Does soltice signify vitamin D time? – The Morning Call – Allentown Morning Call
Wednesday is the solstice, the first day of winter and the day in the northern hemisphere with the fewest hours of daylight.
In the Lehigh Valley, where the sun rises at 7:22 a.m. and sets at 4:38 p.m., we’ll have to make do with barely nine hours — which is why many of us are thinking about vitamin D.
Vitamin D is known to promote strong bones and teeth and mounting research suggests it also plays a role in gene regulation and other bodily functions, possibly helping to prevent heart disease, cancer, diabetes and even the wintertime blues known as seasonal affective disorder, or SAD.
“It’s more than just a nutrient, it acts like a hormone,” said Dorothy McFadden, a bariatric dietician at St. Luke’s University Health Network. “We are still learning about it, everything that it does.”
Unlike most other vitamins, vitamin D is a nutrient the body makes mostly on its own when our skin is exposed to sunlight. So this time of year — when sunlight is in short supply and we’re covered up under layers of winter clothing — our vitamin D levels tend to decline and, in some of us, markedly so.
We know this because in recent years more and more doctors have added vitamin D screening to their patients’ routine blood work. They are checking our vitamin D as they do our cholesterol. Anything under 20 nanograms per milliliter is low, according to the international Endocrine Society in Washington, D.C.
For people who are already suffering the effects of vitamin D deficiency, the benefits of supplementation are well documented.
Take for example rickets, a common childhood disease in many developing countries. Caused by malnutrition and specifically vitamin D deficiency, it can result in extreme bow-leggedness.
Rickets was once fairly common in the United States and other western countries, as well. It’s decline is linked to vitamin D fortification in milk, since vitamin D assists in the absorption of calcium.
As a bariatric dietrician, McFadden is especially concerned about vitamin D deficiency in obese patients. That’s because fat cells tend to capture and withhold vitamin D, preventing it from reaching other parts of the body where it’s needed.
Also at greater risk to deficiency are people with darker complexions, since their skin’s greater tolerance to sunlight means it needs more light to trigger adequate vitamin D production. (For basically the same reason, those with lighter complexions who use a lot of sunblock to prevent skin cancer are vulnerable too.)
In addition to supplements, McFadden said she encourages her patients to consume foods known to be rich in vtamin D. Besides fortified milk, such foods include fatty fish, egg yoke and beef liver.
“My primary goal is to maintain [a] patient’s bone density,” she said.
So for the rest of us, then, taking vitamin D supplements, which can be bought at just about any pharmacy or grocery story, should be a no-brainer this time of year, right?
Well, not necessarily, according to the U.S. Preventive Services Task Force, an independent panel of experts.
Turns out, the Task Force, authorized by an act of Congress, isn’t even sure if healthy adults should be screened for vitamin D in the first place. After reviewing the research, it concluded in 2014 that “the current evidence is insufficient to assess the balance of benefits and harms of screening.”
Separately, the Task Force looked at taking vitamin D and calcium to prevent fractures. While it found supplementation showed some benefit for people 65 and older living in nursing homes, it was unable to draw conclusions about the impact on younger healthy men and women, or on healthy post-menopausal women who did not live in nursing homes.
“The current evidence is insufficient,” it noted once again.
What: A nutrient the body makes when skin is exposed to sunlight. Also available in some foods and vitamin supplements.
How it works: The body turns it into a hormone called “activated vitamin D” or “calcitriol”
Role in the body: Promotes healthy bones and teeth. Helps to regulate genes. May also help to prevent diseases.