Sunday, November 29, 2009

Junk Food Alters Intestinal Bacteria in Just One Day

After just one day of switching from a plant-based diet to a high-fat-and-sugar diet, mice with human intestinal bacteria developed bacteria associated with obesity in humans, and soon became grossly obese (Science Translational Medicine, November 11, 2009).

Dr. Jeffrey Gordon of Washington University in St Louis first showed that certain types of bacteria in the human intestinal tract can break down food more efficiently and help you absorb a greater percentage of calories from the food that you eat. He also showed that humans whose intestinal tracts are dominated by these bacteria tend to be overweight.

In this new study, Dr. Gordon created germ-free mice and fed them a low-fat, plant-rich diet. Then he fed them bacteria extracted from human stool and continued to feed them a low-fat, plant-based diet for one month. By sequencing the microbes' 16S rRNA gene, he showed that the intestinal bacteria in the mice were the same as those living in a healthy human's intestines.

One month later, he switched half the mice to a high-fat, high-sugar diet. After 24 hours, the intestines of the mice had increases in the obesity-causing bacteria, Firmicutes, and decreases in the obesity-preventing Bacteroidetes. The mice continued to grow fatter and fatter, even when switched back to the low-fat, plant-based diet.

What does this mean to you? When you eat a diet rich in refined carbohydrates (fruit juices, sugared drinks and foods made from flour and sugar) and fat (meat, fried foods, and fatty desserts), you develop intestines full of bacteria that thrive on these foods, break down these foods more efficiently, and then absorb far more calories from these foods. If you want your gut flora to help you maintain a healthful weight, you should eat primarily fruits, vegetables, whole grains, beans, seeds and nuts.

Monday, November 23, 2009

New Vitamin D Recommendations

At the University of Toronto School of Medicine's "Diagnosis and Treatment of Vitamin D Deficiency" conference on November 3, 2009, thirty of the world's leading researchers on vitamin D recommended 2,000 IU of vitamin D daily (the current recommendation is 600 IU). Vitamin D3 blood levels should be 100-150 nmol/L (40-60 ng/ml); the existing recommendation is 30-50 nmol/L.

Vitamin D pioneer Dr. Cedric Garland presented data showing that raising vitamin D levels to 200 nmol/L decreased breast cancer risk more than 77 percent. He said: "Breast cancer is a disease so directly related to vitamin D deficiency that a woman's risk of contracting the disease can be virtually eradicated by elevating her vitamin D status to near that level." Recent work has shown that all cells in the body have "vitamin D receptors" to control normal cell growth. Garland presented new evidence that low vitamin D status compromises the integrity of calcium-based cellular bonding within tissues, which allows rogue cancer cells to spread more readily.

Vitamin D deficiency is associated with at least 24 cancers, diabetes, multiple sclerosis, heart disease, falls and fractures, psoriasis and many other health problems.
More on Vitamin D

Wednesday, November 18, 2009

Will avoiding dietary sugar prolong life?

Nobody has yet shown any way to extend the life span of humans. However, both exercise and calorie restriction (with adequate nutrients) have been shown to extend the life span of animals. Both of these measures apparently extend life by increasing the number and size of mitochondria in cells and making them turn food into energy more efficiently. Each cell in your body contains up to several hundred mitochondria which provide the most efficient chemical reactions in your body for converting food into energy.

An exciting new study on worms offers a potential method for you to prolong life and good health. When blood sugar levels rise too high, sugar enters cells in large amounts. An earlier study showed that adding sugar to the diet of the worm, C. Elegans, shortens its life (Cell Metabolism, October 2007). Now the researchers have found that preventing sugar from entering cells by altering the genes for DAF-2, DAF-16 and Heat Shock Factor-1 causes the same changes as avoiding sugar and extends the worms' life span up to 20 percent (Cell Metabolism, November 2009). These benefits could also occur in humans because we have the same three genes that control sugar entry into cells as those of the worms.

Calorie restriction and exercise probably prolong life by the same mechanism: they enlarge and activate mitochondria in cells that turn food to energy. This helps mitochondria to clear free radicals much more rapidly from the body. Free radicals can damage cells and therefore shorten life. The worms' cells responded to the absence of sugar inside cells by increasing their ability to clear free radicals from their bodies which prolonged their lives. Indeed, when sugar was allowed to again enter their cells, they still could clear free radicals faster and live longer because their enlarged mitochondria were more efficient in removing free radicals.

This research on worms questions the way doctors treat type II diabetes when they prescribe drugs to lower blood sugar levels by driving sugar into cells. The best treatment may be to develop diets and drugs that prevent blood sugar from entering cells in the first place.

For now, we know that you will shorten your life and increase risk for many diseases by allowing blood sugar levels to rise too high after meals. A diet that keeps sugar from rising too high after meals (and reduces the entry of sugar into cells) can prevent diabetes, help control all the side effects of diabetes (JAMA, December 16, 2008), cause the most weight loss, and allow many type II diabetics to safely stop their medications (Nutrition and Metabolism, January 2009). Avoid foods that cause the highest rise in blood sugar levels: sugar in liquid form (sugared drinks, fruit juices, and adding sugar to any drink); foods made from flour (bread, spaghetti, macaroni, pretzels, bagels and so forth); and foods with added sugar.

You should also exercise every day. Exercise causes muscles to remove sugar from the bloodstream at a very rapid rate and this effect lasts maximally for about half hour after you stop exercising, then tapers off until it stops completely after about 17 hours. Furthermore, since lack of vitamin D causes high blood sugar levels, you should make sure that your blood level of vitamin D3 is above 75 nmol/L. New vitamin D recommendations

Monday, November 16, 2009

Just Getting Old Does Not Cause Diabetes

A study from the University of Pittsburgh shows that the marked increase in diabetes in older people is caused by obesity and lack of exercise, not by aging alone (Diabetes Care, August 2009). Most cases of diabetes are caused by cells not being able to respond to insulin, rather than by lack of insulin. Inability to respond adequately to insulin is caused by being overweight, not exercising, lacking vitamin D and/or eating too many refined carbohydrates.

In this study, the same insulin responses were found in young and old endurance-trained athletes, young and old normal-weight subjects, and young and old obese subjects. Regardless of age, athletes had better insulin responses than normal-weight sedentary subjects, who had better insulin responses than overweight people.

If you are overweight, try to lose the extra weight. Check with your doctor and start or continue an exercise program. Get a blood test called vitamin D3. If it is below 75 nmol/L, you need more sunlight or vitamin D pills. When you are not exercising, avoid sugar water and flour.
More on diabetes prevention and treatment

Monday, November 09, 2009

No Evidence Cycling Weakens Bones

No data exists in the scientific literature showing that any type of exercise weakens bones. Bone growth depends on the forces exerted on them by gravity and contracting muscles. So any activity or exercise that causes you to contract your muscles will strengthen bones (Medicine & Science in Sports & Exercise, November 2009).

Previous studies showed that world class cyclists had reduced bone densities in their spines. However, bone density tests do not measure bones strength. They measure how much bones block X-rays that try to pass through them. The only way to measure bone strength is to see how much force it takes to break a bone.

The most likely explanations for broken bones in cyclists are high-impact crashes and/or lack of vitamin D. I recommend that all cyclists get a blood test called Vitamin D3 in December or January. If it is below 75 nmol/L, they are deficient in vitamin D and at increased risk for breaking bones. To prevent fractures, they should do winter training in the southern sunbelt or take at least 800 IU of Vitamin D3 per day.

A recent review of 12 blinded, controlled scientific studies showed that oral vitamin D reduced non-vertebral and hip fractures in patients over 65 years of age (Evidence-Based Medicine, October 2009). Blood levels of vitamin D below 75 nmol/L cause parathyroid hormone levels to rise too high, which causes osteoporosis. A main function of vitamin D is to increase calcium absorption from the intestines into the bloodstream. When blood levels of vitamin D fall below 75 nmol/L, levels of ionizable calcium drop. This causes the parathyroid gland to produce large amounts of its hormone. Higher than normal blood parathyroid hormone levels take calcium out of bones to cause osteoporosis.

Monday, November 02, 2009

Fasting Does Not Increase Endurance

Some people think (incorrectly) that fasting before a race or competition will increase their endurance. Fasting weakens and tires you. How long you can exercise a muscle depends on how much sugar, called glycogen, you can store in that muscle and how long you can keep it there. When a muscle runs out of its stored glycogen, it slows down because it requires more oxygen to burn more fat. It also accumulates more lactic acid to become acidic which causes a burning pain, and it becomes more difficult to coordinate.

Every time you move a muscle, some of the stored glycogen is used up. Every time you eat, some of the food can be stored as glycogen in that muscle. When you go for more than an hour without eating, you use up glycogen without replacing it. If you don't eat before you compete, you start with reduced stores of glycogen in your muscles and you will not be able to compete at your best.

It is nonsensical to claim that fasting increases endurance by causing muscles to burn more fat and less glycogen so muscles can retain their stored glycogen longer. When you start with less glycogen, you still use it up faster and run out of fuel earlier. You can increase endurance by cutting back on exercise four days before your competition and eating as much or more than usual. Eat one to three hours before competing. If your event lasts more than an hour, take fluid, sugar and protein (whole grain bars, sugared drinks, etc.) during your event.