How Much Vitamin D is Too Much? Take This Vitamin D Quiz to Find Out!

Previous Article Next Article
December 27, 2003 | 327,162 views

There is much confusion about vitamin D and vitamin D toxicity. I encourage you to take the quiz and even pass it along to your doctor, as very few U.S. physicians are aware of vitamin D's importance.

Winter is the time of year when most of us in the United States need to be very diligent about keeping our vitamin D levels within optimal levels. I recommend that most take a high-quality cod liver oil, which is an excellent source of vitamin D, regularly from fall until early spring. However, it is essential to understand that in order to know how much vitamin D you should be taking, you should get your blood level checked. If you use beneficial products like cod liver oil without doing blood tests for vitamin D levels, you should keep the dose at one to two teaspoons per day to prevent overdosing.

This is a major point: excess vitamin D will cause, not prevent, osteoporosis and hardening of your arteries. Please be very careful with cod liver oil. If you are unable to obtain vitamin D testing, then please do not exceed one to two teaspoons of cod liver oil. So please do yourself a favor--read the article on vitamin D testing and be sure to have your level measured. As I mentioned above, nearly all physicians are not aware how to have this checked and how to interpret the normal reference ranges, so I encourage you to print out the article on vitamin D testing not only for your own records but also for your doctor so he or she can become aware of this vitally important nutrient.

The Vitamin D Council, the non-profit group that contributed the excellent quiz below, is another great resource for vitamin D information. The Vitamin D Council is a group of citizens concerned about vitamin D deficiency and the diseases associated with that deficiency. I encourage you to check out their website and sign up for their informative newsletter. Their goal is an important one: to draw attention to the problem of vitamin D deficiency through the education of professionals, the media, government officials and average citizens.

By John Jacob Cannell, M.D.
Executive director of The Vitamin D Council

1. If an otherwise healthy adult tried to kill himself by taking an entire bottle (250 capsules) of 1,000 iu cholecalciferol, which of the following would happen?

a) The person would die within 24 hours from severe hypercalcemia and widespread calcinosis.
b) If the person received intensive treatment for hypercalcemia he may survive.
c) Hypercalcemia would be severe but require only supportive treatment.
d) Such doses are called "Stoss" therapy and are occasionally used therapeutically although they do not replicate normal physiology. As most Americans are vitamin D deficient, such a one-time dose would probably be a health benefit for the majority of Americans.

The correct answer is d. One of the most recent examples is the use of stoss therapy to reduce fracture rates in the elderly (100,000 IU of oral cholecalciferol every four months for five years) by Dr. Trivedi and colleagues (University of Cambridge School of Clinical Medicine) published in the British Medical Journal. How high do you think average 25-hydroxyvitamin D levels were in the subjects after they received 100,000 IU of cholecalciferol every four months for five years? Answer: about 29 ng/ml, still mildly deficient! (Source)

2. Acute poisoning leading to rapid death from ingestion of vitamin d capsules (successful suicide attempt),

a) Has frequently been reported in the literature.
b) Has occasionally been reported in the literature
c) Has never been reported in the literature.

The answer is C, as far as we know. If you know of a report of a successful suicide attempt, accidental death or murder from overdosing on vitamin D supplements, let us know. We do know of one interesting case that demonstrates the relative safety of vitamin D. Industrial strength crystalline vitamin D was added to table sugar, either by accident or on purpose. The two men poisoned were getting about 1,700,000 IU of cholecalciferol every day for seven months. Again, they were getting at least, 1,700,000 units [440 times the Institute of Medicine's toxicity warning (LOAEL)] every day for seven months! Both got very sick but recovered. (Source)

3. True of false: water has a higher (safer) therapeutic index (the median lethal dose divided by the median effective dose) than cholecalciferol?

a) True
b) False
c) About the same

The answer is b. Although exact human studies have never been done for obvious ethical reasons, water intoxication leading to hyponatremia, cerebral edema and occasional death is common in psychiatric populations and may become evident if one drank 80 glasses of water a day, instead of eight. Heaney, et al, recently showed healthy humans utilize about 4,000 IU of cholecalciferol a day, if they can get it. 40,000 IU a day is certainly not acutely toxic. In fact, some research reported that young white humans get up to 50,000 IU from one full body summer sun exposure. (Source)

4. If a person totally avoided the sun and regularly took two standard multivitamins a day for several years, each containing 400 iu of ergocalciferol, as his sole source of vitamin d, he would,

a) Rapidly become vitamin D toxic and require medical attention for symptoms of hypercalcemia.
b) Slowly become vitamin D toxic and eventually become symptomatic.
c) Slowly develop hypervitaminosis D but remain asymptomatic.
d) Obtain a healthful vitamin D blood level.
e) Inexorably become vitamin D deficient.

The answer is e. Two standard multivitamins contain 800 IU of ergocalciferol, equivalent to about 500 IU of cholecalciferol. If you totally avoided the sun, as many dermatologists routinely recommend with impunity (so far), one would have enough vitamin D to prevent rickets and osteomalacia but would still have a suboptimal 25-hydroxyvitamin D and thus be at risk to develop numerous other chronic inflammatory diseases, not just osteoporosis. For a review of such illnesses, see Zittermann. (Source)

The key is "totally avoided the sun." Remember, most people get 90 percent of their vitamin D requirement from very casual sun exposure, like the sunlight that strikes the uncovered and unsunblocked face, arms and hands when you walk to your car. Vitamin D production in the skin is that fast. Of course, some people follow their doctor's advice and take obsessive steps to prevent sunlight from ever striking their unprotected skin. A host of chronic inflammatory diseases may await the patients who follow such advice, just as trial lawyers may await the doctors that give it.

5. Of the three medications listed below, which is the safest in overdose?

a) Vitamin D (250 of the 1,000 IU capsules)
b) Aspirin (250 of the 325 mg tablets)
c) Tylenol (250 of the 500 mg tablets)

The answer is a. In fact 250,000 IU of vitamin D at one time is used as "stoss" therapy, especially in Europe. For a review of many such studies and the doses needed to achieve toxic 25-hydroxyvitamin D levels, see Vieth. (Source)

6. Which drug has the highest (safest) therapeutic index?

a) Depakote
b) Lithium
c) Coumadin
d) Dilantin
e) Synthroid
f) Theophylline
g) Cholecalciferol

The answer is g. All of the medication listed except cholecalciferol have narrow therapeutic indices and can easily cause death in overdose. Such is not true for vitamin D and, because of the huge number of capsules needed, is not likely unless one has the industrial strength compound. See below for a sample calculation.

7. In 1997, adams and lee wrote a widely publicized paper about vitamin d toxicity in the annals of internal medicine. The adams and lee paper was accompanied by a stern editorial warning of the dangers of vitamin d written by marriott of the national institute of health. The three authors,

a) Correctly diagnosed all five of the patients
b) Were thanked by nationally acclaimed vitamin D scientists for their contributions to understanding vitamin D toxicity.
c) Showed frightening ignorance about vitamin D toxicity and appeared not to know the difference between the two standard deviation upper limit of a Gaussian distribution and levels known to reflect vitamin D toxicity.

The Adams and Lee paper and the editorial by Dr. Marriott are a continued embarrassment to the usually stellar Annals of Internal Medicine. However, the papers are instructive in that they remind us that otherwise educated and intelligent research physicians can confuse the two standard deviation upper limits of a Gaussian distribution with toxicity. For a more detailed critique, as well as several other problematic articles about vitamin D, see this link.

8. By sunbathing for a few minutes in the noonday summer sun, one can easily obtain five times the vitamin d toxicity warning (lowest observed adverse effects level or loael) of the institute of medicine's food and nutrition board.

a) True
b) False

The answer is a, at least for young whites. The IOM lists the Lowest Observed Adverse Effects Level (LOAEL) as 3800 IU for vitamin D. Studies show young whites can make between 10,000 to 25,000 IU in a single, relatively brief, sun exposure. Numerous factors affect the body's ability to make such high amounts of cholecalciferol, with age, race, latitude, clothing, season and sunblock being the main factors. (Source)

9. If humans are twice as sensitive as the most sensitive mammal tested (male rats), then a 110-pound human would have to injest 88,000 capsules (352 bottles containing 250 of the 1,000 iu capsules) of cholecalciferol in order to have a 50 percent chance of dying (ld50) from an acute overdose.

a) True
b) False

False, about 168 bottles would do it. The LD50 for male rats (the most sensitive mammal tested) is 42 mg/kg. If humans were twice as sensitive that would be an LD50 of 21mg/kg or 21,000 ug/kg or 1,050,000 ug for a 50 kg human which is 42,000,000 units or 42,000 capsules or 168 bottles of the 250 capsules of 1,000 IU cholecalciferol. [Dorman DC (1990) Toxicology of selected pesticides, drugs, and chemicals. Anticoagulant, cholecalciferol, and bromethalin-based rodenticides. Vet Clin North Am Small Anim Pract 20(2):339-352].

10) As most american blacks suffer from vitamin d deficiency, some black activists feel unwarranted fear and scare techniques about vitamin d toxicity may be racially motivated. That is, racists may be intentionally repeating and promulgating vitamin d toxicity scares in order to prevent relevant government agencies from dealing with the problem of widespread vitamin d deficiency in the black community.

a) True
b) False

True. The recent NIH conference on vitamin D was most interesting in this regard. Very few Blacks were attendees but several were helping with registration. As the conference progressed into the second day, Blacks helping with registration began to listen to the lectures and became increasingly angry as speaker after speaker pointed out how vitamin D deficiency adversely impacts the black community. One young black man told a sad story of how his infant son was recently diagnosed with rickets. Although the 1997 Food and Nutrition Board was an all-white board, most of the Blacks were angry that nothing is being done currently.

Certainly, it is true that one of the most effective ways to paralyze the government into continued inaction on the pandemic of vitamin D deficiency would be to raise false and frightening toxicity fears. However, remember that it is easy to suspect vast conspiracies, but in the end it is usually simple incompetence. That is certainly true of the mistakes I've made in my life.

11. In the most recent case of vitamin d toxicity described in the literature, a man recovered uneventfully after taking a health supplement every day for two years that contained 156,000 iu of cholecalciferol.

a) True
b) False

True. Actually, it is likely he took more than that. An industrial manufacturing error was implicated. Such reports help confirm what is known from animal data and that is that it takes a lot of vitamin D to hurt you, but it can be done. (Source)

12. One of the world's foremost authorities on vitamin d metabolism and physiology recently said, "worrying about vitamin d toxicity is like worrying about drowning when you are dying of thirst."

a) True
b) False

True. The quote is from one of the vitamin D scientists listed below. One of the problems is that there are so few vitamin D scientists in the world, that misconceptions, especially about toxicity, are the rule rather than the exception, even among medical researchers.

In 1999, Dr. Reinhold Vieth, perhaps the world's leading expert on vitamin D toxicity and metabolism, wrote a systematic and scholarly review of the world's literature debunking the hysteria surrounding fears of vitamin D toxicity. (Source)

Later, Vieth demonstrated the safety of daily dosing with 4,000 IU of cholecalciferol, a dose that exceeded the current toxicity warnings of the IOM's FNB. (Source)

Two years later, Heaney, et al, demonstrated the safety of doses up to 10,000 IU a day while also demonstrating for the first time that healthy humans utilize 3,000 to 5,000 IU of cholecalciferol a day (10 times the Institute of Medicine Food and Nutrition Board's current recommended Adequate Intake). What the human body does with such high amounts of cholecalciferol remains unknown, but we suspect Nature has a plan. (Source)

In a reply to critics of his paper, Vieth challenged anyone in the scientific community to present even a single case of vitamin D toxicity in adults from ingestion of up to 1,000 ug (40,000 IU) a day of cholecalciferol saying, "I welcome any discussion of evidence of harm with vitamin D3 (not D2) in adults at doses <1,000 ug/d." Vieth's challenge remains unanswered and his work remains unrefuted. (Source)