This study compares the impact of dietary counseling that advises the intake of food having cholesterol-reducing properties and diets containing low-saturated fats on the reduction of low-density lipoprotein (LDL), also known as bad cholesterol. The results of this study reveal that LDL levels decrease significantly in people who receive advice on the consumption of cholesterol-reducing foods compared to those who receive advice on consumption of low-saturated fat diets. There was no association between the reduction of LDL and the frequency of diet counseling among the participants of this study.
Reduction of serum lipids, better known as cholesterol, especially LDL, plays an important role in reducing the risk of coronary heart disease. Conventional dietary advice emphasizes the intake of low-fat dairy and whole grain cereals along with fruits and vegetables. The US Food and Drug Administration documents certain foods such as plant sterols (plant sterol-enriched margarine), viscous fibers (from oats, barley, and psyllium), soya protein, and nuts that have significant cholesterol-reducing properties, when taken in isolation or in combination. However, the long-term effects of the consumption of such foods on LDL levels have not been previously assessed. This study was thus conducted in four city centers (Quebec City, Toronto, Winnipeg and Vancouver) to evaluate these effects.
* This study was conducted for a period of six months on 345 participants (134 men and 211 women), with hyperlipidemia and with no other positive history of any other health disorder. Subjects were enrolled in four academic centers across Canada.
* The participants were divided into three groups, namely a control group (which received conventional dietary advice), a routine dietary portfolio group (which followed a dietary portfolio with two diet counseling sessions), and an intensive dietary portfolio group (which followed a dietary portfolio with seven diet counseling sessions).
* Biochemical analysis of the lipid profile (LDL, high-density lipoprotein, and triglycerides) of the participants was done before and after the study.
* The dietary portfolio was aimed at providing the following components per 1,000 calories of diet: 0.94 g of plant sterols, 9.8 g of fiber (from oats, barley, and psyllium), 22.5 g of soy protein, and 22.5 g of nuts. Adherence to the portfolio diet was estimated from seven-day food intake records.
* There was no difference in the lipid profile of the participants in all the groups before the study.
* The reduction in the LDL-cholesterol and total cholesterol was significantly higher (13 to 14 percent and 6 to 8 percent, respectively) for the dietary portfolio group when compared to the control group (3 and 1.4 percent).
* No significant difference in the reduction of LDL-cholesterol and total cholesterol was observed between the intensive and routine dietary profile groups.
* For the dietary portfolio groups, a higher reduction in the diastolic blood pressure was observed compared to the control group.
* The reduction in the calculated 10-year coronary heart disease risk for intensive and routine dietary portfolio groups were much higher when compared to the control group.
The biological interventions of the components of dietary portfolio are complex and the influence of individual components is difficult to assess. The overall dropout rate in the study was high (22 percent). In addition, the participants were predominantly white, with low risk of coronary heart disease and low body mass index. Future studies are necessary on populations that are more diverse.
This study provides conclusive evidence on the cholesterol-reducing effects of a diet rich in cholesterol-reducing foods such as plant sterols, soy proteins and nuts. Many of these foods lower the glycemic index as well, and this may further contribute to their role in reducing the risk of coronary heart disease. The therapeutic effects of such a diet were also seen in participants who were already on a diet that was low in saturated fat and cholesterol, but had earlier failed to reduce their LDL to acceptable levels. There was no significant association between reductions in LDL–cholesterol levels and the number of diet counseling sessions. This suggests that the frequency of counseling sessions does not play a major role in achieving the expected targets.
For More Information:
Effect of a Dietary Portfolio of Cholesterol-Lowering Foods given at 2 Levels of Intensity of Dietary Advice on Serum Lipids in Hyperlipidemia
Publication Journal: Journal of American Medical Association, August 2011
By David J. A. Jenkins, MD; Peter J. H. Jones, PhD; Clinical Nutrition and Risk Factor Modification Center, St Michael’s Hospital, Ontario, Canada and University of Toronto, Ontario, Canada