Vitamin D 3
A recent meta-analysis has found that of all
environmental risk factors for developing dementia, the
evidence pinpointing low vitamin D was the strongest.
Vitamin D deficiency may also impair your brain’s ability to
synthesize serotonin from its precursor tryptophan, leading
to lowered levels of this neurotransmitter in the brain. This
can lead to depression and brain fog.
The main source of vitamin D comes from our exposure
to the sun’s UVB rays. Today, many of us spend a lot of our
time indoors, and our skin’s exposure to the sun is limited—
meaning we’re likely to have lower levels of vitamin D.
There are also many person-to-person differences that affect
our ability to synthesize vitamin D. Young people produce
more vitamin D than older people—for example, a seventy-
year-old makes four times less vitamin D from the sun than
a twenty-year-old. Those with darker skin pigments also
produce less vitamin D. (Melanin, which gives brown skin
its color, is evolution’s natural sunscreen.) That means that
if you’re a person of color living in a northern latitude,
supplementation may be particularly important.
Those who are overweight have less available vitamin D,
because as a fat-soluble vitamin, it gets stored in fat tissue.
This occurs with other fat-soluble vitamins as well (like
vitamin E) and may explain why overweight and obese
people are more likely to be deficient in vitamin D even
with the same sun exposure as their leaner counterparts.
Perhaps it’s not a coincidence that three-quarters of US teens
and adults are estimated to be deficient in vitamin D,