Understanding Vitamin D


All the vitamin D you need or a daily dose is packed in 10 minutes out in the sunshine.  Your body makes this important vitamin from sunlight on your skin.

The Role It Plays

Vitamin D’s most important role is to regulate how much calcium you absorb from your food. Most of that calcium goes to build strong bones and teeth. You also need calcium to send messages along your nerves and to help your muscles contract (like when your heart beats). Vitamin D regulates the amount of calcium in your blood and makes sure you always have enough. The immune system needs vitamin D, and it may help prevent cancer, especially colon cancer.

Types of Vitamin D

Vitamin D does things its own way. To get all the other vitamins, you have to eat them. To get vitamin D, all you have to do is go outside. The ultraviolet light in the sunshine makes a type of cholesterol that’s found just under or skin turn into vitamin D3 or cholecalecalciferol. The vitamin D3 gets carried to our liver, where it gets changed into a more active form; from there it goes to our kidneys, where it becomes even more active.  Some of the vitamin D3 stays in our liver and kidneys, where it helps absorb calcium. The rest goes to our intestines to help absorb calcium from our food. 

Vitamin D is found naturally in some foods, but in a slightly different form called vitamin D2, or ergocalciferol. Our body can use this form just as well – in fact it’s the form that’s used in most Vitamin D supplements.  Vitamin D2 is sometimes also called calcifidiol or calcitrol.  These daily supplements are made from yeast or fish liver.


Age                                        Vitamin D

0-18                                       200 IU

19-50                                     200 IU

51-70                                     400 IU

70+                                         600 IU

Pregnant Women            200 IU

Nursing Women               200 IU

Safe Dosage

Many doctors and nutritionists feel that you need more vitamin D as you get older. Men and women over age 65 should take 700 IU every day.

Do not take more than 1,000 IU of vitamin D supplements daily, it is dangerous.

If you spend a lot of time outdoors in the sun, your body automatically stops making vitamin D after you’ve stored up enough.  So you can’t overdose on yourself. However, the same isn’t true about supplements. Of all the vitamins this is the one you need to be most careful with. Large doses can make calcium build up in your blood, which can have serious consequences. Too much vitamin D might also increase your risk of a heart attack or kidney stones.

Talk to a pediatrician before giving vitamin D supplements to babies and children.

Make It Work Better

You’ll absorb vitamin D a lot better if you take it with dietary fat. Take vitamin D supplements with food.  Many studies have concluded that the relationship between estrogen, magnesium and boron may be essential in the conversion of vitamin D to its active form.  So be sure you’re daily multivitamin has the amounts you need of those supplements.

Good Sources

Many people remember the awful tasting cod liver oil but it wasn’t given as a punishment, it is a good source of vitamin D. Fish oil contains a lot of vitamin D, so get some from eating fish liver, mackerel, herring, sardines, salmon, tuna, and other oily fish. There aren’t many other foods that naturally have vitamin D. Vitamin D is added to a lot of cereals and most people get their vitamin D from fortified milk.


Rickets (bones don’t grow and harden properly) is caused by a crippling shortage of vitamin D. Without enough vitamin D, bones can’t absorb calcium to grow straight and strong.  Rickets is by far not as common as it was 150 years ago but babies who are breast fed and never get any sunshine are at risk.

If you’re an older adult, you’re only making about half as much vitamin D in your skin as when you were younger.

People who are housebound or live in nursing homes are at risk of vitamin D deficiency.

If you have kidney disease or liver disease, you can’t convert vitamin D3 into its more active form.

Some drugs block the absorption of vitamin D and other fat-soluble vitamins. Drugs such as cholestyramine (Cholybar or Questran) block your absorption. Some drugs can deplete your vitamin D level, such as, corticosteroid drugs like cortisone, prednisone, or dexamethasone for allergies, asthma, arthritis, or some other health problems. Other anticonvulsant drugs such as phenytoin (Dilantin) or Phenobarbital will interfere with how you use vitamin D.

If you’re a strict vegetarian or vegan, there is little vitamin D in plant foods so you may not be getting enough vitamin D.

Alcohol blocks your ability to absorb vitamin D in your intestines and store it in your liver. If you abuse alcohol, you may be deficient.  



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