Birgitta Ejdervik Lindblad

Vitamin C supplements and the risk of age-related cataract: a population-based prospective cohort study in women

BACKGROUND Experimental animal studies have shown adverse effects of high-dose vitamin C supplements on age-related cataract. OBJECTIVE We examined whether vitamin C supplements (approximately 1000 mg) and multivitamins containing vitamin C (approximately 60 mg) are associated with the incidence of age-related cataract extraction in a population-based, prospective cohort of women. DESIGN Our study included 24,593 women aged 49-83 y from the Swedish Mammography Cohort (follow-up from September 1997 to October 2005). We collected information on dietary supplement use and lifestyle factors with the use of a self-administrated questionnaire. Cataract extraction cases were identified by linkage to the cataract extraction registers in the geographical study area. RESULTS During the 8.2 y of follow-up (184,698 person-years), we identified 2497 cataract extraction cases. The multivariable hazard ratio (HR) for vitamin C supplement users compared with that for nonusers was 1.25 (95% CI: 1.05, 1.50). The HR for the duration of >10 y of use before baseline was 1.46 (95% CI: 0.93, 2.31). The HR for the use of multivitamins containing vitamin C was 1.09 (95% CI: 0.94, 1.25). Among women aged > or = 65 y, vitamin C supplement use increased the risk of cataract by 38% (95% CI: 12%, 69%). Vitamin C use among hormone replacement therapy users compared with that among nonusers of supplements or of hormone replacement therapy was associated with a 56% increased risk of cataract (95% CI: 20%, 102%). Vitamin C use among corticosteroid users compared with that among nonusers of supplements and corticosteroids was associated with an HR of 1.97 (95% CI: 1.35, 2.88). CONCLUSION Our results indicate that the use of vitamin C supplements may be associated with higher risk of age-related cataract among women.

Metabolic Syndrome Components in Relation to Risk of Cataract Extraction: A Prospective Cohort Study of Women

OBJECTIVE To investigate the association between metabolic syndrome and some of its components with the incidence of cataract extraction. DESIGN Population-based prospective cohort study. PARTICIPANTS A total of 35,369 women, participating in the Swedish Mammography Cohort, aged 49 to 83 years, who completed a self-administered questionnaire about anthropometric measurements and lifestyle factors in 1997. METHODS The women were followed from September of 1997 to October of 2005. The cohort was matched with registers of cataract extraction in the study area. MAIN OUTCOME MEASURES Incident surgical extraction of age-related cataract. RESULTS We identified 4508 incident cases of cataract extractions during 98 months of follow-up. In multivariate analysis, women with a waist circumference >or=80 cm had an 8% increased risk of cataract extraction (rate ratio [RR], 1.08; 95% confidence interval [CI], 0.99-1.17). Women with diabetes had a 43% increased risk of cataract extraction (RR, 1.43; 95% CI, 1.10-1.86), and hypertension was associated with a 12% increased risk (RR, 1.12; 95% CI, 0.99-1.26). Women with all 3 components of the metabolic syndrome (waist >or=80 cm, diabetes, and hypertension) had a 68% increased risk of cataract extraction (RR, 1.68; 95% CI, 1.40-2.02) compared with women without any of these components. Among women aged less than 65 years at baseline with all 3 components of metabolic syndrome, the risk of cataract extraction was approximately 3-fold more (RR, 2.80; CI, 1.94-4.03). CONCLUSIONS Metabolic syndrome and its components, abdominal adiposity, diabetes, and hypertension, seem to be associated with an increased risk for cataract extraction, especially among women aged less than 65 years.

High-Dose Supplements of Vitamins C and E, Low-Dose Multivitamins, and the Risk of Age-related Cataract: A Population-based Prospective Cohort Study of Men

We examined the associations of high-dose supplements of vitamins C and E and low-dose multivitamins with the risk of age-related cataract among 31,120 Swedish men, aged 45-79 years, in a population-based prospective cohort. Dietary supplement use was assessed from a questionnaire at baseline in 1998. During follow-up (January 1998-December 2006), 2,963 incident age-related cataract cases were identified. The multivariable-adjusted hazard ratio for men using vitamin C supplements only was 1.21 (95% confidence interval (CI): 1.04, 1.41) in a comparison with that of non-supplement users. The hazard ratio for long-term vitamin C users (≥10 years before baseline) was 1.36 (95% CI: 1.02, 1.81). The risk of cataract with vitamin C use was stronger among older men (>65 years) (hazard ratio = 1.92, 95% CI: 1.41, 2.60) and corticosteroid users (hazard ratio = 2.11, 95% CI: 1.48, 3.02). The hazard ratio for vitamin E use only was 1.59 (95% CI: 1.12, 2.26). Use of multivitamins only or multiple supplements in addition to vitamin C or E was not associated with cataract risk. These results suggest that the use of high-dose (but not low-dose) single vitamin C or E supplements may increase the risk of age-related cataract. The risk may be even higher among older men, corticosteroid users, and long-term users.

Total antioxidant capacity of the diet and risk of age-related cataract: a population-based prospective cohort of women.

IMPORTANCE To our knowledge, no previous epidemiologic study has investigated the association between all antioxidants in the diet and age-related cataract. The total antioxidant capacity (TAC) concept aims to measure the capacity from all antioxidants in the diet by also taking synergistic effects into account. OBJECTIVE To investigate the association between the TAC of the diet and the incidence of age-related cataract in a population-based prospective cohort of middle-aged and elderly women. DESIGN, SETTING, AND PARTICIPANTS Questionnaire-based nutrition survey within the prospective Swedish Mammography Cohort study, which included 30,607 women (aged 49-83 years) who were observed for age-related cataract incidence for a mean of 7.7 years. EXPOSURE The TAC of the diet was estimated using a database of foods analyzed with the oxygen radical absorbance capacity assay. MAIN OUTCOMES AND MEASURES Information on incident age-related cataract diagnosis and extraction was collected through linkage to registers in the study area. RESULTS There were 4309 incident cases of age-related cataracts during the mean 7.7 years of follow-up (234,371 person-years). The multivariable rate ratio in the highest quintile of the TAC of the diet compared with the lowest was 0.87 (95% CI, 0.79-0.96; P for trend = .03). The main contributors to dietary TAC in the study population were fruit and vegetables (44.3%), whole grains (17.0%), and coffee (15.1%). CONCLUSIONS AND RELEVANCE Dietary TAC was inversely associated with the risk of age-related cataract. Future studies examining all antioxidants in the diet in relation to age-related cataract are needed to confirm or refute our findings.

Hormone replacement therapy in relation to risk of cataract extraction: a prospective study of women.

OBJECTIVE To investigate the association between hormone replacement therapy (HRT) and the incidence of cataract extraction among postmenopausal women. DESIGN Population-based, prospective cohort study. PARTICIPANTS A total of 30 861 postmenopausal women participating in the Swedish Mammography Cohort, age 49 to 83 years, who completed a self-administered questionnaire in 1997 about hormone status, HRT, and lifestyle factors. METHODS The women were followed from September 1997 through October 2005. The cohort was matched with registers of cataract extraction in the study area. MAIN OUTCOME MEASURES Incident operative extraction of age-related cataract. RESULTS We identified 4324 incident cases of cataract extractions during 98 months of follow-up. In multivariate adjusted analysis, ever use of HRT was associated with a 14% increased risk of cataract extraction (rate ratio [RR], 1.14; 95% confidence interval [CI], 1.07-1.21) compared with those who never used HRT. Current use of HRT was associated with an 18% increased risk of cataract extraction (RR, 1.18; 95% CI, 1.10-1.26). A significant linear trend was observed where increasing duration of HRT usage resulted in an increased risk of cataract extraction (P for trend = 0.006). Multivariate RR for current HRT usage for >10 years was 1.20 (95% CI, 1.06-1.36; P for trend = 0.001). Among women drinking on average >1 drink of alcohol per day, current HRT users had a 42% increased risk (RR, 1.42; 95% CI, 1.11-1.80) for cataract extraction, compared with women who neither used HRT nor alcohol. The risk of cataract extraction among current users of HRT was similar among current smokers and those who never smoked. CONCLUSIONS Our prospective, population-based study indicates that postmenopausal women using HRT for a long period of time may be at an increased risk for cataract extraction, especially those drinking >1 alcoholic drink daily.

Are Increased Levels of Systemic Oxidative Stress and Inflammation Associated with Age-Related Cataract?

Oxidative stress and inflammation may be involved in the etiology of age-related cataract. This study is the first to investigate the association between urinary levels of 8-iso-prostaglandin F₂α (PGF₂α; as a biomarker for systemic oxidative stress in vivo) and 15-keto-dihydro-PGF₂α (as a biomarker for systemic inflammation in vivo) and risk of age-related cataract. We observed in a nested case-control study, including 258 women with incident cataract diagnosis and/or cataract extraction and 258 women without cataract, matched on age and date of urine sample collection that, women with higher levels of urinary 8-iso-PGF₂α as compared with lower levels had an increased risk of age-related cataract. There was no difference in 15-keto-dihydro-PGF₂α levels between cases and controls. Our observations lead to the hypothesis that higher systemic oxidative stress increases the risk of developing age-related cataract.

Long-term physical activity and risk of age-related cataract: a population-based prospective study of male and female cohorts.

OBJECTIVE To examine the association of total and specific types of physical activity, including walking or bicycling, exercising, work or occupational activity, home or housework, and leisure time inactivity with the risk of age-related cataract in women and men. DESIGN Population-based prospective cohort study. PARTICIPANTS A total of 52 660 participants (23 853 women and 28 807 men) 45 to 83 years of age from the Swedish Mammography Cohort and the Cohort of Swedish Men. METHODS Physical activity was assessed using a self-administered questionnaire at baseline. Cataract diagnosis and extraction were identified through linkage to registers. MAIN OUTCOME MEASURES Incident age-related cataract diagnosis and cataract extraction. RESULTS During a mean 12.1 years of follow-up (between January 1, 1998, and December 31, 2011; 634 631 person-years), 11 580 incident age-related cataract cases were identified. After adjusting for potential confounders, the highest quartile of total physical activity was statistically significantly associated with 13% decreased risk of cataract compared with the lowest (hazard ratio [HR], 0.87; 95% confidence interval [CI], 0.82-0.92). Walking or bicycling (>60 minutes/day vs. hardly ever; HR, 0.88; 95% CI, 0.82-0.95) and work or occupational activity (heavy manual labor vs. mostly sitting; HR, 0.84; 95% CI, 0.78-0.91) also were associated with decreased risk of cataract. Exercise training and home or housework were not associated with cataract risk. Leisure time inactivity was associated with increased risk of cataract (>6 vs. <1 hours/day; HR, 1.27; 95% CI, 1.07-1.50). The HR for high long-term total physical activity compared with low levels both at 30 years of age and at baseline was 0.76 (95% CI, 0.69-0.85). CONCLUSIONS Our findings indicate that high total physical activity, especially in the long term, and such specific types of physical activity as walking or bicycling and work or occupational activity, may be associated with decreased risk of age-related cataract. Conversely, high inactivity levels may be associated with increased risk of cataract.

Smoking Cessation and the Risk of Cataract: A Prospective Cohort Study of Cataract Extraction Among Men

IMPORTANCE Smoking is a risk factor for cataract development, but the effect of smoking cessation on the risk of cataract is uncertain. OBJECTIVE To examine the association between smoking cessation and the risk of cataract extraction. DESIGN, SETTING, AND PARTICIPANTS A total of 44,371 men, participating in the Cohort of Swedish Men, aged 45 to 79 years, who in 1997 completed a self-administered questionnaire on smoking habits and lifestyle factors. The men were followed up from January 1, 1998, through December 31, 2009. The cohort was matched with the Swedish National Day-Surgery Register and local registers of cataract extraction in the study area. MAIN OUTCOMES AND MEASURES Incident cases of age-related cataract extraction. RESULTS During 12 years of follow-up, we identified 5713 incident cases of age-related cataract extraction. Smoking intensity and cumulative dose of smoking were associated with an increased risk of cataract extraction (P for trend <.001). Current smokers of more than 15 cigarettes per day had a 42% increased risk of cataract extraction (rate ratio, 1.42; 95% CI, 1.28-1.58) compared with never smokers after adjustment for age and other potential risk factors. Smoking cessation significantly decreased the risk for cataract extraction with time (P for trend <.001). After more than 20 years since stopping smoking, men with a mean smoking intensity of more than 15 cigarettes per day had a 21% increased risk of cataract extraction (rate ratio, 1.21; 95% CI, 1.06-1.39) compared with never smokers. Among men who smoked 15 cigarettes or less per day, the effect of smoking cessation was observed earlier, but more than 2 decades after smoking cessation, the risk of cataract extraction did not decrease to the level of never smokers (rate ratio, 1.13; 95% CI, 1.04-1.24). CONCLUSIONS AND RELEVANCE Smoking cessation seems to decrease the risk of cataract extraction with time, although the risk persists for decades. The higher the intensity of smoking, the longer it takes for the increased risk to decline. These findings emphasize the importance of early smoking cessation and preferably the avoidance of smoking.

Metabolic syndrome and some of its components in relation to risk of cataract extraction. A prospective cohort study of men

To evaluate the relationship between metabolic syndrome and some of its components with the incidence of cataract extraction.

High-dose B-vitamin supplements and risk for age-related cataract : a population-based prospective study of men and women

Previous studies that have investigated the association between B-vitamin supplement use and risk for cataract yield conflicting results. The aim of this study was to examine the association between use of high-dose B-vitamin supplements (approximately 10 times recommended daily intake) and risk for age-related cataract in a population-based prospective study of 13 757 women from the Swedish Mammography Cohort and 22 823 men from the Cohort of Swedish Men. Dietary supplement use and potential confounders were assessed using a questionnaire at baseline. Information on cataract diagnosis and extraction was obtained through linkage to registers. During the follow-up period between January 1998 and December 2011, we identified 8395 cataract cases (3851 for women and 4544 for men). The use of B vitamins plus other supplements and B vitamins only was associated with 9 % (95 % CI 2, 17) and 27 % (95 % CI 12, 43) increased risk for cataract, respectively. The hazard ratios for use of B vitamins only and risk for cataract stratified by different age groups were as follows: <60 years: 1·88 (95 % CI 1·47, 2·39); 60-69 years: 1·21 (95 % CI 0·96, 1·53); and ≥70 years: 1·09 (95 % CI 0·91, 1·31) (P interaction=0·002). Our results suggest that the use of high-dose B-vitamin supplements was associated with an increased risk for cataract. This association might be confined to younger participants.