Growing up, I heard a lot about vitamin D. “Drink your milk,” my mom said. “It’ll help you have strong bones.” But what researchers are learning is that vitamin D also may be tied to a strong mind, as in one that is without Alzheimer’s disease.

A team of researchers from Canada and the United Kingdom looked at 37 previously published studies that looked at cognitive function and dementia in order to see if there was an association with vitamin D levels. Their overall analysis which was just published found that lower vitamin D concentration levels may be associated with poorer cognitive function as well as a higher risk of Alzheimer’s disease.  And a 2009 paper out of San Francisco points to observational evidence that low levels have vitamin D have been associated with an increased risk of a variety of conditions, including cardiovascular disease, diabetes, depression, osteoporosis, and periodontal disease. All of these conditions are either considered risk factors for dementia or have been found to precede the development of dementia.

Furthermore, AARP pointed to 2010 research that found that older men and women who have low levels of this vitamin are 25 percent more likely to have issues with memory, attention and logic. This particular study out of England involved 3,325 participants who were at least 65 years of age. The study’s design was created to reflect the aging population in the United States. The researchers found that people who were deficient in vitamin D were over 40 percent more likely to do poorly on tests of memory and attention. Furthermore, study participants who were classified as severely deficient were 400 percent more likely to perform poorly on these tests.

So how much vitamin D should you get? The Mayo Clinic reported that vitamin D is included in many multivitamins, although the strength can vary from 50 20 1,000 international units. The clinic pointed out that the Institute of Medicine has recommended that people between the ages of 1-70 years of age should get 600 international units daily while those who are 71 years and older should increase the amount to 800 international units. However, the clinic also noted that these doses don’t necessarily match up to the amounts that have been effective for various conditions, including cognition, cancer and hypertension. Therefore, talk to your doctor about the proper dosage that’s right for you.

So how do we make sure to get enough vitamin D so we don’t become deficient? According to the Mayo Clinic, this vitamin can be found in a variety of dietary sources. You also can get the proper share through 10 minutes of exposure to the sun daily. ABC News suggested seven great sources, which include: herring (1383 international units in each three-ounce serving); pink salmon that’s been canned (530 international units in each three-ounce serving); halibut (510 international units in each three-ounce serving); oyster (272 international units in each three-ounce serving); dried shitake mushrooms (249 international units in four mushrooms); light meat tuna that’s been canned in oil (200 international units in each three-ounce serving); and a cooked egg (26 international units in a whole egg of which 25 international units are in the yolk). Furthermore, the George Mateljan Foundation reports that both cow’s milk and goat’s milk are good sources for this vitamin. The foundation also recommends eating wild-caught salmon, which has been found to have significantly more vitamin D than non-organically farmed salmon.