Depending on whom you ask, soy products are either a great boon to mankind or the worst crap on Earth. Those who advocate the use of soy in its various forms, including soy protein, tofu and soy flour, point to many studies that show protective effects. A study of Seventh Day Adventist men, for example, associated drinking soy milk with a 70 percent reduction in prostate cancer.

In vitro, or isolated-cell, studies show that the primary active ingredients in soy, isoflavones, can block the growth of prostate cancer cells. Soy also appears to offer protective effects against estrogen-related cancers in women, such as breast and uterine cancers. Incidence of these types of cancer is lower in Asian countries, where soy intake is higher.

Those who eschew soy in any form point out that soy isoflavones are phytoestrogens, or plant estrogens. Although the naturally occurring estrogenlike compounds have only about 1/10,000 the potency of direct estrogen, they can still interact with hormones in the body. In fact, that's the main controversy about soy: It may not only exert estrogenlike effects in men but also interfere with androgen, or testosterone, activity.

Scientists like soy's interference with testosterone because test is linked to prostate cancer. While little or no evidence indicts it as a direct cause of prostate cancer, it does speed the growth of that disease. Many forms of therapy used to treat prostate cancer block the effects of testosterone and such other androgens as dihydrotestosterone (DHT). Blocking androgens before the prostate cancer has spread can lead to a shrinkage or even disappearance of the cancer. Prostate cancer is unaffected by any other type of androgen.

From a bodybuilding perspective it's difficult to justify the use of soy protein. Although considered a complete protein, soy is naturally low in the essential amino acid methionine. Companies that make soy products circumvent that problem by adding methionine, which makes soy protein compare favorably to milk and egg proteins. Like whey protein, it's also rich in the beneficial branched-chain amino acids.

Those pesky soy isoflavones, though, may still interfere. Studies examining the effects of soy protein on testosterone are equivocal, with some indicating an interference and others showing no effect.

In the latest study to examine the issue, 35 men, aged 20 to 40, got either a milk protein isolate or one of two types of soy protein, one having a high isoflavone content and the other having a low isoflavone content.1 After 57 days those getting the soy proteins showed lower levels of DHT than those in the milk group.

DHT is testosterone's evil twin. It has little or no anabolic effect in muscle but promotes prostate enlargement and cancer, acne and male-pattern baldness. Soy lowered DHT without influencing 5-alpha reductase, the enzyme that converts testosterone into DHT. Only the low-isoflavone soy lowered total testosterone, and that occurred at the 29th day of the study. Free, or active, testosterone was also lowered but not to a significant degree. The low-isoflavone soy also increased DHEA-S, the circulating form of the adrenal androgen DHEA in the body. That may have affected the increased estrogen level seen in the low-isoflavone group at day 5, since DHEA is usually converted into estrogen in younger men.

Collectively, these results don't paint a pretty picture of the effects on young men who use soy. The mysterious aspect of the study, which the authors didn't explain, was why only the low-isoflavone soy produced those hormonal effects. Since the isoflavones are considered the active components of soy that affect hormonal activity, the higher-isoflavone soy should have produced the greatest effects, but that wasn't the case. There may be something else in soy that affects hormones. IM

1 Dillingham, B.L.,et al. (2005). Soy protein isolates of varying isoflavone content exert minor effects on serum reproductive hormones in healthy young men. J Nutr. 135:584-91.

The most frequent criticism of today’s popular low-carbohydrate diets is that they’re antithetical to optimum body chemistry. The idea is that since carbohydrates are undeniably the most readily available fuel source, not eating enough carbs leads to a host of physical and mental impairments, such as fatigue and a decrease in training intensity.

Most nutrition authorities say that the ideal diet contains 55 to 60 percent carbohydrate. The preferred forms have the least effect on insulin secretion, usually because of their naturally higher fiber content. One way to figure out which carbs are best to eat is to consult a glycemic index, or GI, chart.

The glycemic index assigns numbers based on how rapidly a carb is absorbed into the blood compared with glucose, which is assigned the number 100. The primary problem with depending on GI numbers is that they apply only to carbs eaten alone, without any protein or fat. Protein and fat slow down carb absorption significantly, thus making GI numbers irrelevant.

With all the admonitions about the importance of carbohydrate intake, you would think that carbs are an essential nutrient. The truth is, though, that essential carb intake hasn’t been identified, as it has for fats and protein, simply because carbs can be synthesized in the liver from protein and, to a lesser degree, from fat in a process called gluconeogenesis. Some studies show that about 57 percent of excess dietary protein is converted to glucose, the carb that circulates in the blood. Ten percent of glycerol, the triglyceride molecule, converts to glucose in the liver. Even by-products of exercise metabolism, such as lactate, readily convert into glucose in the liver.

What’s really important about carb foods is not the carbohydrate per se but the nutrients found in unprocessed carb foods, such as fruits, vegetables and whole grains. They contain fiber and myriad impressive health-preserving nutrients that fall under the umbrella term phytonutrients, such as flavonoids. Processed carbs, such as the abomination known as high-fructose corn syrup, have zero redeeming characteristics and are a primary factor in today’s obesity epidemic.

What would happen if you eliminated carbs from your diet? Surely that would induce metabolic derangement. Many studies examining the relationship between exercise and carbs have demonstrated that eliminating carbs does indeed lead to a significant drop in energy and training intensity. A lot of them are meaningless, however, because they were all short-term’often lasting no more than a week.

People who’ve eaten large amounts of carbs are sugar burners and may experience initial fatigue if their sugar or carb sources are abruptly removed. The body needs time to adjust to using another type of fuel’fat. The metabolic switchover takes about two to three weeks, during which most people feel some level of fatigue and lassitude. If you continue the diet and take certain precautions, however, the symptoms disappear.

That the human body is capable of adapting to a depletion of carbs is evident from the Inuit, or Eskimo, people, whose traditional diet contained about 85 percent fat and 15 percent protein. Despite the lack of carbs’fruits and veggies aren’t readily available in the Arctic’they thrived. Their high intake of fatty fish was the first found evidence of the benefits of omega-3 fatty acids, since the Inuit showed far lower rates of cardiovascular mortality than people living in Denmark, where the diet was more typically Western.

In 1929 an anthropologist named Vilhjalmur Stefansson returned from living with the Inuit for more than five years. To silence scientific skepticism at the time, Stefansson and an associate voluntarily committed themselves to a metabolic ward at Bellevue hospital in New York, where they ate the carb-free Inuit diet for a year under medical scrutiny. They showed no adverse effects on the diet, not even a vitamin C deficiency, which was predicted to occur after three months.

But what of exercise? It’s one thing to sit around in a hospital ward, but what happens if you cut out carbs and try to train at the gym? Studies have examined that aspect of low-carb diets and found surprisingly few adverse effects, as long as a few other factors are accounted for. The first is time for adaptation, starting with the two to three weeks the body needs to switch over to using fat instead of carbs as an energy source. Indeed, including carbs every few days prevents full metabolic adaptation to fat as a primary fuel source. ALL It’s also important to ensure adequate mineral, or electrolyte, intake. Low-carb diets are famous for their diuretic effect. That loss of water is often attributed to a breakdown of stored glycogen, which is stored with 2.7 grams of water for every gram of glycogen. But along with the water go electrolytes, such as sodium, magnesium and potassium, which play vital roles in nerve transmission. When they’re lacking, weakness and lassitude soon follow’along with more severe and even life-threatening effects.

Maintaining a high level of electrolytes also helps preserve lean mass, or muscle. Potassium is particularly important, but without magnesium you can’t retain potassium; you need them both. Adding calcium may also help because the lack of dairy foods limits calcium intake. Among other functions, calcium is required for muscle contraction and to help ward off muscle cramps.

The other key to an optimal low-carb diet for training is a higher protein intake. As you reduce calories or carbs, you must increase protein. That buffers you against nitrogen loss, which would lead to muscle breakdown, or catabolism. The body needs the excess protein converted in the liver to glucose for brain and central-nervous-system operation. Frequent protein meals also suppress appetite, which makes dieting easier.

One aspect that must be considered is the relationship between carb intake and glycogen synthesis. Without carbs, glycogen synthesis is stymied. Insufficient glycogen means lack of muscle pump, decreased recovery and lack of training intensity, since anaerobic exercise’such as bodybuilding workouts’relies on muscle glycogen stores.

The solution is simple. Get the majority of your carbs before and after activity and concentrate on protein when you’re not active. That way you burn bodyfat at a maximum rate while getting the carbs you need to train hard. Also be aware that any carbs you get within the initial two hours after a workout go straight into glycogen replenishment. Carbs taken in at that time do not hinder fat metabolism, contrary to what some have stated. IM