“Mom, do I really need this much sunscreen? It’s December.” Slow down helicopter moms. Your son, whether he knows it or not, might actually be onto something. Most name brand sunscreens stop 99% of UV rays emitted from the sun from reaching the skin, decreasing absorption and synthesis of vitamin D by that the same 99%.1 While some vitamin D can come from foods like milk, cheese, and fatty fishes like tuna, most of your daily vitamin D is acquired from the sun’s UV rays.2 The main activity of vitamin D, often called the “sunshine vitamin,” is in conjunction with calcium. Together, they strengthen and protect bones from devastating fractures.3
The surge in vitamin D deficiency is a twenty-first-century problem.4 With a larger population living longer and spending less time outdoors, thereby reducing sun exposure, vitamin D deficiencies have become more apparent in long-term bone decay.1 Increasingly elderly populations have the highest risk for fractures because bones tend to thin and become more brittle with age.3
Medicare reports an 83-fold increase in vitamin D blood tests from 2000-2010.5 Due to recent angst surrounding vitamin D deficiency, it has become the fifth most common blood test, just behind cholesterol.5 The problem is that most of us are not Vitamin D deficient at all. Only 6% of Americans between 1-70 are truly deficient and only 13% are in danger of deficiency.5 Ameliorating these deficiencies may not solve as many problems as we hope. In fact, most supposed benefits of vitamin D are still unproven or simply white smoke, affecting only a narrow range of our diverse population.5
Recent studies have linked vitamin D deficiency to critical health conditions. A study at the University of Exeter Medical School found that a moderate deficiency was linked to a 53% increase in the chance of developing dementia, and a severe deficiency raised the risk by 125%.6 An epidemiological study found it might contribute to cardiovascular disease.7 Low levels of vitamin D may reduce pregnancy rates in women undergoing in vitro fertilization or, as published in the Clinical Cancer Research Magazine, may lead to aggressive forms of prostate cancer.8 These tests have galvanized conversation on Vitamin D, which is of course a great advancement, but we should not get carried away. These studies display association, not causation. Further work will certainly need to be done to elucidate vitamin D’s role in these illnesses.
We should take vitamin D deficiency seriously, but our strategies need to focus on those most at risk. Excess vitamin D taken in an effort to mitigate these risk can have neutral or even negative effects. A recent study testing over 36,000 postmenopausal women found that taking vitamin D supplements had no noticeable effect on hip fracture rates.9 Furthermore, women in the study who took more than the recommended 600 international units (IU) of vitamin D were at a 28% higher chance to develop aggressive breast cancer.9 Overdosing on vitamin D supplements can lead to calcium in urine, contributing to the development of kidney stones.10 Extreme overdoses can even induce calcium deposits in blood vessels, which can lead to heart attacks and other serious cardiovascular problems over time.10 For many elderly people, maintaining appropriate vitamin D levels is important and may have substantial health benefits because their bone density is so low. A 2014 study at the University of Auckland illustrated that taking vitamin D and calcium supplements produced noticeable benefits on subjects with extremely low bone density, but it had little to no effect on subjects with average to below average bone densities.3 For most of us, taking vitamin D supplements will neither hurt nor help.
For those who have received blood tests confirming they are vitamin D deficient or for those simply concerned they are at risk, there is good news. Most vitamin D tests are notoriously unreliable because they only look at vitamin D levels in the blood and may not tell the full story.10 The FDA recommended daily dosage of vitamin D is 600-800 IU, but taking anymore than 600 IU will only minimally improve bone health and appears to lack any other health benefits.5 There is still great uncertainty about vitamin D and its effects. A current study called VITAL (Vitamin D and Omega-3 Trial) taking place at Harvard Medical School has over 26,000 participants hopes to provide some conclusive evidence for or against the enigmatic nutrient in regard to bone health, cancer risk, and heart disease.10 There will not be any results for another three years, but there is an easy solution to comfort lingering stresses. Enjoy the outdoors. To reduce vitamin D deficiency risk, spend half the time outside each day as it would take you to get mild sunburn.4 Just a few minutes could have a dramatic impact on your health. Vitamin D gives you another reason to go on that hike, play hoops at the local park, or simply sip an ice-cold beverage on your front porch.
References:
Holick, Michael F., and Tai C. Chen. 2008. “Vitamin D Deficiency: A Worldwide Problem with Health Consequences.” The American Journal of Clinical Nutrition 87 (4): 1080S – 1086S.
2. “5 Illnesses Linked to Vitamin D Deficiency.” 2016. EverydayHealth.com. Accessed November 26. http://www.everydayhealth.com/news/illnesses-linked-vitamin-d-deficiency/.
“Do You Really Need to Take Vitamin D Supplements?” 2014. Health Essentials from Cleveland Clinic. May 2. https://health.clevelandclinic.org/2014/05/do-you-really-need-a-vitamin-d-supplement-2/.
“7 Signs and Symptoms You May Have a Vitamin D Deficiency.” 2016. Mercola.com. Accessed November 26. http://articles.mercola.com/sites/articles/archive/2014/05/28/vitamin-d-deficiency-signs-symptoms.aspx.
“Too Many People Are Being Told They Have a Vitamin D Deficiency.” 2016. Washington Post. Accessed November 26. https://www.washingtonpost.com/national/health-science/too-many-people-are-being-told-they-have-a-vitamin-d-deficiency/2016/11/14/1c0de62a-a75e-11e6-ba59-a7d93165c6d4_story.html.
“Alzheimer’s Risk Rises with Level of Vitamin D Deficiency.” 2016. Washington Post. Accessed November 26. https://www.washingtonpost.com/national/health-science/researchers-say-vitamin-d-deficiency-raises-alzheimers-risk/2014/08/06/ed278fde-1da1-11e4-82f9-2cd6fa8da5c4_story.html.
Wang, Thomas J., Michael J. Pencina, Sarah L. Booth, Paul F. Jacques, Erik Ingelsson, Katherine Lanier, Emelia J. Benjamin, Ralph B. D’Agostino, Myles Wolf, and Ramachandran S. Vasan. 2008. “Vitamin D Deficiency and Risk of Cardiovascular Disease.” Circulation 117 (4): 503–11. doi:10.1161/CIRCULATIONAHA.107.706127.
“Vitamin D Deficiency May Reduce Pregnancy Rate in Women Undergoing IVF.” 2016. Accessed November 26. http://medicalxpress.com/news/2014-08-vitamin-d-deficiency-pregnancy-women.html.
“Benefits of Vitamin D and Calcium Supplements Are Minimal, Study Says.” 2016. Washington Post. Accessed November 26. https://www.washingtonpost.com/national/health-science/benefits-of-vitamin-d-and-calcium-supplements-are-minimal-study-says/2013/12/02/f8c064be-5601-11e3-835d-e7173847c7cc_story.html.
Park, Alice. 2015. “Who Should—and Who Shouldn’t—Take Vitamin D.” Time, March 27. http://time.com/3761581/vitamin-d-deficiency/.