragm goes up when the force of your foot strike causes your liver to go down. This stretches the ligaments to cause pain.

You can relieve the discomfort by stopping running and pressing your fingers deep into your liver to raise it up toward your diaphragm. At the same time, purse your lips and blow out as hard as you can against the tightly held lips. Pushing the liver up releases the stretched ligaments. Breathing out hard against resistance lowers your diaphragm. The pain usually goes away immediately and you can resume running.

Monday, November 10, 2008

Reduce Oxidants to Lower Heart Attack Risk

A study from the University of Dundee in Scotland shows that neither antioxidants nor aspirin pills prevent heart attacks in diabetics (British Medical Journal, October 2008). Heart attacks occur when a plaque breaks off from the walls of a coronary artery and travels down an ever-narrowing artery to form a clot and block the flow of blood to the heart muscle. Aspirin helps to prevent clotting and therefore prevents heart attacks. Ibuprofen and other nonsteroidal pain medications block aspirin so they can increase clotting and heart attack risk in susceptible individuals.

One of the strongest risk factors for a heart attack is diabetes; 80 percent of diabetics die of heart disease. Diabetes could be such a strong risk factor for heart attacks that aspirin does not prevent it, or it may be that aspirin should be prescribed only for people with established symptomatic heart disease.

Other studies show that taking antioxidant vitamins (500 milligrams of vitamin C every day, 600 units of vitamin E every other day or 50 milligrams of beta carotene every other day) does not prevent heart attacks (Archives of Internal Medicine, August 2007). As of today, there is no evidence that taking antioxidant pills helps to prevent heart attacks. Now many scientists think that you should aim to prevent your mitochondria from making excessive amounts of oxidants. The cells of your body have tiny chambers in them called mitochondria that help convert food to energy. When they do this, they knock of electrons from nutrients, and these extra electrons can eventually end up attached to oxygen. Electron-charged oxygen, called reactive oxygen species or free radicals, then attach to the DNA in cells to damage them and shorten life.

At this time, the only practical ways to reduce the amount of oxidants produced by mitochondria are exercise or calorie restriction with adequate nutrients. Both help the mitochondria burn food to produce fewer oxidants. In the future the same effect may be accomplished with chemicals, such as resveratrol or dichloroacetate, but studies of these substances in animals have not yet been successfully applied to humans.

Friday, November 07, 2008

Exercise-Induced Asthma

We have known for more than 25 years that exercise-induced asthma is caused by breathing dry, cold air, but for the first time we may know why this happens. Researchers at the Naval Medical Center-San Diego have just shown that exercise-induced asthma is associated with diminished secretion of lung mucous (Chest, September 2008). These same people also produce far less saliva, sweat and tears.

So when certain susceptible people breathe hard and fast, in air that is cold and dry, the bronchial tubes are not protected by an adequate supply of mucous in their lungs. This irritates the bronchial tubes to cause wheezing, coughing and shortness of breath. People who are least likely to suffer exercise-induce asthma would therefore be those who produce large amounts of lung mucous, sweat, saliva and tears.
Late-onset asthma in adults

Monday, November 03, 2008

Eat More Fish and Less Vegetable Oil

The Japanese have the lowest incidence of heart attack in the world, yet they have the same rates of high cholesterol, high blood pressure and diabetes, and they smoke as much as Americans do. It's not because of their genes because Japanese who move to Hawaii and the continental United States have a significant rise in their heart attack rates and the same amount of plaques in their arteries as Americans (Journal of the American College of Cardiology, August 5, 2008).

On the average, Japanese in Japan eat fish eight times a week and they add far less vegetable oils to their prepared foods. This study shows that Japanese living in Japan have twice as much long-chain omega-3s in their blood as those who left Japan. They also have lower blood levels of omega-6 polyunsaturated fatty acids, and fewer plaques in their arteries.

Fats are classified by their chemical structure into saturated, polyunsaturated, and monounsaturated. Polyunsaturated fats are further sub-classified into omega-3, omega'6 and omega-9. Increasing the ratio of omega-6s to omega-3s increases heart attack risk. For two million years, the typical human diet contained a ratio of omega-6s to omega-3s of about two to one. Today we take in large amounts of omega- 6s in the form of extracted vegetable oils and not enough omega-3s from fish, shellfish and some seeds. Now our ratio of omega-6s to omega-3s has risen beyond 12 to one.

We now think that heart attacks are caused to a large extent by an overactive immunity called inflamation. Your immunity is supposed to protect you from infection. However, if your immunity stays active all the time, it attacks you and starts to destroy every tissue in your body, particularly your blood vessels. Omega-3s form certain chemicals in your body called prostaglandins that turn off your immunity. Omega-6s form prostaglandins that turn on your immunity. The activity of your immunity changes with the ratio of omega-6s to omega-3s. For a heart-healthy diet, add more seafood and whole seeds, and eat less of the foods made with polyunsaturated vegetable oils.

Sunday, November 02, 2008

Overweight is not Destiny

Nobody has to be fat, but some people may have to exercise for many hours just to control their weight. For example, a gene associated with fatness has been identified in the Amish who live near Lancaster, PA. A study from the University of Maryland shows that Amish men with that obesity gene who burned more than 980 calories per day through physical activity were not fat. The same applied to women who burned more than 860 calories per day (Archives of Internal Medicine, September 2008).

Exercise causes you to eat more food, but when you are very active, you do not increase the amount of calories to equal what you burn. For example, if your exercise program causes you to burn 1000 more calories per day, you will usually increase your food intake by about 500 calories, and probably significantly less than that. More