Before we answer to question of how much, we should probably look at whether or not vitamin D can help with infections in the first place.
While vitamin D supplementation has been attributed to any number of health effects, there are a few situation where vitamin D seems to shine. This includes long term (10 years or more) risk of cancer, vascular health (heart disease, stroke, dementia) and immune balance. Vitamin D has also been shown in multiple studies to help with respiratory issues (pneumonia, influenza, asthma), but I’m not sure if the benefit is from an actual effect on the respiratory system, or indirectly from vitamin D’s immune effects. Either way, vitamin D has a pretty solid acceptance to support and balance immune function.
This aspect I find interesting, because every flu season there is a massive, expensive push to get every breathing person vaccinated for influenza, but never is there a mention about how to support the immune system through interventions such as vitamin D supplementation.
Doctors think they are doing the right thing by checking patients’ vitamin D levels. There are three problems with this:
- Very, very few patients are at optimal levels (60-100 ng/ml).
- Testing, when insurance is billed, is expensive.
- Even when patients come back deficient, doctors rarely know how much vitamin D to give and what the best forms to give are.
Between these three, we are wasting money testing patients who have a very high likelihood of being less than optimal and when we spend the money to confirm it, we’re not fixing it correctly. No wonder healthcare is so expensive.
Basically, checking vitamin D levels is getting into the realm of functional medicine (much like checking testosterone). I feel very strongly that no doctor should be checking these values unless they fully understand to nuances that go along with functional testing. Consider the mess we’ve gotten into with testosterone, another lab value that I have had more and more patients come in who have had it tested by his or her primary care doctor. Patients who have low testosterone are given some form of testosterone (injections, cream, pills, pellets) rather than fixing the problem in the first place.
But I digress.
Back to this particular study looking at vitamin D’s ability to lower the need for an antibiotic prescription in a group of 644 Australian residents aged 60–84 years of age who were given monthly doses of a placebo or 30,000 IU of vitamin D3 (1,000 / day) or 60,000 IU D3 (2,000 / day) for up to a year. Here’s what the researchers found:
- Those taking 60,000 IU were 28% less likely to have had antibiotics prescribed.
- Specifically, in subjects old than 70 years of age, this group was 47% less likely.
- In those aged 60-70, they werere only 7% less likely.
When you consider that the senior population, who are the most likely to suffer complications from influenza, benefit the least from the influenza vaccination, it makes the findings of this study even more important.
One last note—2,000 IU / day of vitamin D is still a very low level. This is the dosage I start patients on who already get decent sun exposure and little risk of chronic disease. Makes you wonder how much more powerful the study would have been at levels of 4,000 or 6,000 IU per day.