Most of what we read concerning vitamin D is about the effects of low levels of the vitamin and what that does to our bodies. What I am asked lately by my patients, however, is, Can I get too much vitamin D? What happens if I do get too much vitamin D? What are the symptoms of too much vitamin D?
Controversy surrounds vitamin D. Some medical organizations quote 20 nanograms per milliliter as the low normal blood levels. Others say the blood concentration should be no less than 30 ng/mL. Similarly, the upper normal blood levels vary from 70 to 80 ng/mL, depending on the group making the recommendation. Optimal blood levels are felt to be 50 ng/mL by many, but the Cleveland Clinic suggests that we try to obtain at least 70. According to the National Institutes of Health, vitamin D levels that measure consistently over 200 ng/mL are potentially toxic while others caution not to exceed 150 ng/mL.
In the Midwest, we experience very little sunshine. The Cleveland Clinic, in its Wellness and Prevention Course, stated, Just advise that every adult in the Midwest take 40,000 international units (IU) per day of vitamin D3 and dont even measure their levels. Everyone is low, and spending $70 for a blood level is not warranted. (Doses of vitamins are measured in international units.)
Low vitamin D blood levels have been associated with multiple sclerosis, diabetes, depression, hypertension, weak bones (osteoporosis), various cancers and more. Vitamin D can be obtained either from the sun or from supplements. It doesnt occur naturally in foods except in fatty fish and fatty liver and oils.
The Institute of Medicine recommends that adults obtain the minimum daily requirement of 600 IU of vitamin D. Remember, this recommendation is based solely on preventing disease from lack of vitamin D. It is not necessarily the optimal level needed to obtain all the benefits from more vitamin D. So how much vitamin D can we safely take?
Its Easter. Are you looking forward to those chocolate Easter eggs? As you know, a little chocolate is good, but too much of a good thing can make you sick. Having too much vitamin D (hypervitaminosis D or vitamin D toxicity) is extremely rare but it can happen and occurs in only the most extreme conditions. It has been estimated that toxicity could occur if one took 10,000 IU daily for an extended period of time. The IOM suggests that the safe upper limit of vitamin D supplements taken on a long-term basis are as follows:
0-6 months old: 1,000 IU
7-12 months old: 1,500 IU
1-3 years old: 2,500 IU
4-8 years old: 3,000 IU
9+ years old: 4,000 IU
Pregnancy and nursing: 4,000 IU
Others suggest that the adult limit should be 5,000 IU per day. Remember, this is the total intake of vitamin D from supplements, vitamins, vitamin D in calcium pills, the added vitamin D to milk or orange juice, etc.
In Midland, many if not all have found that they are indeed vitamin D deficient if their blood levels are measured. Many times, they will be given 50,000 IU per week, either orally or by an intramuscular injection, to catch up. 50,000 IUs daily for five weeks (1,750,000 IU total) is generally thought to be safe. Vitamin D is stored in fat and is kept in the body for long periods. Toxicity reports can occur at about 2 million IU as the total dose. Toxicity is usually caused by mega-doses of vitamin D supplements, not by diet or sun exposure.
The main abnormality from excessive vitamin D is the buildup of calcium in the blood (hypercalcemia). Symptoms can include loss of appetite, nausea, vomiting, frequent urination, kidney problems, constipation, dehydration, fatigue, irritability, muscle weakness, excessive thirst and high blood pressure. These are all rather non-specific symptoms and can be attributed to almost any condition. (Doesnt it almost sound like one of the ads on TV where they list an encyclopedia of possible adverse effects of a particular drug?) The diagnosis of vitamin D toxicity is confirmed by documenting high blood calcium levels.
You are at greater risk of vitamin D toxicity if you have liver or kidney conditions, or if you take certain types of water pills (thiazide-type diuretics).
Vitamin K deficiency can also increase the likelihood of vitamin D toxicity. Vitamin D increases calcium absorption. Vitamin K helps direct the deposition of calcium in the right spot into the bones, not the artery walls (atherosclerosis). Vitamin K can be taken as a supplement but is also found in green leafy vegetables, collards, parsley, green lettuce, broccoli, Brussel sprouts, kale, spinach, scallions, asparagus, cabbage, prunes, cucumbers and fermented dairy.
An important consideration is that vitamin D levels and requirements vary for genetically variant populations. Different ethnic groups most probably have different tolerances and different optimal levels for vitamin D.
Many are appropriately taking vitamin D supplements, although the final recommendations and the values are still being debated. Toxicity is a potential problem but judging from the scientific literature it is extremely rare and there is a large range of safety if taking the normally recommended supplement amount. Following the guidelines reviewed here should keep everyone safe.
So, just like the chocolate Easter candies, enjoy some, but not too much. So it is with vitamin D.
Happy Easter, everyone!
Dr. John L. Pfenningers office, Medical Procedures Center, is located in Midland.
Read more here:
A Word from Dr. Pfenninger What happens with too much vitamin D?| - Midland Daily News
