News
Increased magnesium intakes may reduce mortality risk
5 December 2013
A new study from Spain says that people at a high risk of cardiovascular disease may reduce their risk of dying by increasing magnesium intakes.
29 September 2010
Intake of supplements containing vitamin C, vitamin E, beta-carotene, selenium and zinc may increase the risk of developing melanomas in women, a French follow-up study claims.
In 2007, the results of the randomized controlled SU.VI.MAX trial suggested an up to 4-fold higher risk of total skin cancers and melanomas in a group of women receiving a daily combination of antioxidants (120 mg vitamin C, 30 mg vitamin E, 6 mg beta-carotene, 100 mcg selenium and 20 mg zinc) compared to a placebo after a median of 7.5 years (1). Conversely, in men, no significant differences were found between the treatment groups. In order to investigate possible residual or delayed effects of antioxidant supplementation on skin cancer incidence, the SU.VI.MAX participants were followed up for additional 5 years after the end of the supplementation period (2). The results of this follow-up study indicate that the elevated skin cancer risk receded when antioxidant supplementation was stopped.
The researchers speculate that supplementation may play a causative role in the enhanced development of pre-existing skin tumors in women. They concede that it is unlikely that new tumors of the skin may develop over a time period as short as the supplementation periods of their trials. The findings that only women (and not men) showed an increased disease risk should be interpreted with caution because of the relatively small number of events within subgroups of skin cancer, which is a principal limitation of the study, they commented.
In other large studies, no evidence of an association between daily use of supplemental antioxidants (at doses similar to those used in the SU.VI.MAX trial) and melanoma risk was found, and the results did not vary by sex (3, 4). Experts criticize that the findings of the SUVIMAX trial and the follow-up study could be explained by methodological shortcomings: the analyses were limited to a subsample of participants who agreed to answer a single question on their lifetime sun exposure, which could introduce selection bias and limit generalizability. In addition, the statistical analysis was based on only 16 skin cancer cases, limiting its significance (5).
Among the multiple melanoma risk factors, sunlight exposure at early ages, number of nevi and family history are believed to be the most important ones.
5 December 2013
A new study from Spain says that people at a high risk of cardiovascular disease may reduce their risk of dying by increasing magnesium intakes.
1 November 2014
The eye is rich in nutrients and other dietary components that support and complement each other. Some nutrients are necessary for the basic physical structure of the eye, some for the physiology of sight, and others for protection. Nutrients within the visual system can be thought of as a hierarchy representing a complex of interacting factors: while vitamin A (retinol) is essential for the formation of visual pigments, the antioxidants vitamin E, vitamin C, lutein and zeaxanthin help to protect the lens and retina against light-induced oxidative damage, and the long-chain omega-3 fatty acid docosahexaenoic acid (DHA) enriches neural tissues including the photoreceptor cells. These nutrients are known to be important for visual development early in life, starting from the fetus through infancy to early childhood. Visual acuity gradually improves until about age four, when it is comparable to that of adults. For adults a sufficient intake of these nutrients is needed throughout the lifespan to maintain visual performance, such as the ability to adapt to low light, recover from intense light and distinguish objects from their background.
31 January 2014
A new study from China suggests that pregnant women living in Beijing are facing a higher risk of vitamin D deficiency as the air has become increasingly polluted in recent years.