Carbs essential to strength, study shows

According to a new study from researchers at the University of Connecticut, exercisers who switched from a carb- and protein-balanced nutrition plan to a "ketogenic diet," characterized by very low carbs (about 8 percent of total calories) and high amounts of protein and fat, experienced a 7 percent to 9 percent reduction in peak muscular power over a period of six weeks. The ketogenic plan, the researchers found, also negatively impacted the athletes' cardiovascular fitness, causing a 6 percent decrease in VO2 peak over the study period.

These results shouldn't come as a surprise given that carbohydrates are the most important energy source for exercising muscles and are the only food that can be used for anaerobic energy needed for weight training. Carbohydrates are also the most efficient fuel for aerobic exercise in that they are able to produce energy at a rate three times faster than that of fat and require less oxygen to do so.

Optimal exercise performance, numerous studies have shown, is best fueled by maintaining adequate stores of carbohydrates (glycogen) in muscles and liver, which is best achieved through carbohydrate- and protein-balanced eating.

Vitamins/minerals found lacking in low-carb eating

People concerned with optimal intake of the important vitamins and minerals should steer clear of the popular no-/low-carbohydrate plans and stick with basic, balanced nutrition, according to results of a new study presented before 12,000 scientists at the 2003 Experimental Biology conference in San Diego.

In her investigation, Beth Zupec-Kania, R.D., C.D., a dietician at the Children's Hospital of Wisconsin, analyzed a three-day very low-carbohydrate diet, providing 1,250 calories a day, for vitamin and mineral content. Zupec-Kania notes that nutrient-dense foods were purposely selected for the study to optimize results. Still, of the 24 micronutrients evaluated, disturbingly, 19 were below the Dietary Reference Intakes (DRIs).

Worse, 11 essential micronutrients were provided at less than 50 percent of the DRIs. These include thiamin, folate, pantothenic acid, calcium, copper, iron, magnesium, manganese, molybdenum, selenium and zinc.

"A selection of less nutritionally dense foods would have resulted in even lower intakes of these nutrients," Zupec-Kania says.

Micronutrient deficiencies, especially ones as severe as those noted in this study, are serious and carry major health implications, new research is showing. According to Dr. Bruce Ames, a professor of molecular and cell biology at the University of California, Berkeley, vitamin and mineral deficiencies can lead to DNA damage. In fact, in his research, Dr. Ames has found that cells lacking vitamins and minerals suffer DNA and mitochondrial damage similar to that caused by irradiation (e.g., excessive X-rays). This damage, he says, could cause you to age prematurely and could lead to cancer and degenerative diseases such as Alzheimer's and Parkinson's. "Inadequate intake of essential vitamins and minerals might explain the epidemiological findings that people who eat only small amounts of fruits and vegetables have an increased risk of developing cancer," he says.

Balanced breakfasts life health, spirits

People who consume a protein- and carb-balanced breakfast every morning have greater mental and physical health than non-breakfast eaters, according to a new report published in the International Journal of Food Science and Nutrition.

In the study, researchers from the United Kingdom's University of Bristol studied 127 people and compared information about their nutritional regimens with their mood states and overall mental health. According to the researchers, "People who consumed a balanced breakfast each day were less depressed, less emotionally distressed and had lower levels of perceived stress than those who did not eat breakfast each day."

What's more, breakfast eaters were more physically fit, had lower bodyfat percentages and were less likely to smoke or drink alcohol than people who skipped breakfast.

Do low carbs equal high cholesterol?

Researchers at the Johns Hopkins Children's Center report that very low-carbohydrate "ketogenic" nutritional regimens may markedly raise children's cholesterol and levels of lipids (fat) in the blood. The ketogenic diet has long been used to help reduce the incidence of seizures in children with epilepsy. It seems ketones, a chemical byproduct of fat produced by the body as a backup fuel in the absence of carbs, may somehow inhibit seizures.

Results of the study, published recently in the Journal of the American Medical Association (JAMA), show that after following the diet for six months, only one in six children in the 141-child study group had either a cholesterol or triglyceride level considered acceptable for children.

Nevertheless, the researchers concluded that the diet should remain a treatment option because children typically remain on the diet temporarily—only one to two years. "These high cholesterol and triglyceride levels are unlikely to be associated with a long-term increase in risk for cardiovascular disease in adulthood," says the study's lead author, Peter O. Kwiterovich, Jr., M.D., director of the Division of Lipid Research and Atherosclerosis at the Children's Center.

"Although we know that, in adults, high cholesterol and triglyceride levels may increase one's risk for heart disease, we believe that children following the ketogenic diet do not stay on it long enough for these high levels to become a problem," he says. "Typically, when the children resume a normal diet, these levels return to normal."

What influence the ketogenic diet may have on the cholesterol and triglyceride levels of adults isn't certain. A recent shortterm investigation reported in the May 2003 issue of the New England Journal of Medicine found the popular Atkins diet, a ketogenic plan, had no negative impact on total cholesterol or blood lipids. However, the absence of long-term data has many cardiologists concerned. "There is no doubt that you lose weight initially, but there is a grave risk of a dramatic rise in cholesterol during the (weight loss) maintenance phase," Dr. Jim Mann, an endocrinologist at the University of Otago, New Zealand, told the physicians attending the 2003 European Society of Cardiology meeting in Vienna.

"There is no long-term data. The majority of people lose weight with the Atkins diet and initially cholesterol levels seem to be lower. But when weight loss is maintained—or as often happens, there is a weight gain—we have observed that a lot of people experience a rise in cholesterol levels greater than when they started the diet."

Balanced eating boosts fat loss

Balancing dietary protein with carbohydrates may preserve lean muscle and boost abdominal fat loss, according to new research from the Department of Medicine at Australia's Adelaide University. To determine the effect of a balanced protein and carbohydrate intake on lean muscle preservation and fat loss compared with a nutrition plan top heavy in carbohydrates and lacking in protein, researchers split a group of 54 subjects into one of two eating plans: A balanced macronutrient intake (30 percent protein, 40 percent carbs, 30 percent fat) or a high-carb, low-protein eating regimen (15 percent protein, 55 percent carbs, 8 percent fat). Those eating nutritionally balanced meals, results showed, lost significantly more total fat (11.66 pounds vs. 6.16 pounds) and abdominal fat (2.86 pounds vs. 1.54 pounds) when compared to people on the high-carb, low-protein plan.

"The greater reductions in total and abdominal fat mass (on the balanced plan) suggest that this is a valid nutritional choice," the researchers concluded.

Expectant moms should not cut out carbohydrates

Women who are pregnant, or expect to be pregnant in the near future, should steer clear of low-carb diets and stick with smart, balanced eating, advise researchers from the United Kingdom.

According to Dr. Kirsten Herrick and her colleagues from the U.K.'s University of Southampton, carbohydrate-restrictive diets may increase levels of the powerful "stress hormone" cortisol in pregnant women, thereby exposing the fetus to excess cortisol and programming lifelong hypersecretion of cortisol. Hypersecretion of cortisol, termed "hypercortisolemia," has been linked to numerous deleterious health conditions, including cognitive impairments, clinical depression, hypertension, diabetes and obesity.

In the study, reported in the August 2003 edition of the Journal of Clinical Endocrinology & Metabolism, Dr. Herrick and colleagues found that fasting plasma cortisol concentrations were highly elevated in the 251 test subjects, ages 28 to 30, whose mothers had been advised to avoid carbohydrate foods during late pregnancy. The greater the imbalance in the diet, the greater the elevations in fasting cortisol, results showed.

"While our findings suggest that avoidance of an unbalanced high-protein diet is most important in late pregnancy, there is also other evidence which suggests that it should be avoided in early pregnancy as well," study co-author Keith Godfrey, Ph.D., told us in a recent interview.

As more and more research surfaces illustrating the dangers of unbalanced nutritional regimens, it's becoming more and more clear that balanced nutrition, rich in fruits, vegetables, lean protein and high-quality carbohydrates, is the intelligent choice.

Nutritious eating enhances memory

People who keep to strict "weight-loss" diets often have poorer memory and mental capabilities than do non-dieters, according to new research published in the American Journal of Clinical Nutrition.

In their investigation, Dr. Randall J. Kaplan and his colleagues from the University of Toronto found that dietary protein, carbohydrates and fat all play an important role in memory and cognition, and people who skimp on these essential macronutrients are likely not living up to their cognitive potential.

"To our knowledge, the present study is the first to show that pure dietary protein, carbohydrate and fat all enhance memory," write the researchers. "The finding that protein and fat enhanced memory was novel, whereas the benefits of glucose are supported by numerous studies in humans and animals."

And the effects are immediate, they report. After fasting overnight, 11 men and 11 women consumed either a nutrition shake containing whey protein, carbohydrates and essential fats or a non-energy placebo on four separate mornings. Cognitive tests were administered 15 and 60 minutes after ingestion of the drinks. Compared with the placebo, all three macronutrients (protein, carbs and fat) improved recall and memory within 15 minutes after ingestion, says Dr. Kaplan. "The proportion of North Americans with cognitive impairments is increasing as the population ages," the authors conclude. "It is important to understand environmental factors, such as nutrition, that may help to prevent or reduce such deficits."

The bottom line is this: Eating a balance of essential nutrients, including healthy carbs, is a bright idea.