Vitamin D Side Effects
Wednesday, January 6th, 2010By Curtis Alexander, Pharm.D.
America’s Natural Pharmacist
Summary: Vitamin D side effects are rare and often cases are sensationalized by the media. The risk of vitamin D deficiency side effects is a greater threat. However, like any supplement, the side effects of vitamin D are real and can happen.
Dear Curtis: I’ve read recently that D Vitamin side effects are becoming more and more common. I’m a little worried as I supplement with an over-the-counter preparation of vitamin D (400 International Units). Do you think I should be concerned and should I change anything?
My Answer: I think the claims of vitamin D side effects have been overblown and sensationalized. Can you get toxic from too much vitamin D? Of course. You can get toxic with too much water if you try hard enough. But, vitamin D toxicity takes a long time to happen and is frankly difficult to do. But, it can happen. Here are some risk factors and a little background to help you decide.
Do You Need a Vitamin D Supplement?
Before I get started let’s establish two things:
- Vitamin D is really important for a number of functions in your body (including maintaining calcium balance which can help control osteoporosis risk, improving your immune system, help protect against uncontrolled cell proliferation, blood pressure regulation, improving muscle strength, playing a role in diabetes and in preventing cancer).
- From my personal experience and opinion, most Americans have a higher risk of vitamin D deficiency that vitamin D toxicity due to decreased exposure to the suns UV rays which are required for natural vitamin D production.
But, that doesn’t mean everyone should start supplementing with vitamin D. Where do you live?
For me, vitamin D supplementation is a near requirement as I live in Montana. Generally, from November to March or April the only sun exposure I get is behind a pane of glass. Which, in case your wondering, is not effective for synthesizing vitamin D.
Also, what is your skin color? I’m a fair skinned person with Scandinavian and Northern European ancestry. I’m not going to be the posterboy for sun tan lotion anytime soon. So, I don’t need as much sun exposure to get my share of natural vitamin D. During the summer I personally aim for 15 minutes a day of full body (I am wearing shorts of course, I don’t want the neighbors staring) exposure.
For dark skinned people they’ll need more. Probably like 30 minutes. Higher exposure is also needed the older you get as your ability to synthesize vitamin D from the sun decreases.
You should know that adequate sun exposure during the summer allows excess vitamin D to be stored in your fat reserves. But, for obese people they have a harder time accessing those stores do to their high body fat composition. Also, there has never been any evidence to suggest that you can get vitamin D toxicity from too much sun exposure.
So, if you can’t get good skin exposure to the sun at least two to three times a week as I’ve described above, supplementation is not only recommended…it’s probably needed.
**SIDENOTE** Remember when I was talking about how vitamin D improves immune function. Well, I haven’t been doing my usual cod liver oil supplementation during the winter months. I’ve now had my first serious cold for nearly 3 years. Perhaps a coincidence…perhaps not?
Vitamin D From Food
Yes, some foods contain vitamin D and yes, some foods are fortified with vitamin D. But, my mantra is if it’s not natural try not to eat it. In other words, if it’s in a box or package, avoid it if you can. This limits a lot of the fortified foods including orange juice, cows milk and oatmeals.
There are a limited number of naturally occurring foods with vitamin D in them including cold water fatty fish like salmon, sardines and mackerel. On average, you can expect around 200 to 300 IUs (International Units) for sardines and mackeral (canned). Salmon will likely give you the biggest vitamin D bang for your buck coming in at around 500 IUs for a 3 ounce serving of canned salmon.
As an aside, egg yolks can provide around 20 IUs but that is pretty minimal.
In short, yes you can get vitamin D from foods – but it’s not as much as you might expect.
Vitamin D Supplements
If you are supplementing it is likely the vitamin D3 form (cholecalciferol) which is more potent than ergocalciferol (vitamin D2).
Most over the counter supplements will contain 400 IUs of vitamin D3 per serving.
Vitamin D Recommendations
Right now, the general consensus with vitamin D intake is that there is no consensus.
Because vitamin D from the skin confounds so many studies and is hard to measure most experts have tried to come up with a tolerable upper level for vitamin D supplementation. Unfortunately, this is where a lot of the vitamin D toxicity worries arise from.
For example, recently the Amercian Academy of Pediatrics recently doubled their old vitamin D recommendation from 200 IU/day to 400 IU/day. Why? Mounting evidence that vitamin D might reduce risks for cancer, diabetes and heart disease.
But what about adults?
Right now the medical mainstream says 400 IUs/day would be sufficient for most adults (aside from sun exposure) and offer a more liberal 600 IU/day for people older than 71 years of age.
Most experts (myself included) feel the governments vitamin D recommendations are too conservative. In fact, if pediatric patients need 400 IU/day it stand to reason that adults could use more than that. In fact, there have been studies in pediatric patients (if memory serves me correctly the study was done on children in poorer countries who may have been malnourished) and showed no side effects from 2,000 IU’s a day.
Everyone Is Different: Here’s What I Do
Personally, I think a vitamin D intake of 1000-2,000 IU/day is sufficient. Notice I said intake – that is not all in supplement form. I do NOT supplement during the summer months and I don’t think it is needed if you are getting adequate sun exposure (for me 15 minutes a day). So, for me, some cod liver oil during the winter months and an occassional 2,000 IU vitamin D3 tablet. Then, when spring comes around I rely solely on my diet and sun exposure.
Risk Factors
I don’t want to pretend that everyone can do this. There are some people who are naturally at higher risk for vitamin D side effects even at lower doses. And, rather than a true vitamin D toxicity presenting with nausea, vomiting and so forth – they actually exhibit signs and symptoms of too much calcium as calcium and vitamin D are very interrelated in your body.
For example, people with primary hyperparathyroidism, sarcoidosis, tuberculosis, and lymphoma can develop hypercalcemia related to increases in vitamin D intake. If you have any of these conditions it’s very important you consult your health care provider prior to taking any vitamin D supplements.
Vitamin D Measurements
If you are truly concerned about suffering from vitamin D toxicity the best way to find out is to have your blood levels measured.
Your doctor or lab will likely suggest conservative numbers. But this could be a mistake based on the most recent research.
It is generally accepted that clinical vitamin D deficiency (rickets and osteomalacia) occur at blood levels less than 8-10 ng/mL. While some doctors suggest a low range of 20 ng/mL it appears that calcium absorption is not optimized until 32 ng/mL. Therefore, I would shoot for blood levels of 30-50 ng/mL.