The health benefits of vitamins include their ability to prevent and treat various diseases including heart problems, high cholesterol levels , eye disorders, and skin disorders. Given the consistency of these results — large effects in observational data, nothing in randomized trials — it’s worth asking what might be going on to better understand whether or not other relationships we see in observational data on vitamins are likely to be replicated in randomized trials.
A recent review identified 290 observational studies on vitamin D. For the most part, these studies measure the amount of 25-hydroxy vitamin D — the marker of vitamin D concentration — in participants’ blood and analyze the relationship between that concentration and various measures of health.
Specific diseases uniquely associated with deficiencies in vitamin B6, riboflavin, or pantothenic acid have not been found in humans, though persons who have been starving, or consuming poor diets for several months, might be expected to be deficient in most of the nutrients, including vitamin B6, riboflavin, and pantothenic acid.
In fact, a recent study found that people with higher levels of omega-3 fatty acids in their blood had larger brains and performed better on memory tests, planning activities, and abstract thinking, compared with individuals with lower levels—which suggests that omega-3 fatty acids play a role in maintaining brain health in addition to the other known benefits, says the study’s lead author, Zaldy S. Tan, MD, MPH, medical director of the Alzheimer’s and Dementia Care Program at UCLA.
Where to get it: Fatty fishes—including swordfish, salmon, and mackerel—are among the few naturally occurring dietary sources of vitamin D. (Cod liver oil is tops, with 1,360 IU per tablespoon , while swordfish is second with 566 IU, or 142% DV.) Most people tend to consume vitamin D via fortified foods such as milk, breakfast cereals, yogurt, and orange juice.