Vitamin D
By Mayo Clinic Staff
Vitamin D is necessary for building and maintaining healthy bones.
That’s because calcium, the primary component of bone, can only be absorbed by your body when vitamin D is present.
Your body makes vitamin D when direct sunlight converts a chemical in your skin into an active form of the vitamin (calciferol).
Vitamin D isn’t found in many foods, but you can get it from fortified milk, fortified cereal, and fatty fish such as salmon, mackerel and sardines.
The amount of vitamin D your skin makes depends on many factors, including the time of day, season, latitude and your skin pigmentation. Depending on where you live and your lifestyle, vitamin D production might decrease or be completely absent during the winter months. Sunscreen, while important, also can decrease vitamin D production.
Many older adults don’t get regular exposure to sunlight and have trouble absorbing vitamin D, so taking a multivitamin with vitamin D will likely help improve bone health. The recommended daily amount of vitamin D is 400 international units (IU) for children up to age 12 months, 600 IU for ages 1 to 70 years, and 800 IU for people over 70 years.
Evidence
Research on vitamin D use for specific conditions shows:
Cancer. Research suggests that vitamin D, especially when taken with calcium, might help prevent certain cancers.
Cognitive health. Early research suggests that vitamin D might play a role in cognitive health. In one small study of adults age 60 years and older being treated for dementia, researchers found that taking a vitamin D supplement helped improve cognitive function.
Inherited disorders. Vitamin D supplements can be used to help treat inherited disorders resulting from an inability to absorb or process vitamin D, such as familial hypophosphatemia.
Multiple sclerosis. Research suggests that long-term vitamin D supplementation reduces the risk of multiple sclerosis.
Osteomalacia. Vitamin D supplements are used to treat adults with severe vitamin D deficiency, resulting in loss of bone mineral content, bone pain, muscle weakness and soft bones (osteomalacia).
Osteoporosis. Studies suggest that people who get enough vitamin D and calcium in their diets can slow bone mineral loss, help prevent osteoporosis and reduce bone fractures.
Psoriasis. Applying vitamin D or a topical preparation that contains a vitamin D compound called calcipotriene to the skin can treat plaque-type psoriasis in some people.
Rickets. This rare condition develops in children with vitamin D deficiency. Supplementing with vitamin D can prevent and treat the problem.
Without vitamin D your bones can become soft, thin and brittle. Insufficient vitamin D is also connected to osteoporosis and some types of cancer. If you don’t get enough vitamin D through sunlight or dietary sources, you might need vitamin D supplements.
Safety and side effects
Taken in appropriate doses, vitamin D is generally considered safe.
However, taking too much vitamin D can be harmful. Children age 9 years and older, adults, and pregnant and breast-feeding women who take more than 4,000 IU a day of vitamin D might experience:
Nausea
Vomiting
Poor appetite
Constipation
Weakness
Weight loss
Confusion
Disorientation
Heart rhythm problems
Kidney damage
Interactions
Possible interactions include:
Aluminum. Taking vitamin D and aluminum-containing phosphate binders long term might cause harmful levels of aluminum in people with kidney failure.
Anticonvulsants. The anticonvulsants phenobarbital and phenytoin (Dilantin, Phenytek) increase the breakdown of vitamin D and reduce calcium absorption.
Atorvastatin (Lipitor). Taking vitamin D might affect the way your body processes this cholesterol drug.
Calcipotriene (Dovonex). Don’t take vitamin D with this psoriasis drug. The combination might increase the risk of too much calcium in the blood (hypercalcemia).
Cholestyramine (Prevalite). Taking this weight-loss drug can reduce your absorption of vitamin D.
Cytochrome P450 3A4 (CYP3A4) substrates. Use vitamin D cautiously if you’re taking drugs processed by these enzymes.
Digoxin (Lanoxin). Avoid taking high doses of vitamin D with this heart medication. High doses of vitamin D can cause hypercalcemia, which increases the risk of fatal heart problems with digoxin.
Diltiazem (Cardizem, Tiazac). Avoid taking high doses of vitamin D with this blood pressure drug. High doses of vitamin D can cause hypercalcemia, which might reduce the drug’s effectiveness.
Orlistat (Xenical, Alli). Taking this weight-loss drug can reduce your absorption of vitamin D.
Thiazide diuretics. These blood pressure drugs might decrease urinary calcium excretion. This could lead to hypercalcemia if you are taking vitamin D.
Steroids. Taking steroid mediations such as prednisone can reduce calcium absorption and impair your body’s processing of vitamin D.
Stimulant laxatives. Long-term use of high doses of stimulant laxatives can reduce vitamin D and calcium absorption.
Verapamil (Verelan, Calan). Avoid taking high doses of vitamin D with this blood pressure drug. High doses of vitamin D can cause hypercalcemia, which might reduce the drug’s effectiveness.
https://www.mayoclinic.org/drugs-supplements-vitamin-d/art-20363792
After reading all those warnings, I’m afraid to keep taking it.
Thanks for posting that. One side effect I have with higher doses of Vitamin D is insomnia. Once I start having insomnia I start dialing back my Vitamin D intake for a couple days. Seems to work. Also, I try to take it in the morning as there has been evidence that it intersects with your melatonin production.
My reaction was about the antagonists to bone health, something even doctors take for granted (the public is oblivious).
For example, drug & alcohol use, including pharmaceuticals, combined with poor gut health (low absorption) and kidney function (same).
There’s also another factor pertaining to hormonal imbalance which I believe triggers the body to sap calcium from the bones, but they probably won’t figure out that one for another few decades (if ever; no money in prevention). I can’t recall if they have a scientific name for that factor, but they do for the effects: Rickets/Osteomalacia. Thyroid health is a biggie, something which I believe pertains to a majority of the population (most people I speak with have more than a few symptoms of impaired thyroid health which shouldn’t be ignored, but they do anyway...until an unpleasant symptom expresses).
Cortisol is the one hormone many people fail to grasp/understand, as it’s not just “stress”. I’m a heavy critic of crossfit training as a non-athletic lifestyle to maintain health. I do not believe the elevated cortisol levels are healthy and if you look for it there’s evidence to support that assertion.
The only people who need D2/D3 are those who live in northern latitudes due to lack of sun exposure. Seasonally I take it from time to time, but certainly not for anything related to bone health. Others who have a perceived need are probably for other reasons which should be explored, not masked by consuming a supplement (symptoms are markers for investigation; who paints over dry rot?).
True story: When I realized I had an imbalance of D years ago it was after I responded to one of those radio commercials about a free trial (something I almost never do). After a bit of research, I called and took them up on it. I realized no perceived benefit from the 30 days of the D3, but the following year I had been struggling with fatigue (this was prior to my health recovery when I was a hormonal wreck. Male, btw).
I was engaging a yard project and realized in retrospect after working 2 days in the sun (WITH a shirt) I felt energized. It was like I plugged into some recharging station. 2 weeks later the fatigue returned and I worked in the yard for a mere 2 hours this time: Same recharging results. In hindsight, I now know that I had a combined hormonal imbalance, poor kidney function and lousy absorption due to gut issues. I haven’t had the need to take D for several years now, but it’s in my cupboard if I start feeling the fatigue (unless I have some work to do outside).
To be clear, I am a proponent of real food and “real food supplements” and opponent of ingestion the prior PLUS USP and pharmaceutical chemicals for either prevention or symptom abatement without first investigating other factors (good luck doing that with an orthodox “doctor”).
Self-medication can be more dangerous than doing nothing at all, the result suddenly presenting after decade(s) of progressive damage.
Pertinent supplemental information since most people don’t have a clue the complex biological processes behind what supplement manufacturers proffer to fix with “a pill” (sorry for not formatting...too busy):
Vitamin D is a fat-soluble vitamin. It exists in four different forms: cholecalciferol, calcifediol, calcitriol, and ergocalciferol.
Forms of Vitamin D
Cholecalciferol: This form is also called vitamin D3, and it’s made from cholesterol in your body when your skin is exposed to ultraviolet light. For most of us, it takes about 5 to 30 minutes of sun exposure two days each week to make sufficient amounts of vitamin D though it varies based on weather conditions and time of year. Cholecalciferol is not biologically active; it has to travel through your bloodstream to the liver where is it converted into another form of vitamin D called calcifediol.
Calcifediol: The storage form of vitamin D is called 25-hydroxyvitamin D or calcifediol. It’s also the form of vitamin D that’s measured in blood tests when your health care provider wants to determine when you have symptoms of vitamin D deficiency. If your calcidiol levels are low, you may not be making enough vitamin D, which can lead to a softening and weakening of your bones. In children, this is called rickets and in adults, it’s called osteomalacia. Osteomalacia can result in osteoporosis.
Calcitriol: Your kidneys take calcifediol and convert it to the biologically active form of vitamin D called 1,25-hydroxyvitamin D, or calcitriol. This kind of vitamin D promotes calcium absorption and helps balance the blood levels. It also has a role in normal cell growth and nerve and muscle function. Calcitriol is also necessary for a healthy immune system and may help to reduce inflammation. Your body regulates your blood levels of calcitriol very carefully, so it isn’t a proper form for testing or monitoring vitamin D deficiency. In fact, calcitriol levels may remain normal while calcifediol levels begin to drop.
Ergocalciferol: Vitamin D2, or ergocalciferol, is similar to cholecalciferol, but it’s the form of vitamin D synthesized in plants. Your liver can convert ergocalciferol to the calcifediol. It isn’t converted to calcidiol as efficiently as cholecalciferol, but it appears to be sufficient for use as a dietary supplement.
Where Does Vitamin D Come From?
Vitamin D isn’t found in many foods unless they have been fortified, such as milk, yogurt, soy milk and breakfast cereals. Small amounts of vitamin D are found in oily fish and beef liver.
Your body makes vitamin D when your skin is exposed to the ultraviolet B (UVB) rays in sunlight. About 5 to 30 minutes of exposure to the skin on your face, arms, back or legs (without sunscreen) two times every week is enough.
But, too much exposure to sunlight is a risk for skin cancer, so you should use sunscreen after a few minutes in the sun, even on hazy or cloudy days.
The amount of exposure also depends on the time of the year. In the northern hemisphere, the UVB rays are more intense during the summer months and less intense during the winter months. In fact, if you live north of the 42-degree latitude, you’ll have a difficult time getting enough sun exposure from November through February.
Picture a map of North America. If you live north of a line drawn on a map from the northern border of California to Boston, Massachusetts, you will probably need to get more vitamin D from the foods you eat (or from supplements) during the winter months, even if you do go outside every day.
The intensity of UVB rays is also reduced by clouds and pollution. The UVB rays will not travel through glass so sitting next to a window will not give you enough sunlight to make vitamin D.
Why Do You Need Vitamin D?
Your body needs vitamin D to absorb and utilize calcium, which keeps your bones and teeth strong, and is essential for normal blood clotting and muscle and nerve function.
A vitamin D deficiency can happen if you don’t get enough sun exposure, if your kidneys cannot convert the storage form to the active form, or if you can’t absorb vitamin D from due to problems with your digestive system. A chronic lack of vitamin D leads to weakened bones and diseases called rickets in children and osteomalacia in adults.
Thanks!
“However, taking too much vitamin D can be harmful. Children age 9 years and older, adults, and pregnant and breast-feeding women who take more than 4,000 IU a day of vitamin D might experience:”
Nausea - Nope, not since the last time I went drinking with Kavanaugh.
Vomiting - Ditto.
Poor appetite - that has NEVER happened to me.
Constipation - coffee fixes that, but it usually isn’t an issue.
Weakness - nah, I benched 200 pounds just before hitting 57 earlier this year, and had only been working out for a few weeks.
Weight loss - Oh, HELL no - see “Poor appetite.”
Confusion - About what? Where? When? I’m writing to President Reagan about this!
Disorientation - only when drinking with Kavanaugh.
Heart rhythm problems - keeps ticking, no problems.
Kidney damage - nope, keep peeing just fine, no issues.
Oh, yeah, and I take between 5,000 and 10,000 IU per day.
In all seriousness, I’d love to know who sponsored this meta-study - some drug company that makes a calcium-enhancing drug?
BTW, I take Vitamin D primarily for the impact on my immune system - and it has been damned effective, I’ve barely been sick for years, despite my kids coming home after exposure to every bug in the world at school.