Dark-skinned people who live in high latitudes with mild sunlight are at an increased risk – especially in the winter – of vitamin D deficiency. As a consequence of vitamin D deficiency, they are at a higher risk of developing rickets, and numerous types of cancers, and possibly cardiovascular disease and low immune system activity.[1][17] However, some recent studies have questioned if the thresholds indicating Vitamin D deficiency in light-skinned individuals are relevant for dark-skinned individuals, as they found that, on average, dark-skinned individuals have higher bone density and lower risk of fractures than lighter-skinned individuals with the same levels of Vitamin D. This is possibly attributed to lower presence of Vitamin D binding agents (and thus its higher bioavailability) in dark-skinned individuals.[18][19]