Muscles are made up of proteins which are polymers of amino acids. When you exercise, you burn energy that was stored in your body. If you want to burn fat and not muscle, it is important that you maintain your muscles by supplementing your diet with protein, in order for your body to get the building blocks (the amino acids) it needs. Otherwise, your muscle themselves will be digested as you exercise, thwarting your efforts. Since vegetables contain less protein on a weight per weight basis than meat, one rarely hears of vegetarian body builders.
Though soy and other legumes are a fairly good source of protein, they do not compete with red meat and egg. Until recently, egg white was the all-time favourite protein source, since excessive red meat consumption has been connected with health problems. These days, though, whey is by far the protein champion.
Whey is the watery concentrate left behind after a cheese curdles. The curds themselves are a mixture of fat and protein, mostly casein. Whey contains among other things the protein alpha-lactalbumin, vitamins and minerals. It is particularly rich in the essential branched chain amino acids (leucine, isoleucine, and valine) and the biochemically vital cysteine. Essential means our bodies cannot produce these compounds so we must obtain them from our diet.
When whey is undenatured, that is, when the protein has not been heated to the point of changing its original 3-D molecular conformation, it is the best source of protein for your muscles possible. That is not to say, however, that ingesting whey protein will make your muscles burst into growth. No evidence exists to this effect, in spite of all the hype surrounding 鈥減ump you up鈥� whey protein formulas on the market. Resistance training will make your muscles larger, whey will only ensure that your body has what it needs to make the necessary expansion. Clinical trials on HIV+ women showed that a combination of regular resistance training and whey consumption significantly slowed the process of 鈥渨asting鈥�, the rapid reduction in lean body mass typical of AIDS.
The whey debate really only applies to very, very serious athletes and body builders. Most healthy, active people are already getting much more protein daily than their body needs to maintain or even build muscle mass. Only if you spend most of your time exercising should protein source be a serious concern for you, so long as your diet is balanced. It should be noted, however, that there is some evidence suggesting that calcium (found in whey and all听dairy products) has the ability to inhibit adiposity (fat storage), favouring a shift toward a leaner body composition.
By the Whey...
Besides being an excellent source of protein, whey offers other interesting benefits. Of late, it has been celebrated as an antioxidant, an immune-builder and even a mood-stimulator. The immune response to toxins and pathogens in the body depends on the rapid proliferation of lymphocytes, a kind of white blood cell. Glutathione regulates these frontline defenses by stimulating lymphocyte production. Glutathione synthesis in the body depends on the presence of the amino acid cysteine, an amino acid that abounds in whey protein. Whey formulas that have high cysteine content have shown a measurable effect on immune response in immunosuppressed individuals such as the HIV positive or people suffering from chronic fatigue syndrome (CFS). Whey鈥檚 capacity to build the immune system reinforces its appeal for athletes who may suffer from immunosuppression as the result of intense physical exertion. So far, whey is the only practical vehicle for cysteine, N- acetylcysteine being an emetic (causes nausea) and pure cysteine being toxic at the required levels.
Furthermore, there is some preliminary evidence showing that certain whey formulas may reduce the incidence of cancerous tumors and slow their growth. The explanation for this observation comes from whey鈥檚 ability to decrease cancer cells鈥� glutathione levels. Though this may seem to contradict whey鈥檚 ability to increase glutathione concentration in healthy cells, the difference rests on a negative feedback mechanism whereby glutathione would inhibit its own synthesis when it is present at high levels. In cancer cells, glutathione levels are so high that anti-tumor drugs are often ineffective against their rapid proliferation. Consuming whey might be one way to reduce tumor cells鈥� defense, making chemotherapy much more effective.
Whey also has antioxidant properties since glutathione is involved in inactivating oxygen free radicals. Free radicals are highly reactive species with an unpaired electron that wreak havoc on the body by causing oxidation of chemical bonds in DNA and important enzymes. These processes are thought to lead to cancer, heart disease and the neurodegeneration associated with aging. Glutathione peroxidase and peroxide dismutase are two enzymes that inactive these harmful species and these are both activated by the compounds present in whey extract.
Finally, whey contains tryptophan, a synthetic precursor for serotonin, the neurotransmitter responsible for good mood and relaxation. Some scientists have suggested that for this reason whey may have mood-elevating properties. Indeed, people consuming whey report feeling happier, but perhaps this is only a product of their satisfaction in doing something healthy and positive for themselves. Only time will tell...
Lauren Lapointe-Shaw studied Biology at 捆绑SM社区 and is now an Assistant Professor at the University of Toronto and听practicing General Internal Medicine at the Toronto General Hospital Research Institute.
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