Vitamin D3 and Fish Oil’s Effects on Brain-Related Blood Markers: A Closer Look

This study took a fresh look at data from the large VITAL trial, which originally tested whether daily vitamin D3 (2000 IU) and omega-3 fatty acids (1 gram) could help prevent heart disease and cancer. Researchers examined blood samples from 929 participants to see if these supplements affected four biomarkers linked to Alzheimer’s disease and related dementias, measuring changes over four years.

Overall, neither vitamin D3 nor omega-3 supplementation significantly changed these brain-related biomarkers compared to placebo when looking at the full group of participants.

However, when researchers broke the data down by sex and race, some interesting patterns emerged. Men taking vitamin D3 showed a small reduction in one marker (NT1) that wasn’t seen in women. Among Black participants, vitamin D3 was linked to lower levels of a marker called NfL, while omega-3s were linked to lower levels of another marker called GFAP. The researchers were careful to note these subgroup findings weren’t statistically adjusted for multiple comparisons, meaning they should be viewed as early signals that need further research, not confirmed effects.