Supplements & Your Health: Vitamin C and Insulin..

Vitamin C and Insulin

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Insulin is a hormone secreted by the beta cells of the pancreas. Its primary function involves shuttling sugars into cells for energy production. Insulin also plays an anabolic role in muscle by promoting the entry of amino acids into it for use in protein synthesis. A lesser known but related function is that it increases bodyfat deposition by stimulating the enzyme lipoprotein lipase.

Bodybuilders who have a genetic predisposition for fat cells that are both enlarged and more numerous than normal must be careful about excess insulin secretion, people with this type of fat distribution tend to be insulin insensitive due to a decrease in cell receptor sites for insulin. What this means is that these people secrete more insulin than normal, a condition called hyperinsulinemia.

Secreting excess insulin perpetuates obesity because of the aforementioned fat cell enzyme stimulation. If you diet properly, your fat cells, or lipocytes, will shrink. As they shrink, insulin receptor sites open up. That's why type II diabetics, who are also insulin insensitive, are strongly advised to lose bodyfat. In many cases diabetics can reduce or eliminate insulin injections if they lose sufficient amounts of bodyfat.

Recently, the trace mineral chromium has been touted as an effective weight-loss aid. Chromium increases insulin potency by allowing it to bind more effectively to cell receptors, if your insulin works better, your body doesn't have to secrete as much. This, in turn, means you have Jess insulin to stimulate fat deposition. Another way to modulate insulin flow is to take a soluble fiber supplement when you eat a meal that's high in simple or refined sugars.

Simple sugars cause the greatest insulin release because they contain no dietary fiber. In contrast, the usually higher fiber content of complex carbohydrates provides a slow release of sugar, and you don't get a heavy insulin surge. This explains why you are far less likely to add bodyfat when you eat complex carbohydrates compared to simple carbs.

Examples of simple carbs include fruit juices and candy or other refined sugar products. Complex carbs are unrefined foods that are high in fiber, such as whole grains and vegetables. Fruit falls somewhere in the middle because while most fruit does contain fiber, it's also rich in simple sugars. The same holds true for maltodextrin, which is found in many carbohydrate supplements. While maltodextrin is structurally a complex carb, studies show that it enters the blood just a bit more slowly than simple sugars in many people. Pasta acts like a complex carb unless it's overcooked, which more or less converts it into a simple carb.

When you add a soluble fiber, such as is found in fruits and beans, to a meal high in simple sugar, the fiber locks onto the sugar, delaying its release into the blood. Thus, you can convert a simple sugar to one that mimics a complex carb by serving it with something that contains soluble fiber, Other sources of soluble fiber include gums, such as those found in oatmeal and beans. A few commercial soluble fiber supplements are also effective for this purpose, including Fibersol, which is produced by TwinLab.

Media nutrition experts Durk Pearson and Sandy Shaw have advised people who tend to get hypoglycemia, or low blood sugar, from excess insulin to supplement their diets with the amino acid cysteine. This recommendation is based on the fact that insulin has two disulfide, or sulfur bonds. Cysteine, a sulfur-containing amino acid, may break those insulin bonds, which may reduce the potency of insulin.

A recent animal study shows that another nutrient may also reduce insulin release. Researchers from the National Institutes of Health in Bethesda, Maryland, cultured rat and mouse pancreatic cells in glucose, the same sugar that circulates in the blood. Half the samples were cultured in vitamin C, and the researchers discovered that the more vitamin C they added to the culture, the greater the inhibition of insulin release. For example, 200 micrograms of vitamin C caused a 50 percent insulin release reduction, and 400 micrograms increased the reduction to 90 percent.

This study shows that vitamin C may inhibit excess insulin release after you eat simple sugars. The next step involves determining an effective dose of vitamin C to create this response in humans.

Preventing Exercise Fatigue With Amino Acids

Bodybuilders are frequently advised to consume plenty of complex carbohydrates to increase energy, and it's true that the degree of stored carbohydrate in your muscle, known as glycogen, reflects the amount of carbohydrate foods you eat. This is significant because muscle glycogen is the primary fuel that powers bodybuilding workouts. It takes anywhere from 12 to 48 hours to replenish depleted muscle glycogen, however, which means that the muscle glycogen content that fuels today's workout reflects yesterdays intake of carbohydrate.

Eating a meal rich in complex carbohydrate two to four hours before a workout helps prevent possible premature glycogen exhaustion during the exercise, although in reality a muscle is never completely depleted of glycogen. If the glycogen dips too low, you'll feel a loss of muscle strength and your pump will be notably less intense.

Despite the above information, eating a carb meal before training can have a paradoxical effect in some bodybuilders. Carbohydrates stimulate insulin flow, and when insulin is secreted, it facilitates the removal of all circulating amino acids in the blood-except one. With all other amino acids eliminated from the blood through insulin action, tryptophan has clear access to the brain. Normally, tryptophan competes with other aminos for brain uptake, and it usually loses.

Upon entering the brain, tryptophan rapidly converts through enzyme action into a brain chemical called serotonin. This substance has a relaxing effect on the brain and is involved in the onset of sleep. That explains why tryptophan was a popular supplement for inducing sleep until the Food and Drug Administration removed it from the marketplace a few years ago because of a biochemical false alarm.

Unfortunately, relaxation translates into premature fatigue during a workout. One suggested remedy for this is supplementing branched- chain amino acids, or BCAA, before a workout. As noted above, tryptophan competes with other amino acids for entry into the brain and usually loses to large neutral amino acids, such as the BCAA. Past studies show that taking BCAA before a workout offsets the carbohydrate/ insulin/tryptophan effect, thus preventing central nervous system fatigue.

A recent study performed with rats appears to contradict this suggestion, however. Rats ingested either glucose or branched-chain amino acids before doing exhaustive exercise on a mini-treadmill. The group that ingested the BCAA showed a greater level of fatigue, which is curious, since glucose is a simple sugar that's supposed to cause the greatest insulin release.

The scientists concluded that the BCAA caused a larger insulin release than glucose, and this led to premature fatigue through two mechanisms: 1) removal of blood glucose by insulin; and 2) decreased breakdown and release of stored liver glycogen, which is needed to maintain a proper blood glucose level.

The practical lesson to be learned from this study is that a combination of high carbohydrates and high levels of BCAA can cause premature fatigue during a workout, particularly a session that lasts more than two hours. After a workout, however, the situation reverses.

That's when you want a heavy insulin flow to promote muscle protein synthesis. In effect, if you consume a supplement like one of the metabolic optimizers that are rich in both carbs and BCAA, you'd be advised to do it after you train if you want to maintain a high energy level during the workout.




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