A vitamin study done right

B12More evidence that single nutrients are not silver bullets

Nutrition can be so frustrating!  On one hand, we have consumers falling for the latest fad diet or “healthy” marketing ploy.  On the other hand, we have researchers studying single nutrients — one vitamin or one mineral or one type of fat.  As if nutrients were Drugs Lite.  They are not.

Take Alzheimer’s disease, or cognitive decline, which we all associate with aging.  Prevention would be ideal, so plenty of researchers pick a vitamin or some other nutrient and study whether that one molecule can ward off dementia.  Invariably, that one nutrient isn’t effective.  And why should it be?  The brain and nerves don’t operate on a single nutrient.  The cells and biochemicals involved in brain function are made of dozens of nutritional building blocks.  Focusing on just one nutrient is like believing that the only thing that matters to keep your car running is tires.

Here’s a study that looked at nutrition and brain function in a more comprehensive way.  Researchers studied the effect of 2 years of a B vitamin supplement (folic acid, B12 and B6) on elderly people with mild cognitive impairment.  The twist is this: omega-3 fatty acid status was also measured.  The subjects weren’t given omega-3 supplements; their blood levels were simply measured.

Results: Compared to placebo, the B vitamin supplement slowed brain atrophy in those people who had high blood levels of omega-3 fatty acids.  For people with low omega-3, the B vitamins didn’t have much effect.  In other words, the benefit came from the interaction of both sets of nutrients.  The researchers went on to suggest that perhaps omega-3 fatty acids only provide benefit with people have good intake of B vitamins.

Compare this to a review of the impact of vitamin B12 and neurological health in elderly people.  As we age, B12 absorption becomes less efficient, and low B12 is common in the elderly.  B12 plays key roles in neurological function, so one might conclude that poor B12 status would adversely affect neurological health.  Yet, according to this review of published studies, there’s little evidence for that.  The authors at least recognized that better research was needed to clarify this.  Based on the results of the omega-3/B-vitamin study, it might be a good idea to examine B12 in combination with lots of other nutrients.

One other target of lots of this single-nutrient research: vitamin D.  For some reason, researchers think it should:

  • fix high blood pressure
  • cure metabolic syndrome
  • prevent heart disease
  • prevent cancer
  • etc.

It’s a nutrient.  It has an important role to play, but on its own it’s not going to cure anything.

Take Away Message

When your hear a news report about a single nutrient (or a single food component) that didn’t seem to have any benefit for some specific health problem, don’t conclude that the nutrient is useless and unimportant.  They’re all important.  That’s why they’re called nutrients.  They all work together.

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