Biomedical subjects

B Rosner

Publications and source records attributed to B Rosner.

At least 37 records · Page 2Linked to original sources

PubMed2000

Diesel exhaust exposure and lung cancer: adjustment for the effect of smoking in a retrospective cohort study.

BACKGROUND: The extent that cigarette smoking may confound the relationship between diesel exhaust exposure and lung cancer was assessed in a retrospective cohort study of 55,395 U.S. railroad workers followed from 1959 to 1976. METHODS: The relative risk (RR) of lung cancer due to diesel exhaust was indirectly adjusted using job-specific smoking data from a case-control study of railroad workers who died between 1981-1982 and from a survey of 514 living workers from an active railroad in 1982. Adjustment factors were developed based on the distribution of job-specific smoking rates. RESULTS: The unadjusted RR for lung cancer was 1.58 (95% CI = 1.14-2. 20) for workers aged 40-44 in 1959, who experienced the longest possible duration of exposure, and the smoking adjusted RR was 1.44 (1.01-2.05). CONCLUSIONS: After considering differences in smoking rates between workers exposed and unexposed to diesel exhaust in a relatively large blue-collar cohort, there were still elevated risks of lung cancer in workers in jobs with diesel exhaust exposure.

Cohort Studies↗

PubMed2000

A prospective study of alcohol consumption and cataract extraction among U.S. women.

PURPOSE: Alcohol consumption has been implicated in the pathogenesis of cataract in some, but not all analytic studies. To date, no prospective analysis of the relationship between alcohol consumption and cataract has been conducted in women. METHODS: We examined the association between alcohol consumption and cataract extraction in a prospective cohort of female registered nurses. In 1980, 50,461 women were included and others were added as they became 45 years of age for a total of 77,466 women. Information on alcohol consumption and incidence of senile cataract extraction was ascertained during 12 years of follow-up with biennial questionnaires. RESULTS: We observed 1468 cases of cataract extraction in 761,036 person-years of follow-up. Compared to nondrinkers, those consuming alcohol were not at increased risk of cataract, even up to 25 grams or more per day (2 or more drinks). Results remained unchanged after controlling for cataract risk factors including cigarette smoking, body mass index, and diabetes. When risk was examined for specific cataract subtypes only, those in the highest category of consumption had a multivariate relative risk of 1.10 for nuclear cataracts and 1.50 for posterior subcapsular cataracts only. CONCLUSIONS: These prospective data suggest that there is no substantial overall increased risk of senile cataract due to alcohol intake. The possibility that alcohol consumption leads to a modest increased risk of posterior subcapsular type opacities requiring extraction merits further exploration.

Adult↗

PubMed2000

Stress management intervention for primary prevention of hypertension: detailed results from Phase I of Trials of Hypertension Prevention (TOHP-I).

PURPOSE: Stress Management Intervention (SMI) was one of seven nonpharmacologic approaches evaluated in Phase I Trials of Hypertension Prevention (TOHP-I) for efficacy in lowering diastolic blood pressure (BP) in healthy men and women aged 30 to 54 years with diastolic BP 80-89 mm Hg. METHODS: A total of 242 and 320 participants were randomized to SMI or an "assessment only" SMI Control, respectively, at four clinical centers. The SMI consisted of 37 contact hours in 21 group and two individual meetings over 18 months and included: training in four relaxation methods, techniques to reduce stress reactions, cognitive approaches, communication skills, time management, and anger management within a general problem-solving format. Standardized protocols detailed methods and timing for collecting BP, psychosocial measures, and urinary samples from both SMI and SMI Control participants. RESULTS: In intention-to-treat analyses, although significant baseline to termination BP reductions were observed in both groups, net differences between the SMI and SMI Control groups' BP changes (mean (95% CI)) were not significant: -0.82 (-1.86, 0.22) for diastolic BP, and -0.47 (-1.96, 1.01) for systolic BP. Extensive adherence sub-group analyses found one effect: a significant 1.36 mm Hg (p = 0.01) reduction in diastolic BP relative to SMI Controls at the end of the trial for SMI participants who completed 61% or more of intervention sessions. CONCLUSIONS: While the TOHP-I SMI was acceptable to participants as evident from high levels of session completion, the absence of demonstrated BP lowering efficacy in intention-to-treat analyses suggests that the TOHP-I SMI is an unlikely candidate for primary prevention of hypertension in a general population sample similar to study participants. The isolated finding of significant diastolic BP lowering in SMI participants with higher adherence provides very weak evidence of SMI BP lowering efficacy and may be a chance finding. Whether similar or other stress management interventions can produce significant BP lowering in populations selected for higher levels of BP, stress, or intervention adherence remains to be demonstrated.

Adult↗

PubMed2000

Effects of nicotine gum dose by level of nicotine dependence.

We used the Heaviness of Smoking Index, a subset of the Fagerstrom Test for Nicotine Dependence, to classify 608 cigarette smokers planning a cessation attempt as low or high in nicotine dependence. Subjects within each level of dependence were then randomly assigned to placebo, 2-mg, or 4-mg nicotine gum treatment. Subjects were also provided brief (5-10 min per visit) behavioral counseling during a 1-year period of follow-up. At 1 year post-cessation, quit rates were 11.2, 19.5, and 18.4% for low-dependence smokers receiving placebo, 2-mg, and 4-mg gum, respectively (plinear trend = 0.20). For high-dependence smokers, quit rates at 1 year were 6.1, 15.7, and 20.7% for the placebo, 2-mg, and 4-mg gum conditions, respectively (plinear trend = 0.002). The interaction of nicotine-gum dose and dependence group was not significant (p = 0.42), nor did the 2-mg and 4-mg doses differ significantly in effectiveness, though both 2-mg and 4-mg gum were significantly more effective than placebo gum. We also found a significant dose-related effect for nicotine gum to moderate post-cessation heart-rate decline. Other variables related to abstinence at 1 year post-cessation were a longer period of abstinence on a prior quit attempt, being married, higher education level, and having a non-smoking spouse or significant other. Results indicate that nicotine gum is a significant aid to smoking cessation, more than doubling the odds of successful cessation compared to the odds for placebo-gum users. The 4-mg dose provided a non-significant increase in cessation rates for high-dependence smokers. Smoking history and demographic variables also have a significant impact on the outcome of a quit-smoking attempt.

Adult↗

PubMed2000

Systolic and diastolic blood pressure, pulse pressure, and mean arterial pressure as predictors of cardiovascular disease risk in Men.

We compared systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP), and mean arterial pressure (MAP) in predicting the risk of cardiovascular disease (CVD), stratifying results at age 60 years, when DBP decreases while SBP continues to increase. We prospectively followed 11 150 male physicians with no history of CVD or antihypertensive treatment through the 2-year questionnaire, after which follow-up began. Reported blood pressure was averaged from both the baseline and 2-year questionnaires. During a median follow-up of 10.8 years, there were 905 cases of incident CVD. For men aged <60 years (n=8743), those in the highest versus lowest quartiles of average SBP (>/=130 versus <116 mm Hg), DBP (>/=81 versus <73 mm Hg), and MAP (>/=97 versus <88 mm Hg) had relative risks (RRs) of CVD of 2.16, 2.23, and 2.52, respectively. Models with average MAP and PP did not add information compared with models with MAP alone (P>0.05). For men aged >/=60 years (n=2407), those in the highest versus lowest quartiles of average SBP (>/=135 versus <120 mm Hg), PP (>/=55 versus <44 mm Hg), and MAP (>/=99 versus <91 mm Hg) had RRs of CVD of 1.69, 1.83, and 1.43, respectively. The addition of other blood pressure measures did not add information compared with average SBP or PP alone (all P>0.05). These data suggest that average SBP, DBP, and MAP strongly predict CVD among younger men, whereas either average SBP or PP predicts CVD among older men. More research should distinguish whether MAP, highly correlated with SBP and DBP, better predicts CVD.

Adult↗

PubMed1999

Waist circumference, waist:hip ratio, and risk of breast cancer in the Nurses' Health Study.

This study examined prospectively the associations of waist circumference and waist:hip circumference ratio with risk of breast cancer. A total of 47,382 US registered nurses who reported their waist and hip circumferences in 1986 were followed up through May 1994 for identification of incident cases of breast cancer. During 333,097 person-years of follow-up, 1,037 invasive breast cancers were diagnosed. In proportional hazards analyses, waist circumference was nonsignificantly related to risk of premenopausal breast cancer but was significantly associated with postmenopausal breast cancer after adjustment for established breast cancer risk factors (for the highest quintile of waist circumference vs. the lowest, relative risk (RR) = 1.34; 95% confidence interval (CI): 1.05, 1.72). When the analysis was limited to postmenopausal women who had never received hormone replacement therapy, a stronger positive association was found (RR = 1.88; 95% CI: 1.25, 2.85). After the data were further controlled for body mass index, the positive association was only slightly attenuated (RR = 1.83; 95% CI: 1.12, 2.99). Among past and current postmenopausal hormone users, no significant associations were found. Similar but slightly weaker associations were observed between waist:hip ratio and breast cancer risk. These data suggest that greater waist circumference increases risk of breast cancer, especially among postmenopausal women who are otherwise at lower risk because of never having used estrogen replacement hormones.

Abdomen↗

PubMed1999

Prospective study of snoring and risk of hypertension in women.

Whether snoring increases the risk of hypertension remains unclear. The authors examined the association between snoring and risk of hypertension in a cohort of 73,231 US female nurses aged 40-65 years and without diagnosed cardiovascular disease or cancer in 1986. Blood pressure levels and physician-diagnosed hypertension were self-reported through validated questionnaires. During 8 years of follow-up, 7,622 incident cases of physician-diagnosed hypertension were reported. Older age, smoking, body mass index, waist circumference, waist-hip ratio, weight gain, less physical activity, and sleeping on the back were directly associated with regular snoring. After adjustment for age, body mass index, waist circumference, and other covariates, snoring was associated with a significantly higher prevalence of hypertension at baseline (odds ratio = 1.22, 95% confidence interval (CI): 1.16, 1.27 for occasional snoring and odds ratio = 1.43, 95% CI: 1.33, 1.5 for regular snoring). In prospective analyses using incident cases of hypertension as the outcome, the multivariate relative risks of hypertension were 1.29 (95% CI: 1.22, 1.37) for occasional snoring and 1.55 (95% CI: 1.42, 1.70) for regular snoring. In addition, snoring was associated with significantly higher systolic and diastolic blood pressure levels. These data suggest that snoring may increase risk of hypertension in women, independent of age, body mass index, waist circumference, and other lifestyle factors.

Adult↗

PubMed1999

Dietary factors and the survival of women with breast carcinoma.

BACKGROUND: Little is known regarding how specific dietary factors affect the survival of women with breast carcinoma. METHODS: Female registered nurses were followed with biennial questionnaires in a prospective cohort with 18 years of follow-up. Participants were women with breast carcinoma (n = 1982) diagnosed between 1976-1990 who completed a food frequency questionnaire after diagnosis. The main outcome measure was time to death from any cause. Analysis was made by multivariate Cox proportional hazards models. RESULTS: In multivariate analyses of diet after diagnosis, no apparent association was found between fat intake and mortality. The relative risk (and 95% confidence interval) of mortality comparing the highest with the lowest quintile of protein intake was 0.65 (0.47-0.88). There was no association between red meat and mortality. These associations were similar in analyses with breast carcinoma death as the outcome. CONCLUSIONS: No survival advantage was found for a low fat diet after a diagnosis of breast carcinoma. However, increased survival was observed among women eating more protein, but not red meat. The findings suggest that differences in diet may affect survival after a diagnosis of breast carcinoma and should be examined in greater detail.

Breast Neoplasms↗

PubMed1999

Comparisons of measures of interclass correlations: the general case of unequal group size.

A problem often encountered in epidemiology is the evaluation of the validity of a short questionnaire for diet or physical activity administered to large numbers of subjects, where the gold standard is a diet record or physical activity diary. It is well known that random measurement error can attenuate the interclass correlation coefficient (validity coefficient) between these two variables. Several authors have proposed a de-attenuated (or corrected) correlation coefficient which is an estimate of the true correlation between the two variables after removing the effect of random measurement error. By true correlation we mean the correlation between the questionnaire and the mean of a large or 'infinite' number of diaries (representing the truth). In this paper the authors propose three methods (two ad hoc methods, the pairwise and weighted sib-mean estimators, and the maximum likelihood with confidence limits computed using the Wald statistic and profile likelihood approaches) to estimate the true correlation between a single questionnaire and the mean of an infinite number of follow-up diaries, in the general case where an unequal number of diaries are available for each individual. A simulation study is done under the assumption that the measured variables are normally distributed. Under the null hypothesis of no correlation between the questionnaires and the diaries, all methods had negligible biases. In cases closer to what is usually seen in practice (true correlation between 0.4 and 0.6), the degree of bias and coverage probability depends heavily on the reliability (intraclass correlation) of the diaries. The maximum likelihood estimator with confidence intervals computed by the profile likelihood approach, while not systematically outperforming the other methods, is shown to be the best of the three proposed approaches.

Bias↗

PubMed1999

Use of the Mann-Whitney U-test for clustered data.

The Mann-Whitney U-test is ubiquitous in statistical practice for the comparison of measures of location for two samples where the assumption of normality is questionable. Frequently, one has replicate data for each individual in a group and would like to compare measures of central tendency between groups without assuming normality. For this purpose, we present a generalization of the Mann-Whitney U-test for clustered data. The test is performed by computing zc = (Wc - mu c)/sigma c, approximately N(0, 1) under H0, where Wc, mu c are the observed and expected Mann-Whitney U-statistic based on a comparison of all pairs of replicates in the two groups and sigma c is the standard deviation of Wc that is modified to account for clustering effects within a cluster. We obtain an explicit variance formula that is a function of four clustering parameters. We validate the properties of the test procedure in a simulation study. We illustrate the methods with an example comparing the baseline Humphrey visual field between two treatment groups in a randomized clinical trial of patients with retinitis pigmentosa (RP).

Cluster Analysis↗

PubMed1999

Age at natural menopause and risk of cardiovascular disease.

BACKGROUND: Early natural menopause has been postulated to increase the risk of cardiovascular disease. OBJECTIVE: To examine the relation of age at natural menopause with risk of coronary heart disease (CHD) and stroke in the Nurses' Health Study. METHODS: Analysis was restricted to 35 616 naturally postmenopausal women who never used estrogen replacement therapy and with no diagnosed cardiovascular disease at baseline, followed up from 1976 to 1994. Information on menopausal status, age at menopause, and other risk factors was obtained in 1976 and updated every 2 years by mailed questionnaires. RESULTS: During 354326 person-years of follow-up, we documented 757 incident cases of CHD and 350 incident cases of stroke. After adjusting for age, smoking status, and other cardiovascular risk factors, the relative risks (RRs) across categories of age at natural menopause (<40, 40-44, 45-49, 50-54, and > or = 55 years) were 1.53, 1.42, 1.10, 1.00 (reference), and 0.95, respectively; the RR for each 1-year decrease in age at natural menopause was 1.03 (95% confidence interval, 1.01-1.05). Elevated risk with younger age at menopause was observed among current smokers (RR, 1.04 [95% CI, 1.01-1.07] for each 1-year decrease in age at natural menopause) but not among never smokers (RR, 1.00; 95% CI, 0.96-1.04). Age at natural menopause was not significantly associated with ischemic stroke (RR, 1.01; 95% CI, 0.97-1.04) or hemorrhagic stroke (RR, 1.03; 95% CI, 0.97-1.10). CONCLUSIONS: We observed an overall significant association between younger age at menopause and higher risk of CHD among women who experienced natural menopause and never used hormone therapy. This increased risk was observed among current smokers but not among never smokers. The apparent elevated risk of CHD with decreased age at natural menopause among smokers might reflect residual confounding by smoking.

Age of Onset↗

PubMed1999

Plasma prolactin levels and subsequent risk of breast cancer in postmenopausal women.

BACKGROUND: In animal studies, prolactin has been found to be important for mammary epithelial development and its administration has been shown consistently to increase the rate of mammary tumor formation. Previous epidemiologic studies of prolactin and breast cancer risk in postmenopausal women have been limited in size, and the results have been inconsistent. We conducted a nested case-control study within the prospective Nurses' Health Study cohort to better determine the relationship between plasma prolactin levels and postmenopausal breast cancer risk. METHODS: Blood samples were collected from cohort members during the period from 1989 through 1990. Prolactin levels were measured by use of a microparticle enzyme immunoassay. Included in this analysis were 306 postmenopausal women who were diagnosed with breast cancer after blood donation but before June 1994. One or two postmenopausal control subjects were matched per case subject on the basis of age, postmenopausal hormone use, and time of day and month of blood collection; the study included a total of 448 control subjects. RESULTS: In conditional logistic regression analyses, a significant positive association was observed between plasma level of prolactin and postmenopausal breast cancer risk (highest versus lowest quartile, multivariate relative risk = 2.03; 95% confidence interval = 1.24-3.31; two-sided P for trend = .01). The relationship was independent of plasma sex steroid hormone levels and was similar after excluding case subjects diagnosed in the first 2 years after blood collection. CONCLUSIONS: These prospective data suggest that higher plasma prolactin levels are associated with an increased risk of breast cancer in postmenopausal women.

Adult↗

PubMed1999

Association of dietary intake of fat and fatty acids with risk of breast cancer.

CONTEXT: High intakes of fat and specific fatty acids, including total, animal, saturated, polyunsaturated, and trans-unsaturated fats, have been postulated to increase breast cancer risk. OBJECTIVE: To determine whether intakes of fat and fatty acids are associated with breast cancer. DESIGN AND SETTING: Cohort study (Nurses' Health Study) conducted in the United States beginning in 1976. PARTICIPANTS: A total of 88795 women free of cancer in 1980 and followed up for 14 years. MAIN OUTCOME MEASURE: Relative risk (RR) of invasive breast cancer for an incremental increase of fat intake, ascertained by food frequency questionnaire in 1980, 1984, 1986, and 1990. RESULTS: A total of 2956 women were diagnosed as having breast cancer. Compared with women obtaining 30.1% to 35% of energy from fat, women consuming 20% or less had a multivariate RR of breast cancer of 1.15 (95% confidence interval [CI], 0.73-1.80). In multivariate models, the RR (95% CI) for a 5%-of-energy increase was 0.97 (0.94-1.00) for total fat, 0.98 (0.96-1.01) for animal fat, 0.97 (0.93-1.02) for vegetable fat, 0.94 (0.88-1.01) for saturated fat, 0.91 (0.79-1.04) for polyunsaturated fat, and 0.94 (0.88-1.00) for monounsaturated fat. For a 1% increase in energy from trans-unsaturated fat, the values were 0.92 (0.86-0.98), and for a 0.1% increase in energy from omega-3 fat from fish, the values were 1.09 (1.03-1.16). In a model including fat, protein, and energy, the RR for a 5% increase in total fat, which can be interpreted as the risk of substituting this amount of fat for an equal amount of energy from carbohydrate, was 0.96 (95% CI, 0.93-0.99). In similar models, no significant association of risk was evident with any major types of fat. CONCLUSION: We found no evidence that lower intake of total fat or specific major types of fat was associated with a decreased risk of breast cancer.

Adult↗

PubMed1999

Dietary fiber and the risk of colorectal cancer and adenoma in women.

BACKGROUND: A high intake of dietary fiber has been thought to reduce the risk of colorectal cancer and adenoma. METHODS: We conducted a prospective study of 88,757 women, who were 34 to 59 years old and had no history of cancer, inflammatory bowel disease, or familial polyposis, who completed a dietary questionnaire in 1980. During a 16-year follow-up period, 787 cases of colorectal cancer were documented. In addition, 1012 patients with adenomas of the distal colon and rectum were found among 27,530 participants who underwent endoscopy during the follow-up period. RESULTS: After adjustment for age, established risk factors, and total energy intake, we found no association between the intake of dietary fiber and the risk of colorectal cancer; the relative risk for the highest as compared with the lowest quintile group with respect to fiber intake was 0.95 (95 percent confidence interval, 0.73 to 1.25). No protective effect of dietary fiber was observed when we omitted, adjustment for total energy intake, when events during the first six years of follow-up were excluded, or when we excluded women who altered their fiber intake during the follow-up period. No significant association between fiber intake and the risk of colorectal adenoma was found. CONCLUSIONS: Our data do not support the existence of an important protective effect of dietary fiber against colorectal cancer or adenoma.

Adenoma↗

PubMed1999

Prospective study of smoking, antioxidant intake, and lung cancer in middle-aged women (USA).

BACKGROUND: Although substantial evidence suggests that higher intake of fruits and vegetables can reduce the adverse impact of smoking on lung cancer risk, great uncertainty exists regarding the specific foods and their constituents that are protective. We therefore examine prospectively the relation between cigarette smoking and lung cancer incidence among women, and quantify the associations between dietary antioxidants, other nutrients, and lung cancer risk. METHODS: In a 16-year prospective cohort study (the Nurses' Health Study), 593 cases of lung cancer were confirmed during 1,793,327 person-years of follow-up. Dietary data, including vitamin supplement use and food intake, were collected in 1980 using a validated semiquantitative food frequency questionnaire. RESULTS: The risk of lung cancer increased with the number of cigarettes smoked and with early onset of cigarette smoking. The risk decreased rapidly with the discontinuation of smoking but took 15 years to fall to about the level of risk for women who had never smoked. Dietary intake of fat was not related to the risk of lung cancer. Although beta-carotene intake was not related to risk, intake of carrots showed a strong inverse relation: women who reported consuming five or more carrots per week had a relative risk of 0.4 (95% CI = 0.2-0.8) compared with the risk for women who never ate carrots. CONCLUSIONS: Smoking is the most important risk factor for lung cancer in women, as it is in men. Higher vegetable consumption, particularly of carrots, may significantly reduce the risk of lung cancer, but dietary modification cannot be considered a substitute for smoking prevention and cessation.

Adult↗

PubMed1999

Cholesterol-lowering effects of dietary fiber: a meta-analysis.

BACKGROUND: The effects of dietary soluble fibers on blood cholesterol are uncertain. OBJECTIVE: This meta-analysis of 67 controlled trials was performed to quantify the cholesterol-lowering effect of major dietary fibers. DESIGN: Least-squares regression analyses were used to test the effect on blood lipids of pectin, oat bran, guar gum, and psyllium. Independent variables were type and amount of soluble fiber, initial cholesterol concentration, and other important study characteristics. RESULTS: Soluble fiber, 2-10 g/d, was associated with small but significant decreases in total cholesterol [-0.045 mmol L(-1).g soluble fiber(-1) (95% CI: -0.054, -0.035)] and LDL cholesterol [-0.057 mmol.L(-1).g(-1) (95% CI: -0.070, -0.044)]. The effects on plasma lipids of soluble fiber from oat, psyllium, or pectin were not significantly different. We were unable to compare effects of guar because of the limited number of studies using 2-10 g/d. Triacylglycerols and HDL cholesterol were not significantly influenced by soluble fiber. Lipid changes were independent of study design, treatment length, and background dietary fat content. CONCLUSIONS: Various soluble fibers reduce total and LDL cholesterol by similar amounts. The effect is small within the practical range of intake. For example, 3 g soluble fiber from oats (3 servings of oatmeal, 28 g each) can decrease total and LDL cholesterol by approximately 0.13 mmol/L. Increasing soluble fiber can make only a small contribution to dietary therapy to lower cholesterol.

Adult↗

PubMed1999

Safety of <7500 RE (<25000 IU) vitamin A daily in adults with retinitis pigmentosa.

BACKGROUND: Vitamin A supplementation is being used successfully to treat some forms of cancer and the degenerative eye disease retinitis pigmentosa. The daily biological need for vitamin A is estimated to be 800 retinol equivalents (RE)/d (2667 IU/d) for adult women and 1000 RE/d (3300 IU/d) for adult men; doses > or = 7500 RE (> or = 25000 IU)/d are considered potentially toxic over the long term. OBJECTIVE: We assessed the safety in adults of long-term vitamin A supplementation with doses above the daily biological need but <7500 RE (<25000 IU)/d. DESIGN: Adults aged 18-54 y with retinitis pigmentosa but in generally good health (n = 146) were supplemented with 4500 RE (15000 IU) vitamin A/d for < or = 12 y (group A) and compared with a similar group (n = 149) that received 23 RE (75 IU)/d (trace group). Mean total consumption of vitamin A in group A was 5583 RE (18609 IU)/d (range: 4911-7296 RE/d, or 16369-24318 IU/d) and that in the trace group was 1053 RE (3511 IU)/d (range: 401-3192 RE/d, or 1338-10638 IU/d). RESULTS: Patients in group A showed an 8% increase in mean serum retinol concentration at 5 y and an 18% increase at 12 y (P < 0.001); no retinol value exceeded the upper normal limit (3.49 micromol/L, or 100 microg/dL). Mean serum retinyl esters were elevated approximately 1.7-fold at 5 y and remained relatively stable thereafter. No clinical symptoms or signs of liver toxicity attributable to vitamin A excess were detected. CONCLUSIONS: Prolonged daily consumption of <7500 RE (<25000 IU) vitamin A/d can be considered safe in this age group.

Adolescent↗

PubMed1999

A prospective study of carotenoid and vitamin A intakes and risk of cataract extraction in US women.

BACKGROUND: Oxidation of lens proteins plays a central role in the formation of age-related cataracts, suggesting that dietary antioxidants may play a role in prevention. However, the relation between specific antioxidants and risk of cataract remains uncertain. OBJECTIVE: Our objective was to examine prospectively the association between carotenoid and vitamin A intakes and cataract extraction in women. METHODS: A prospective cohort of registered female nurses aged 45-71 y and free of diagnosed cancer was followed; in 1980, 50461 were included and others were added as they became 45 y of age for a total of 77466. Information on nutrient intake was assessed by repeated administration of a food-frequency questionnaire during 12 y of follow-up. RESULTS: During 761762 person-years of follow-up, 1471 cataracts were extracted. After age, smoking, and other potential cataract risk factors were controlled for, those with the highest intake of lutein and zeaxanthin had a 22% decreased risk of cataract extraction compared with those in the lowest quintile (relative risk: 0.78; 95% CI: 0.63, 0.95; P for trend = 0.04). Other carotenoids (alpha-carotene, beta-carotene, lycopene, and beta-cryptoxanthin), vitamin A, and retinol were not associated with cataract in multivariate analysis. Increasing frequency of intakes of spinach and kale, foods rich in lutein, was associated with a moderate decrease in risk of cataract. CONCLUSIONS: Lutein and zeaxanthin and foods rich in these carotenoids may decrease the risk of cataracts severe enough to require extraction.

Adolescent↗