Vitamin D and heart failure

vitamin DHeadline nutrition misleads again

Here are some mass media headlines for articles on a new vitamin D study:

So without bothering to read the articles, you could conclude that vitamin D will help your heart, make it work “better”, and if you’d like a healthier heart, just take some D supplements.  In fact,that’s not what the study said at all.

Here’s the title of the actual research report, from the Journal of American College of Cardiology: Effects of Vitamin D on Cardiac Function in Patients with Chronic Heart Failure (HF).  No surprise, the title of the actual research report is far more specific.

The study was limited to patients who were being treated for heart failure, who also were vitamin D deficient.

  • Half of the subjects got 4000 IU/day of vitamin D3, the rest got a placebo.
  • They were followed for a year.
  • After 12 months, the patients on the vitamin showed significantly improved cardiac function, although their hearts were not functioning at a completely healthy level.
  • Despite improved heart function, the supplemented group did not show improvement in physical fitness, as measured by distance walked in 6 minutes.

The researchers were very impressed by the improvement in heart function; one described it to the BBC as “stunning”.  They suggested that improving D status in deficient heart failure patients might eliminate the need for these people to have implanted cardio defibrillaltors, which are expensive and invasive.  They also noted that more research needs to be done to clarify who would benefit, what dose and blood level of D is most helpful and whether there are further improvements in heart function or exercise tolerance beyond 12 months.

The study did not say anything whatsoever about improvement in heart function for already-healthy people, or for people with any other heart condition, such as damage from a heart attack.   It also didn’t suggest that people who already have adequate vitamin D levels would benefit from taking more of the vitamin.

So vitamin D is:

  1. important? Yes.
  2. a cure for heart disease? No.
  3. a way to boost heart health?  Possibly, if you have heart failure and are vitamin D deficient.
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