Study: Vitamin D supplements may accelerate cognitive decline when taken without need

A recent study suggests that taking vitamin D supplements among older adults who already have sufficient levels of the vitamin may be associated with a faster decline in certain cognitive abilities. However, researchers emphasized that the findings do not prove that the supplements are the direct cause, according to the health website Very Well Health.

The study, published in the journal BMJ Open, included 5,065 older adults over a six-year period. Participants underwent cognitive ability tests and reported their use of vitamin D supplements. Approximately 40 percent of them regularly took these supplements.

Researchers found that supplement use among individuals who obtained adequate vitamin D from diet and sun exposure was associated with poorer performance in memory, attention, and information processing speed.

However, neurologist Augusto Miravalle, who was not involved in the study, cautioned against interpreting the results as evidence that vitamin D harms the brain. The study did not specify the doses of supplements taken by participants, and its observational nature does not allow for the establishment of a causal relationship.

Additionally, so-called “reverse causality” may also be at play, meaning that some individuals who were already more susceptible to cognitive decline may have turned to taking supplements.