It’s only if we manage to squeeze enough time in our hectic, hermetically-sealed indoor lives and expose our skin to sunlight that we’ll reap the benefits of vitamin D without food, such as prevention of osteoporosis and rickets.
Despite the lack of large-scale randomized and controlled clinical studies that factor skin color, geographic location, and lifestyle factors such as diet, some researchers claim that increased Vitamin D intake might also help with the following:
- Developing stronger immune systems (evidence about preventing cancer is mixed but preventing Multiple Sclerosis [MS] is solid)
- Facilitating insulin secretion
- Bone strengthening and remodeling
- Maintaining proper heart muscle function (also mixed clinical results)
- Improving muscle strength
Answer: you’ll want to buy UV lighting and supplement with one teaspoon of cod liver oil a few days a week.
What if you live in Boston, during a normal winter, unlike the unusually mild one of this year?
Answer: Get outside, you’ll still get UV ray exposure, but still consider supplementing and eating foods rich in Vitamin D, like salmon and egg yolks.
Does being outside on a cloudy day for an hour supply you with adequate Vitamin D synthesis?
Answer: If it’s late spring and early summer, most likely. But the further away from the equator you are, and if it's late fall or winter, the more you’ll need to supplement.
What if you’re wearing a hat?
Answer: Don’t wear it for the first 10-15 minutes unless you’re in the tropics and burn easily.
And sunglasses?
Answer: You’ll still get UV exposure if other areas of your skin but try to go those first 10-15 minutes without shades to stimulate your regulatory glands.
And sunscreen?
Answer: Only use 100% all-natural (very few brands on the market are truly 100% natural) if you’re going to be in the sun for a long time and burn easily; do try and get some exposure without sunscreen. Northern Europeans who settled in America long ago, like the Vikings, aren’t known to have died from skin cancer.
Do dark skinned-people need more or less sun exposure?
Answer: More. The darker the skin, the more sun exposure you need.
What’s the amount of Vitamin D I need daily?
Answer: It depends on who you ask.
The Fed’s Conservative Take on D versus other independent researchers
Current statistics by the Institute of Medicine claim that people require at least 600 International Units (IUs) of D a day, with an upper intake level recommendation of 4000 IUs.
Prior to 2010, though, the Institute’s upper intake suggestion was 2000 IUs, assuming lack of adequate sun exposure.
Some researchers, however, believe that the recommended daily value of Vitamin D should be doubled.
University of California-Riverside researcher Dr. Anthony Norman is one advocate of increased Vitamin D intake. He tells Mother Nature Network he feels comfortable with people taking the upper intake levels of 4000 IUs per day.
Vitamin D: not really a vitamin?
In a paper he co-authored, titled ‘13th Workshop Consensus for Vitamin D Nutritional Guidelines’ Norman and other researchers concluded that half the elderly in North America and two-thirds of the rest of the world lack adequate intake of Vitamin D, hence his life’s work trying to clinically prove the benefits of increased Vitamin D intake.
Norman, in 1967, was the first scientist to discover that the form of Vitamin D we get from sunlight or food—D3—gets converted into a hormone.
“I don’t know a single thing that D3 does in our bodies except serve as a precursor for the production of the steroidal hormone form of Vitamin D, which we in the scientific community call ‘125 dihydroxy D’ ” says Norman.
“D3 itself is biologically inactive unlike all the other vitamins,” he clarifies.
Two years after discovering Vitamin D was a hormone, Norman’s lab determined, in 1969, that the biologically active form of D is a steroidal hormone. All steroidal hormones function as chemical messengers.
“And all chemical messengers have their personal receptor each of which has a unique binding site for their cognate hormone. And where my lab first found the receptor for ‘125 dihydroxy D’ was in the intestines and bone cells,” adds Norman.
Bones are the obvious receptor sites
If you’ve taken a nutrition class, perhaps you’ve seen heart-breaking pictures of young children with extremely bowed legs or disturbingly distended pot bellies, two of the symptoms associated with the Vitamin D-deficiency commonly called rickets.
The scientific community first became aware that sunlight can prevent rickets in the early 1800s.
First noticed in the mid-1600s in England, as Europe’s industrial transformation was underway, rickets, though highly preventable, still exists all too often, mostly in the developing world, though cases still are reported in the U.S. (Rickets is rare in the tropics because of its sunny climate.)
Dr. Norman says that the Institute of Medicine’s former guidelines (prior to 2010) were “extraordinarily conservative…based on observations that just 400 IUs could help prevent bone decay.”
In 2008, Norman and another researcher recommended that the daily value of Vitamin D be increased to 2000 IUs.
Norman says that the federal guidelines failed to take into account that Vitamin D receptor sites are located in several other areas of the body besides bones.
Where are these other receptor sites?
In muscle cells, the pancreas and heart, among other places. The most recently discovered receptor sites are the brain and male sperm.
“We can’t yet definitively conclude what the benefits of hormonal D brain receptors are, but our guess is that if you don’t get enough vitamin D in utero, developmental problems may result,” says Norman.
In the case of muscle cells, if not enough D receptor sites are activated by sunlight or food, muscle myopathy or increased risk of falls may result.
It was Danish scientists who expanded on the knowledge that D receptors are in sperm cells. They concluded that healthy motility and function of sperm has a direct correlation with sufficient Vitamin D levels in blood.
What about skin cancer? Shouldn’t I stay out of the sun?
According to the journal, Cancer, cancer rates are twice as high in the northeast U.S. as compared to those in the southwest. The journal concluded in one article that, “many lives could be extended through increased careful exposure to solar UV-B radiation and more safely, vitamin D3 supplementation, especially in nonsummer months.”
When it comes to balancing getting adequate amounts of Vitamin D at the risk of getting sunburned, Dr. Jacob Teitelbaum, author of ‘Real Cause, Real Cures’ (available as an iPhone app), suggests, “Just use common sense and don’t be paranoid about being out in the sun.”
Teitelbaum adds, “Historically people spent most of the day outside, weren’t dipped in sunscreen and didn’t have sunglasses on. They got plenty of sunshine. That was the normal way to get Vitamin D.”
Judd Handler is a health coach and writer based in Encinitas, CA.
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