Record Vitamin D Lows As Winter Arrives

Millions suffer from vitamin D deficiency mainly during winter, especially older people.

Just as blizzards cover most of the U.S. and Canada in a blanket of snow, it’s time to put the spotlight on “vitamin D winter”. What is it? It’s the time period, centered around winter solstice (Dec. 21-22), when the sun’s UVB rays are simply too weak to make their way through the atmosphere and stimulate the skin to synthesize the sunshine vitamin.

With virtually no production of vitamin D, most of the population are left with dangerously low levels.

Earlier this December the Harvard Health Letter reported that, “millions of Americans, especially older people” suffer from low levels of vitamin D (year-round and mostly in winter), which includes 75 percent of those with cardiovascular disease.

Vitamin D is critical for keeping the heart healthy, keeping bones healthy, for avoiding statin-related muscle soreness, helping with control of blood pressure, helping to ward off infections along with help with other possible conditions.

Those at greatest risk of vitamin D deficiency, the Letter states, are the elderly, because less vitamin D is made with advancing age; African Americans, because melanin-rich dark skin acts as a natural sunblock requiring longer UVB exposure times; and obese people, because higher amounts of fat in the body absorb the vitamin, making it unusable.

According to researchers Dr. John Cannell and Dr. Bruce Hollis, depending on latitude along with other factors such as air pollution, ozone and weather, “vitamin D winter”  can last a while—if you live in Boston, for example, you can expect “vitamin D winter” to last four months and, in northern Europe or Canada, up to six months.

The Harvard Letter states that, while sensible sun exposure was appropriate for getting sufficient vitamin D during the summer, “if you live north of a line connecting San Francisco with St. Louis and Richmond, Virginia, don’t bother [trying to get sun for vitamin D] between November and March.”

“Furthermore, “ Dr. Cannell and Dr. Hollis add, “properly applied sunblock, common window glass in homes and cars, and clothing all effectively block UVB radiation—even in the summer. Those who avoid sunlight—at any latitude—are at risk of vitamin D deficiency any time of the year.”

For example, they add, “a surprisingly high incidence of vitamin D deficiency exists in Miami, Florida, despite its sunny weather and subtropical latitude.”    

Reversing “Vitamin D Winter”

How can you make sure you’re getting enough vitamin D, daily? Despite what people might think, vitamin D is found only rarely in foods (wild-caught oily fish and wild reindeer meat) and the amounts in fortified foods such as milk are not enough to reverse a vitamin D deficiency.

Current vitamin D recommendations of 400 IU daily, in fact, have become the target of a hotly contested debate that will be settled next year with a change in recommendations from the Food and Nutrition Board.

Consider that on a summer’s day, less than a hour in the sun between the hours of 10 a.m. and 3 p.m. is enough for skin to generate a whopping 10-20,000 IU of vitamin D—that’s 200 times more than what’s found in a glass of milk.

The Letter states that, at this time, supplements are the “simplest, safest way to get vitamin D” and suggests that supplementing with 800-1,000 IU daily is “a good goal.”

Dr. Cannell and Dr. Hollis disagree advising that the target is a lot more likely to be 1,000 IU per kilogram bodyweight to obtain desired blood levels (for an 150-kilogram obese person, that can mean up to 10,000 IU daily). In addition, they recommend a “loading period” with doses of up to 50,000 IU per day for a week.

To be absolutely sure you’re receiving enough vitamin D daily (particularly if you’re at high risk of deficiency), the Letter states that it’s worth getting tested for vitamin D by asking a doctor about testing or ordering a home test from a non-profit organization such as Grassroots Health.

However, according to Dr. Michael Holick, who is a leading vitamin D researcher from the Boston University Medical Center, “If a normal adult isn’t taking at least 1,500 to 2,000 IU from supplements and diet—and you can’t really get it from diet—we know you’re vitamin D deficient.”