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Vitamin D: Super Vitamin?

Q: My doctor checked my vitamin D levels and told me to take 1000 units of vitamin D daily. Is this a good idea?

Dr. Chris Prakash
Dr. Chris Prakash

A: Your doctor appears to be on the right track. Most of us know we need vitamin D for strong bones. Vitamin D allows your body to absorb calcium. Without it, your bones can become brittle and weak (osteoporosis).

Now it appears that this nutrient, or rather a lack of it, may play a role in several diseases. The number of research studies on vitamin D has soared in recent years (almost 4000 citations last year). The following disease associations have been postulated based on research:

  • One randomized controlled trial suggested that vitamin D supplementation reduced acute respiratory tract infections in children during the long, cold, and dark Mongolian winter.
  • Low levels of vitamin D have been linked to type1 diabetes.
  • Numerous epidemiologic studies suggest that a low vitamin D level increases the risk for cardiovascular disease.
  • Children ages 6 to 18 years who are overweight are more likely to have low vitamin D levels.
  • Vitamin D supplementation may help breast cancer survivors adhere to adjuvant treatment with aromatase inhibitors.
  • People with Alzheimer’s disease tend to have low levels of vitamin D, and better cognitive test results are linked to higher vitamin D levels.
  • Low vitamin D levels appear to be linked to the need for steroids in asthma and may also blunt the effectiveness of asthma treatment.

So, it appears that Vitamin D may be more important to our health, than we realized.

How can you get Vitamin D?

Your body produces its own vitamin D. However the trick is exposing some portion of your skin to direct sunlight for 15 to 30 minutes a few days a week. But the UV rays that stimulate production of vitamin D can also cause skin cancer. So, most experts don’t recommend getting your vitamin D from sun exposure. One way to get vitamin D is through your diet. In the U.S., nearly all milk is fortified with vitamin D, and many brands of orange juice are, too. Even ready-to-eat breakfast cereals can contain a healthy dose. Fish, especially fatty fish like salmon, tuna, mackerel, and sardines, are a good source of vitamin D. Other food sources of vitamin D include egg yolks, cod liver oil, beef liver, margarine, yogurt, and some cheeses.

What should your vitamin D levels be in the blood?

The level of Vitamin D can be checked by a simple blood test – 25-hydroxyvitamin D test, also called 25(OH) D. Ask your doctor to order the right test (not the 1,25-dihydroxy-vitamin D). Most commercial labs still state the normal range as 20 – 56 ng/ml. However, most experts believe that 25(OH) D levels should be above 50 ng/ml (125 nmol/L) year-round, in both children and adults (Bruce Hollis, Robert Heaney, Neil Binkley et al). The Vitamin D Council recommends the 25(OH)D levels should be between 50–80 ng/ml, year-round.

How much Vitamin D should you take?

This is a controversial topic, and there is a lack of consensus among experts. The recommended dietary allowance, as per Institute of Medicine is 600 IU per day for adults up to 70, and 800 IU for ages 71 or older. You should have your levels tested, and if lower than 50, you may need a higher supplemental dose to optimize the Vitamin D levels.

How Much Is Too Much?

There is an upper limit to how much vitamin D you can safely take. The Institute of Medicine recommendations for adults say that a daily intake of up to 4,000 IU of vitamin D is safe. Taking more than 10,000 IU per day can cause kidney and tissue damage. The best approach is to check with your health care provider before taking vitamin D supplements.

This information is strictly an opinion of Dr Prakash, and is not intended to replace the advice of your doctor. Dr Chris Prakash is a contributing columnist, and author of eParisExtra’s “The Doctor is In” column. He is a medical oncologist at Texas Oncology Paris. He is board certified in Internal Medicine, Oncology and Hematology. He lives in Paris, TX with his wife and two children, and can be reached at 9037850031, or

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