Source: DGNews  |  Posted 2 years ago

By Shazia Qureshi

AMSTERDAM, Netherlands -- May 12, 2009 -- One year on a low-carbohydrate, high-saturated-fat diet led to a 19% rise in low-density lipoprotein (LDL) cholesterol, compared with no change in LDL cholesterol with a high-carbohydrate, low-fat diet, researchers reported here at the 17th European Congress on Obesity (ECO).

In addition, the risk of atherosclerosis may have increased in the patients who were following the low-carb diet, as shown by a deterioration in flow-mediated dilatation (FMD).

"The substantial increase in LDL cholesterol seen with a low-carb, high-fat diet outweighs the benefits of weight loss seen with these popular diets," said Peter Clifton, MBBS, PhD, Commonwealth Scientific and Industrial Research Organisation - Human Nutrition, Adelaide, Australia, in a presentation on May 8.

The randomised study included 49 overweight and obese patients with a mean age of 50.0 +- 7.7 years and mean body mass index (BMI) at baseline of 33.7 +- 4.1 kg/m².

The patients were randomly assigned to consume either a very-low-carbohydrate, high-saturated-fat diet or a conventional high-carbohydrate, low-fat diet for 1 year. Both diets were calorie-restricted to a total daily intake of 6,000-7,000 kJ, representing a 30% energy deficit.

The researchers found that LDL cholesterol increased by 0.6 mmol/L (19%) in the low-carb group and did not change in the high-carb group.

High-density lipoprotein (HDL) cholesterol, however, rose by 21% among patients eating the low-carb diet and by 5% in those consuming the high-carb diet. The greater (numerically, but not statistically) weight loss in the low-carb group may have in part led to the larger positive impact on HDL cholesterol, according to the researchers.

The researchers also measured changes in FMD in all patients. Among patients on the low-carb diet, FMD fell from 5.7% +- 3.6% to 3.7% +- 2.7% (P = .001) but remained unchanged in the high-carb group (from 5.9% +- 2.5% to 5.5% +- 3.5%; P = .60). The time × diet effect was significant (P = .045), meaning that the longer patients remained on the low-carb diet, the more FMD deteriorated.

However, pulse-wave velocity improved in both groups.

The amount of weight loss was not significantly different between the groups even though it was numerically greater in the low-carb group. Low-carb patients lost a mean of 14.9 +- 10.5 kg of body weight while high-carb patients lost 11.5 +- 7.4 kg ([]P[] = .20).

"Long-term consumption of a low-carb diet may have detrimental effects on cardiovascular risk," Dr. Clifton concluded.

Funding for this study was provided by the National Heart Foundation of Australia and the National Health and Medical Research Council of Australia.

[Presentation title: Long Term Effects of Weight Loss From a Very-Low-Carbohydrate Diet on Endothelial Function in Subjects With Abdominal Obesity. Abstract T5:OS1.2]