COLDWATER — Most people in Michigan need to supplement their vitamin D, especially during the winter with its cloudy skies and less skin exposed to the sun.

Dr. Lauren Vogel, medical director for the Branch-Hillsdale-St. Joseph Community Health Agency, pointed out 40 percent of the population is vitamin D deficient.

“It controls your bone metabolism but it also is en enzyme modulator for tissue repair,” Vogel said.

This is important because it helps regulate genetic changes in cells that can lead to cancers, he explained.

There are a lot of disease which have a strong relationship to vitamin D, such as breast cancer and colon cancer, which show a 50- to 70-percent increase in those with a vitamin D deficiency. The list does not stop there. For coronary heart disease there is a 70 percent increase with those lacking vitamin D.

The deficiency also has been tied to erectile dysfunction, multiple sclerosis, dementia, muscle aches, obesity, and a long list of others.

Most people don’t get enough vitamin D, and products like milk with vitamin D supplementing the drink or even supplemental vitamins are not enough to increase levels for those low on the essential vitamin, the doctor warned.

“They don’t put enough in foods,” Dr. Vogel said. “Multiple vitamins are better than nothing.”

Research shows that 50 percent of children ages 1 to 5 are deficient. That increases to 70 percent until teenaged years. Then again, the same research jumps to 95 percent of the elderly.

The way to determine if your are deficient is a blood test ordered by your physician. A level of 20 nanograms/milliliter to 50 ng/mL is considered adequate for healthy people. A level less than 20 ng/mL indicates vitamin D deficiency.

Dr. Vogel also warned the vitamin can be toxic if the level gets above 80 ng/ml.

Once a person begins taking the vitamin, it can take four to six weeks to build up levels in the bloodstream, and you may need to wait 10 to 12 weeks before a new tests to see if your vitamin D levels are rising.

Those lving in the winter climates are especially susceptible. The body does manufacture some of its own vitamin D from the sun. But it is the same sun that can cause problems — potentially changing cells to become skin cancer.

The vitamin D deficiency warning drew praise from board member Hillsdale County commissioner Bruce Caswell, whose brother is a nationally recognized and published research scientist in skin protection.

Caswell said his brother suggested he have his vitamin D levels tested after he was diagnosed with skin cancer.

“Mine was 17,” Caswell said. “Now I’ve got it up around 36, and I haven’t had any more problems.”

Vogel said above 30 to 50 ng/ml was an appropriate level. As for a vitamin D deficiency, “for the most part it is silent,” although it can cause muscle pain and gastrointestinal issues.

For the most part, the health industry looks at cost effectiveness and does not recommend it unless you have issues, including those such as diabetes, obesity or a strong family history of colon cancer or bone density problems.