Sunday, December 30, 2007

Growth Hormone Does Not Prevent Loss of Muscle Strength

As you age, expect to lose muscle fibers and strength unless you exercise. A study from the University of Florida in Gainesville shows that a program of exercise training later in life helps aging rats to reverse this age-related loss of muscle size and strength (American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, November 14, 2007). The study also showed that short-term administration of growth hormone late in life does not prevent loss of muscle strength. Previous studies show that it may help people get rid of fat.

At this time, there is not enough evidence for an older person to take growth hormone to improve muscle strength, and there is no long-term data on safety. Sudden deaths reported in athletes who have taken growth hormone are probably due to the effect of enlarging the heart muscle without also adequately enlarging the blood supply. The larger heart requires more blood and cannot meet its needs for oxygen, so it starts to beat irregularly. More on growth hormone; growth hormone releasers; growth hormone and aging

Thursday, December 27, 2007

Job Fatigue? Carb Snacks Can Help

If you have a physically demanding job that keeps you moving all day, you may have greater endurance if you eat small snacks throughout the day instead of having a single large meal at lunchtime. Researchers at the University of Montana in Missoula showed that snacking on carbohydrates may prolong your endurance during a long day of continuous movement. They asked men and women to exercise intermittently for ten hours. Each hour, they performed nine minutes of upper-body weight lifting, 19 minutes of cycling, and 20 minutes of walking on a treadmill, with a one-minute rest between each exercise. This was followed by a 10-minute rest and feeding period. Those who took carbohydrates every hour were able to keep more sugar (glycogen) in their muscles, and were able to exercise longer without feeling tired. Journal reference

When you exercise, your muscles get their energy from muscle sugar and fat stored in muscles, sugar and fat from the bloodstream, and to a lesser degree from protein. When your muscles run out of their stored sugar, they require more oxygen to burn food for energy. This can make your muscles feel tired and be more difficult to coordinate. Eating any source of sugar or carbohydrates during exercise preserves muscle sugar and increases endurance. More

Wednesday, December 19, 2007

Longevity Linked More to Fitness than Weight

Being in shape helps to prolong your life, even if you are overweight and even if you store fat primarily in your belly, which is a major risk factor for diabetes, heart attacks, and probably certain types of cancers (JAMA, December 5, 2007). As people age, most gain weight and become progressively less active. Researchers at the University of South Carolina in Columbia showed that a person's fitness level was a far stronger predictor of premature death than body fat. Those who were fit suffered less than half the death rate of those who were out of shape. They also showed that those who store fat primarily on their bellies are at significantly greater risk for dying early and that people with abdominal obesity who exercise are far less likely to die early than those who did not exercise.

The authors describe fitness as walking briskly at least five days a week. Abdominal obesity is defined as having a waist circumference over 40 inches for men or 35 inches for women. In this study, the least fit 20 percent had a death rate twice as high as people who did 30 minutes of walking five days a week. Those who were more fit had an even lower death rate. Furthermore, higher levels of fitness were inversely related to all causes of death in both the normal-weight and overweight groups.

Sunday, December 16, 2007

Intestinal Bacteria May Cause Weight Gain

Why are some people skinny, even though they eat large amounts of food, while others become fat? Jeffery Gordon of Washington University in St. Louis thinks it's because some people have types of bacteria that cause them to absorb more calories from their food.

You have two absorption systems in your body. You absorb most of your food as it passes through your small intestines. Food that is not absorbed in the small intestine goes to your colon. The colon contains a huge colony of bacteria that work to ferment undigested carbohydrates such as soluble fiber into short chain fatty acids and simple sugars that can then be absorbed through the colon walls into the bloodstream. Most people get about ten percent of their total calories from food absorbed through their colons.

Animal studies lead us to the next step. The dominant bacteria in the gut of obese mice are Firmicutes, types of bacteria that have more genes for breaking down the complex starches and fiber. Mice who are thin have more Bacteroidetes in their guts, and these bacteria are not as efficient in breaking down fiber and complex carbohydrates. Transplanting Firmicutes bacteria into the guts of lean mice made them fat.

These researchers also found that fat humans had far more Firmicutes bacteria than thinner ones. They then asked their overweight subjects to go on a low-fat, low-refined- carbohydrate diet for one year. As they lost weight, their bacteria changed to predominantly Bacteroidetes.

Today you may be able to lose weight by changing the composition of your diet in a way that changes the bacteria in your gut so you absorb fewer calories. In the future, you may be able to get a pill that contain primarily Bacteroidetes bacteria, take it daily and watch the pounds melt off because of the change in intestinal bacteria. Fitness, Nutrition and Health newsletter

Thursday, December 13, 2007

Clementines: Healthful Snacking and More

Clementines are the small citrus in boxes or mesh bags that appear in markets during the winter months. This year's crop is tasty, juicy and plentiful (prices are low!).
They're great for snacking, dessert or in fruit salads. Clementines also make a wonderful addition to almost any green salad. Or try Diana's Recipes Using Clementines.

In Canada and perhaps elsewhere clementines may be called mandarins. Technically clementines are a cross between mandarins (Citrus reticulata) and Seville oranges (Citrus auratium). Recipes using clementines can be made with any of the tangerine-sized citrus or with oranges sections cut into bite-size pieces.

To prepare clementines for salads, just peel and section. If they are large or you want more flavor from the juice in your salad, cut the peeled fruit in half cross-wise before you separate the sections.

Look for boxes of small, firm fruit. I find that the smaller clementines often have the best flavor, although they may be more difficult to peel. If you get a box with poor flavor, look for another "brand" (from the box labels) and try again. They come from Spain, Morocco, South America and various other countries; I haven't found any reliable way to tell which will taste best. If you can find the ones from California (often labelled "California Cuties", in mesh bags), they seem to be consistently good.

Just a few years ago no one had heard of clementines; now they're everywhere and they sell like hotcakes. I hope that food marketers will take note that SHOPPERS WILL BUY healthful foods if they are tasty, attractively packaged and reasonably priced. Vote with your pocketbook; buy lots and enjoy!

Monday, December 10, 2007

Lactose Intolerance: How to Eat Healthfully

Fifty percent of North Americans are lactose intolerant. They lack the enzyme to split the double sugar, lactose, found in milk and other dairy products. Since you can only absorb single sugars, if you can't split the double sugar, it passes to your large intestine where it is attacked by bacteria and fermented, causing gas and cramping. Some people deal with this by adding the lactase enzyme to their diet.

You can eliminate all dairy products and still have a perfectly healthful diet. Yes, milk is a good source of calcium, vitamin D, protein and other nutrients, but it is far from essential. You can get all the calcium you need from a variety of other foods.

Many doctors, dieticians and vegetarians oppose the use of dairy products, and back their position with extensive research data. Check the Physicians Committee for Responsible Nutrition web site, www.pcrm.org, for some interesting articles and journal references.

You can get plenty of calcium in your diet if you include lots of leafy green vegetables, a wide variety of beans and whole grains, and perhaps fortified products such as soy milk, cereals and juices. The RDA for calcium ranges from 800mg for young children to 1500mg for older people and pregnant or nursing women. If you're not sure you are getting that amount in your diet, it won't hurt to take a calcium supplement.

Here's the calcium content of some typical beans, vegetables and fruits (Portion size is 1 cup, cooked, unless otherwise noted):

Black beans - 103 mg
Chick peas - 80 mg
Pinto beans - 82 mg
Soybeans - 175 mg
White beans - 161 mg
Broccoli - 94 mg
Collard greens - 358 mg
Spinach - 244 mg
Swiss chard - 102 mg
Dried figs (10)- 269 mg
Orange (1) - 56 mg
Raisins - (2/3 cup) - 53 mg
Tofu (½ cup) - 258 mg.)

Sunday, December 09, 2007

Wound Healing Time Increases with Age; Exercise Can Help

Animal studies suggest that exercise may be even more important for older people than for younger ones. A report from the University of Illinois at Urbana-Champaign shows that exercise significantly decreased wound size and increased healing rate in older mice. However, exercise had little effect on the rate of wound healing in young mice. (American Journal of Physiology - Regulatory, Integrative and Comparative Physiology, November 14, 2007).

Mice ran on a treadmill at moderate intensity for 30 minutes a day for eight days. They then were given four full- thickness skin wounds and the rate of wound healing was checked daily for 10 days. Compared to age-matched non- exercising mice, the older exercisers healed faster.

The leading theory is that aging delays wound healing presumably because aging causes your body to produce more free radicals that damage the genetic material in cells. After you eat, food travels into mitochondria, small areas in cells that turn food into energy. They do this by removing electrons and hydrogen from nutrients. The electrons then attach to oxygen to form free radicals that stick to and damage the genetic material DNA in cells. This can delay healing and presumably even shorten life. Exercise causes the mitochondria to turn food into energy without producing as many free radicals, and therefore could hasten healing from any type of injury or illness. More on mitochondria and aging

Wednesday, December 05, 2007

Stretching: Know When, How and Why

Stretching the leg muscles improves muscle flexibility and strength, running speed, and jumping distance, according to a study from Louisiana State University. Stretching elongates muscles and tendons. Longer tendons allow muscles to exert a greater torque on the joint to exert more power to help you lift heavier, jump higher and run faster.

However, other studies show that you should not stretch before a competition involving speed and strength. The longer the athletes stretched, the weaker they became. Prolonged stretching fatigues muscle fibers so that they contract with reduced force. Do slow deliberate stretches lasting a few seconds to several seconds, rather than rapid hard pulls on your muscles that can tear them. Stretching cold muscles can also tear them and increase risk for injury. Warm up before stretching or stretch after your workout, but realize that prolonged stretching before a competition can harm performance. Journal references; more on stretching

Sunday, December 02, 2007

Athletes Harm Others with Performance Enhancing Drugs

Some people think that we should let athletes take performance-enhancing drugs because they think that these athletes can only harm themselves and do not harm others. We already know that anabolic steroids can cause liver damage, heart attacks and strokes, and that growth hormone causes heart attacks by causing the heart muscle to outgrow its blood supply. Now a two-year study of former East German athletes shows that athletes who take these drugs can harm their children.

In the 1970s and 80s, almost all government sponsored East German athletes were forced to take anabolic steroids and other performance-enhancing drugs. A study of 69 children of 52 of these athletes showed that seven had birth defects and four were mentally retarded, an unusually high incidence for a group of this size. More than 25 percent had allergies and 23 percent had asthma. The women suffered 32 times the normal incidence of miscarriage and stillbirth, 25 percent suffered cancer and 61 percent had therapy for mental disorders. The study was conducted by Dr. Giselher Spitzer at Humbolt University in Germany.

Many people are not aware that at this time, there is no test to catch athletes who take growth hormone. The winner of the 2006 Tour de France and the leader of the 2007 tour were disqualified for allegedly taking performance-enhancing drugs. This was just the tip of the iceberg. Martial Saugy, director of the Swiss Laboratory for Analysis of Doping in Lausanne, Switzerland, told a Belgian newspaper that 47 of 189 riders raced on blood transfusions or EPO in the 2007 Tour de France. The tests did not meet standards necessary to disqualify the riders. He also suspects that the riders also took testosterone and growth hormone. More