Higher Β-carotene Concentrations Research Articles

Antioxidants in adipose tissue and risk of myocardial infarction: the EURAMIC study

SummaryLaboratory and epidemiological studies suggest that the antioxidants, vitamin E and β-carotene, protect against coronary heart disease. In a European multicentre case-control study α-tocopherol and β-carotene concentrations were measured in adipose-tissue samples collected in 1991-92 from 683 people with acute myocardial infarction and 727 controls.Mean adipose-tissue β-carotene concentration was 0·35 μg/g in cases and 0·42 in controls, with age-adjusted and centre-adjusted mean difference 0·07 μg/g (95% confidence interval [Cl] 0 04-0·10). Mean α-tocopherol concentrations were 193 μg/g and 192 μg/g for cases and controls, respectively. The age-adjusted and centre-adjusted odds ratio for risk of myocardial infarction in the lowest quintile of β-carotene as compared with the highest was 2·62 (95% Cl 1·79-3·83). Additional control for body-mass index and smoking reduced the odds ratio to 1·78(95% Cl 1·17-2·71); other established risk factors did not substantially alter this ratio. The increased risk was mainly confined to current smokers: the multivariate odds ratio in the lowest β-carotene quintile in smokers was 2·39 (95% Cl 1·35-4 25), whereas it was 1·07 for people who had never smoked. A low α-tocopherol concentration was not associated with risk of myocardial infarction.Our results support the hypothesis that high β-carotene concentrations within the normal range reduce the risk of a first myocardial infarction. The findings for α-tocopherol are compatible with previous observations of reduced risk among vitamin E supplement users only. The consumption of β-carotene-rich foods such as carrots and green-leaf vegetables may reduce the risk of myocardial infarction.

Mode of Action of the Massively Accumulated β-Carotene of Dunaliella bardawil in Protecting the Alga against Damage by Excess Irradiation

When grown under defined conditions Dunaliella bardawil accumulates a high concentration of beta-carotene, which is composed primarily of two isomers, all-trans and 9-cis beta-carotene. The high beta-carotene alga is substantially resistant to photoinhibition of photosynthetic oxygen evolution when compared with low beta-carotene D. bardawil or with Dunaliella salina which is incapable of accumulating beta-carotene. Protection against photoinhibition in the high beta-carotene D. bardawil is very strong when blue light is used as the photoinhibitory agent, intermediate with white light, and nonexistent with red light. These observations suggest that the massively accumulated beta-carotene in D. bardawil protects the alga against damage by high irradiation by screening through absorption of the blue region of the spectrum. Irradiation of D. bardawil by high intensity blue light results in the following temporal sequence of events: photoinhibition of oxygen evolution, photodestruction of 9-cis beta-carotene, photodestruction of all-trans beta-carotene, photodestruction of chlorophyll and cell death.

The Role of Carotenoids in Resistance of Fungi to Cercosporin

Cercospora spp. produce large quantities of the singlet-oxygen-generating toxin cercosporin and are not harmed by it. We investigated carotenoid production by these fungi to determine if carotenoids (which quench singlet oxygen) play a role in resistance. Cercospora spp. produce high concentration of β-carotene at early stages of the growth cycle, up to 12 μg/g dry weight. (...)

Peripartum Changes of Plasma and Milk Vitamin A and β-Carotene among Dairy Cows with or without Mastitis

Over 12 mo we studied the relationship between peripartum concentrations of vitamin A and β-carotene in blood plasma and milk of 93 Holsteins with or without subsequent mastitis. Blood was sampled daily from 7 days prepartum through 7 days postpartum and on alternate weeks through wk 10 of lactation. Milk samples were collected daily for 7 days postpartum and then biweekly for 10 wk. Somatic cell counts were on biweekly milk samples. Vitamin A and β-carotene of blood plasma decreased rapidly prepartum to reach minimum concentrations at calving (vitamin A) or on day 4 to 6 postpartum (β-carotene). Thereafter, both vitamin A and β-carotene increased rapidly through 10 wk postpartum. Concentrations of vitamin A and β-carotene in colostrum were higher than concentrations in milk.Cows with mastitis (somatic cells >5 00,000 cells/ml milk) had lower vitamin A in blood plasma during days 0 to 7 and wk 2 and 4 postpartum than cows without mastitis. When data were analyzed with loge of somatic cell count as an independent regression variable, results were similar. In contrast to vitamin A, peripartum β-carotene in blood plasma was higher among mastitic cows and was related to higher loge of somatic cell count. No significant difference was observed between mastitic and non-mastitic cows for vitamin A and β-carotene in milk. Lower concentrations of plasma vitamin A and higher concentrations of β-carotene during the immediate postpartum period were associated with higher milk somatic cell counts among dairy cows during lactation.