Abstract
In a randomized, single-blind and controlled trial, the effects of guava fruit substitution were studied on vitamin C metabolism and coronary risk factors in 52 group A and 49 group B patients of essential hypertension with mild to moderate hypercholesterolaemia. At entry to the study, the mean age, mean body mass index, percentage male sex and risk factors were comparable. The dietary adherence to the guava intake was checked by a questionnaire and by the weighing of guava at 24 and 36 weeks into the follow-up. The study included a 24-week period of guava intake followed by a 12-week no-guava period. After 24 weeks of intervention, there was a self-imposed decreased intake of total fat and saturated fat and an increased polyunsaturated : saturated fat ratio in the diet in the group A patients. The total carbohydrate, soluble dietary fibre, potassium and vitamin C intakes were also higher in intervention group A than in group B. The increased consumption of vitamin C and other nutrients was associated with a significant net increase (p 0.001) in plasma ascorbic acid (45.3%, 95% confidence interval (CI) 21.6-96.6) in group A compared to group B. There was a significant net reduction in the serum total cholesterol (11.9%, 95% CI 3.5-19.5, p 0.01), triglycerides (8.1%, 95% CI 0.4-15.8, p 0.05), systolic blood pressure (5.0%, 95% CI 0.1-9.8) and diastolic blood pressure (6.4%, 95% CI 0.6-12.2) (p 0.05) and a significant net increase in the high-density lipoprotein cholesterol (8.9%, 95% CI 4.4-13.4%, p 0.01). At 36 weeks, 12 weeks after ceasing guava supplementation, there was an increase in the blood lipids and blood pressure from the levels at 24 weeks, indicating that the changes were due to the guava fruit intake. These changes in the vitamin C levels and risk factors may be due to an increased intake of soluble dietary fibre, potassium and vitamin C which may have decreased the coronary risk, leading to better prospects for the prevention of coronary artery disease.