Cardiovascular disease risk factors in free-living men: comparison of two prudent diets, one based on lactoovovegetarianism and the other allowing lean meat.

In general, vegetarians have lower serum lipids and blood pressures than omnivores have. We tested the blood pressure and serum lipid lowering effects of two fat-modified diets differing primarily in their source of protein. Twenty-six men were randomized in an incomplete block design to two of three diets: a high-fat diet, a fat-modified lactoovovegetarian diet (LOV) and a diet in which 60% of plant protein in the LOV was replaced with lean meat (LM). Compared with the high-fat diet both prudent diets significantly lowered blood pressure, serum total cholesterol (TC), and LDL cholesterol but significantly increased serum triglycerides. The LOV diet had a significantly greater cholesterol-lowering effect than did the LM diet (10% vs 5% decrease) but blood pressure reductions were similar. The partial substitution of lean meat for plant protein in a fat-modified diet did not negate the overall cardiovascular-risk lowering of the lactoovovegetarian diet.

Effect of dietary cholesterol in normolipidemic subjects is not modified by nature and amount of dietary fat.

A double-blind, cross-over study of the effects of adding cholesterol to the diet, equal to about two egg yolks daily, was carried out in 25 men with an average plasma cholesterol of 5.3 mmol/L. There were no significant elevations in the mean plasma concentrations of cholesterol, low-density-lipoprotein cholesterol, or apolipoprotein B. The absence of an effect was seen against two background diets, one high in saturated fatty acids and the other modified in fat content and in fatty acid composition. Although the mean high-density-lipoprotein (HDL) cholesterol concentration did not change, the proportion of HDL2 particles (radius greater than 4.4 nm) increased significantly, especially in subjects who did not show a rise in plasma cholesterol; this may represent a means of clearing dietary cholesterol. The results suggest that reducing dietary cholesterol might be emphasized for hypercholesterolemic subjects rather than for the population generally.

Comparative effects of three cereal brans on plasma lipids, blood pressure, and glucose metabolism in mildly hypercholesterolemic men.

Dietary fiber lowers atherogenic serum lipids and blood pressure and improves glucose metabolism. We compared in 24 mildly hypercholesterolemic men the effects of adding 11.8 g dietary fiber/d from each of three cereal brans (wheat, rice, and oat) to a low-fiber diet for 4 wk each. A double-blind, crossover design incorporated brans into bread and muffins. Plasma total- and low-density-lipoprotein-cholesterol concentrations were significantly lowered only by oat bran. Compared with wheat bran, the ratios of plasma high-density-lipoprotein cholesterol to total cholesterol and of apolipoprotein A-I to B were significantly increased with oat bran (both by 4.7%, P less than 0.05), and rice bran (2.3%, P less than 0.05, and 3.9%, P less than 0.05, respectively). Blood pressure, blood glucose, and serum insulin responses to a common test meal were unaltered. Oat and rice bran exert a small but potentially useful effect on plasma lipoprotein risk factors for cardiovascular disease.

n-3 fatty acids of marine origin lower systolic blood pressure and triglycerides but raise LDL cholesterol compared with n-3 and n-6 fatty acids from plants.

We compared the cardiovascular risk-reduction potential of three major polyunsaturated fatty acids in a double-blind study. Thirty-three normotensive and mildly hypercholesterolemic men were randomly allocated to one of three diets supplemented with linoleic acid (14.3 g/d), alpha-linolenic acid (9.2 g/d), or eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) (3.4 g/d). Diets were matched to provide similar amounts of the major classes of fatty acids and cholesterol. Blood pressure and plasma lipids were measured for 6 wk after a 3-wk run-in period on the linoleic acid supplement. For the diet supplemented with EPA plus DHA compared with the linoleic acid diet systolic blood pressure fell 5.1 mm Hg (p = 0.01); plasma triglyceride and VLDL cholesterol fell by 39% (p = 0.001) and 49% (p = 0.01), respectively; and LDL cholesterol rose by 9% (p = 0.01). There were no significant changes with the diet supplemented with alpha-linolenic acid. The net effect on cardiovascular risk therefore is complex and the systolic blood pressure reduction was substantial.

Effects of dietary fat intervention on mental health in women.

Several studies have identified potential detrimental sequelae of cholesterol and fat-lowering interventions in randomized trial. Little research has been published to document changes in mental health in women as a result of fat and cholesterol lowering interventions to prevent chronic disease. This paper examines the relationships among changes in dietary fat consumption and mental health in the Women's Health Trial, a randomized, controlled trial to determine whether lowering fat consumption to 20% of daily calories could reduce the incidence of breast cancer in women ages 45-69 years. Assessments were made at baseline and at the 12-month follow-up of several aspects of quality of life, including negative and positive affect and past, present, and future perceptions of health. Mental health variables were measured by the Mental Health Inventory, a standardized scale used in the Medical Outcomes study. Dietary intake was assessed for all subjects with the use of semiquantitative food frequency questionnaires. The change in mental health values (follow-up minus baseline) was significantly different between intervention and control groups for three of the four psychological variables: (a) anxiety; (b) depression; and (c) vigor. In all three cases, the direction of the change for intervention women was positive. Neither randomization assignment nor percent of calories from fat at the follow-up visit were significant predictors of mental health at the 1-year follow-up. Cholesterol changes were not related to levels of mental health variables in a sample of the women. These data indicate that lowering fat in the diets of healthy women does not produce overall lowering of any mental health variables.(ABSTRACT TRUNCATED AT 250 WORDS)

The association between participant characteristics and serum concentrations of beta-carotene, retinol, retinyl palmitate, and alpha-tocopherol among participants in the Carotene and Retinol Efficacy Trial (CARET) for prevention of lung cancer.

As part of the multicenter Carotene and Retinol Efficacy Trial (CARET) lung cancer prevention study, we investigated the associations of baseline demographic, health history, and nutritional intake information and the prerandomization serum concentrations of beta-carotene, retinol, retinyl palmitate, and alpha-tocopherol in a random subset of 1182 smokers and asbestos-exposed workers. Dietary intake was estimated via a self-administered food frequency questionnaire using the recently updated United States Department of Agriculture/National Cancer Institute database. In multiple regression analyses, supplemental vitamin use was the strongest predictor of each of the four analytes. There was a statistically significant inverse relationship between smoking and beta-carotene concentrations. Lower serum beta-carotene was associated with current smoking, higher daily cigarettes smoked, and more pack-years. Serum beta-carotene concentrations were higher with increasing years since stopping cigarette use, which suggests a biological mechanism for the lower serum concentration of beta-carotene in smokers. We found weak inverse associations between alcohol intake and the serum concentrations of both beta-carotene and retinol. As in previous reports, dietary intakes as measured by a food frequency questionnaire can only moderately predict serum concentrations of beta-carotene, retinol, retinyl palmitate, and alpha-tocopherol.

The Women's Health Trial Feasibility Study in Minority Populations: design and baseline descriptions.

The Women's Health Trial: Feasibility Study in Minority Populations (WHT:FSMP), a randomized trial of 2208 women, was conducted to investigate three questions. First, can women from minority and low-socioeconomic-status populations be recruited in numbers sufficient to evaluate a dietary intervention designed to lower fat intake. Second, the efficacy of a low fat, increased fruit/vegetable/ grain product intervention for reducing fat consumption. Third, will participation in the intervention lower plasma cholesterol and estradiol levels relative to the controls. The baseline results showed that an adequate number of minority and low SES women could be recruited to test the study hypotheses. A diverse study population of postmenopausal women consuming a high fat diet was recruited: 28% of participants were Black, 16% were Hispanic, 11% had less than a high school level of education, and 15.5% had household incomes of < $15,000.

Linoleic acid lowers LDL cholesterol without a proportionate displacement of saturated fatty acid.

We tested the specificity of the plasma cholesterol-lowering effect of linoleic acid in a comparison of linoleate-rich and saturated fatty acid-rich foods. Twelve mildly hypercholesterolemic men and women ate the two diets for three weeks each in a random cross-over design, after a two-week baseline period. A linoleic acid-rich supplement was added to the baseline diet so that the saturated and monounsaturated fatty acid content did not change significantly. Despite the consequent increase in total fat intake, the linoleate-rich diet (23 per cent energy from polyunsaturated fatty acids) significantly lowered plasma total and low-density lipoprotein (LDL) cholesterol (-8 per cent and -14 per cent respectively), while high-density lipoprotein (HDL) cholesterol rose 8 per cent. The direction of these changes was similar in all 12 subjects. Compared with a supplement that raised dietary saturated fatty acids to 30 per cent energy, the linoleate acid-rich diet gave lower total cholesterol (-14 per cent), LDL cholesterol (-18 per cent) and HDL cholesterol (-12 per cent) concentrations. Linoleic acid lowers LDL cholesterol even when saturated fatty acids are not significantly displaced and substantially more when there is such displacement.

Role of free radicals in cancer and atherosclerosis.

As aerobic creatures, normal living requires that not only are human beings exposed to oxygen but are dependent on oxygen. Humans have evolved mechanisms to cope with living in an aerobic environment; however, modern humans may be more exposed to oxidant stresses. Much indirect evidence implicates reactive oxygen species in diseases such as cancer and atherosclerosis. There are also other diseases that are influenced by oxidative balance, including the normal process of aging. Common environmental factors that could cause oxidative stress include a low intake of dietary antioxidants, a high intake of polyunsaturated fatty acids, and exposure to ozone, ionizing radiation, and cigarette smoke. The recent development of overall measures of oxidant status, such as breath pentane; highly sophisticated measures, such as electron spin resonance and specific measures of base damage to DNA by mass spectrometry; and other methods will allow much more specific data to be collected on the importance of reactive oxygen species in many disease states. Such measures can serve as end points for a variety of studies in experimental animals and humans that will allow for the testing of many potential prooxidant and antioxidant compounds. Other important evidence will be available soon from, for example, large scale chemoprevention trials that are currently under way. As an indicator of the increased interest in oxidant balance, several reference laboratories now have nutritional biochemistry sections that offer measurement of specific free-radical scavenging enzymes. These enzyme measures complement the more routinely available measurements of trace element and antioxidant nutrients.

The use of unproven remedies for rheumatoid arthritis in Australia.

It is important for a medical practitioner to be aware of his or her patient's use of non-prescribed, unproven remedies. This is especially so in a chronic relapsing disease of unknown cause such as rheumatoid arthritis. We selected 90 consecutive patients with classic or definite rheumatoid arthritis who attended the rheumatology clinic of a teaching hospital in 1982. The patients were asked about their previous or current use of an unproven remedy; 82% had used more than one unproven remedy since the diagnosis was made and 52% were currently using an unproven remedy. In all, 352 separate unproven remedies were used, with a mean of 4 +/- 0.3 remedies per patient. Avoidance of a particular food substance or use of a copper bracelet were the most common of such remedies. Fourteen per cent of remedies were deemed to be useful and 3% were felt to have resulted in an adverse effect.

Perspectives on integrating experimental and epidemiologic research on diet, anthropometry and breast cancer.

Three perspectives on the integration of experimental and epidemiologic research on diet, anthropometry and breast cancer are presented. 1) Although body weight and height have been linked to breast cancer risk by epidemiologic research, their roles have not been directly explored with animal models. However, basic, clinical and epidemiologic research on obesity and associated metabolic alterations may be pertinent. Individual differences in the timing and magnitude of weight gain and loss during adult life need to be considered in epidemiologic studies of adiposity and breast cancer, along with individual differences in the pattern of body fat deposition, the hormonal and metabolic changes that accompany the adiposity, and family history of obesity-related chronic diseases. Animal models with genetic predispositions to obesity, diabetes and breast cancer merit further exploration, as well as models that can evaluate exposures occurring after puberty. 2) The synergy between experimental and epidemiologic studies on fat and energy intake and breast carcinogenesis has been productive because each discipline has had to incorporate recent findings of the other. Dietary studies utilizing animals with different genetic profiles are promising, but require identification of the critical genes in human carcinogenesis. 3) Controlled dietary intervention studies with human participants using intermediate endpoints can bridge the gap between animal and epidemiologic studies, but generally accepted intermediate endpoints for breast cancer need to be developed. Such studies would permit better control of diet than large clinical trials and the opportunity to explore mechanisms.

Relationship between sensitivity to dietary fat and dietary cholesterol.

A group of 56 hypercholesterolemic and normocholesterolemic men and women were given approximately 700 mg a day of egg yolk cholesterol in a double-blind, crossover study while they were on a background diet containing approximately 30% of energy as fat. Overall there was a 0.23 mmol/l rise in plasma cholesterol (3.7%, p less than 0.001) after 4 weeks, a 0.19 mmol/l rise in low density lipoprotein (LDL) cholesterol (4.9%, p = 0.002), and a 0.07 mmol/l rise in high density lipoprotein (HDL) cholesterol (5.4%, p less than 0.001). Plasma triglycerides fell by 0.07 mmol/l (5.1%). Normocholesterolemic individuals (plasma cholesterol less than 5.2 mmol/l) experienced small, nonsignificant rises of 0.06, 0.02, and 0.05 mmol/l in total, LDL, and HDL cholesterol, respectively. Hypercholesterolemic subjects were classified on the basis of their response to a low fat diet. Diet-sensitive subjects were defined by a greater than 10% fall in plasma cholesterol on a 25% fat, low cholesterol (less than 200 mg/day) diet. These individuals were found to be more responsive to the effect of dietary cholesterol than were diet-insensitive subjects; the respective changes in the two groups were rises of 0.36 mmol/l versus 0.19 mmol/l in plasma cholesterol (p = 0.06) and rises of 0.30 versus 0.15 mmol/l in LDL cholesterol (p = 0.06). In addition to elevating HDL cholesterol by 0.09 mmol/l and 0.07 mmol/l, respectively, dietary cholesterol also produced an increase in the proportion of HDL2, from 40% to 44% of HDL protein (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of fish oil on lipoproteins, lecithin:cholesterol acyltransferase, and lipid transfer protein activity in humans.

A group of 33 mildly hypercholesterolemic men were stratified into three groups on diets closely matched except for the polyunsaturated fatty acid supplement. The first group received 14 g/day of linoleic acid (safflower oil); the second group, 9 g of alpha-linolenic acid (linseed oil); and the third group, 3.8 g of n-3 fatty acids (fish oil). Only fish oil lowered plasma triglycerides (by 24% at 6 weeks, p less than 0.05 compared to safflower oil). Very low density lipoprotein (VLDL) apoprotein (apo) B, triglyceride, and cholesterol all fell significantly with the fish-oil diet (p less than 0.01). Low density lipoprotein (LDL) cholesterol fell by 0.18 and 0.10 mmol/l, respectively, with the safflower-oil and linseed-oil diets, but rose by 0.24 mmol/l with the fish-oil diet (p less than 0.05). There was a strong correlation between the changes in VLDL triglyceride and LDL cholesterol with the fish-oil diet (r = -0.84, p less than 0.002). High density lipoprotein (HDL) cholesterol fell slightly in all three groups (p less than 0.02 with the linseed-oil diet only). However, the apo A-I/A-II ratio rose by 5% (p less than 0.05), and the HDL2/HDL3 protein ratio increased by 28% with the fish-oil diet (p less than 0.005). Fish oil reduced the capacity for transfer of cholesteryl ester between LDL and HDL by 23% (p less than 0.02 compared to baseline), reduced plasma lecithin:cholesterol acyltransferase activity by 21% (p less than 0.05), and reduced maximal stimulated thromboxane production by 9% (p less than 0.05). Thus fish oil produced three potentially beneficial changes: significant decreases in VLDL concentration and in thromboxane production and an increase in the HDL2/HDL3 ratio. The increase in the average HDL particle size probably reflected reduced cholesteryl ester acceptor capacity within the smaller pool of VLDL, as well as the decline in lipid transfer activity in plasma involving transfer protein itself, LDL, and HDL.

Diet and rheumatoid arthritis in women: a possible protective effect of fish consumption.

Some researchers have hypothesized that omega-3 fatty acids, found primarily in fish oils, may protect against the development of rheumatoid arthritis. We conducted a population-based case-control study in women, comparing 324 incident rheumatoid arthritis cases with 1,245 controls. We used a food frequency questionnaire to ascertain diet during a 1-year period 5 years before a reference date (first physician visit for joint-symptoms). Consumption of broiled or baked fish, but not of other types of fish, was associated with a decreased risk of rheumatoid arthritis. The adjusted odds ratios (OR) for 1- < 2 servings and > or = 2 servings of broiled or baked fish per week, compared with < 1 serving, were 0.78 [95% confidence interval (CI) = 0.53-1.14] and 0.57 (95% CI = 0.35-0.93). Other analyses showed associations with protein as a percentage of calories (adjusted OR for the top quartile as compared with the bottom quartile = 0.65; 95% CI = 0.46-0.94) and total calories (adjusted OR for the top quartile = 1.62; 95% CI = 1.15-2.28). The associations with broiled or baked fish, protein, and calories became stronger when we restricted our analysis to cases positive for rheumatoid factor. These results support the hypothesis that omega-3 fatty acids may help prevent rheumatoid arthritis.

Assessment of trans-fatty acid intake with a food frequency questionnaire and validation with adipose tissue levels of trans-fatty acids.

Past studies of the association of trans-fatty acid intake with coronary heart disease have been hindered by the lack of a database on the trans-fatty acid content of various foods. The authors used new data from the US Department of Agriculture to estimate trans-fatty acid intake using a self-administered food frequency questionnaire (FFQ), and they assessed the validity of the FFQ by comparing the dietary estimates with trans-fatty acid concentrations in adipose tissue. The 1996 study included 27 women and 24 men aged 51-78 years. The mean consumption of total trans-fatty acids estimated from the FFQ was 2.24 g per day and 5% of total dietary fat. The mean concentration of total trans-fatty acids in buttock adipose tissue was 4.7% of total fatty acids. Pearson correlations between total dietary intake of trans-fatty acids and total trans-fatty acid levels in adipose tissue were 0.67 (95% confidence interval (CI) 0.36-0.84) among men and 0.58 (95% CI 0.26-0.79) among women. After adjustment for energy intake, age, and body mass index, the correlation coefficients were 0.76 (95% CI 0.51-0.89) among men and 0.52 (95% CI 0.17-0.75) among women. The FFQ validated in this study is an important new tool for assessing usual intake of trans-fatty acids.

Dietary soy isoflavone intake in older Japanese American women.

OBJECTIVE: In a sample of older Japanese American women, we aimed to: (1) describe the most commonly consumed soy foods, (2) estimate dietary soy isoflavone intake, (3) describe characteristics associated with dietary soy isoflavone intake, and (4) compare our estimates with previously published estimates in other Japanese samples. DESIGN: A 14-item soy food-frequency questionnaire was administered to older Japanese American women and responses were converted to quantitative estimates of soy isoflavones (genistein plus daidzein). Multiple regression was used to examine characteristics associated with dietary soy isoflavone intake, including self-reported lifestyle and cultural factors and dietary intake of various foods ascertained from a semi-quantitative food-frequency questionnaire. To compare our estimates with other samples, a review of the literature was conducted. SETTING/SUBJECTS: Data are from 274 women aged 65+ years, recruited from a longitudinal cohort study of Japanese Americans in King County, Washington State. RESULTS: The soy foods most commonly consumed were tofu (soybean curd), miso (fermented soybean paste) and aburaage (fried thin soybean curd). The mean intake of dietary soy isoflavones was 10.2 (standard deviation (SD), 12.4) mg day(-1), approximately a quarter to a half that of previously published estimates in Japanese samples. Dietary soy isoflavone intake was positively associated with speaking Japanese, the consumption of traditional Japanese dishes (kamaboko, manju and mochi), low-fat/non-fat milk and yellow/red vegetables, vitamin E supplement use, and walking several blocks each day. Dietary soy isoflavone intake was negatively associated with the consumption of butter. CONCLUSIONS: The estimated dietary soy isoflavone intake in Japanese American women living in King County, Washington State was about a quarter to a half that of women living in Japan. Dietary soy isoflavone intake was associated with speaking Japanese and healthy lifestyle and dietary habits.

Oat products and lipid lowering. A meta-analysis.

OBJECTIVES: To test the a priori hypothesis that consumption of oats will lower the blood total cholesterol level and to assess modifiers and confounders of this association. DATA SOURCES: A computerized literature (MEDLINE) search and the Quaker Oats Co identified published and unpublished trials as of March 1991. Raw data were requested for all trials. STUDY SELECTION: Trials were included in summary effect size estimates if they were randomized and controlled, if a formal assessment of diet and body weight changes occurred, and, if raw data were not received, if there was enough information in the published report to perform calculations. DATA SYNTHESIS: Twenty trials were identified. Using the methods of DerSimonian and Laird, a summary effect size for change in blood total cholesterol level of -0.13 mmol/L (-5.9 mg/dL) (95% confidence interval [CI], -0.19 to -0.017 mmol/L [-8.4 to -3.3 mg/dL]) was calculated for the 10 trials meeting the inclusion criteria. The summary effect size for trials using wheat control groups was -0.11 mmol/L (-4.4 mg/dL) (95% CI, -0.21 to -0.01 mmol/L [-8.3 to -0.38 mg/dL]). Calculation of Keys scores demonstrated that substituting carbohydrates for dietary fats and cholesterol did not account for the majority of blood cholesterol reduction. Larger reductions were seen in trials in which subjects had initially higher blood cholesterol levels (greater than or equal to 5.9 mmol/L [greater than or equal to 229 mg/dL]), particularly when a dose of 3 g or more of soluble fiber was employed. CONCLUSION: This analysis supports the hypothesis that incorporating oat products into the diet causes a modest reduction in blood cholesterol level.

The Women's Health Trial Feasibility Study in Minority Populations: changes in dietary intakes.

This randomized clinical trial examined the feasibility of low-fat dietary interventions among postmenopausal women of diverse backgrounds. During 1992-1994, 2,208 women aged 50-79 years, 28% of whom were black and 16% Hispanic, enrolled at clinics in Atlanta, Georgia, Birmingham, Alabama, and Miami, Florida. Intervention/support groups met periodically with a nutritionist to reduce fat intake to 20% of energy and to make other diet modifications. At 6 months postrandomization, the intervention group reduced fat intake from 39.7% of energy at baseline to 26.4%, a reduction of 13.3% of energy, compared with 2.3% among controls. Saturated fatty acid and cholesterol intakes were reduced, but intakes of fruits and vegetables, but not grain products, increased. Similar effects were observed at 12 and 18 months. Black and non-Hispanic white women had similar levels of reduction in fat, but the decrease in Hispanic women was less. Changes did not vary significantly by education. While bias in self-reported intakes may have resulted in somewhat overestimated changes in fat intake, the reported reduction was similar to the approximately 10% of energy decrease found in most trials and suggests that large changes in fat consumption can be attained in diverse study populations and in many subgroups.