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Why Sugar Can Shorten or Lengthen Your Life

A high rise in blood sugar can damage every cell in your body. When blood sugar levels rise too high, sugar can stick to the surface of cell membranes. Once stuck there, it can never get off. In a series of chemical reactions, glucose (the only sugar that circulates in your bloodstream) is converted to another sugar called fructose and eventually to a sugar alcohol called sorbitol that destroys the cell to cause every know side effect of diabetes: blindness, deafness, heart attacks, strokes, kidney damage and so forth.

When you eat, sugar can go into:
• your muscles, to make you a better athlete and prolong your life,
• your brain, to keep you smart and alert, or
• your liver to store sugar for future use. Sending too much sugar to your liver can make you fat, increase your risk for a heart attack and shorten your life.

At rest, your brain requires more sugar than the rest of your body combined. Ninety-eight percent of the energy to fuel your brain comes from sugar, so your brain has to have sugar available all the time. A constant supply of blood sugar to your brain helps keep you smart and alert. If your blood sugar level drops too low, you pass out, so your liver always tries to protect you from low blood sugar levels. When blood sugar starts to drop too low, your liver works to save your brain by releasing stored sugar from its cells into your bloodstream. If not enough sugar is available, the liver converts protein into sugar to keep your brain supplied.

Resting muscles are passive and can draw sugar from the bloodstream only with the help of insulin. Contracting muscles can remove sugar directly from the bloodstream without needing insulin. Contracting muscles are also extraordinarily sensitive to insulin, so it takes far less insulin to supply your muscles with sugar during exercise. These beneficial effects are maximal during exercise and for up to an hour afterward and then taper off to zero about 17 hours after you finish exercising.

When your muscles are inactive, you should avoid sugar and all refined carbohydrates. When your blood sugar rises too high, all the extra sugar goes to your liver, and that's when you damage your health. The high rise in blood sugar causes your pancreas to release huge amounts of insulin. This increases risk for a heart attack because insulin constricts arteries leading to your heart to block blood flow there. Insulin converts sugar to triglycerides and your blood fills with this fat (high triglycerides). High triglycerides increase risk for clotting, so your body tries to protect you by using the good HDL cholesterol to carry triglycerides from your bloodstream to your liver (low good HDL cholesterol). The increase in triglycerides can cause liver damage (fatty liver). Insulin also causes the extra fat to be deposited into fat cells in your belly (fat belly). Full belly fat cells block insulin receptors to make the blood sugar and insulin levels rise even higher.

People who have small buttocks are most likely to deposit fat in their bellies and are at the highest risk for diabetes and heart attacks. If you have a fat belly and small hips, you already have insulin levels that are high enough to cause severe damage to your health and are at high risk for diabetes and heart attacks. The combination of high blood insulin, triglycerides and sugar, low good HDL cholesterol and deposition of fat in the belly is called Metabolic Syndrome which means you are at high risk for diabetes and heart attacks. It happened because you eat too much sugar and refined carbohydrates when you are not exercising.

On the other hand, taking sugar when you exercise is good for you. I'll explain why in next week's eZine.


Dear Dr. Mirkin: Why do I get painful belly cramps near the end of a hard workout? Intense exercise often causes giant contractions of your colon that move stool, gas and fluids toward the end of your colon to stretch it and hurt. To prevent this from happening to you, you need to empty your colon prior to your intense workouts and races.

After you eat, food passes to your stomach and the pyloric sphincter at the end of your stomach closes. Food is not allowed to pass until it is turned into a liquid soup. Food can remain in your stomach for up to five hours. Then your stomach contracts and squeezes the liquid soup into your intestines. The liquid soup does not solidify until it reaches your colon, where large amounts of fluid are absorbed. The longer stool remains in your colon, the more fluid is absorbed and the harder it becomes so it is more difficult to pass. You want to get the soft stool out soon before it hardens. Fiber holds water in the stool and helps to keep it soft.

Switch to a high-fiber diet with lots of fruits and vegetables that produces residue that will hold water in your stool. Restrict the great constipators, bread and spaghetti. On the morning of your hard workouts, eat your preferred breakfast and then spend time to empty your colon as much as possible. Try just after breakfast, because food entering your stomach stimulates a gastro-colic reflex that causes your colon to contract and push stool towards its opening.

If your belly cramps are accompanied by light-headedness, dizziness, blurred vision, chest pain or irregular heart beats, or if you have a history of heart problems, check with your doctor.


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Dear Dr. Mirkin: Do I need to protect my skin from sunlight in winter?

Everyone should try to get about half an hour of sunlight on a few inches of skin at least three days a week to get vitamin D. If you are outdoors much longer than that, you need protection from sun even in wintertime when the sun's angle is low. Researchers in Valencia, Spain had competitive cyclists wear sun-exposure gauges (Brand name Viospor) on their helmets in June-July and again in February-March ([Photochemistry and Photobiology, May-June 2010). Their exposure to ultra-violet light in the wintertime was 11 times the amount that causes skin redness (it was 32 times that amount in summer). This means that there is enough cumulative exposure to the sun's rays in the winter to cause skin aging, wrinkling and cancer. Valencia is about the same latitude as Philadelphia.

All outdoor athletes and others who spend time outdoors should protect their skin 12 months a year. Clothing is the best protection. The safety of many sunscreens is being questioned; see my report on sunscreens.


Recipe of the Week:

Vegetable Curry with Peaches

You'll find lots of recipes and helpful tips in The Good Food Book - it's FREE

June 21st, 2013
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About the Author: Gabe Mirkin, MD

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D., brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. The Dr. Mirkin Show, his call-in show on fitness and health, was syndicated in more than 120 cities. Read More
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