How Do I Figure Out How Much Vitamin D to Take?

Fresh salmon steaks
Vitamin D3

The health care community continues to debate the answer to the question "How much vitamin D should I take," and one of the only things there's agreement about is that too many people are deficient in this nutrient. Scientists continue to study whether currently prescribed daily allowances are the optimal for people of different genders, age groups and states of health.

So How Much Vitamin D Should I Take?

Some sources say that there shouldn't be a "one size fits all" recommended daily allowance for vitamin D. Some believe the ideal amount depends on gender and age, while others argue additional factors. The National Institutes of Health and the National Cancer Insitute outline a number of factors that may influence optimal vitamin D dosage. These include:

  • Body weight
  • Body mass index, or percentage of fat
  • Where fat is distributed in the body
  • Skin coloration and texture
  • Vulnerability to skin irritation or inflammation
  • Usage of sunblock
  • Amount of direct exposure to sunlight, without covering the skin or using sunscreen
  • Climate and geography
  • A person's overall health and immunity
  • Family history of cancer
  • Family history of osteoporosis
  • Family history of autism and multiple sclerosis
  • Family history of respiratory ailments
  • Family history of thyroid problems
  • Phosphorus and calcium levels in the body

Food Versus Supplements

A person's overall diet and any food allergies or sensitivities may determine how much vitamin D should be taken as supplements. The nutrient occurs in the following foods:

  • Tuna
  • Salmon
  • Herring
  • Mackerel
  • Sardines
  • Oysters
  • Cheese
  • Cream
  • Butter
  • Margarine
  • Fortified milk
  • Fortified cereals

Causes of Shortages

If you don't consume any of the aforementioned foods, it's possible you could have a deficiency in vitamin D. However, diet is only one determinant of possible shortages of vitamin D. People exhibit deficiencies of vitamin D for reasons both obvious and not. They include:

  • Not consuming enough of the nutrient
  • Having a disorder whose symptoms include inability to absorb nutrients
  • Below average body weight or percentage of fat
  • Insufficient exposure to direct sunlight, which activates vitamin D supplies in the body into useable formats

Some Numbers

According to the Office of Dietary Supplements at the National Institutes of Health, the average recommended daily allowance of vitamin D for an adult is about 600 international units. The daily allowance recommendation for seniors is a little higher at 800 international units.

Get a Blood Test First

Before you start taking any dose of vitamin D, consider getting a blood test to find out whether you have a normal quantity of the nutrient in your body. Your doctor could use the outcome of the blood test to advise you on whether you need to increase your intake of vitamin D. You might want to ask your physician to run similar assessments for all nutrients in your body using the same blood sample. Vitamins and minerals work together to promote health, so only looking at one nutrient in the body won't provide the most accurate picture. Vitamin D is stored in fat, and regulates levels of calcium and phosphorus in the body, so learning the levels of essential fatty acids, calcium and phosphorus would be helpful.

Get the Right Amount

Even the experts still ask, "How much vitamin D should I take?" It may seem confusing that the ideal amount of vitamin D in the diet is subject to debate, but the real issue is whether your body contains proper levels of the nutrient. The only way to know this definitively is to request a blood test from your physician. Once you know the vitamin D content in your body, you can adjust your intake accordingly.

How Do I Figure Out How Much Vitamin D to Take?