I promised to write one column about the side effects of vitamin B1 (thiamine), vitamin B3 (niacin, niacinamide), vitamin C, and vitamin D (cholecalciferol). Deficiency in these four vitamins causes beri beri, pellagra, scurvy, and rickets respectively. I’m going to start with vitamin D because it causes the most problems.
I’ve been hesitant to write these columns because they make the vitamins sound scary. In my experience, the benefits of vitamins are difficult to prove (and to feel) while the side effects are obvious. I’m a scientist. Like all active micronutrients (think drugs), the benefits of vitamins must respond to dose. If you want the full benefit, you have to apply massive doses. Of course, this isn’t practical. Side effects also respond to dose. So, you have to find a dose that balances benefits and side effects. Side effects are your friend. They are usually very very mild at the outset. Once recognized, they let you know that most of your body has plenty. They allow you to find the form of each vitamin supplement that is best suited to you (enables the highest dose before the onset of side effects). I can only plead with readers to trust me. The side effects are worth it. Vitamins have the power to lead to a step change reduction in the severity of the chronic illnesses plaguing us.
Vitamin D is the only one of the four vitamins responsible for deficiency that is acutely toxic in overdose. A single dose, sufficiently large, is lethal. This dose is determined by scientists by feeding rats. The data from the rats indicates that a single dose of vitamin D between 3 million and 4 million IU would kill most adults. It is virtually impossible for a consumer to take a dose like this. In fact, vitamin D is so safe that it is sold in bottles without childproof caps. I purchase large bottles of 1000 IU vitamin D tablets that contain 300 tablets. If I swallowed the entire bottle, I’d be taking 300,000 IU of vitamin D. I’d have to swallow ten entire bottles at once to reach the lethal dose.
Much lower doses of vitamin D, taken regularly, build up in the body over time and cause serious illness. not surprisingly, the Mayo Clinic (are they defending themselves against Linus Pauling's accusations?) is the best source I've found on-line for vitamin side effects. Here is their list:
Late symptoms of severe overdose (emerge after months or years of starting supplements)
High blood pressure
High fever
Irregular heartbeat
Stomach pain (severe)
Check with your doctor as soon as possible if any of the following side effects occur:
Early symptoms of overdose (emerge within days or weeks of starting vitamin D supplements)
Bone pain
Constipation (especially in children or adolescents)
Diarrhea
Drowsiness
Dryness of mouth
Headache (continuing)
Increased thirst
Increase in frequency of urination, especially at night, or in amount of urine
Irregular heartbeat
Itching skin
Loss of appetite
Metallic taste
Muscle pain
Nausea or vomiting (especially in children or adolescents)
Unusual tiredness or weakness
Late symptoms of overdose (emerge within weeks or months of starting supplements)
Bone pain
Calcium deposits (hard lumps) in tissues outside of the bone
Cloudy urine
Drowsiness
Increased sensitivity of eyes to light or irritation of eyes
Itching of skin
Loss of appetite
Loss of sex drive
Mood or mental changes
Muscle pain
Nausea or vomiting
Protein in the urine
Redness or discharge of the eye, eyelid, or lining of the eyelid
Runny nose
Weight loss
Stories can be more helpful than lists. The best case history I know of is from an outstanding book called “The Right Dose, How to Take Vitamins and Minerals Safely.” A family of ten all drank regularly from a condensed milk product given to them by a friend. This condensed milk turned out to be a product used commercially by the milk industry to fortify milk with vitamin D. The family members were, on average, most likely taking somewhere between 50,000 and 100,000 IU/day of vitamin D. Here is the relevant excerpt from the case report:
“A male patient was admitted to the Dept. of Pediatrics of the Cook County Hospital because of nausea, vomiting, weight loss, and abdominal pain. Anorexia began three weeks prior to admission, followed by vomiting which was associated with vague intermittent abdominal pain. During the week prior to admission, he started to have severe nausea with frequent vomiting and was unable to attend school. He lost 11 pounds of weight during this period. Muscle weakness and frequency of urination were noted. The child’s 35 year old mother was admitted simultaneously, with severe abdominal pain, anorexia, vomiting, and weight loss of two weeks’ duration. The patient was thin, moderately dehydrated, and appeared chronically ill.”
This case report was a fantastic piece of good luck. Obviously, an experiment like this can’t be designed. It had to happen by accident. The reason it was such good luck, was that it also illustrates why vitamin D toxicity is so controversial. Eight other members of this same family took similar levels of vitamin D over this period and “did not become ill”. Eighty percent of this family was able to take between 50,000 and 100,000 IU of vitamin D for 6 weeks with no ill effects. No wonder the two patients kept on drinking the milk long after they fell seriously ill. Why would they suspect the “condensed milk” when everyone was drinking it and was fine?
According to the book, the symptoms in the case report are “classic signs” of vitamin D overdose. Here’s the write-up on the full list of classic symptoms:
“Nausea, vomiting, loss of appetite, headache, dry mouth, abdominal or bone pain, and dizziness are the classic symptoms of vitamin D toxicity. As the condition progresses, signs of impaired kidney function, such as excessive urination, may arise. Itching, calcification of organs and blood vessels, osteoporosis, and seizures are still other signs that develop at the later stages.” Note the excellent overlap with the more comprehensive list from the Mayo Clinic.
Readers are never going to take 50,000 to 100,000 IU per day of vitamin D. No one recommends sustained doses in this range. So, what’s the best evidence that doses in the range of normal can also be toxic? The best evidence comes from the experience of the British physicians who worked out the recommended daily doses for vitamin D back in the 1930’s and 1940’s. Rickets among babies and toddlers was a major problem in England before the milk supply was fortified with vitamin D. Today, one cup of milk is fortified with 100 IU of vitamin D. The British started out with by fortifying milk at about double this level (200 IU per cup). The program succeeded in eliminating rickets among families that drank fortified milk. Unfortunately, the program made significant numbers of children ill and had to be adjusted down to the current level. Tragically, the present dose doesn’t protect all children from rickets.
The problem with milk fortification is that not only is there a wide range of sensitivity to vitamin D, there is also a wide range of intake. In my opinion, this data suggests that sensitive individuals develop vitamin D side effects from daily use of 1000 to 2000 IU of vitamin D. For example, my son drinks an average of 2 to 3 quarts of milk every day. This means he gets between 800 and 1200 IU of vitamin D from milk and then probably averages over the course of the year another 400 IU/day from sun exposure. The babies in Britain showing up with vitamin D side effect were probably getting plenty of sunshine and drinking plenty of fortified milk. My sense that 1000 to 2000 IU regularly causing side effects was reinforced by a thorough internet search for advice on vitamin D supplement programs from clinicians who help clients put together supplement programs. I found several clinician reports of 2000 IU/day doses leading to problems after months of use.
If you’ve been reading my column, and reading the information at the Vitamin D Council website, you’ll know that 1000 to 2000 IU/day is often not enough. So, the hard facts are that there is no known dose of vitamin D that provides everyone with full benefits without causing anyone side effects.
I read all the information summarized above before I started taking vitamin D. Sadly, this information about specific symptoms was not very useful to me. What was most useful to me was what I read between the lines. I felt that the words of advice from experienced clinicians expressed a deep-seated unease with vitamin D supplements.
With that unease in mind, I chose to supplement with 4000 IU per day of vitamin D, fully expecting to experience side effects. So, from here on the story is based on my personal experience. It will take time to tell how relevant my experiences have been.
I have not experienced any symptoms bad enough to require any treatment, or to cancel any plans, or even to go to bed early. I experienced no side effects for three months at 4000 IU/day. For the past 10 months I’ve been alternating between vitamin D abstinence for 1 to 2 weeks and supplementation for 1 day. Some of the time I supplement by sunbathing in shorts at noon for 30 minutes to 1 hour. Some of the time I take a 1000 IU tablet. Every time I supplement I experience side effects. So, I’m confident that for me, the following side effects are caused by vitamin D. I'm updating this item in early April, 2009. For the past 6 months I have gotten all my vitamin D from sunshine. I lie in the sun at noon for between 10 and 20 minutes 9 out of ten sunny days here at latitude 40 N. Many claim that there is insufficient UV intensity at 40 N in the winter to produce vitamin D. My experience strongly suggests that this view is incorrect.
1) Irritable lungs. For example, when I breath in alcohol vapors I need to cough. When I drink my coffee in the morning I need to cough (probably a reaction to the caffeine).
2) Sensation in the teeth. I feel my teeth. I can’t decide if this is good or bad. What is definitely bad is that when I switch from warm food to a cool drink I get nasty electric shocks in my teeth. Rarely I have experienced tooth-ache like pain as a result of chilling my teeth with cold air or cold food. This pain lasts for 10 or fifteen minutes.
3) Bone pain in the fourth finger on my left hand. This is very strange. Often within minutes of taking a vitamin D supplement (but not from sun-bathing), I notice a slight pain in the fourth finger of my left hand and nowhere else. I first experienced this feeling while taking 4000 IU/day and, at that dose, the pain got quite severe on the last day I took that dose.
4) Nausea with fatigue. For me, this side effect is more severe from sunshine and less severe from supplements.
5) Ringing ears.
6) Chest pain and heart sensations. I find this to be the worst and most alarming side effect. It caused me to shun all forms of vitamin D for two months. I went for a full cardiac workout and blood testing. I was informed that I’m in terrific health. Like the bone pain, for me this side effect is more severe from supplements than from sunshine.
7) A bad mood. Vitamin D is known to have psychological effects. It is supposed to improve mood. I’m really uncomfortable with listing this as a side effect because it is so subjective. The other side effects are sufficient to put me in a bad mood. But my gut tells me it is worse than that and that the excess vitamin D is actually causing some depression.
The following side effects have just emerged in April 2009. They are perfectly described on the Mayo Clinic list:
8) Discharge of the eye, eyelid, and lining of the eyelid
9) Increased sensitivity of eyes to light or irritation of eyes
These early side effects are totally harmless if recognized as such and acted upon. When vitamin D supplementation is stopped, they fade away in a few days. So, it isn’t that hard to manage as long as you are willing to pay attention to how you feel and not worry about the minor discomfort.
Unfortunately, even here I have to add a word of caution. Staying out of the sun and stopping vitamin D supplements from bottles is not enough for everyone. There is a small subset of the population that drinks a lot of milk. Each cup of milk contains 100 IU of vitamin D. One quart is 400 IU – a large fraction of the 1000 IU tablets that are causing me trouble.
Every report I was able to read about vitamin D claimed that overdosing from sun exposure is unknown. This remains true. It is one of the reasons I'm overdosing. I simply can't believe that every expert writing about vitamin D side effects is wrong. Especially when for me, overdosing from the sun is easy. Amazingly, I have to conclude that almost no one has tried to overdose from the sun (avoid tanning and get into the noon sun for 10 to 30 minutes of full body exposure). I experienced a different severity order from the sun than from the supplements. The really distinctive signs – my finger and my heart – are almost unnoticeable from sun overdose. The fatigue and nausea are much worse – and much harder to say with certainty are from vitamin D and not a bad breakfast or a virus or any of the hundreds of other causes of nausea and fatigue. The only side effect with similar severity from both the sun and supplements is the feelings in my teeth. Since I first wrote this the feelings in my teeth have subsided and I rarely get shocks from drinking cold fluids. Now my eyes are more sensitive than my teeth. Maybe this will fade with time to be replaced by yet a differrent first side effect. It seems impossible to "line out" a vitamin D dose. After two years of wrestling with supplements and sunshine, I've rid myself of some of the most annoying early side effects only to have them replaced by different side effects. For whatever it is worth, I've had similar problems with niacin, B-complex, and TTFD supplements. Vitamin C is the only one of the four special nutrients - vitamin C, niacin, thiamine, and vitamin D - that I find easy to use. It doesn't surprise me that it is the most popular vitamin supplement.
Vitamin D is an amazing nutrient. Used in optimal doses, it has incredible potential for improving human health. The early side effects of vitamin D are mild and a blessing. They enable you to find the maximum dose you can take without experience the terrible side effects described in the case report. Don’t let fear of side effects stop you from enjoying the full benefits of vitamin D.