Today is October first, which means that if you live in the Northern Hemisphere above the 37th parallel (I’m talking to you, New York, San Francisco, Chicago, St. Louis, etc.), you are not going to be getting your Vitamin D from the sun until late March/early April. Having inadequate levels of Vitamin D as shown on a Serum 25-Hydroxyvitamin D [25(OH)D] test (<50 nmol/L or <20 ng/mL, according to this article from the National Institutes of Health site) could impact your immunity, along with a whole host of other health conditions. (Just google “Vitamin D immunity” and critically look at what you find and then talk to your doctor!)
The best way to get Vitamin D is from the proper, timely sun exposure, but in lieu of that in the winter months, one of the many ways to get it is from Cod Liver Oil. My favorite brand of Cod Liver Oil is currently on sale, through tomorrow, at Whole Foods (at least in the NYC area).
Personally, I take 2 tablespoons of it a day plus a Vitamin D supplement (because I am near deficient, according to the test above). Maybe it’s related, maybe it’s not, but I haven’t had a flu or a serious cold since I seriously started on this regimen, and I never get the flu shot. Perhaps it is coincidence – who knows?
However, if you are interested, you should talk to your doctor about it before taking it. If you feel like your doctor doesn’t know anything about it, or brushes off your concern, or worse yet, just mindlessly pushes a flu vaccine on you instead, you should think about getting a new doctor. All nutrients, foods and your own body chemistry work together, and taking something in isolation without understanding the whole picture is not a great idea. For example, to be absorbed, Vitamin D needs to be taken with fat. It works together with Magnesium, Phosphorus, Vitamin K and Calcium, and others, all in different amounts. Messing up the balance of your body is a bad idea. Gather information on your own in order to ask informed questions of experts (don’t just rely on some layperson blogger like myself).
Speaking of immunity, see these prior, seasonal posts of mine: