Effect of advice to increase carbohydrate and reduce fat intake on dietary profile and plasma lipid concentrations in healthy postmenopausal women

Abstract

Background: The current dietary guidelines advise an increase in carbohydrate intake. However, there is concern regarding the effect this may have on coronary heart disease (CHD) risk, in particular in postmenopausal women, in light of the knowledge that raised triacylglycerol (TAG) may pose a stronger risk for CHD in this group.

Aim: To evaluate the effect of advice to increase carbohydrate intake to 50% of energy intake as part of advice to follow current dietary guidelines on the dietary profile, including dietary glycaemic index (GI) and plasma lipids in healthy postmenopausal women.

Methods: Twelve healthy postmenopausal women (56 +/- 6.5 years) took part in the study. Habitual diet was assessed by a 7-day weighed intake. On the basis of the results, subjects were advised to increase their carbohydrate intake to comply with the current dietary guidelines. Subjects were asked to follow this diet for 4 weeks, in a free-living situation. Fasting blood samples were obtained at baseline and after 1 and 4 weeks.

Results: There was a significant decrease in body mass index (BMI; p < 0.05) after 4 weeks. There was a significant increase in fasting TAG concentrations after 1 week (p < 0.05), and the high-density lipoprotein (HDL) cholesterol concentration was significantly decreased (p < 0.05) after 1 and 4 weeks. The subjects significantly increased their percentage of energy from carbohydrates and starch (p < 0.05 and p < 0.01, respectively) after 1 week, and their percentage of energy from starch after 4 weeks (p < 0.05). Dietary GI was significantly increased (p < 0.05) after 1 and 4 weeks. Fruit and vegetable intake was significantly increased after 1 week (p < 0.01), as was fruit intake alone (p < 0.05), and there was a significant increase (p < 0.05) in the 'antioxidant power' as measured by the ferric reducing ability of plasma assay.

Conclusion: In postmenopausal women, following the UK dietary guidelines resulted in changes in the lipid profile that were more likely to favour an increased risk of CHD, as TAG concentrations were increased and HDL cholesterol concentrations were reduced. However, in addition, we found a significant reduction in BMI and a significant increase in the 'antioxidant power' of plasma, which should benefit health.