Once known only for its important role in bone health, vitamin D is now recognized for its ability to help protect against an array of chronic conditions. A seven-year study published in the Journal of Gerontology found that older women with the highest dietary vitamin D intake had a lower risk of developing Alzheimer’s disease than women with the lowest intake. Don’t know about you, but that’s the kind of news we like to hear!
Watching for signs of dementia
The study took place in France and included 498 women over 75 years old who were already participating in a larger osteoporosis trial. Women were only included if they had no signs of dementia and had not used vitamin D supplements in the previous 18 months. They answered diet and lifestyle questionnaires at the beginning of the study and underwent thinking (cognitive) tests at the beginning and end of the study.
More than 27% of the women developed dementia during the study, about half diagnosed with Alzheimer’s disease and the other half with other forms of dementia. As expected, women who were older and had more disability and poorer cognitive function at the beginning of the study were more likely to develop dementia.
High vitamin D intake linked to less dementia
In addition, the researchers found differences linked to vitamin D intake:
- Women who developed Alzheimer’s disease got less vitamin D in their diets than women who developed other types of dementia and women who stayed dementia-free.
- Alzheimer’s disease risk was reduced by 77% in women with the highest dietary vitamin D intake (averaging about 4,000 IU per week), compared to women with the lowest intake.
- More frequent midday sunlight exposure was also associated with a reduced Alzheimer’s disease risk.
- Sunlight exposure and dietary vitamin D did not appear to protect against other forms of dementia.