Serum antioxidants and myocardial infarction. Are low levels of carotenoids and alpha-tocopherol risk factors for myocardial infarction?

BACKGROUND: In vitro, animal and epidemiological studies suggest that lipoprotein oxidation may play an important role in atherosclerosis. Antioxidants may protect against lipoprotein oxidation and in that way inhibit atherosclerosis and its clinical sequelae. To investigate this possibility, we examined the association between levels of several antioxidants and myocardial infarction using serum specimens collected 7 to 14 years before the onset of myocardial infarction. METHODS AND RESULTS: A nested case-control design was used. Cases and control subjects were selected from the 25,802 persons who had donated 15 mL of blood in 1974 for a serum bank. Cases comprised 123 persons with a subsequent first diagnosis of myocardial infarction who ranged from 23 through 58 years of age in 1974 and who had had their first diagnosis of myocardial infarction during 1981 to 1988. Two groups of control subjects matched to the cases for sex and age were selected from donors to the serum bank, one from those with hospital admissions during the same period and the other from the total group of donors. Sera were assayed for four carotenoids (beta-carotene, lycopene, lutein, and zeaxanthin), alpha-tocopherol, and cholesterol. Because associations with these serum nutrients showed similar trends whether based on hospital or community controls, the two control groups were combined. There was a significantly increasing risk for subsequent myocardial infarction with decreasing levels of beta-carotene in 1974 (P value for trend, .02) and a suggestive trend with decreasing levels of lutein (P = .09). When the results were stratified by smoking status, the excess risk of myocardial infarction associated with low serum levels of carotenoids was limited to smokers. A protective association with higher levels of alpha-tocopherol was suggested only among persons with high levels of serum cholesterol. CONCLUSIONS: Low serum levels of carotenoids were associated with an increased risk of subsequent myocardial infarction among smokers.

Plasma pepsinogens, nutrients, and diet in areas of Italy at varying gastric cancer risk.

In a survey of 930 adults aged 35-74 years randomly sampled from the general population of four areas of Italy at different risks for gastric cancer (GC), plasma levels of pepsinogens (PGI and PGII) and fat-soluble vitamins were assayed. Pepsinogen levels were used to identify individuals with chronic atrophic gastritis (CAG). Severe CAG (PGI < or = 20 pg/liter) affected 5.8% of the population, but the prevalence rose with increasing age and declining social class. Severe CAG was 5 times more common in areas with high compared to low rates of GC. Risk also rose with increasing consumption of salted/dried fish but was inversely related to dietary intake of beta-carotene and to plasma retinol and cholesterol levels. The prevalence of moderate CAG (PGI > 20 pg/liter, but PGI/PGII < or = 2.9) was 6.3%. Moderate CAG was also related to age and social class and increased 1.8-fold in areas where GC rates were high, but was not strongly associated with diet or plasma nutrients. The authors discuss these findings in relation to those from a previous case-control study of GC in the same areas.

Serologic precursors of cancer. I. Prediagnostic serum nutrients and colon cancer risk.

A study was undertaken to determine whether prediagnostic serum levels of retinol, beta-carotene, vitamin E, and selenium are lower in colon cancer cases compared with matched, population-based controls. Sera were available from 25,802 participants of a serum collection campaign conducted in Washington County, Maryland in 1974. The authors identified from these participants 72 white colon cancer cases, who were first diagnosed with colon cancer during 1975-1983, and 143 white, living, cancer-free controls, matched to cases on the basis of age, sex, month of serum collection, and enumeration in a 1975 private census of Washington County. The mean values of serum nutrients in cases and controls, respectively, were 59.1 micrograms/dl and 61.8 micrograms/dl for retinol (p = 0.22), 32.9 micrograms/dl and 34.4 micrograms/dl for beta carotene (p = 0.52), 1.17 mg/dl and 1.27 mg/dl for vitamin E (p = 0.10), and 11.0 micrograms/dl and 11.5 micrograms/dl for selenium (p = 0.07). There were no consistent trends in the relative odds of colon cancer by quintiles of serum levels for any of the nutrients; however, a relative odds of 3.2 (95% confidence interval = 1.1-8.7) was found when persons in the four lowest quintiles of retinol were compared with those in the highest. No interactions with matching factors or between serum nutrients and no confounding effects of covariables were identified through conditional logistic regression analysis. The findings of this study do not support a strong association of low serum levels of retinol, beta-carotene, vitamin E, and selenium with an increased risk of subsequent colon cancer.

Serum vitamin levels and the risk of cancer of specific sites in men of Japanese ancestry in Hawaii.

Serum specimens were obtained from over 6800 men of Japanese ancestry in Hawaii from 1971 to 1975. Since then, the following numbers of newly diagnosed cancer cases have been identified: 81 colon, 74 lung, 70 stomach, 32 rectum, and 27 urinary bladder. The stored sera of the cases and 302 controls were tested to determine their beta-carotene, vitamin A, and vitamin E levels. There was no association of either vitamin A or E with any of the cancers. For serum beta-carotene, there was a significant association only with lung cancer (20.0 micrograms/dl in cases versus 29.0 in controls, P less than 0.005). The lung cancer odds ratio for men in the lowest quintile of beta-carotene was 3.4 relative to men in the highest quintile. These findings suggest that a low serum beta-carotene level is a predictor of increased lung cancer risk in men.

Antiviral activity in sera of patients with Crohn's disease.

Sera from patients with Crohn's disease were tested for antiviral activity using a microtiter assay with end points showing 50% reduction of cytopathic effects. Patients were significantly more likely to have serum antiviral activity equivalent to interferon levels of 20 or more units/ml than were control subjects. The mean antiviral activity in the patients' sera (34 +/- 20 (s.d.) units/ml) was significantly greater than that in the control subjects' sera (0.6 +/- 1.7 (s.d.) units/ml). Following acidification the mean antiviral activity of the patients' sera (28 +/- 17 (s.d.) units/ml) had not changed significantly while heat inactivation resulted in significant loss of activity (7.5 +/- 2.7 (s.d.) units/ml). These findings are suggestive of the presence of circulating leucocyte interferon in the sera of patients with Crohn's disease.

Vitamin B1, B2, B6, and C status in hospital inpatients.

The status of vitamin B1, B2, B6 and C was investigated in 656 hospital inpatients by means of a dietary interview, biochemical studies, and clinical investigation. The daily intake was lower than the Recommended Dietary Allowance for vitamin B1 in 57%, B2 in 47%, B6 in 53%, and C in 9% of the patients; it was less than half the Recommended Dietary Allowance in 19, 12, 15, and 3%, respectively. A biochemical deficiency was observed in 25% of the patients for vitamin B1, in 11% for B2, in 25% for B6, and in 14% for C. On the basis of the parameters selected for this study, the biochemical vitamin status, the dietary vitamin intake, and the clinical symptoms correlated significantly with each other except in the case of vitamin B6.