Oat bran lowers total and low-density lipoprotein cholesterol but not lipoprotein(a) in exercising adults with borderline hypercholesterolemia

Global review of heart health claims for oat beta-glucan products

Coronary heart disease (CHD) is the leading cause of death globally. Consumption of whole grains and cereal fiber, as part of a healthy diet, can lower the risk of CHD. Health claims on food products are effective in helping consumers select healthful diets. The US Food and Drug Administration was the first to approve a health claim, in 1997, between beta-glucan soluble fiber from whole oats, oat bran, and whole oat flour and reduced risk of CHD. Only a few countries have approved similar claims. Since 1997, a significant amount of additional evidence has been published on the relationship between oat beta-glucan and CHD. To assist other jurisdictions in potentially utilizing this claim, the full extent of data that supports this claim (ie, the evidence utilized by the US Food and Drug Administration to substantiate the claim, as well as the results of 49 clinical trials published since 1997) are reviewed here. The complexities involved in authoring evidence-based health claims, including the impact of processing on beta-glucan cholesterol-lowering efficacy in approving eligible beta-glucan products, are also discussed.

Oats and CVD risk markers: a systematic literature review

High consumption of whole-grain food such as oats is associated with a reduced risk of CVD and type 2 diabetes. The present study aimed to systematically review the literature describing long-term intervention studies that investigated the effects of oats or oat bran on CVD risk factors. The literature search was conducted using Embase, Medline and the Cochrane library, which identified 654 potential articles. Seventy-six articles describing sixty-nine studies met the inclusion criteria. Most studies lacked statistical power to detect a significant effect of oats on any of the risk factors considered: 59 % of studies had less than thirty subjects in the oat intervention group. Out of sixty-four studies that assessed systemic lipid markers, thirty-seven (58 %) and thirty-four (49 %) showed a significant reduction in total cholesterol (2–19 % reduction) and LDL-cholesterol (4–23 % reduction) respectively, mostly in hypercholesterolaemic subjects. Few studies (three and five, respectively) described significant effects on HDL-cholesterol and TAG concentrations. Only three out of twenty-five studies found a reduction in blood pressure after oat consumption. None of the few studies that measured markers of insulin sensitivity and inflammation found any effect after long-term oat consumption. Long-term dietary intake of oats or oat bran has a beneficial effect on blood cholesterol. However, there is no evidence that it favourably modulates insulin sensitivity. It is still unclear whether increased oat consumption significantly affects other risk markers for CVD risk, and comprehensive, adequately powered and controlled intervention trials are required to address this question.

Combination diet and exercise interventions for the treatment of dyslipidemia: an effective preliminary strategy to lower cholesterol levels?

At present, dyslipidemia is most commonly treated with drug therapy. However, because safety concerns regarding the use of pharmaceutical agents have arisen, a need for alternative nonpharmacological therapies has become increasingly apparent. The National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) recommends lifestyle therapies, which include a combination of diet and exercise modifications, in place of drug treatment for patients who fall into an intermediate range of coronary heart disease (CHD) risk. This review examined the cholesterol lowering efficacy of the following 2 NCEP-recommended combination therapies: 1) low saturated fat diets combined with exercise, and 2) nutritional supplementation, i.e., fish oil, oat bran, or plant sterol supplementation, combined with exercise, in the treatment of dyslipidemia. Combination therapies are particularly advantageous because diet and exercise elicit complementary effects on lipid profiles. More specifically, diet therapies, with some exceptions, lower total (TC) and LDL cholesterol (LDL-C) concentrations, whereas exercise interventions increase HDL cholesterol (HDL-C) while decreasing triglyceride (TG) levels. With respect to specific interventions, low saturated fat diets combined with exercise lowered TC, LDL-C, and TG concentrations by 7-18, 7-15, and 4-18%, respectively, while increasing HDL-C levels by 5-14%. Alternatively, nutritional supplements combined with exercise, decreased TC, LDL-C, and TG concentrations by 8-26, 8-30, and 12-39%, respectively, while increasing HDL-C levels by 2-8%. These findings suggest that combination lifestyle therapies are an efficacious, preliminary means of improving cholesterol levels in those diagnosed with dyslipidemia, and should be implemented in place of drug therapy when cholesterol levels fall just above the normal range.

Dietary advice given by a dietitian versus other health professional or self-help resources to reduce blood cholesterol

BACKGROUND

The average level of blood cholesterol is an important determinant of the risk of coronary heart disease. Blood cholesterol can be reduced by dietary means. Although dietitians are trained to provide dietary advice, for practical reasons it is also given by other health professionals and occasionally through the use of self-help resources.

OBJECTIVES

To assess the effects of dietary advice given by a dietitian compared with another health professional, or the use of self-help resources, in reducing blood cholesterol in adults.

SEARCH STRATEGY

We searched The Cochrane Library (to Issue 2 1999), MEDLINE (1966 to January 1999), EMBASE (1980 to December 1998), Cinahl (1982 to December 1998), Human Nutrition (1991 to 1998), Science Citation Index, Social Sciences Citation Index, hand searched conference proceedings on nutrition and heart disease, and contacted experts in the field.

SELECTION CRITERIA

Randomised trials of dietary advice given by a dietitian compared with another health professional or self-help resources. The main outcome was difference in blood cholesterol between dietitian groups compared with other intervention groups.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed study quality.

MAIN RESULTS

Eleven studies with 12 comparisons were included, involving 704 people receiving advice from dietitians, 486 from other health professionals and 551 people using self-help leaflets. Four studies compared dietitian with doctor, seven with self-help resources, and one compared dietitian with nurse. Participants receiving advice from dietitians experienced a greater reduction in blood cholesterol than those receiving advice only from doctors (-0.25 mmol/L (95% CI -0.37, -0.12 mmol/L)). There was no statistically significant difference in change in blood cholesterol between dietitians and self-help resources (-0.10 mmol/L (95% CI -0.22, 0.03 mmol/L)). No statistically significant differences were detected for secondary outcome measures between any of the comparisons with the exception of dietitian versus nurse for HDLc, where the dietitian groups showed a greater reduction (-0.06 mmol/L (95% CI -0.11, -0.01)). No significant heterogeneity between the studies was detected.

REVIEWER'S CONCLUSIONS

Dietitians were better than doctors at lowering blood cholesterol in the short to medium term, but there was no evidence that they were better than self-help resources. The results should be interpreted with caution as the studies were not of good quality and the analysis was based on a limited number of trials. More evidence is required to assess whether change can be maintained in the longer term. There was no evidence that dietitians provided better outcomes than nurses.

Lipoprotein(a) concentrations in non-selected hospitalised patients between 18 and 100 years of age: comparison with cholesterol fractions and triacylglycerols in patients with lipid status requests

In a study designed to measure lipoprotein(a), cholesterol, cholesterol fractions and triacylglycerols in serum 4004 hospitalised individuals aged between 18 and 100 years were examined. Lipoprotein(a) was determined in 1313 patients (438 males, 875 females) aged 18-59 years and 489 patients (234 males, 255 females) aged 60-100 years. Cholesterol, cholesterol fractions and triacylglycerols were determined in a further 2037 patients (1084 males, 953 females) aged 18 to 100 years, for whom a lipid-status request had been made. Lipoprotein(a) concentrations in 619 females measured directly postpartum were not significantly different from aged-matched female in-patients (n = 104) and age-matched female hospital staff (n = 114). Lipoprotein(a) concentrations in women (n = 77) aged 30-74 undergoing chronic haemodialysis were significantly higher (p < 0.001) than in men (n = 95) of the corresponding age group. Median lipoprotein(a) serum concentrations showed a peak between 60-69 years in both men and women, i.e. at times of reported increased cardiovascular disease in both sexes. The lipoprotein(a) levels found in old age are comparable with those found in children and adolescents. The lipoprotein(a) patient group was assessed according to age and clinic. Eight groups of patients were analysed. The maternity patients were significantly younger (median age 26 a) than the other seven groups (p < 0.05 - < 0.01), the hospital employees (median age 31 a) attending the annual check-up being younger than the remaining six groups (p < 0.01). Lipoprotein(a) concentrations were marginally higher (p = 0.05) in the dialysis patients, when compared with those on internal medical wards. Of the 'traditional' lipid analytes, the ratio LDL-cholesterol:HDL-cholesterol was of interest, being significantly higher in males aged 70-79 years of age, when compared with males under 30 years of age. Triacylglycerols were higher in men aged between 30 and 59 years (p = 0.05 - < 0.01). The relationship between median analyte concentration and age was different for lipoprotein(a) than for the ratio LDL-cholesterol:HDL-cholesterol and triacylglycerols, thus further supporting the fact that lipoprotein(a) may be an independent risk factor for the development of atherosclerotic disease.