Vitamin D And Cancer
Vitamin D has been observed in numerous studies to have a protective effect against cancer, but only in patients with a sufficiently high level of vitamin D (at least 36 ng/mL). This protective effect extends to all cancers, making vitamin D one of the most potent anticarcinogenic nutrients we know of!
The mechanism through which vitamin D prevents cancer is different depending on the type of cancer, but in all cases there was a strong inverse correlation between sunshine intake/vitamin D levels and cancer incidence. For certain cancers, the reduction in rate is incredible. Studies suggest that maintaining blood levels of vitamin D above 32 ng/mL over a lifetime can reduce the risk of colorectal cancer by 50%. Similarly, maintaining levels of vitamin D above 42 ng/mL over a lifetime reduced breast cancer risk by 30%!
Vitamin D And Depression
Vitamin D deficiency has been tied to depression and other mood disorders, but more research needs to be done to understand the nature of the link. In adults suffering from depression, blood levels of vitamin D were found to be 14% lower than those not suffering from depression. In addition, levels of PTH, the hormone which is secreted in larger amounts by individuals deficient in vitamin D, were 5-33% higher depending on severity of depression, with the highest amounts being found in those with the most severe depression.
As with other markers of depression, it is not 100% clear at this point whether vitamin D deficiency leads to depression, or whether depression leads to vitamin D deficiency. In either case, obtaining sufficient levels of vitamin D could play a preventative or restorative role in our brain chemistry, as it does in adults with seasonal affective disorder (SAD).
For adults with SAD, testing has shown blood vitamin D levels to be of much more significance in improving mood than phototherapy (the use of bright lights to simulate sunlight). This suggests that the link to depressive moods in those suffering from SAD is not the amount of sunlight available, as has been theorized, but rather the amount of vitamin D available. Vitamin D may be produced in sufficient amounts during the summer months for SAD sufferers, but in some areas the winter sun is too weak to stimulate any vitamin D production, making supplementation more important than adequate light exposure in these individuals.