It seems like there is more to vitamin D than just helping to keep bones strong and healthy. As a dietitian most of the cancer patients I see have low vitamin D levels at some stage during their cancer journey. I suppose that this is not all that surprising when you consider that these patients are often undergoing treatment such as chemotherapy, and generally spend less time outdoors with quite often a reduced food intake. However, I am also seeing many other patients too with a history of low vitamin D levels. These have included people with diabetes, IBS, arthritis and a range of other health conditions (1,2).
Anecdotally, I hear reports how since their vitamin D levels have increased to within an appropriate range of around 75nmol/L (1,2), they no longer feel the same degree of fatigue, and quite often it can also help to reduce their general aches and pains. These observations correspond with reports in the scientific literature claiming that vitamin D can positively influence the immune system, help with inflammatory conditions and promote healthy cells across a whole range of health conditions (1,2,3,4). Given all the potential health benefits of having adequate vitamin D levels you would expect that this measure would be part of a routine annual health screen; however, surprisingly it is not.
As a nutrient that is present in a relatively limited range of foods, such as fortified dairy, oily fish and eggs, it is difficult for many people to meet their daily requirements for vitamin D from their diet (4). In fact, the main source of vitamin D is from sunshine (UV-B radiation), but once again access to this can also be compromised because of a person’s geographical location, indoor lifestyle, and other factors such as their genetic predisposition, and the pigmentation of their skin. For example, darker skinned people need more sunlight exposure because their melanin (skin pigment) can block UV rays and reduce the level of pre-active vitamin D formed in the skin (2,4). From the skin vitamin D goes through metabolic processes in the liver, and then the kidney to become physiologically active vitamin D3 (1,2,4).
Many older people may not only have limited access to sunshine, and a poor diet, but also a range of other chronic conditions which could involve reduced gut and kidney function, putting them at risk of lower than ideal levels of vitamin D. While we know that around 75nmol is a good minimum level for vitamin D, as yet we don’t know much about upper blood measures of this nutrient. However, it is generally recommended that vitamin D levels should not exceed 150nmol (3), and so people should be cautious about taking a vitamin D or any other supplement, without medical supervision. It would seem to me that some regular screening of vitamin D levels especially among individuals at high risk of and suffering from various diseases, could be an excellent investment in the promoting the health and well-being of an aging population.
References
- Spedding S, Vanlint S, Morris H, Scragg R. Does vitamin D sufficiency equate to a single serum 25-hydroxyvitamin D level or are different levels required for non-skeletal diseases? Nutrients. 2013; 5:5127–5139. [PMC free article] [PubMed]
- McCullough M. Vitamin D deficiency in adults. Aust Prescr: 2010; 33:103-61 Aug 2010DOI: 10.18773/austprescr.2010.053
- National Institutes of Health. Vitamin D — Health Professional Fact Sheet https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/ (accessed 25/9/16)
- Victoria State Government. Better Health Channel. Vitamin D. https://www.betterhealth.vic.gov.au/health/healthyliving/vitamin-d (accessed 25/9/16)