A simple Google search for “what does vitamin D do?” highlights the widely used dietary supplement’s role in regulating calcium absorption and promoting bone growth.
But now it appears that vitamin D has much wider effects. Research at the Buck Institute shows that vitamin D works through genes known to influence longevity and impacts processes associated with many human age-related diseases.
The study, published in Cell Reports, may explain why vitamin D deficiency has been linked to breast, colon and prostate cancer, as well as obesity, heart disease and depression.
The study focused on how vitamin D improves the ability of proteins to maintain their shape and function over time.
Normal aging often results in the accumulation of toxic insoluble protein aggregates implicated in a number of conditions, including Alzheimer’s, Parkinson’s and Huntington’s diseases, as well as type 2 diabetes and some forms of heart disease.
Vitamin D3, which is converted into the active form of vitamin D, suppressed protein insolubility and prevented the toxicity caused by human beta-amyloid which is associated with Alzheimer’s disease.
Clinicians suggest that vitamin D is as crucial for total body function and the muscles as it is for bones. Vitamin D influences hundreds of genes, and most cells have vitamin D receptors.
How much vitamin D do humans need and how do they best get it? The issue is confusing with disagreement rampant among experts.
The Institute of Medicine’s (IOM) recommends a daily intake of 600 International Units (IU) for people between 1 and 70 years old, and 800 IU daily for those older.
The upper limit (the levels above which health risks are thought to increase) was set at 4,000 IU per day for adults.
Excess vitamin D can raise blood levels of calcium which leads to vascular and tissue calcification, with subsequent damage to the heart, blood vessels and kidneys.
Many vitamin D researchers and some health organizations disagreed with the IOM’s recommendations for daily intake, instead recommending supplementation of 800 to 2,000 IU per day, at least for people known or likely to have low blood levels.
The disagreement highlights another difficulty: measuring blood levels of vitamin D is problematic given a lack of standardization and reliability among labs.
Based on problems with laboratory standards and a lack of agreed-upon meaning of results, researchers agree that the costs of universal testing for vitamin D levels would outweigh the benefits.
Instead, they recommend universal supplementation of between 800 – 1000 IU of vitamin D daily for adults.
In addition, older adults may be particularly prone to vitamin D deficiency because the skin’s ability to manufacture vitamin D from sun or UV light exposure declines with age.
In addition, the elderly is less likely to spend time in the sun, are more likely to have diets lacking in sources of vitamin D, and may suffer from gastrointestinal disorders that make it harder to absorb vitamin D.
Others prone to vitamin D deficiency include those with darker skin and those who live in higher latitudes where the sun’s angle is low in the sky.
Future research will test vitamin D in mice to measure and determine how it affects aging, disease and function, and clinical trials in humans will go after the same measurements.
Citation: Mark KA, et al. (2016). Vitamin D Promotes Protein Homeostasis and Longevity via the Stress Response Pathway Genes SKN-1, IRE-1, and XBP-1. Cell Reports, published online. DOI: 10.1016/j.celrep.2016.09.086.
Figure legend: This Knowridge.com image is for illustrative purposes only.