肥胖会降低人体维生素D含量

Obesity¹ can lower vitamin D levels in the body, a study suggests. ,
,研究显示
，肥胖会降低体内维生素D含量
。, ,The report, in the journal PLOS Medicine, analysed genetic ² data from 21 studies - a total of 42,000 people., ,It found every 10% rise in body mass index (BMI) - used as an indicator ³ of body fat - led to a 4% drop of available vitamin D in the body., ,As vitamin D is stored in fatty tissue, the authors suggest the larger storage capacity in obese ⁴ people may prevent it from circulating in the bloodstream. , ,BMI it is calculated by taking weight (in kilograms) and dividing it by height (in metres) squared. Those with a BMI of 30 or above are considered obese. , ,Lead author Dr Elina Hypponen, from the University College London Institute of Child Health, said the study "highlights the importance of monitoring and treating vitamin D deficiency in people who are overweight or obese". , ,Vitamin D is made in the skin after sun exposure and can be taken in dietary supplements. , ,Healthy levels are about 50 nanomole per litre - less than 30 nanomole per litre can cause the softening ⁵ and weakening of bones, leading to rickets⁶（佝偻病） in children and osteomalacia（软骨病） in adults., ,Prof David Haslam, from the National Obesity Forum ⁷, said: "Food intake ⁸ and genetics all play a part in obesity - but this research is a reminder ⁹ that physical activity, like walking the dog or going for a run out in the sunshine, shouldn't be forgotten and can help correct both weight and lack of vitamin D."