Low vitamin D levels linked to increased risk of bladder cancer

 Vitamin D deficiency is associated with an increased risk of developing bladder cancer, according to a systematic review of seven studies presented today at the Society for Endocrinology annual conference in Brighton. Though further clinical studies are needed to confirm the findings, the study adds to a growing body of evidence on the importance of maintaining adequate vitamin D levels.

Vitamin D, which is produced by the body through exposure to sunshine, helps the body control calcium and phosphate levels. Vitamin D can also be obtained from food sources such as fatty fish and egg yolks. Previous studies have linked vitamin D deficiency with a host of health problems including cardiovascular disease, cognitive impairment, autoimmune conditions, and cancer.

In countries with low levels of sunlight, it is difficult to obtain enough vitamin D from food alone. In the UK, 1 in 5 adults are vitamin D deficient and 3 in 5 have low levels. This is especially prevalent in people with darker skin: in winter, 75% of dark-skinned people in the UK are vitamin D deficient.

In this work, researchers from the University of Warwick and University Hospital Coventry and Warwickshire investigated the link between vitamin D and bladder cancer risk. They reviewed seven studies which ranged from having 112 to 1125 participants each. Five out of the seven studies linked low vitamin D levels to an increased risk of bladder cancer.

To validate their findings, the researchers then looked at the cells that line the bladder, known as transitional epithelial cells, and found that these cells are able to activate and respond to vitamin D, which in turn can stimulate an immune response. According to lead author of the study Dr Rosemary Bland, this is important because the immune system may have a role in cancer prevention by identifying abnormal cells before they develop into cancer.

“More clinical studies are required to test this association, but our work suggests that low levels of vitamin D in the blood may prevent the cells within the bladder from stimulating an adequate response to abnormal cells,” said Dr Bland. “As vitamin D is cheap and safe, its potential use in cancer prevention is exciting and could potentially impact on the lives of many people.”

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Vitamin D pill a day may improve exercise performance and lower risk of heart disease

Taking vitamin D supplements can improve exercise performance and lower the risk of heart disease, according to the findings of a preliminary study presented today at the Society for Endocrinology annual conference in Edinburgh.

Vitamin D, which is both a vitamin and a hormone, helps control levels of calcium and phosphate in the blood and is essential for the formation of bones and teeth. Sources of Vitamin D include oily fish and eggs, but it can be difficult to get enough through diet alone. Most people generate vitamin D by exposing their skin to ultraviolet B rays in sunlight.

Previous studies suggest that vitamin D can block the action of enzyme 11-βHSD1, which is needed to make the “stress hormone” cortisol.  High levels of cortisol may raise blood pressure by restricting arteries, narrowing blood vessels and stimulating the kidneys to retain water. As Vitamin D may reduce circulating levels of cortisol, it could theoretically improve exercise performance and lower cardiovascular risk factors.

In this study, researchers from Queen Margaret University in Edinburgh gave 13 healthy adults matched by age and weight 50μg of vitamin D per day or a placebo over a period of two weeks.

Adults supplementing with vitamin D had lower blood pressure compared to those given a placebo, as well as having lower levels of the stress hormone cortisol in their urine. A fitness test found that the group taking vitamin D could cycle 6.5km in 20 minutes, compared to just 5km at the start of the experiment. Despite cycling 30% further in the same time, the group taking vitamin D supplements also showed lower signs of physical exertion.

Around ten million people in England may have low vitamin D levels. On average, one in ten adults has low levels of vitamin D in summer, compared to two in five in winter. Because people with darker skin are less efficient at using sunlight to make vitamin D, up to three out of four adults with dark skin are deficient in winter.

“Our pilot study suggests that taking vitamin D supplements can improve fitness levels and lower cardiovascular risk factors such as blood pressure”, said Dr Raquel Revuelta Iniesta, co-author of the study. “Our next step is to perform a larger clinical trial for a longer period of time in both healthy individuals and large groups of athletes such as cyclists or long-distance runners”.

"Vitamin D deficiency is a silent syndrome linked to insulin resistance, diabetes, rheumatoid arthritis, and a higher risk for certain cancers", said lead author of the study Dr Emad Al-Dujaili. “Our study adds to the body of evidence showing the importance of tackling this widespread problem”.