Taking vitamin D is unlikely to prevent falls or fractures. Here's what it does

It's that time of year when your body produces less vitamin D.

Sunshine is the main source of vitamin D, and we need it to keep our bones and muscles strong. Many people take supplements to meet the shortfall, but they're not a magic bullet of protection.

Vitamin D and calcium supplements offer no "net benefit" for the prevention of falls or fractures in older adults, according to a draft recommendation from the U.S. Preventive Services Task Force, a panel of experts who reviewed all of the existing scientific evidence on the supplements.

"This doesn't mean that vitamin D and calcium are not useful overall for bone health and for other functions within the body," says Dr. Goutham Rao, a task force member who is also the chair of the Department of Family Medicine at Case Western Reserve University.

Vitamin D helps your body absorb calcium, keeping bones and muscles strong. It also plays a role in supporting your immune system. Lack of sun exposure during winter months can increase the risk of a deficiency.

The National Academy of Medicine recommends that adults get 600 to 800 international units (IU) of vitamin D per day, depending on your age.

Prevalence studies suggest up to 40% of adults in the U.S. have insufficient levels of vitamin D in their blood. In the absence of sun exposure, fortified foods such as milk and yogurt can help meet daily recommendations. And more than 1 in 3 adults ages 60 and older take a vitamin D supplement.

"But in terms of their effectiveness in preventing fractures or falls, we did not find any evidence to support that," Rao says. The draft USPSTF recommendation is similar to the task force's previous conclusion, as more research has cast doubt on the usefulness of supplements to prevent age-related bone fractures among postmenopausal women and men over 60. The recommendation does not apply to people with osteoporosis or those at high risk who may require other treatments such as prescription medication.

So, how should people interpret what appear to be conflicting messages about vitamin D?

We turned to Dr. Wendee Gozansky, a geriatrician with Kaiser Permanente for some answers. Vitamin D has "multiple effects" on the body, she explains. In addition to promoting good bone and muscle health among healthy people throughout life, research shows it may help reduce the risk or severity of colds and flu. "It has direct effects on immune cells and function and a plethora of impacts across the body. That is why you have to be sure you have enough across the lifespan," Gozansky says.

"I think the key message really is that just because vitamin D is not the be-all to prevent falls and fractures doesn't mean that there isn't a role for having adequate intake of vitamin D for general health," Gozansky says.

Strategies to reduce falls and fractures

Gozansky says people need to take extra measures to reduce the risk of falls. "There are multiple things that we need to do, like weight-bearing exercise," she says.

There's lots of evidence to show that physical activity, including resistance training, can help keep people strong and fend off age-related muscle loss. Options include weight-lifting, resistance bands and other exercises that make your muscles contract against the resistance of your body weight or other equipment.

The Centers for Disease Control and Prevention recommends 150 minutes of moderate-intensity aerobic exercise each week, so about a half hour, five days a week. This can include brisk walking, dancing, water aerobics, swimming, hiking or anything that gets your heart rate up.

And the CDC says people 65 and older should aim for a mix of aerobic, muscle-strengthening and balance activities each week. Yoga, pilates and tai chi classes are options to check out.

Gozansky says it's so important to stay active, because a fall can be devastating. Nearly 40% of older people who fall and break a hip are not able to walk independently a year later.

In addition, she says it's important to keep tabs on your eyesight and hearing. If your hearing declines, your risk of a fall can increase, and hearing aids may help. "All of that sensory input is critical to balance," Gozansky says.

In addition, people should communicate with their doctors about medications that can increase the risk of a fall.

The National Institute on Aging recommends these six tips to prevent falls, and people can use it as a checklist to reduce their risk.

How much vitamin D, and what kind, do you need?

A blood test can determine whether you're deficient in vitamin D, Gozansky says. When she has patients who could benefit from a supplement, she typically recommends a daily D3 supplement.

"It's a Goldilocks situation. You don't want too little. You don't want too much," she says.

Vitamin D can be toxic at very high levels, and supplementation can also increase the risk of kidney stones. So, she says talk to your health care provider about supplementing at the proper level.

People need to resist the thinking that if a little of something is good for you, more of it must be better. She says the studies show that when people are getting the right amounts of vitamin D, "adding more isn't going to make a difference."