PDWENYlVE
CARDtDLoGY
Effect of Fat4Vlodified and Fruit- and Vegetable-Enriched Diets on Blood Lipids in the Indian Diet Heart Study Ram B. Singh, MD, Shanti S. Rastogi, MD, Mohammed A. Niaz, PhD, Saraswati Ghosh, PhD, Reema Singh, DDPH, and Shobha Gupta, PhD
This study was deslgned to test the efficacy of the administration of fruits and vegetables for 12 weeks as an adjunct to a prudent diet in decreasing blood lipids in 310 (intervention; group A) and 311 (control; group B) patients with risk factors of coronary artery disease (CAD) in a parallel, single-blind fashton. At entry to the study, sex, mean age, body welght, body mass index, systolic and diastolic blood pressures, and blood lipoproteins were comparable between both groups. Tasty fruits and vegetables were given to patlents to eat before major meals for better nutrient adherence and adequacy. Dletary intakes were determined by questionnaires and by weighing of fruit and vegetable intake. Fruits and vegetables decreased total cholesterol level by 6.5% and tow-density lipoprotdn cholesterol level by 7.3% in group A, whereas the levels were unchanged in group B. The high-denslty lipoproteht chotesterol levels that decreased during the diet stabllizatton period in both groups, lnereased by 5.6% in group A after 12 weeks. Serum triglycerides also decreased (7%) more in group A than B. Fasthtg blood glucose decreased by 6.9% in group A and by 2.6% in group B. The combfned effect of a fat-modified diet plus fruits and vegetables was greater than these changes. Because tasty fruits were taken by the patients before meals (when they are hungry) and are easily available at reasonable cost in our marketing and buying capactty, the complllnce was excellent. It is possible that fruits and vegetables may be a safe adjunct to a prudent diet in free-living subjects with risk factors of CAD for the modulation of blood lipoproteins and for the prevention of CAD. (Am J Cardiol1992;70:669-974)
From the Heart ResearchLaboratory, Medical Hospital and Research Centre, Moradabad, India. Manuscript received February 25, 1992; revisedmanuscript receivedJune 12,1992, and acceptedJune 13. Addressfor reprints: Ram B. Sin& MD, Heart ResearchLaboratory, Medical Hospital and ResearchCentre, Civil Lines, Moradabad10,UP, 244 001, India.
I
n most developingcountries, there has been a rapid increase in coronary artery disease (CAD).’ In South Asian immigrants in the United Kingdom,2 a rapid death rate for CAD has been related to modest changesin risk factors3such as glucoseintolerance, insulin resistance, low high-density lipoprotein (HDL) cholesterol and hypertriglyceridemia. Becausemost of theserisk factors are related to diet,4-6there is an ongoing effort to increasepublic awarenessregarding a prudent diet5 and develop new, safe methods to decrease serum cholesterol levels in patients in whom adjunctive therapy may be desirable. Whereas drugs work by different mechanisms,each drug also has its own side effects. Several studies have demonstrateda reduction in cardiovascular events in patients independently treated with lipid-lowering drugs and a fat-modified diet. No study to date has shown a favorable effect on the overall death rate.‘J It appearsthat there is a need to modify our approach for decreasing serum cholesterol, which should be safeand also counteract other multiple mechanisms3v9 underlying CAD. One such suggestednew ap preach showed that foods containing water-soluble fibers10-13such as oat bran, certain legumes, and fruits and vegetables can effectively decrease serum cholesterol without significant risk. Apart from the modulation of blood lipoproteins, a fruit- and vegetableenriched diet may also inhibit hyperinsulmemia,4J4 hyperglycemia, hypertriglyceridemia and hypertension, and provide antioxidant4,9vitamins and minerals that are known to be protective against CAD. In a current approach,I* 10.2 g/day of psyllium hydrophilic mucilloid was administered for 8 weeks after initiation of the American Heart Association Step I diet.s There were 4.8 and 8.2% reductions in total and low-density lipoprotein (LDL) cholesterollevels, respectively. Similar observationsi2J5J6were made in other trials using soluble fiber by this approach.In the present study, we examined the effect of fruits and vegetables, in a randomized and controlled manner (possibly for the first time in a large number of patients by the current approach), on blood lipoprotein levels in patients with risk factors of CAD. Patients received a 4-week initial diet therapy with a fat-modified, prudent diet, followed by 12 weeksof treatment with fruits and vegetablesin the intervention group. METHODS Patients were recruited through advertisementsin local clubs, clinics and newspapersfrom the middle socioeconomic class during a period of 2 years and had a EFFECT OF DIET ON BLOOD LIPIDS
999
proven diagnosis of either angina pectoris, myocardial infarction or major risk factors of CAD. Of 1,050 respondents,653 subjectsvolunteered to participate in the trial. During the observation period, all patients were asked to maintain their usual lifestyle and dietary habits, and daily drug and dietary diaries. Clinical, electrocardiographic, radiologic and laboratory data were obtained in all subjectsbefore admission to the study. Exclusion criteria were chronic diseasessuch as diarrhea, dysentry, blood urea of 40 mg/dl (6.6 mmol/liter) and cancer. Blood pressures(systolic and diastolic phase V of Korotkoff) were measuredafter 5 minutes of rest lying comfortably in the supine position by a single-mercury sphygmomanometer and by the same clinician. Electrocardiograms after exercise (bicycle ergometer [n = 5911and treadmill test [n = 361) were obtained in all patients to find the extent of CAD. Nutrient intakes before entry to the study were obtained by 24-hour dietary recalls. Essential hypertension was diagnosedas blood pressure >150/95 mm Hg, diabetes mellitus by a positive glucose tolerance test showing fasting blood glucose at >110 mg/dl (6.1 mm/liter) and postprandial 2 hours after 75 g of oral glucose at >140 mg/dl (7.7 mmol/ liter), hypercholesterolemiaby serum cholesterol >250 mg/dl (6.47 mmol/liter), hypertriglyceridemia by serum triglyceride >I90 mg/dl (2.14 mmol/liter), and smoking by consumption of >l cigarette/day. Overweight was considered a body mass index >25 kg/m2 and obesity an index >30 kg/m2, alcohol abuseby consumption of >60 g/week of alcohol, and physical inactivity by 240 mg/dl, age >50 years, body massindex >25 kg/ m2, and presenceof angina pectoris or myocardial infarction. After stratifications, patients with each risk factor in each group were assignedto diet A or B by blindly selecting a card from a stack with equal numbers of each. Thus, patients with each risk factor and those with CAD were divided into 2 approximately equal groups to receive either diet A or B, while the responsible physician was unaware of the assigned dietary regimen. At the beginning of the diet stabilization period, all patients were instructed to follow the American Heart Association Step I diets (total calories from fat
CARDtDLoGY
Effect of Fat4Vlodified and Fruit- and Vegetable-Enriched Diets on Blood Lipids in the Indian Diet Heart Study Ram B. Singh, MD, Shanti S. Rastogi, MD, Mohammed A. Niaz, PhD, Saraswati Ghosh, PhD, Reema Singh, DDPH, and Shobha Gupta, PhD
This study was deslgned to test the efficacy of the administration of fruits and vegetables for 12 weeks as an adjunct to a prudent diet in decreasing blood lipids in 310 (intervention; group A) and 311 (control; group B) patients with risk factors of coronary artery disease (CAD) in a parallel, single-blind fashton. At entry to the study, sex, mean age, body welght, body mass index, systolic and diastolic blood pressures, and blood lipoproteins were comparable between both groups. Tasty fruits and vegetables were given to patlents to eat before major meals for better nutrient adherence and adequacy. Dletary intakes were determined by questionnaires and by weighing of fruit and vegetable intake. Fruits and vegetables decreased total cholesterol level by 6.5% and tow-density lipoprotdn cholesterol level by 7.3% in group A, whereas the levels were unchanged in group B. The high-denslty lipoproteht chotesterol levels that decreased during the diet stabllizatton period in both groups, lnereased by 5.6% in group A after 12 weeks. Serum triglycerides also decreased (7%) more in group A than B. Fasthtg blood glucose decreased by 6.9% in group A and by 2.6% in group B. The combfned effect of a fat-modified diet plus fruits and vegetables was greater than these changes. Because tasty fruits were taken by the patients before meals (when they are hungry) and are easily available at reasonable cost in our marketing and buying capactty, the complllnce was excellent. It is possible that fruits and vegetables may be a safe adjunct to a prudent diet in free-living subjects with risk factors of CAD for the modulation of blood lipoproteins and for the prevention of CAD. (Am J Cardiol1992;70:669-974)
From the Heart ResearchLaboratory, Medical Hospital and Research Centre, Moradabad, India. Manuscript received February 25, 1992; revisedmanuscript receivedJune 12,1992, and acceptedJune 13. Addressfor reprints: Ram B. Sin& MD, Heart ResearchLaboratory, Medical Hospital and ResearchCentre, Civil Lines, Moradabad10,UP, 244 001, India.
I
n most developingcountries, there has been a rapid increase in coronary artery disease (CAD).’ In South Asian immigrants in the United Kingdom,2 a rapid death rate for CAD has been related to modest changesin risk factors3such as glucoseintolerance, insulin resistance, low high-density lipoprotein (HDL) cholesterol and hypertriglyceridemia. Becausemost of theserisk factors are related to diet,4-6there is an ongoing effort to increasepublic awarenessregarding a prudent diet5 and develop new, safe methods to decrease serum cholesterol levels in patients in whom adjunctive therapy may be desirable. Whereas drugs work by different mechanisms,each drug also has its own side effects. Several studies have demonstrateda reduction in cardiovascular events in patients independently treated with lipid-lowering drugs and a fat-modified diet. No study to date has shown a favorable effect on the overall death rate.‘J It appearsthat there is a need to modify our approach for decreasing serum cholesterol, which should be safeand also counteract other multiple mechanisms3v9 underlying CAD. One such suggestednew ap preach showed that foods containing water-soluble fibers10-13such as oat bran, certain legumes, and fruits and vegetables can effectively decrease serum cholesterol without significant risk. Apart from the modulation of blood lipoproteins, a fruit- and vegetableenriched diet may also inhibit hyperinsulmemia,4J4 hyperglycemia, hypertriglyceridemia and hypertension, and provide antioxidant4,9vitamins and minerals that are known to be protective against CAD. In a current approach,I* 10.2 g/day of psyllium hydrophilic mucilloid was administered for 8 weeks after initiation of the American Heart Association Step I diet.s There were 4.8 and 8.2% reductions in total and low-density lipoprotein (LDL) cholesterollevels, respectively. Similar observationsi2J5J6were made in other trials using soluble fiber by this approach.In the present study, we examined the effect of fruits and vegetables, in a randomized and controlled manner (possibly for the first time in a large number of patients by the current approach), on blood lipoprotein levels in patients with risk factors of CAD. Patients received a 4-week initial diet therapy with a fat-modified, prudent diet, followed by 12 weeksof treatment with fruits and vegetablesin the intervention group. METHODS Patients were recruited through advertisementsin local clubs, clinics and newspapersfrom the middle socioeconomic class during a period of 2 years and had a EFFECT OF DIET ON BLOOD LIPIDS
999
proven diagnosis of either angina pectoris, myocardial infarction or major risk factors of CAD. Of 1,050 respondents,653 subjectsvolunteered to participate in the trial. During the observation period, all patients were asked to maintain their usual lifestyle and dietary habits, and daily drug and dietary diaries. Clinical, electrocardiographic, radiologic and laboratory data were obtained in all subjectsbefore admission to the study. Exclusion criteria were chronic diseasessuch as diarrhea, dysentry, blood urea of 40 mg/dl (6.6 mmol/liter) and cancer. Blood pressures(systolic and diastolic phase V of Korotkoff) were measuredafter 5 minutes of rest lying comfortably in the supine position by a single-mercury sphygmomanometer and by the same clinician. Electrocardiograms after exercise (bicycle ergometer [n = 5911and treadmill test [n = 361) were obtained in all patients to find the extent of CAD. Nutrient intakes before entry to the study were obtained by 24-hour dietary recalls. Essential hypertension was diagnosedas blood pressure >150/95 mm Hg, diabetes mellitus by a positive glucose tolerance test showing fasting blood glucose at >110 mg/dl (6.1 mm/liter) and postprandial 2 hours after 75 g of oral glucose at >140 mg/dl (7.7 mmol/ liter), hypercholesterolemiaby serum cholesterol >250 mg/dl (6.47 mmol/liter), hypertriglyceridemia by serum triglyceride >I90 mg/dl (2.14 mmol/liter), and smoking by consumption of >l cigarette/day. Overweight was considered a body mass index >25 kg/m2 and obesity an index >30 kg/m2, alcohol abuseby consumption of >60 g/week of alcohol, and physical inactivity by 240 mg/dl, age >50 years, body massindex >25 kg/ m2, and presenceof angina pectoris or myocardial infarction. After stratifications, patients with each risk factor in each group were assignedto diet A or B by blindly selecting a card from a stack with equal numbers of each. Thus, patients with each risk factor and those with CAD were divided into 2 approximately equal groups to receive either diet A or B, while the responsible physician was unaware of the assigned dietary regimen. At the beginning of the diet stabilization period, all patients were instructed to follow the American Heart Association Step I diets (total calories from fat
