Dietary vitamin A and risk of cancer in the Western Electric study

Dietary vitamin D and calcium and risk of colorectal cancer: a 19-year prospective study in men

Mortality rates from colon cancer in the USA are highest in populations exposed to the least amounts of natural sunlight; differences in endogenous vitamin D production and calcium absorption could be responsible. To investigate this possibility, the association of dietary vitamin D and calcium with 19-year risk of colorectal cancer was examined in 1954 men who had completed detailed, 28-day dietary histories in the period 1957-59. Risk of colorectal cancer was inversely correlated with dietary vitamin D and calcium. In the quartiles of a combined index of dietary vitamin D and calcium, from lowest to highest, observed risks of colorectal cancer were 38.9, 24.5, 22.5, and 14.3/1000 population. This association remained significant after adjustment for age, daily cigarette consumption, body mass index, ethanol consumption, and percentage of calories obtained from fat.

Risk of cancer in relation to serum concentrations of selenium and vitamins A and E: matched case-control analysis of prospective data

The independent and joint associations of serum selenium and vitamin A (retinol) and E (alpha tocopherol) concentrations with the risk of death from cancer were studied in 51 case-control pairs--that is, 51 patients with cancer, each paired with a control matched for age, sex, and smoking. Case-control pairs came from a random sample of some 12000 people aged 30-64 years resident in two provinces of eastern Finland who were followed up for four years. Patients who died of cancer during the follow up period had a 12% lower mean serum selenium concentration (p = 0.015) than the controls. The difference persisted when deaths from cancer in the first follow up year were excluded. The adjusted risk of fatal cancer was 5.8-fold (95% confidence interval 1.2-29.0) among subjects in the lowest tertile of selenium concentrations compared with those with higher values. Subjects with both low selenium and low alpha tocopherol concentrations in serum had an 11.4-fold adjusted risk. Among smoking men with cancer serum retinol concentrations were 26% lower than in smoking controls (p = 0.002). These data suggest that dietary selenium deficiency is associated with an increased risk of fatal cancer, that low vitamin E intake may enhance this effect, and that decreased vitamin or provitamin A intake contributes to the risk of lung cancer among smoking men with a low selenium intake.

A mild, rapid, and efficient method of lipid extraction for use in determining vitamin E/lipid ratios

A new, general method for lipid extraction and measurement of vitamin E/total lipid ratios in tissue and cell samples has been developed. The new extraction procedure uses a combination of sodium dodecylsulfate, ethanol and n-heptane, and is mild, clean, convenient, efficient and rapid (less than or equal to 5 min). The efficiency of the new method has been confirmed for human plasma, red blood cells and rat liver homogenate by the comparison of the yields of vitamin E, O-acyl lipid and cholesterol with the yields obtained following conventional extraction procedures. Extraction efficiency also has been confirmed for multilamellar vesicles composed of known quantities of vitamin E, egg lecithin and cholesterol.

Vitamin A and lung cancer: a perspective

Sixteen studies of the relationship between lung cancer and vitamin A in humans are critically reviewed: eight dietary studies and eight serum studies. Of the eight dietary studies, only five had case samples large enough to warrant meaningful statistical analysis. Three dietary studies reported a negative association between vitamin A intake and lung cancer after proper adjustment for cigarette smoking and socioeconomic effects; the results suggested that daily consumption of green-yellow vegetables reduces the risk of lung cancer in all categories of smokers. The reduction in risk was found to be greatest in persons in the higher socioeconomic strata. Four dietary studies suggested that high intake of dietary vitamin A has a protective effect against the development of squamous and small cell carcinoma of the lung in smokers. Three studies revealed a lower risk of lung cancer among persons who consume carrots and milk daily. None of the eight serum studies reviewed had large enough samples of lung cancer cases to allow for meaningful statistical analysis. However, four of the serum studies reported significantly lower serum vitamin A levels in lung cancer cases than in controls. Analysis of the above studies demonstrated shortcomings in each. Future studies should include all of the following factors: more complete vitamin A indices, examination of the histological type of lung cancer, a large enough pool of both male and female patients for statistical analysis, and proper adjustment for the effects of age, sex, smoking, and socioeconomic status.

Nutrition and prostate cancer: a case-control study

This one-to-one, age- and race-matched case-control study involved 181 histologically confirmed black prostate cancer patients and 181 controls seen at three major hospitals in Washington, DC, during the period 1979-1982. Personal interviews were conducted to obtain the number of times food items of specified serving size were consumed per week by cases and controls during the age periods 30-49 and 50 years and older. Then the average daily consumption of each of 18 nutrients per 1,000 calories was calculated. There was risk enhancement associated with increased intake of proteins, total fat, saturated fat, oleic acid, and vitamin A during the age period 30-49 years. The association was highly significant for vitamin A and approached statistical significance for the other four nutrients. A hypothesis based on disturbance of the zinc-retinol binding protein-vitamin A axis was put forward to explain the relative risk enhancement effect of vitamin A on prostate cancer.

Indicator foods for vitamin A assessment

Epidemiological interview studies examining the association between vitamin A and cancer at various sites have been hampered by restricted time available for interview; consequently, studies have included varying lists of food items or broad food groups, thus making comparability of results difficult. To identify a standardized list of indicator foods that adequately assess total vitamin A intake, we examined the 24-hour dietary recall of 13,201 adults who participated in the First National Health and Nutrition Examination Survey (NHANES I) from 1971 to 1974. Food items reportedly consumed were ranked by contribution to overall (aggregated) intake in various subpopulations by an index of vitamin A contribution, which reflected the frequency of consumption, portion size, and vitamin A concentration (IUs/100 g). A comparison of these ranks identified certain food items that had a relative contribution to vitamin A intake which varied by sex/race group, season of interview, age, or region of the country; income level had little effect on the food rankings. The top-ranking 50 foods were sufficient to correctly classify 80%-90% of the individuals into low-, moderate-, and high-consumer categories. The major contributing foods for any subpopulation examined included both retinol (e.g., dairy products, liver) and carotenoid sources of vitamin A (e.g., certain fruits and vegetables) in addition to items (e.g., mixed tomato and cheese dishes) not included in earlier questionnaire studies. Recommendations are made for future questionnaires designed to assess vitamin A.

Use of the micronucleus test to monitor the effect of vitamin A, beta-carotene and canthaxanthin on the buccal mucosa of betel nut/tobacco chewers

The frequency of exfoliated cells with micronuclei in buccal swabs was used to estimate the protective effect of vitamin A, beta-carotene and canthaxanthin (4,4'-diketo-beta-carotene) on the buccal mucosa of betel (areca) nut/tobacco chewers. Micronuclei were scored on exfoliated cells taken by swabbing and stained with the Feulgen reaction and fast green. The betel (areca) nut/tobacco chewers served as their own controls. Prior to the administration of vitamin A and beta-carotene, the examined betel quid chewers had elevated frequencies of micronucleated buccal mucosa cells, averaging 4.03% +/- 1.24 SD (n = 26) and 3.43% +/- 1.22 SD (n = 25), respectively. The frequency of micronucleated buccal mucosa cells in non-chewers and non-smokers was 0.51% (n = 52). Following a 9-week ingestion of vitamin A (150,000 IU/week) and beta-carotene (180 mg/week in 6 capsules), the frequency of micronucleated cells decreased significantly (p less than 0.001) to 1.70% and 1.16%, respectively. No significant shift in the frequencies of micronucleated cells was observed following the intake of canthaxanthin (180 mg/week in 6 capsules) for 9 weeks or that of a placebo. The lack of protective activity of canthaxanthin, which is a good trapper of oxygen singlets but cannot be converted into vitamin A, suggests that vitamin A and beta-carotene exert their inhibitory effect on the formation of micronuclei by a mechanism not involving the scavenging of free radicals. The efficacy of beta-carotene as an inhibitor of micronucleated cell formation, the lack of toxicity, and its availability from a multitude of dietary sources should focus attention on this carotenoid as a promising chemopreventive agent.

A practical prescription for cancer prevention--synergistic use of chemopreventive agents

Enzyme inducers, selenium, and retinoids exert broad-spectrum chemopreventive actions in animal models of carcinogenesis. The mechanisms of action of these three categories of agents are clearly distinct and complementary. BHA, selenium, and beta-carotene are probably safe and non-toxic for humans in doses which, in light of animal studies, can be expected to provide significant cancer protection. The concurrent application of safe, appropriate doses of these three agents could exert a potent synergistic chemopreventive effect, and, if continued throughout life, would in all likelihood substantially reduce cancer risk.

Prospective study of alcohol consumption and cancer

The relation between alcohol consumption and the subsequent occurrence of the five most frequent cancers in Japanese men in Hawaii (cancer of the stomach, colon, rectum, lung, and prostate) was analyzed in a prospective study of 8006 subjects. Information on alcohol consumption was obtained through interviews in the mid-1960s, and the cohort has been followed since then. The analysis, which was adjusted for the effects of age and cigarette smoking, revealed a positive association between consumption of alcohol and rectal cancer, accounted for primarily by an increased risk in men whose usual monthly consumption of beer was 500 oz (15 liters) or more (relative risk, 3.05; P less than 0.01, as compared with those who did not drink beer). A significant positive relation between alcohol consumption and lung-cancer incidence was also found, accounted for primarily by an increased risk among subjects who consumed larger amounts of wine or whiskey, as compared with the risks among nonconsumers of these beverages (relative risk, 2.19, [P = 0.03] and 2.62 [P less than 0.01], respectively). No significant relation between alcohol consumption and the incidence of the other three cancers was found.

Plasma retinol, beta-carotene and vitamin E levels in relation to the future risk of breast cancer

In a prospective study of 5,004 women in Guernsey, plasma samples were collected and stored. Retinol, beta-carotene and vitamin E levels were later measured in the samples from 39 women who subsequently developed breast cancer and from 78 controls who did not develop cancer. Plasma retinol levels were not related to the risk of breast cancer, mean levels among cases and controls being 485 micrograms l-1 and 479 micrograms l-1 respectively. Plasma vitamin E levels showed a clear association, low levels being associated with a significantly higher risk of cancer. The mean vitamin E levels among cases and controls were 4.7 mg l-1 and 6.0 mg l-1 respectively (P less than 0.025), and the risk of breast cancer in women with vitamin E levels in the lowest quintile was about 5-times higher than the risk for women with levels in the highest quintile (P less than 0.01). beta-carotene levels showed a tendency to be lower in women who developed cancer than in controls (36 micrograms l-1 among cases compared with 50 micrograms l-1 among controls) but the difference was not statistically significant.

Relation of serum vitamins A and E and carotenoids to the risk of cancer

Epidemiologic studies suggest that low carotene intake and low levels of serum retinol may be associated with an increased risk of cancer. Likewise, in some animal studies vitamin E has been associated with a reduced rate of induced cancers. Therefore, we measured retinol, retinol-binding protein, vitamin E (alpha-tocopherol), and total carotenoids in serum collected in 1973 from 111 participants in the Hypertension Detection and Follow-up Program who were free of cancer at the time but were diagnosed as having cancer during the subsequent five years. These measurements were compared with those in 210 controls who were matched for age, sex, race, and time of blood collection, and who remained free of cancer. Mean values for retinol were similar for cases and controls (67.3 and 68.7 micrograms per deciliter, respectively [95 per cent confidence limits for case-control difference, -6.7 to 3.5]). Values were also similar for retinol-binding protein (6.01 and 5.94 mg per deciliter [-0.42 to 0.56]), and carotenoids (114.5 and 111.6 micrograms per deciliter [-9.1 to 15.9]). The mean base-line retinol level in the 18 subjects with subsequent lung cancer was higher than that in their matched controls (79.0 vs. 71.4 micrograms per deciliter, -4.9 to 19.7). Serum vitamin E levels were somewhat lower in subjects who later had cancer than in controls (1.16 and 1.26 mg per deciliter, -0.22 to 0.02), in part because of the confounding effect of serum cholesterol levels (when adjusted for lipid levels, the case-control difference was -0.05 mg per deciliter; -0.17 to 0.07). These data do not support hypotheses relating intake or serum levels of antioxidant vitamins to a reduced cancer risk.

Activities of fatty acid desaturases and fatty acid composition of liver microsomes in rats fed beta-carotene and 13-cis-retinoic acid

The fatty acid composition of microsomal lipids and the activities of delta 9- and delta 6-desaturases in liver microsomes of rats fed diets supplemented with beta-carotene and two levels of 13-cis-retinoic acid were studied. Four groups of male, weanling rats were fed semipurified diets containing 0 or 100 mg beta-carotene per kg diet, and 20 or 100 mg 13-cis-retinoic acid per kg diet. After 11 weeks of feeding, the rats were killed, liver microsomes were prepared and assayed for delta 9-desaturase and delta 6-desaturase activities. The activity of delta 9-desaturase was lower in liver microsomes of rats fed beta-carotene-supplemented diet or the diet supplemented with the higher level of 13-cis-retinoic acid. Microsomal delta 6-desaturase activity was, however, higher in liver of rats fed 13-cis retinoic acid; there was no effect of beta-carotene on delta 6-desaturase activity. The fatty acid compositional data on total lipids of liver microsomes were consistent with the diet-induced changes in fatty acid desaturases. Phospholipid composition of liver microsomes was also altered as a result of feeding beta-carotene or 13-cis-retinoic acid-containing diets. The proportions of phosphatidylethanolamine were generally higher, whereas those of phosphatidylcholine were lower in the experimental groups as compared with the control.

Vitamin therapy in the absence of obvious deficiency. What is the evidence?

Vitamins are a group of organic compounds occurring naturally in food and are necessary for good health. Lack of a vitamin may lead to a specific deficiency syndrome, which may be primary (due to inadequate diet) or secondary (due to malabsorption or to increased metabolic need), and it is rational to use high-dose vitamin supplementation in situations where these clinical conditions exist. However, pharmacological doses of vitamins are claimed to be of value in a wide variety of conditions which have no, or only a superficial, resemblance to the classic vitamin deficiency syndromes. The enormous literature on which these claims are based consists mainly of uncontrolled clinical trials or anecdotal reports. Only a few studies have made use of the techniques of randomisation and double-blinding. Evidence from such studies reveals a beneficial therapeutic effect of vitamin E in intermittent claudication and fibrocystic breast disease and of vitamin C in pressure sores, but the use of vitamin A in acne vulgaris, vitamin E in angina pectoris, hyperlipidaemia and enhancement of athletic capacity, of vitamin C in advanced cancer, and niacin in schizophrenia has been rejected. Evidence is conflicting or inconclusive as to the use of vitamin C in the common cold, asthma and enhancement of athletic capacity, of pantothenic acid in osteoarthritis, and folic acid (folacin) in neural tube defects. Most of the vitamins have been reported to cause adverse effects when ingested in excessive doses. It is therefore worthwhile to consider the risk-benefit ratio before embarking upon the use of high-dose vitamin supplementation for disorders were proof of efficacy is lacking.

Epidemiologic studies on vitamin A and cancer

Data derived from epidemiologic studies on human populations are consistent with the protection from cancer afforded by vitamin A seen in animal studies. The populations studied are diverse, including groups living in India, Singapore, Norway, the United Kingdom, and the United States. The methodologies brought to bear on the question have been equally varied. Although there are inconsistencies in findings, and instances in which an association has not been observed, the weight of evidence suggests that the intake of vitamin A from dietary or other sources may inhibit the onset of lung cancer and possibly other cancers. However, the evidence from human populations is not experimental and it is conceivable that the associations observed are not causal. Additional epidemiologic research is needed to determine what sites of cancer may be inhibited by vitamin A and whether cancer growth at any other site is enhanced by high vitamin A intakes. It is also important that controlled trials using vitamin A as a chemopreventive agent be considered as a means of determining whether the epidemiologic findings are of clinical significance.

Potential clinical applications for high-dose nutritional antioxidants

High but well-tolerated doses of the nutritional antioxidants selenium and vitamins E and C have significant immunostimulant, anti-inflammatory, and anti-carcinogenic effects which are well documented in the existing biomedical literature. In addition, these antioxidants help to protect the structural integrity of ischemic or hypoxic tissues, and may have useful anti-thrombotic actions as well. Supplementation with high-dose nutritional antioxidants may eventually gain a broad role in the prevention, treatment, or palliation of cancer, cardiovascular disease, infection, inflammatory disorders, and certain diabetic complications.

Dietary cholesterol and lung cancer risk in a multiethnic population in Hawaii

We interviewed 364 subjects with lung cancer and 627 age- and sex-matched controls among the multiethnic population of Hawaii. Quantitative estimates of dietary cholesterol and vitamin A intakes were obtained, as well as smoking and occupational histories. Using multiple logistic regression analysis to control for potential confounding variables, we found a monotonic positive dose-response relationship between dietary cholesterol and lung cancer risk in all subjects, in smoking subjects, and in men. In each of these groups, subjects in the highest quartile of dietary cholesterol were at significantly increased risk of lung cancer (lower 95% confidence limit greater than 1.0). Among females, however, no clear association of dietary cholesterol with lung cancer risk was apparent.

Dietary carotenoids block photocarcinogenic enhancement by benzo (a)pyrene and inhibit its carcinogenesis in the dark

The carotenoids beta-carotene (C) and canthaxanthine (CX), with and without pro-vitamin A activity, respectively, when perorally administered to mice, markedly prevent benzo(a)pyrene photocarcinogenic enhancement (BP-PCE), continue to block such BP-PCE and protect significantly against BP carcinogenesis in mice maintained in the dark. These results appear relevant to both the pathogenesis of chemical carcinogenesis and rational programs of skin cancer prevention in humans.

Dietary recommendations for coronary heart disease prevention: implications for non-cardiovascular diseases

In order to reduce the lipoprotein-related risk of coronary heart disease, nutritional recommendations have been formulated for use by communities prone to atherosclerosis and its complications. As such recommendations are potentially of widespread application they require careful scrutiny to assess possible risks as well as benefits. Epidemiological, clinical and experimental data concerning relationships between these nutrients and non-cardiovascular diseases are reviewed with emphasis on cancer mortality. Changes in intake of fats, including polyunsaturated fat, of cholesterol, carbohydrate, fibre, sodium and beta-carotene are discussed, and evidence of a relationship between serum cholesterol concentration and cancer is examined. These considerations offer reasonable reassurance as to the safety of recent dietary recommendations for the reduction of coronary heart disease.

The distribution of selenium and cancer mortality in the continental United States

An hypothesis was proposed that selenium concentration in the environment, as measured by the uptake of this element by forage crops, exerted an apparent effect on cancer incidence, such that cancer mortality in the continental United States was lower where the selenium concentration was high than where the concentration was low. The purpose of the present study is to test this hypothesis for statistical significance and to discover whether the apparent pattern of cancer mortality in relation to selenium distribution holds true with respect to all ages. Two main types of statistical analyses were employed: analysis of variance and trend analysis, both applied to all age groups and both sexes. Data presented in this paper show that significant interactions exist between selenium distribution and sex in relation to deaths caused by cancer of the digestive organs, respiratory organs, and the breast. Geographic variations in selenium may be viewed as variations in the intake of this element in the diet. A significant interaction may thus suggest that the particular cancer in question has in its origin a dietary factor that includes some measure of selenium intake. A discussion involving contributions from various disciplines is presented to explain the significant results reported in this paper. This paper shows that a pattern exists between the geographical distribution of selenium using forage crops as a guide for dietary intake and cancer mortality (ICD 140-209,150-159,160-163, and 174) such that an inverse relationship exists between selenium concentration in an area and cancer mortality in the same area.

Cancer prevention: assessing causes, exposures, and recent trends in mortality for U.S. males, 1968-1978

This paper addresses some enduring issues concerning prevention of environmental and occupational cancer. The first part reviews methodological problems of estimating cancer risks and outlines some research priorities. The second part documents countervailing trends in chemical production during the past two decades, noting the doubling of some synthetic organic human carcinogens and the leveling off of some heavy metal carcinogens. The final section details recent increases in site-specific causes of cancer mortality for men old enough to have developed workplace cancers (ages 35 to 84), considering those cancers that have been linked with exposures to toxic chemicals and to cigarette smoking. This paper points out that Doll and Peto's (1981) analysis of U.S. cancer trends does not indicate some important increases in older males; they conclude that apart from cigarette smoking, there is no generalized increase in cancer for persons up to age 64. In fact, there has been a sharp reduction in cancer mortality for those under age 45. This reduction more than offsets increases in some cancers for those ages 45 to 65. Men ages 55 to 84 have experienced major increases in mortality for certain cancers plausibly associated with occupational exposures, including cancers of the brain, lung, and multiple myeloma. These older age groups have potentially sustained longer workplace exposures to carcinogens, some of which have 25-year or greater latencies. Changes in infectious diseases, workplace exposures, diagnostic trends, environment, and nutrition require further study.

Hypocholesterolaemia and non-cardiovascular disease: metabolic studies on subjects with low plasma cholesterol concentrations

Some epidemiological studies have suggested an inverse relation between serum cholesterol concentration and mortality from cancer. Two hypotheses that might explain such a relation were investigated. To assay potentially deleterious effects of hypocholesterolaemia on cell membranes the lipid content and fluidity of blood mononuclear cells were measured in healthy male volunteers with a wide range of serum cholesterol concentration (3.2-10.0 mmol/l (124-387 mg/100 ml)). Fluidity, unesterified cholesterol content, and the ratio of cholesterol to phospholipid were unrelated to serum cholesterol and to low density lipoprotein cholesterol concentrations. Similar measurements were made on fibroblasts and mononuclear cells incubated with a range of concentrations of low density lipoprotein; fluidity was altered only at extremely low concentrations, suggesting that changes in cell membranes are unlikely to occur at serum cholesterol concentrations attainable by dietary or drug treatment of hyperlipidaemia. In the same population direct relations were confirmed between low density lipoprotein concentration and plasma concentrations of retinol and beta carotene. This is compatible with the suggestion that an association between low cholesterol concentration and cancer may be secondary to a relation between low retinoid concentrations and cancer.

Dietary habits and lung cancer risk

A previously reported negative association between a high index of dietary vitamin A and lung cancer incidence was confirmed in an extended follow-up, covering 11 1/2 years, of 13,785 men and 2,928 women, Responses to a postal questionnaire provided the dietary information. Relationships between the major dietary items and lung cancer were explored for various diagnostic subsets of the 168 lung cancer cases diagnosed among the study subjects. Analyses were stratified for sex, age, residence characteristics, cigarette smoking and, at times, socioeconomic group. Although the data do not permit a firm interpretation in terms of risk enhancement by a marginal retinoid deficiency, we found that the apparent protection afforded by higher intakes of vitamin A or its provitamins was particularly strong for lung cancer appearing as squamous-cell carcinoma and among those with higher alcohol intakes. The individual food items which showed the strongest negative association with lung cancer were carrots and milk. These two items made a major contribution to the vitamin A index and its variation among the respondents.

Vitamin A: evidence for its preventive role in human cancer

Both the provitamin beta-carotene and natural vitamin A and its derivatives (the retinoids) are being proposed as potential chemopreventive agents. The biochemistry and pharmacology of vitamin A suggest a number of mechanisms whereby carcinogenesis can be affected. Epidemiologic studies have consistently demonstrated an increased relative risk of cancer for people with low vitamin A intake or low-to-normal serum retinol values. Chemoprevention trials in humans are only now beginning. In the interim, daily consumption of vitamin-A-containing foods may be a "prescription" worth following.

Inhibition of protein pyrolysate mutagenicity by retinol (vitamin A)

The mutagenicity in the Ames Salmonella-microsome test of four protein pyrolysate products, formed during the cooking of meat, (Trp-P-1, Trp-P-2, Glu-P-1 and Glu-P-2) was found to be inhibited by the addition of vitamin A in vitro in the form of retinol. The effect is interpreted as an inhibition of the metabolic activation of the mutagens to their respective ultimate mutagenic forms since retinol has been shown to have no effect on the survival of the Salmonella cells, no effect on directly acting mutagens and no effect on the formation of NADPH in the test system. The results demonstrate the need for an increased understanding of the interaction of dietary components in evaluating mutagenic/carcinogenic risks from processed food.

Mortality among health-conscious elderly Californians

In an attempt to obtain epidemiologic evidence regarding the mortality rate among vitamin supplement users, a prospective study was made of 479 elderly Californian respondents to a 1974 questionnaire carried in Prevention, a health magazine that advocates vitamin supplement usage. Based on self-reported questionnaire data obtained in 1974 and 1977, this cohort does indeed consume large quantities of vitamin and mineral supplements. In addition, the cohort is quite health conscious and appears to have taken up a "Prevention life-style" in recent years. For instance, these individuals are primarily nonsmokers, although about 50% formerly smoked cigarettes. Most of them eat meat, poultry, or fish but do so in moderation; and they consume only modest amounts of alcohol, whole milk, white bread, salt, and sugar. Their socioeconomic status is somewhat higher than the national average. Because this group differs from the general population in many ways it is difficult to separate the various factors that might influence their health. During 6 years of follow-up, a total of 107 deaths occurred. Based on comparison with 1977 United States whites, the standardized mortality ratio (SMR) is 78% for the males, 54% for the females, and 68% for both sexes combined. All three SMR values are significantly less than 100% (P less than 0.05). For both sexes combined, the SMR is 86% for cancer, 62% for total cardiovascular diseases, and 73% for all other causes. Only the cardiovascular SMR is significantly lower than 100%. The death rate for the males is approximately the same as that reported among other healthy nonsmoking questionnaire respondents. but the death rate for females is significantly less (P less than 0.01). The only notable relationships between questions asked in 1974 and subsequent mortality are those indicating a higher mortality rate associated with inactivity, heart trouble, and very low and very high levels of vitamin E intake. For this highly selected cohort, the overall "Prevention life-style" appears to be a healthy one, but the cohort experiences no clear reduction in total mortality because of high levels of vitamin intake per se.

Dietary fibre and 10-year mortality from coronary heart disease, cancer, and all causes. The Zutphen study

In 1960, 871 middle-aged men in the town of Zutphen, The Netherlands, participated in a survey of risk indicators (including diet) for coronary heart disease (CHD). Information was collected about the usual food intake for the 6--12 months before the interview by the cross-check dietary history method. During 10 years of follow-up, 107 men died from all causes, 37 from CHD, and 44 from cancer. Mortality from CHD was about four times higher for men in the lowest quintile of dietary-fibre intake than for those in the highest quintile, but this inverse relation disappeared after multivariate analyses. Rates of death from cancer and from all causes were about three times higher for men in the lowest quintile of dietary-fibre intake than for those in the highest quintile, and these relations persisted after multivariate analyses. A diet containing at least 37 g dietary fibre per day may be protective against chronic diseases in Western societies.