Mikko J. Virtanen

Diet and risk of colorectal cancer in a cohort of Finnish men

Objectives: Based on previous epidemiological studies, high fat and meat consumption may increase and fiber, calcium, and vegetable consumption may decrease the risk of colorectal cancer. We sought to address these hypotheses in a male Finnish cohort.Methods: We analyzed data from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC Study) where 27, 111 male smokers completed a validated dietary questionnaire at baseline. After an average of 8 years of follow-up, we documented 185 cases of colorectal cancer. The analyses were carried out using the Cox proportional hazards model.Results: The relative risk (RR) for men in the highest quartile of calcium intake compared with men in the lowest quartile was 0.6 (95% CI 0.4–0.9, p for trend 0.04). Likewise, the intake of milk protein and the consumption of milk products was inversely associated with risk of colorectal cancer. However, intake of dietary fiber was not associated with risk, nor was fat intake. Consumption of meat or different types of meat, and fried meat, fruits or vegetables were not associated with risk.Conclusions: In this cohort of men consuming a diet high in fat, meat, and fiber and low in vegetables, high calcium intake was associated with lowered risk of colorectal cancer.

Gender, socioeconomic status and family status as determinants of food behaviour

This study examines social structural and family status factors as determinants of food behaviour. The data were derived from the FINMONICA Risk Factor Survey, collected in Finland in spring 1992. A multidimensional framework of the determinants of food behaviour was used, including social structural position, family status and gender. The associations between the determinants of food behaviour were estimated by multivariate logistic regression models, adjusted for age and regional differences. Food behaviour was measured by an index including six food items which were chosen based on Finnish dietary guidelines. In general, womens food behaviour was more in accordance with the dietary guidelines than that of men. The pattern of association between educational level and food behaviour was similar for both genders, but slightly stronger for men than women. Employment status was associated only with womens food behaviour, but the tendency was the same for men. Marital status was associated with mens as well as womens food behaviour. The food behaviour of married men and women was more in line with the dietary guidelines than the food behaviour of those who had been previously married. Parental status, however, was only associated with womens food behaviour, that is, the food behaviour of women with young children was more closely in line with the dietary guidelines than that of the rest of the women.

Effects of supplemental α-tocopherol and β-carotene on colorectal cancer: results from a controlled trial (Finland)

AbstractBackground:Some epidemiological investigations suggest that higher intake or biochemical status of vitamin E and β-carotene might be associated with reduced risk of colorectal cancer. Methods:We tested the effects of α-tocopherol and β-carotene supplementation on the incidence of colorectal cancer in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study, a double-blind, placebo-controlled trial among 29,133 50–69-year-old male cigarette smokers. Participants were randomly assigned to receive α-tocopherol (50 mg), β-carotene (20 mg), both agents, or a placebo daily for 5–8 years. Incident colorectal cancers (n = 135) were identified through the nationwide cancer registry, and 99% were histologically confirmed. Intervention effects were evaluated using survival analysis and proportional hazards models. Results:Colorectal cancer incidence was somewhat lower in the α-tocopherol arm compared to the no α-tocopherol arm, but this finding was not statistically significant (relative risk (RR) = 0.78, 95% confidence interval (CI) 0.55–1.09; log-rank test p = 0.15). β-Carotene had no effect on colorectal cancer incidence (RR=1.05, 95% CI 0.75–1.47; log-rank test p = 0.78). There was no interaction between the two substances. Conclusion:Our study found no evidence of a beneficial or harmful effect for β-carotene in colorectal cancer in older male smokers, but does provide suggestive evidence that vitamin E supplementation may have had a modest preventive effect. The latter finding is in accord with previous research linking higher vitamin E status to reduced colorectal cancer risk.

Intake of flavonols and flavones and risk of coronary heart disease in male smokers.

Flavonols and flavones are antioxidant polyphenolic compounds found in tea, vegetables, fruits, and wine. In experimental studies they have been effective free radical scavengers, metal chelators, and antithrombotic agents. In the few epidemiologic studies of these agents, some have suggested an inverse association between intake of flavonols and flavones and the risk of cardiovascular disease. Our study population comprised 25,372 male smokers, 50–69 years of age, with no previous myocardial infarction. They were participants of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, which was a randomized, double-blind, placebo-controlled trial with daily supplementation of alpha-tocopherol (50 mg per day) and/or beta-carotene (20 mg per day). The men completed a validated dietary questionnaire at baseline. After 6.1 years of follow-up, there were 1,122 nonfatal myocardial infarctions and 815 coronary deaths. In the multivariate model, the relative risk of nonfatal myocardial infarction was 0.77 (95% confidence interval = 0.64–0.93) among men in the highest (median 18 mg per day) compared with the lowest (median 4 mg per day) quintile of flavonol and flavone intake. The respective relative risk for coronary death was 0.89 (95% confidence interval = 0.71–1.11). Thus, intake of flavonols and flavones was inversely associated with nonfatal myocardial infarction, whereas there was a weaker association with coronary death.

Reproducibility and validity of a food frequency questionnaire in a case-control study on breast cancer

A 110-item food frequency questionnaire was tested among 152 community controls of the Kuopio Breast Cancer Study. They completed the questionnaire twice and kept two 7-day diet records at 3-month intervals. The intraclass correlations for nutrients varied from 0.49 (thiamine with supplements) to 0.81 (lactose), and for foods from 0.52 (poultry) to 0.84 (alcoholic drinks). The Pearson correlations between the first food frequency questionnaire and the 14-day diet records, after adjustment for energy, varied for nutrients from 0.18 (thiamine without supplements) to 0.80 (alcohol), and for foods from 0.30 (inner organs) to 0.90 (coffee). Comparison of quintile classification between the two methods is reasonably accurate when observed restrictions concerning some nutrients and foods are taken into account. A low association (r = 0.12) was observed between toenail selenium and dietary selenium intake, indicating the difficulty of estimating selenium intake in the Finnish diet.

Diet and prostate cancer risk in a cohort of smokers, with a specific focus on calcium and phosphorus (Finland)

AbstractBackground:Calcium, phosphorus, fructose, and animal protein are hypothesized to be associated with prostate cancer risk, potentially via their influence on 1,25-dihydroxyvitamin D3. We examined these nutrients and overall diet and prostate cancer risk in the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study (ATBC Study). Materials and methods:The ATBC Study was a randomized 2 × 2 trial of alpha-tocopherol and beta-carotene on lung cancer incidence conducted among Finnish male smokers; 27,062 of the men completed a food-use questionnaire at baseline, and comprise the current study population. There were 184 incident clinical (stage 2–4) prostate cancer cases diagnosed between 1985 and 1993. We used Cox proportional hazards models to examine associations between dietary intakes and prostate cancer. Results:We did not observe significant independent associations for calcium and phosphorus and prostate cancer risk. However, men with lower calcium and higher phosphorus intake had a multivariate relative risk of 0.6 (95% CI 0.3–1.0) compared to men with lower intakes of both nutrients, adjusting for age, smoking, body mass index, total energy, education, and supplementation group. Of the other foods and nutrients examined, none was significantly associated with risk. Discussion:This study provides, at best, only weak evidence for the hypothesis that calcium and phosphorus are independently associated with prostate cancer risk, but suggests that there may be an interaction between these nutrients.

Magnesium, Calcium, Potassium, and Sodium Intakes and Risk of Stroke in Male Smokers

BACKGROUND A high intake of magnesium, calcium, and potassium and a low intake of sodium have been hypothesized to reduce the risk of stroke. However, prospective data relating intake of these minerals to risk of stroke are inconsistent. METHODS We examined the relationship of dietary magnesium, calcium, potassium, and sodium intake with risk of stroke in a cohort of 26 556 Finnish male smokers, aged 50 to 69 years, who were free from stroke at baseline. Dietary intake was assessed at baseline using a detailed and validated food frequency questionnaire. During a mean follow-up of 13.6 years (1985-2004), 2702 cerebral infarctions, 383 intracerebral hemorrhages, and 196 subarachnoid hemorrhages were identified in the national registries. RESULTS After adjustment for age and cardiovascular risk factors, a high magnesium intake was associated with a statistically significant lower risk of cerebral infarction but not with intracerebral or subarachnoid hemorrhages. The multivariate relative risk of cerebral infarction was 0.85 (95% confidence interval, 0.76-0.97; P for trend = .004) for men in the highest quintile of magnesium intake compared with those in the lowest quintile. The inverse association between magnesium intake and cerebral infarction was stronger in men younger than 60 years (relative risk, 0.76; 95% confidence interval, 0.64-0.89; P for interaction = .02). Calcium, potassium, and sodium intake was not significantly associated with risk of any subtype of stroke (P for trend > .05). CONCLUSION These findings in male smokers suggest that a high magnesium intake may play a role in the primary prevention of cerebral infarction.

Coffee and Tea Consumption and Risk of Stroke Subtypes in Male Smokers

Background and Purpose— Coffee and tea consumption could potentially reduce the risk of stroke because these beverages have antioxidant properties, and coffee may improve insulin sensitivity. We examined the associations of coffee and tea consumption with risk of stroke subtypes. Methods— We used prospective data from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, a cohort study of 26 556 male Finnish smokers aged 50 to 69 years without a history of stroke at baseline. Coffee and tea consumption was assessed at baseline using a validated food-frequency questionnaire. During a mean follow-up of 13.6 years, from 1985 through December 2004, 2702 cerebral infarctions, 383 intracerebral hemorrhages, and 196 subarachnoid hemorrhages were ascertained from national registries. Results— After adjustment for age and cardiovascular risk factors, both consumption of coffee and tea was statistically significantly inversely associated with the risk of cerebral infarction but not intracerebral or subarachnoid hemorrhage. The multivariate relative risk of cerebral infarction for men in the highest category of coffee consumption (≥8 cups/d) was 0.77 (95% CI, 0.66 to 0.90; P for trend <0.001) compared with those in the lowest category (<2 cups/d). The corresponding relative risk comparing men in the highest category of tea consumption (≥2 cups/d) with those in the lowest category (nondrinkers) was 0.79 (95% CI, 0.68 to 0.92; P for trend=0.002). Conclusions— These results suggest that high consumption of coffee and tea may reduce the risk of cerebral infarction among men, independent of known cardiovascular risk factors.

Serum enterolactone concentration is not associated with breast cancer risk in a nested case-control study.

The lignan enterolactone produced by the intestinal microflora from dietary precursors has been hypothesized to protect against hormone‐dependent cancers. We conducted a nested case‐control study to examine the relationship between serum enterolactone concentration and risk of breast cancer. Enterolactone concentrations were measured by time‐resolved fluoroimmunoassay in serum collected at 4 independent cross‐sectional population surveys from 206 women with breast cancer diagnosed during follow‐up (mean 8.0 years) and from 215 controls frequency‐matched to cases by study cohort, 5‐year age group and study area. Mean serum enterolactone concentration (nmol/l) did not significantly differ between case and control subjects [25.2 (SD 22.2) vs. 24.0 (SD 21.3), respectively]. Odds ratios for breast cancer risk estimated by conditional logistic regression for increasing concentration of enterolactone in quartiles were 1.00 (referent), 1.67 (95% CI 0.95–2.95), 1.71 (95% CI 0.96–3.06) and 1.30 (95% CI 0.73–2.31), and p for trend was 0.48. Our findings do not support the hypothesis that high serum enterolactone concentration is associated with reduced risk of breast cancer.

Diet and the Risk of Breast Cancer in a Case-Control Study: Does the Threat of Disease Have an Influence on Recall Bias?

It has been suggested that recall bias may explain the discrepant results between case-control and cohort studies on diet and the risk of breast cancer. Two control groups were used for this case-control study of 25 to 75-year-old breast cancer cases (n = 310). The first group consisted of population controls drawn from the Finnish National Population Register (n = 454). The second group consisted of women who were referred to the same examinations as were the cases because of clinical suspicion of breast disease but who were later diagnosed as healthy (referral controls; n = 506). Because the diagnosis was unknown at the time of interview, it was possible to assess by comparing the two control groups whether the self-reporting of diet changed under the threat of disease. Dietary habits were examined using a validated, self-administered food-frequency questionnaire. Premenopausal women misreported their consumption of liquid milk products, tea, and sugar. Reporting bias was also associated with the intake of fat and vitamins. Postmenopausal women misreported consumption of milk products. When recall bias was taken into consideration, milk was associated with increased risk of premenopausal breast cancer, whereas high consumption of poultry or high intake of monounsaturated fatty acids, n-3 fatty acids, n-6 fatty acids, and vitamin E were related to lower risk. The study suggested that oil, milk, cheese, coffee and beta-carotene may act as protective factors in postmenopausal women, whereas butter and cream may be risk factors for breast cancer. In summary, it is possible that some food items may be overreported or underreported under the threat of disease in health-conscious population. However, most of the results in this study were not modified by recall bias.