Fruits and vegetables and the risk of stroke.

Combining data from two large-scale prospective observational studies in women and men, investigators link the consumption of fruits and vegetables to the risk of ischemic stroke. Of interest is their breakdown of these foods into cruciferous vegetables and citrus fruit juice, which confer the greatest protection.

Creatine: a dietary supplement and ergogenic aid.

Creatine is an amino acid that plays a vital role as creatine phosphate (phosphocreatine) in regenerating adenosine triphosphate in skeletal muscle to energize muscle contraction. Oral administration increases muscle stores. During the past decade, with notable popularity this past year, creatine has assumed prominence as an ergogenic aid for professional and elite athletes. Safety issues of long-term use, however, have not been addressed satisfactorily.

Breast cancer risk and intake of fat.

The popular hypothesis that dietary fat intake is an important risk factor for breast cancer in women has been challenged by data from numerous epidemiologic studies that show no relationship of the quantity or type of fat to disease incidence. Reasons for this discrepancy and current recommendations are discussed.

Nonpharmacologic interventions successfully treat hypertension in older persons.

A randomized controlled multicenter trial of nonpharmacologic intervention in elderly with treated hypertension concluded that reduced sodium intake and weight loss are feasible, effective, and safe nonpharmacologic treatments for hypertension. This and other trials provide compelling evidence that a variety of dietary interventions are important in the prevention and treatment of hypertension in all age groups.

How grapefruit juice potentiates drug bioavailability.

Grapefruit juice enhances the effect of some commonly used medications by increasing their bioavailability via the selective down-regulation of a specific subfamily of the cytochrome P450 enzyme system in the small intestine.

Networks for medical nutrition education--a review of the US experience and future prospects.

Nutrition education for physicians in the United State and Canada, remains an orphan discipline with no improvement or changes in the past decade. This status has led to the creation of regional nutrition centers and networks to develop nutrition education programs in health professional schools. The expanded network concept now covers geographic areas in the northeastern, southeastern, and middle United States, with plans to extend to the far West and to establish a national coordinating center or "network of networks." The barriers to progress in nutrition education must be overcome, and their conquest could form the basis for initiating new regional networks or a coordinating center. Strategies for nutrition networking are applicable to other disciplines and provide guidance for creating consortia to deal with the diminished need for medical and surgical subspecialties and play an important role in the training of generalist physicians.

Nutrition concepts for the primary care/generalist physician.

Important nutrition concepts will aid primary care/generalist physicians to implement practical aspects of health promotion and disease prevention in their practice, and improve the overall health of their patients. In today's society, chronic diseases that are related variably to overnutrition and dietary excesses or imbalances (obesity, diabetes mellitus, hypertension and atherosclerotic cardiovascular disease, some cancers) warrant knowledgeable diet modifications in high-risk individuals. However, serious nutritional deficiency diseases also still occur (as in alcoholic patients), and instituting appropriate diet and supplements will aid in preventing further morbidity and mortality. Nutrition knowledge changes with new scientific evidence, and the physician must be aware of reliable sources of continuing education and information appropriate for the practitioner and the patient.

The independent effects of exercise and estrogen on lipids and lipoproteins in postmenopausal women.

OBJECTIVE: To assess the effects of a moderate exercise program with and without oral estrogen replacement on levels of lipids and lipoproteins in postmenopausal women. METHODS: One hundred one postmenopausal women were randomized into four groups: control or sedentary (N = 20), exercise alone (N = 25), estrogen replacement using 0.625 mg conjugated equine estrogen (N = 28), and exercise supplemented with conjugated equine estrogen (N = 28). The exercise groups were placed on a moderate exercise program. Following baseline testing, each group returned at 3 and 6 months for cardiorespiratory fitness testing and serum lipid and lipoprotein profiles. RESULTS: We found a significant decrease in systolic blood pressure (P < .05) in all treatment groups. The maximum oxygen uptake increased by 9.0 and 7.8% in the exercise and conjugated equine estrogen/exercise groups, respectively, compared to the other groups (P < .05). These responses were seen at both 3 and 6 months. Total exercise time (time spent on the treadmill until exhaustion during testing) significantly increased in the exercise group by 21% (P < .01). Exercise alone was associated with significant decreases in total cholesterol (5.2%, P < .05), triglycerides (2%, P < .05), and low-density lipoprotein (LDL) cholesterol (10%, P < .01), and a significant increase in the high-density lipoprotein (HDL) cholesterol-LDL ratio (17.2%, P < .01). Significant changes were noted in these values, as well as increases in HDL cholesterol (16 and 14.8%; P < .01) and apolipoprotein A1 (25.6 and 26.5%; P < .001) in the conjugated equine estrogen and conjugated equine estrogen/exercise groups, respectively. However, there were no differences in the changes observed in the conjugated equine estrogen groups with versus without exercise. No direct correlation was seen between measures of exercise performance and the changes seen in lipids and lipoproteins. CONCLUSIONS: Estrogen therapy alone had the greatest beneficial effect on lipids and lipoproteins. Exercise alone resulted in a significant reduction in cholesterol, triglycerides, and LDL cholesterol, and an increase in the HDL-LDL ratio. However, combined conjugated equine estrogen and exercise did not demonstrate an added improvement in lipid metabolism. Physical fitness levels increased in the exercise groups, but not in the control group or the estrogen-alone treated women.

Dietary intervention and chemoprevention--1992 perspective.

BACKGROUND: Diet, including excess or scarcity of specific foods and nutrients, is important in the etiology of 30-60% of a variety of cancers. Dietary changes may favorably affect cancer risk and incidence. This overview summarizes recommended dietary changes and their nutritional implications and considers the problems of selecting and implementing such a program and identifying and targeting appropriate populations and subjects. RESULTS: Dietary changes that decrease the intake of fat and pickled/smoked foods, limit calorie intake and alcohol consumption, and increase the intake of fiber, fruits, and vegetables should help to decrease risk for cancers of the breast, colon, oral cavity, upper gastrointestinal tract, lung, and cervix. Micronutrients to increase include vitamins C, E, A, beta-carotene and other carotenoids, and folic acid. The diet should contain a variety of yellow-orange fruits and vegetables, green leafy and cruciferous vegetables, legumes, whole grains, low-fat dairy products, and lean meats, fish, and poultry. This diet must be adequate in proteins and minerals, palatable, affordable, and add to the quality of life. It is important that we target appropriate subjects and populations, modify foods, and design and fund research studies in areas of nutrient availability and metabolism and the biologic mechanisms of nutritional chemoprevention. CONCLUSION: A program of nutritional intervention by sound dietary changes that is effective, safe, and acceptable in chemoprevention should be the cornerstone of a cancer prevention strategy starting now. Directions for future research are discussed.

The efficacy of intensive dietary therapy alone or combined with lovastatin in outpatients with hypercholesterolemia.

BACKGROUND: A diet low in saturated fat and cholesterol is the standard initial treatment for hypercholesterolemia. However, little quantitative information is available about the efficacy of dietary therapy in clinical practice or about the combined effects of diet and drug therapy. METHODS: One hundred eleven outpatients with moderate hypercholesterolemia were treated at five lipid clinics with the National Cholesterol Education Program Step 2 diet (which is low in fat and cholesterol) and lovastatin (20 mg once daily), both alone and together. A diet high in fat and cholesterol and a placebo identical in appearance to the lovastatin were used as the respective controls. Each of the 97 patients completing the study (58 men and 39 women) underwent four consecutive nine-week periods of treatment according to a randomized, balanced design: a high-fat diet-placebo period, a low-fat diet-placebo period, a high-fat diet-lovastatin period, and a low-fat diet-lovastatin period. RESULTS: The level of low-density lipoprotein (LDL) cholesterol was a mean of 5 percent (95 percent confidence interval, 3 to 7 percent) lower during the low-fat diet than during the high-fat diet (P < 0.001). With lovastatin therapy as compared with placebo, the reduction was 27 percent. Together, the low-fat diet and lovastatin led to a mean reduction of 32 percent in the level of LDL cholesterol. The level of high-density lipoprotein (HDL) cholesterol fell by 6 percent (95 percent confidence interval, 4 to 8 percent) during the low-fat diet (P < 0.001) and rose by 4 percent during treatment with lovastatin (P < 0.001). The ratio of LDL to HDL cholesterol and the level of total triglycerides were reduced by lovastatin (P < 0.001), but not by the low-fat diet. CONCLUSIONS: The effects of the low-fat-low-cholesterol diet and lovastatin on lipoprotein levels were independent and additive. However, the reduction in LDL cholesterol produced by the diet was small, and its benefit was possibly offset by the accompanying reduction in the level of HDL cholesterol.

Plasma ascorbic acid concentrations relate inversely to blood pressure in human subjects.

This study relates antioxidant status and blood pressure (BP) in 168 healthy residents of Augusta, GA, following usual diets. BP ranges were systolic (S) 84-152, mean 112 +/- 1 mm Hg, and diastolic (D) 52-96, mean 72 +/- 1 mm Hg. Plasma concentrations of ascorbic acid (AA) were significantly inversely related to SBP (r = -0.18, P < 0.05) and DBP (r = -0.20, P < 0.01); with regression equations SBP vs AA = -0.083C + 116 and DBP = -0.077C + 76. Highest and lowest quintiles of AA differed significantly in mean SBP (108 +/- 2, 113 +/- 2 mm Hg) and DBP (69 +/- 1, 74 +/- 2), P < 0.05. Plasma AA concentrations were significantly lower in the smokers. By deleting smokers, the inverse relations of SBP and DBP with plasma AA and the slopes of the equation were enhanced. Plasma selenium, alpha-tocopherol, alpha-tocopherol:cholesterol ratio, retinol and taurine were not related to BP; whereas male gender, body mass index, body fat distribution, plasma cholesterol, low density lipoprotein cholesterol, and triglycerides correlated.

Vitamin A in hypercholesterolemia.

This study evaluated the relationship between plasma vitamin A and cholesterol in 48 patients with hypercholesterolemia studied before and after treatment with a cholesterol-lowering diet, with or without lipid-lowering medication. Plasma vitamin A levels were higher in hypercholesterolemic subjects than in healthy controls (2.58 +/- 0.15 vs. 1.82 +/- 0.14 mmol/L, p = 0.025) despite similar values for retinol binding protein (RBP). Successful cholesterol lowering, defined as greater than 25% reduction in low density lipoprotein cholesterol, was achieved in 16 patients. In this subset, plasma vitamin A declined from 3.00 +/- 0.32 (pretreatment) to 2.34 +/- 0.15 mmol/L (post treatment; p = 0.018). A nonsignificant increase in RBP was observed, resulting in a significant decrease in the molar ratio of vitamin A to RBP (1.05 +/- 0.06 vs. 0.80 +/- 0.05, p = 0.013). These data suggest an interaction between vitamin A and cholesterol that is independent of the transport mechanisms for vitamin A in association with chylomicrons (post absorptive) and with RBP. Further examinations of the form or forms of vitamin A (retinol, retinyl ester), its distribution within the plasma lipoproteins, and the mechanisms of origin and removal are warranted to explain these findings.

Saturated and hydrogenated fats in food in relation to health.

The report of the National Cholesterol Education Program (NCEP) expert panel on detection, evaluation, and treatment of high blood cholesterol in adults published in 1988 evoked great interest from the medical profession, the public, and food manufacturers. The merits of different dietary interventions to lower plasma cholesterol are debated in advertising, popular publications, and research publications. The present paper is a review of the contributions of saturated and trans fatty acids (FA) to the US diet, their metabolism, and effects upon plasma cholesterol. Saturated (SFA) and trans FA are metabolized to yield energy. They are not dietary essentials; SFA can be biosynthesized, and trans FA are not naturally occurring in plants, with only very small amounts in animals. Trans FA are produced in hydrogenation of liquid vegetable oils and are estimated to contribute 3-7% of the fat consumed. Most of the SFA in the US diet (35% of total fat consumed) is obtained from meat, poultry, fish, and dairy products (approximately 60%). The fats and oils consumed directly or as components of food products, mostly baked goods, contribute approximately 20% of the SFA. More than 30 years of research led the NCEP to conclude that SFA was the most potent dietary component in increasing plasma cholesterol, and that no more than 10% of the energy (en%) of the diet should be SFA. Trans FA are metabolized similarly to SFA, but no recommendation has been made about their consumption. Reduction of consumption of SFA should be practiced in a prudent manner, by reducing consumption of foods high in SFA, and not by eliminating classes of foods. Some changes in formulations of foods or preparation practices (type of frying fat) can be made. These modifications may decrease the palatability of the food, thereby presenting a challenge to the food industry. Substitution of fats hydrogenated to contain trans FA for fats high in SFA may not be beneficial to health. Labeling of foods would improve the ability of the consumer to make appropriate choices.

Physician's office guide to a lipid-lowering diet.

To properly treat patients with hyperlipidemia, the physician should have a general knowledge of lipid-lowering diets. The basic principles of these diets, as well as practical application, are discussed.