Internist Vicky Lopachin is up on the latest research and makes sure her patients - like Jean Crystal - are getting enough vitamin D, which means more than the recommend daily 400 units.
"As you go through menopause and really start to think about bone loss, it's important to have vitamin D, and probably more than we used to think," Lopachin said.
Nutrition experts like Harvard's Walter Willet say adequate vitamin D may help prevent disease.
"There's very strong evidence that not getting enough vitamin D is likely to lead to excess risk of colon cancer, probably some other cancers, probably multiple sclerosis, probably asthma," Willet said. "And the list is rapidly growing."
The main sources of "D" are the sun - our bodies manufacture it when UV rays hit our skin - and foods like fortified milk.
Willet says most Americans are still getting too little.
"It looks like about two-thirds of Americans are not getting enough vitamin D," Willet said. "That's largely because we've, in our civilization, put on clothes. We work inside, and more recently, we're even putting on sunscreen."
The choice between getting more sun and taking supplements is clear to the American Academy of Dermatology. They say rising skin cancer rates mean Americans need to boost their "D" through diet and supplements - not by spending more time in the sun. Increasing the recommended daily amount of vitamin D is the next step, Willet says.
"What's quite clear now is that more will be better for most people," he said. "We don't know exactly how much more, so that's why most of us are recommending a fairly cautious increase."
The exact amount of vitamin D people should be getting everyday is still under debate, but 1000 International Units per day is considered safe. Some say the level needs to be even higher - especially for some groups like the elderly or those with darker skin if they are going to get health benefits.