The Miracle of Vitamin D – Toxicity Issues & Conclusion

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Krispin Sullivan, CN is a researcher, clinical nutritionist and author of Naked at Noon: The Importance of Sunlight and Vitamin D. In this extensive article, Krispin looks at the health benefits of vitamin D and how it is used in the body.

Part 7 of The Miracle of Vitamin D discusses the dangers of too much vitamin D supplementation from pharaceutical drugs. Part 7 also concludes the entire article by Krispin Sullivan.

The Miracle of Vitamin D

By Krispin Sullivan, CN

Toxicity Issues

Vitamin programs usually omit vitamin D because of concerns about toxicity. These concerns are valid because vitamin D in all forms can be toxic in pharmacological (drug-like) doses. The dangers of toxicity have not been exaggerated, but the doses needed to result in toxicity have been ill defined with the unfortunate result that many people currently suffer from vitamin-D deficiency or insufficiency.

Abnormally high levels of vitamin D are indicated by blood levels exceeding 65 ng/ml or 162 nmol/l for extended periods of time and may be associated with chronic toxicity. Levels of 200-300 nmol/l or higher have been seen in several studies using supplementation and quickly resolve when supplementation is stopped. In such cases no long-term problems have been found. Long-term supplementation, without monitoring, may have serious consequences.

Before 1993, there was no affordable and available blood test for vitamin D. Now there is. To avoid problems, anyone engaging in levels of vitamin-D supplementation above 1,000 iu daily should have periodic blood tests. Don’t forget to calculate your total vitamin-D intake from all sources-sunlight, food (including vitamin D in milk) and supplements, including cod liver oil.

Dr. Vieth suggests that critical toxicity may occur at doses of 20,000 IU daily and that the Upper Limit (UL) of safety be set at 10,000 IU, rather than the current 2,000 IU. While this may or may not be the definitive marker for safety in healthy persons with no active liver or kidney disease, there is no clinical evidence that long-term supplementation needs to be greater than 4,000 IU for optimal daily maintenance. This level would be somewhat lower when combined with exposure to UV-B.3;76

Doses used in clinical studies range from as little as 400 IU daily to 10,000-500,000 IU, given either as a single onetime dose or daily, weekly or monthly. Such large doses are given either as a prophylactic or because compliance is considered a problem. There seems to be some evidence that vitamin D works better, without toxicity, when given in lower, more physiologic doses of 2,000-4,000 IU daily rather than as 100,000 IU once a month. However, a single monthly dose of 100,000 IU did replete low levels of vitamin D in adolescents during winter.77

In my experience and that of other researchers, high, infrequent dosing can lead to problems. In one recent study, blood levels rose from low to extremely high, (more than 300 nmol/l) 2 to 4 hours after a 50,000 IU oral dose,65 and then slowly returned to pretreatment suboptimal levels. Clearly this must disrupt normal feedback mechanisms in D and calcium regulation.

Vitamin A can be administered in large, infrequent doses from consumption of animal or fish liver (or injections, used in third world countries to prevent blindness) because we have storage capacity for vitamin A in our livers. Vitamin D is different. It has only a small storage pool in the liver and peripheral fat. Our ancestors most definitely did not get vitamin D in large, infrequent doses. While vitamin D is stored in body fat, storage is not sufficient to maintain optimum blood levels during winter months.78 A single exposure to UV-B light will raise levels of vitamin D over the next 24 hours and then return to baseline or slightly higher within 7 days. Historically our requirements for D were satisfied by daily exposure to sunlight and/or daily intake from food. Lowfat diets and lack of seafood in the diet further contribute to the current worldwide insufficiency of vitamin D.

Sunlight on the Inside

If any nutrient incorporates the properties of sunlight, it is vitamin D. The healthy “primitive” peoples that Dr. Price observed not only had broad, round, “sunny” faces, they also had sunny dispositions and optimistic attitudes towards life in spite of many hardships. Typical food intakes for peoples who have not been “civilized” range from 3,000 IU-6,000 IU. Modern intakes are paltry in comparison. The standard American diet provides vitamin D only in very low quantities.

The first step towards redressing some of the ills of civilized life-from depression to road rage, from cavities to osteoporosis-would be to get more light, inside or outside. Vitamin D adds sunlight to life from childhood through the golden years. In nonagenarians and centagenarians high levels of vitamin D in the blood and normal thyroid function were the strongest markers of health and longevity.79

Whether in the form of sunlight or dietary vitamin D from food and fish oils, optimal levels of the sunshine vitamin allow your body and mind to thrive, even during periods of stress.

About the Author

Krispin Sullivan, CN is a researcher and clinical nutritionist in practice in Woodacre, California. She is currently working on a book, Naked at Noon: The Importance of Sunlight and Vitamin D, to be published in 2001.

Instructions for physician monitoring of vitamin D, calcium and magnesium repletion are available from or by contacting Krispin at or 1-415-488-9636.



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D for Deficiency « The Hopsack said:

on September 24th, 2010

[…] Clinical Nutritionist and vitamin D researcher Krispin Sullivan states that as a pro-hormone, too much supplementary vitamin D has the potential to harm. She advocates testing, treating (if necessary) and re-testing until you […]

vitamin d3 said:

on December 24th, 2010

Actually on the topic of Vitamin D I just found that these days, with the rapid growth of science and technology, performing a vitamin D test can be self-administered. It is not necessary to visit the doctor anymore to get this test performed. There are blood test spot kits available and you can take help of these kits to do it all by yourself. The finger is punctured at a spot to obtain a bit of blood on a unique kind of paper. The result is generally accurate and easy to understand. I took the home test and found I did have a minor deficiency.


vitamin d3 said:

on December 24th, 2010

Some might not know about Vitamin D but you should aim to get at least around a half hour of sunlight daily. This is because your body will naturally produce the Vitamin D the minute your body is exposed to the sun. If you normally wear sunscreen all the time, for this time frame, skip wearing it. This is because the chemicals in the sunscreen will prevent your body’s natural absorption of sunlight. Another great benefit of sunshine is that it is good at fighting fatigue and depression. If you have medium to dark skin, then you should try to stay out for 10 minutes more in the sun to receive all the benefits.


vitamin d3 said:

on December 24th, 2010

When it comes to the how vitamin D benefits the life and health of a person in many more ways than is commonly known. The ‘sunshine’ vitamin, as it is sometimes called, is commonly known for its effect on strengthening the bones and joints in the human body by aiding the absorption of calcium. It also helps the body build up immunity. Our bodies can produce vitamin D on it’s own, if we have sufficient amounts of sun (at least an hour a week). Alternatively, it can be found added to certain foods such as milk, egg yolks, fatty fish, sardines, mackerel, tuna and salmon. These vitamin d rich foods are known to be a plentiful source of omega 3 fatty acids. Cod liver oil capsules are one of the most widely used nutrient and Vitamin D dense supplements. I’ve found that adequate vitamin D levels are absolutely essential for a healthy body. I hope it helps you as much as it did for me.


ryan @ vitamin d3 said:

on December 24th, 2010

Some might not know about Vitamin D but you should aim to get at least at the very least fifteen minutes of sun on a daily basis. This is because your body will organically create the Vitamin D the minute your skin is exposed to sunlight. If you usually wear sunscreen all the time, for this time frame, skip wearing it. This is because the chemicals in the sunscreen will stop your body’s natural absorption of sunlight. Another good part of sunshine is that it is great for fighting fatigue and depression. If you have medium to dark skin, then you should try to stay out for 10 minutes more in the sun to reap the full benefits.


paganel99 said:

on April 26th, 2018

When you get into high doses (above 20000IU) you have to take Vit K; about 1000 mcg per 10000IU. My levels now are 112 and I feel fine. Ocassionally I also take the sun fo an hour or so. See The Miraculous Results of Extremely High Doses of Vitam D3.


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