Apr
19
2020

What are Toxic Doses For Vitamins and Supplements?

We hear that vitamins and supplements are good for us, but what are toxic doses for vitamins and supplements?

I am going to review the common supplements of vitamin A, C, D3 and calcium. Most people have no problems sorting out the correct dose of other supplements. But these 4 are fairly contentious.

Vitamin A toxicity

Vitamin A comes in various precursors that are metabolized in the liver into the active form of vitamin A. The precursors are retinol, alpha-carotene, beta-carotene, and beta-cryptoxanthin. The FDA has suggested to label supplements with RDA’s (recommended daily allowance). This is in micrograms instead of the IU’s (International Units). 1 IU of vitamin A is 0.3 micrograms (mcg) of retinol. 1 IU of beta-carotene is 0.6 mcg beta-carotene.

Vitamin A is required for normal vision, reproduction, embryonic development, immune function and growth. The recommended daily allowance is 900 mcg (2700 IU) for men and 700 mcg (2100 IU) for women. The tolerable upper intake level for both sexes is 3000 mcg (9000 IU) of preformed vitamin A per day.

Recommended intake of vitamin A for children and adults

Recommended intake for children and adults is as follows.

  • Infants (0-6 months): 400 mcg (1200 IU) of vitamin A per day
  • Infants (7-12 months): 500 mcg (1500 IU) of vitamin A per day
  • Children 1-3 years: 300 mcg (900 IU) of vitamin A per day
  • Children 4-8 years: 400 mcg (1200 IU) per day
  • Boys and girls age 9-13: 600 mcg (1800 IU) of vitamin A per day
  • Boys age 14-18: 900 mcg (2700 IU) of vitamin A per day
  • Girls age 14-18: 700 mcg (2100 IU) of vitamin A per day
  • Men age 19 to above 70: 900 mcg (2700 IU) of vitamin A per day
  • Women age 19 to above 70: 700 mcg (2100 IU) of vitamin A per day

Symptoms of vitamin A toxicity

With too much vitamin A on board the symptoms are nausea, blurred vision, dizziness (vertigo), headaches, vomiting and lack of  muscular coordination. These symptoms are from transient effects of short-term or single large doses of vitamin A of 150,000 mcg (450,000 IU) per day. Chronic toxicity occurs when 30,000 mcg (90,000 IU) of vitamin A is ingested daily for months and years. This is more than 100-fold of the recommended daily allowance as you see from the table above. These overdoses lead to bone mineral loss in animals and humans. They also cause various cancers as described in the link above.

Evidence of toxicity from vitamin A

High doses like this are causing birth defects in the fetus of pregnant women. High vitamin A doses also cause liver fibrosis, liver cirrhosis and death. The liver is the main organ where vitamin A is metabolized and stored. It is no surprise that the liver is affected with overdoses of vitamin A. People with high alcohol intake, hyperlipidemia and pre-existing liver disease are particularly susceptible to vitamin A toxicity. Here is more information on vitamin A.

Vitamin C, what is a good supplement dose and what is an overdose?

Vitamin C was first found to be necessary to prevent scurvy in sailors. Eventually they took limes along, which contain vitamin C. A lack of vitamin C (scurvy) led to bleeding gums, painful arm and leg muscles, changes of hair growth and death from bleeding. Vitamin C supports the immune system, helps with the body’s chemical reactions to make tyrosine, carnitine, steroid hormones in the adrenal gland and neurotransmitters in the brain.

Daily recommended vitamin C allowances

Here are the recommended daily allowances (RDA) for vitamin C intake.

  • Infants 0-6 months: 40 mg daily
  • Infants 6-12 months: 50 mg daily
  • Children 1 to 13: between 15-45 mg daily
  • Boy teens age 14-18: 75 mg daily
  • Girl teens age 14-18: 65 mg daily
  • Adult men: 90 mg daily
  • Adult women: 75 mg daily
  • Pregnant women: 85 mg daily
  • Women who breast feed: 120 mg daily

Higher doses of vitamin C showed beneficial effects on the reduction of heart attacks. LifeExtension recommends a daily supplementation of vitamin C of 1000 mg to 6000 mg per day. Personally, I take 1000 mg of Esther vitamin C daily (Esther C is better absorbed than plain vitamin C). Vitamin C is eliminated from the body within 24 hours. This means that higher doses than the RDA listed above are easily handled by the body as there is no accumulation of vitamin C in the body.

Mega doses of vitamin C and adverse effects

Linus Pauling, a chemist who won the Nobel Prize in Chemistry in 1954, thought that higher doses of vitamin C would prolong life. He suggested daily doses of 2300 mg of vitamin C for maintaining good health. However, patients who have a Glucose-6-phosphate dehydrogenase deficiency can develop hemolytic anemia following intravenous vitamin C. With intermittent high dose vitamin C, often combined with glutathione for detoxification, oxalic acid is produced that shows up in the urine as hyperoxaluria. In time this can cause kidney stones with oxalic acid. Other symptoms with megadoses of vitamin C are diarrhea, reduced absorption of vitamin B12 and copper as well as iron overload. In addition, there can be acid erosions of the teeth with chewing of vitamin C tablets. Patients with kidney failure should not receive vitamin C mega doses.

Limit megadoses of vitamin C

The American Association of Poison Control Centers reported 0% deaths from vitamin C toxicity, but levels below 2000 mg per day are much safer in terms of possibly developing kidney stones. If you want to have intravenous glutathione and vitamin C infusions (typically 20,000 to 30,000 mg of vitamin C in one infusion) to detoxify you from mercury, keep the frequency of infusions at no more than once a month.

Vitamin D3 toxicity

Other publications have established that the original recommended dose of vitamin D3 by the Food and Nutrition Board of 2000 IU per day was way too low. According to this publication based on many other papers +/-10,000 IU per day should be considered the new recommendation. I have discussed the use of Mega vitamin D3 therapy for viral illnesses under this link before. Dr. Schwalfenberg stated: “This is a 1-time 50, 000 IU dose of vitamin D3 or 10, 000 IU 3 times daily for 2 to 3 days. The results are dramatic, with complete resolution of symptoms in 48 to 72 hours. One-time doses of vitamin D at this level have been used safely and have never been shown to be toxic.”

The half-life of 25-hydroxy-vitamin D3 is 15.1 days. This means that the transient elevation of 25-hydroxy-vitamin D3 will last only 5 half-lives or 75.5 days. After that time (2 1/2 months) the elevation of vitamin D in the blood from the mega vitamin D3 dose, which was taken over 3 days, is eliminated.

Safety of vitamin D3

What is known about the safety of vitamin D3, particularly the higher vitamin D3 doses? First, it is wise to have your 25-hydroxy vitamin D blood levels taken from time to time. If any of these levels exceed 200 ng/ml it would be prudent to reduce the vitamin D dose or stop supplementation for a while. Otherwise it has been difficult to establish a toxic range. There are those who claim that 40,000 IU of vitamin D3 or more would lead to toxic levels of vitamin D3. With such vitamin D3 levels the blood calcium levels would show an increase and the physician can measure this as hypercalcemia. However, another study done in 2007 showed in MS patients that took 40,000 IU of vitamin D3 per day and that led to a blood level of 400 ng/ml of 25-hydroxy vitamin D did not lead to increased calcium levels and did not lead to hypercalciuria (too much calcium in the urine).

Do not exceed your upper 25-hydroxy vitamin D level 

But you should not exceed your vitamin D3 intake so that your 25-hydroxy vitamin D level exceeds 50-80 ng/ml. This is the ideal level for vitamin D3. Most patients have to take between 4000 IU of vitamin D3 and 6,000 IU of vitamin D3 to reach this blood level. There are slow absorbers of vitamin D3 who need 10,000 IU to achieve a 25-hydroxy vitamin D blood level of 50-80 ng/ml. (I am one of those.)

Evidence did not support toxicity for higher vitamin D3 doses

All of the papers that either indicated to the public that it would be unsafe or unnecessary to take vitamin D3 seem to have other agendas than communicating the truth. Had it been true that calcium leaked from the bones or the gut leaked calcium into the blood, calcifications of the bones or soft tissues, like the heart or kidneys, would have been evident. Also, kidney stones would have developed. However, a low calcium diet combined with corticosteroid drugs usually leads to a full recovery within a month. It is interesting to note that all of the dire predictions regarding toxic vitamin D3 levels did not materialize. Here is another website discussing vitamin D3 dosing.

Anecdotal report of 500,000 IU of vitamin D3 daily for 3 months

I talked to a conference participant (who has a fellowship degree of the A4M) at an Anti-Aging Conference about vitamin D3 toxicity. He told me that a compounding pharmacist made a mistake. His patient accidentally received a dosage of 500,000 Units of vitamin D3 per day for a full three months. Only then did he discover his mistake. The patient felt sluggish, but did not have any other symptoms. The patient stopped the vitamin D3 compound. He had an uneventful recovery with no detrimental effects. Researchers were not able to establish a toxic threshold for vitamin D3. It is needless to emphasize that we should never embark in experiments with “super dosages” of any supplement.

Calcium metabolism

There has been controversy about calcium supplementation. There is a fear of causing hardening of the arteries and a fear of causing kidney stones. Yet, with not enough calcium in the system you may develop osteoporosis.

Calcium levels in the blood are very stable because of a variety of mechanisms.

  • Vitamin D3 regulates the absorption of calcium from the gut.  Vitamin D3 together with vitamin K2 deposit calcium into the bone.
  • There is parathyroid hormone (PTH), which stimulates osteoclasts to release calcium from the bones.
  • The liver and kidneys metabolize calcitriol. It is a metabolic product of vitamin D3. Calcitriol increases the absorption of calcium in the kidneys and increases calcium and phosphorus from the gut. But calcitriol also increases the calcium and phosphorus release from the bones.
  • The parafollicular cells (also called C cells) in the thyroid gland produce calcitonin, another hormone.

Actions of Calcitonin

It counters the actions of the parathyroid hormone. Calcitonin inhibits the action of the osteoclasts thus lowering calcium, which stays in the bones. It also counters the resorption of calcium in the kidneys lowering calcium blood levels. PTH, calcitonin and calcitriol control the calcium level very tightly. This ensures that there is only a minimum of fluctuations of the blood calcium level. Apart from building bones and teeth calcium is important for a regular heartbeat, for blood clotting and for muscle contractions.

Calcium supplements

If you eat balanced meals, you may not need calcium supplements. Dairy products like milk, cheese and yogurt are high in calcium. Green vegetables, Tofu, beans, nuts and seeds also give you enough calcium.

If you don’t have balance in your diet, you may need more calcium intake as calcium supplements. But don’t exceed 1000 mg of calcium citrate or calcium carbonate per day. Calcium and magnesium have to always be balanced in the body. If you decide that you should supplement with calcium, you need to also supplement with magnesium citrate 150 mg twice a day to keep your minerals balanced.

Calcium toxicity

Antacids, hand lotions, mineral supplements and other vitamin and mineral supplements contain calcium. If you eat balanced meals with dairy products and vegetables, you may not need any calcium supplements. Symptoms of calcium overdoses are headaches, abdominal pain, bone pain, confusion, depression, diarrhea, irritability, irregular heart beat and more.

If you take the occasional antacid pills, do not supplement with calcium supplements, because you already consumed extra calcium inadvertently.

What are Toxic Doses For Vitamins and Supplements?

What are Toxic Doses For Vitamins and Supplements?

Conclusion

What are toxic doses for vitamins and supplements? Vitamins and supplements come in different versions. Vitamin A supplementation should not exceed 900 mcg (2700 IU) in men and 700 mcg (2100 IU) in women. But there is a fairly wide safety margin as only 30,000 mcg (90,000 IU) of vitamin A produce toxicity in both men and women.

The American Association of Poison Control Centers reported 0% deaths from vitamin C “toxicity”, but levels below 2000 mg per day are much safer in terms of preventing the  development of kidney stones.

With regard to vitamin D3 the recommended values of vitamin D3 for people is way too low. The 25-hydroxy vitamin D level should be in the 50-80 ng/ml range. Only when these values exceed 400 ng/ml is there cause for concern. Physicians found this level in people who consumed 40,000 IU of vitamin D3 daily. These doses did not lead to an increase in calcium levels and did not lead to hypercalciuria. But researchers consider them close to toxic levels.

Finally, calcium with normal balanced nutrition does not require calcium supplementation, particularly when a person consumes antacids. If a person eats a vegan diet, you may want to add 1000 mg of calcium carbonate or citrate and have your calcium level checked with a blood test.

Incoming search terms:

About Ray Schilling

Dr. Ray Schilling born in Tübingen, Germany and Graduated from Eberhard-Karls-University Medical School, Tuebingen in 1971. Once Post-doctoral cancer research position holder at the Ontario Cancer Institute in Toronto, is now a member of the American Academy of Anti-Aging Medicine (A4M).