Boost Immunity With This Super Vitamin

Add this to the growing resume of vitamin D: it stimulates the immune system.

Oregon State University scientists have discovered that vitamin D induces the expression of a gene that’s actually antimicrobial.

The gene is called cathelicidin, and the researchers believe that it may be responsible for vitamin D’s capacity to function as one’s primary immune response. They also believe that in the future, cathelicidin may form the basis for new immune-based therapies.

Since an estimated 70% of Americans have way less than optimal levels of vitamin D, and nearly a billion people worldwide are vitamin D deficient, the Oregon State Researchers warn of an impending public health problem, in both developed and developing nations.

Food sources are unlikely to provide optimal levels of vitamin D. We get the bulk of this vitamin from the sun, but virtually no one is getting enough of it.

Readers of this newsletter already know that vitamin D improves physical performance in older adults, is essential for strong bones, has anti-cancer effects and improves mood. It also reduces the risk of death from any cause.

And recently, a study in the prestigious Archives of Internal Medicine found that adults with the lowest levels of vitamin D were most likely to have higher levels of cognitive decline as they aged.

Vitamin D is one of the easiest nutrients to supplement with. Even the highest quality vitamin D is relatively inexpensive.  The new emulsion formulas are economical (900 servings per bottle!) and allow you to simply add a few drops to any drink, which is what I do every single day. (For the record, I take 8,000 IUs daily.)




  1. Perry Prevo

    Would it be better to take a vitamin D seperate or within a multi vitamin?

  2. Dr. Jonny

    You can take it along with any other vitamin- it does not need to be taken alone


  3. Pam Frayne


    I’m wondering what is wrong with the sweetner, splenda and why it didn’t make your book, “The 150 Healthiest Foods” — would you use it?

    Pam Frayne

  4. Dr. Jonny

    Hi there–

    well there’s two questions here; one, why didn’t it make it into the book, and that answer is simple: in choosing the 150- healthiest FOODS in the world, i can’t imagine why any artificial sweetener would be included. The second question is what is wrong with splenda; all i can say about this is that there is considerable controversy over the additional chlorine in the formula and though the jury is out on whether that really poses any danger to human health, experience has taught that for MANY of these sweeteners we find out much later on that they were really bad. That may not have happened with splenda yet, but I’m not convinced it’s a particularly healthy way to solve the sweetener problem, particularly when there are much more established and less controversial sweeteners like Xylitol or erythritol.


  5. Monique

    Yes, as well as those, you also have STEVIA Sweet, a 100% natural sweetening ingredient. Stevia (stevia rebaudiana) is a wild plant native to South America. Stevia has been known as “honey leaf” to the original inhabitants and used to sweeten tea and foods. It’s a low calorie (90% less calories than sugar and 40% fibre) sweetener based on natural steviol glycosides extracted from the stevia leaf.
    Of course, Dr Bowden, we wouldn’t put splenda in your book but l find out a few months ago and l’ve been using it ever since, the superfood (CHIA SEEDS) and the long list of their advantages and health benefits. For sure this one will be added to your future books. Thank you always for all the updates on nutrition and health benefits, Dr Bowden.

  6. Brock Spencer

    Dr. Jonny,

    What’s your current take on what likely represents a generally optimal range for Vitamin D Levels in most folks? I have seen various levels postulated, with most (with a few exceptions skewing even higher falling somewhere in the range of 50-80ng/mL, with the middle of that range suggested as a sweet spot.

    But recently I came across the following piece by Chris Masterjohn, which indcated that anything well over 35 ng/mL was pure speculation at this time in terms of being optimal. He also seemed to feel that higher levels may be beneficial in concert with optimal intake of Vitamin’s A and K2 (a definite challenge, given that K2 via food can be a challenge for almost everyone who isn’t living off of goose liver pate and fermented foods), but that even then, the jury will still be out for some time until more specific RCT’s have been conducted.

    Being so well read and always taking such a level-headed approach to these manners, it would be highly educational to hear your thoughts on what you feel is a person’s “best bet” right now (outside of very special situations that may require some sort of marked departure from those guidelines…..such as something like sarcoidosis, perhaps.

  7. Robert

    Dr. Bowden,
    If I spend at least 2 hours a week sun bathing (30 minutes on each side at a time to prevent burning…no lotion) is that typically going to fulfill my requirements for Vitamin D? If this is the case, wouldn’t it only be necessary to supplement with it in the winter if I am receiving adequate sun exposure?


  8. Dr. Jonny

    To be sure why not simply get a 25-hydroxy (vitamin d) blood test? Failing that, everything I’ve seen and read indicates that we would be best supplementing all year long. I live in sunny California and am outdoors every day but I still supplement all year long.


  9. Dr. Jonny

    I generally like chris masterjohn but he is pretty much the only one who is saying this that I know of. I’d stick with the majority opinion on this particular issue.


  10. jill

    Dr. Bowden,

    I love your books, especially The Healthiest Meals on Earth. When reading your information on Vitamin D, I was concerned about the amount (8,000 IU per day) that you take. Isn’t Vitamin D toxic? How much is too much? I am vitamin D deficiant and I take 50,000 every other week. I also go in for blood exams to check the toxicity in my system of this vitamin.

  11. Dr. Jonny

    Thank you! no, vitamin D is certainly not toxic in the amounts you’re talking about. Our bodies will easily make 10,000 IUs with a couple hours in the midday sun. blood tests will tell you if you are in anything like a “too high” range, but most people are nowhere near that.



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