As the controversy surrounding the flurry of high-fat, no carbohydrate diets indicates, there is no simple panacea for achieving optimal cardiovascular health. While some studies have shown a positive impact of low-carb diets on lipid profiles, questions still abound as to just what the optimal diet is for a healthy heart.
|“Moderate carbohydrate restriction to the range of about 25 percent can have significant benefit for some people, even if these same people can’t lose weight.”
In a ground-breaking new study just published in the American Journal of Clinical Nutrition, however, CHORI scientist Ronald Krauss, MD, has set out to answer some of the nagging questions surrounding low-carb diets.
“Previous studies haven’t really distinguished the effects of diet from the effects of weight loss,” explains Dr. Krauss. “We wanted to look at the diet effect itself, separate from weight loss.”
Separating the effects of diet from weight loss isn’t just semantics. As Dr. Krauss discovered, limiting carbohydrate intake to moderate levels (no lower than about 26 percent of calories) had very significant benefits on lipid profiles – prior to any weight loss.
The practical implications of this are important, especially for the management of people with certain types of lipid profiles. As Dr. Krauss explains, “For people at risk of cardiovascular disease because of their lipid profile, this means that moderate carbohydrate restriction to the range of about 25 percent can have significant benefit, even if these same people can’t lose weight.”
In addition to discovering the independent benefits of the low-carb diet, Dr. Krauss unearthed another surprise: saturated fats may not be bad for everybody.
“The saturated fat that we tend to focus on doesn’t really come into play with certain lipid profiles,” says Dr. Krauss.
Never the less, Dr. Krauss also stresses that more research is required to determine health effects of differences in types, as well as amounts, of fat and carbohydrate in the diet.
|“The saturated fat that we tend to focus on doesn’t really come into play with certain lipid profiles,” says Dr. Krauss. “Increasing saturated fat does not appear to reduce the benefits of limiting carbohydrate.”
“It’s the carbohydrate that appears to have most of the effect when it comes to dietary influences. Increasing saturated fat does not appear to reduce the benefits of limiting carbohydrate.”
In fact, when Dr. Krauss compared the low-carb diet with lower saturated fat to the low-carb diet with higher saturated fat, he found that the increase in fat actually corresponded with an increase in the size of low-density lipoproteins (LDL). Larger LDL size is associated with a lower risk of cardiovascular disease than smaller LDL size.
Of course, such results only raise more questions. As the companion editorial to Dr. Krauss’s study in Am J Clin Nutr points out, all of these results confirm the general need to revisit baseline assumptions about the impact of low-fat diets on cardiovascular health.
“Higher fat, lower carbohydrate diets can have benefits,” says Dr. Krauss. “And as far as the low carbohydrate effect, that appears to provide a fairly uniform benefit.”
While there may never be quick fixes or easy answers, Dr. Krauss’s continued research brings us closer, a step at time, to understanding how to best utilize the complex interactions between diet, genes and heart disease to the greatest benefit of cardiovascular health.
Monday, May 16, 2011 11:33 PM