Vitamin D, the sunshine vitamin, can be found in a number of food products, particularly fortified ones, but the actual recommendation from health professionals is to get our vitamin D from sun exposure. Unfortunately, people no longer spend enough time in the sun, often because of their busy lifestyles and because there is also the warning that the sun should be avoided due to the risk of skin cancer. As a result, some 60% of the adult population in this country has a vitamin D deficiency.
Vitamin D’s main role is to help our body absorb phosphorus and calcium, which gives us healthy, strong bones and teeth. However, it does many other things as well. In fact, almost every cell in the body has a vitamin D receptor. This means that the high levels of deficiency must be addressed, which most people do through supplementation.
Guidelines on Dosing
A number of guidelines have been released about intake of vitamin D. These guidelines are frequently reviewed and changed, because so much research is still being done in vitamin D. At present, the dosing suggestions are as follows.
• According to the American Academy of Pediatrics, infants should start taking 400 IU (international unit) per day from birth through to adolescence.
• Adults must take at least 1,000 IU per day to notice an increase in their vitamin D levels
• Many experts now feel that 1,000 IU is too little and that adults should take at least 2,000 IU.
• The obese, the elderly, people with dark skin and those who, for whatever reason, do not get sun exposure should take at least 2,000 IU.
• Those with a diagnosed vitamin D deficiency should take 5,000 IU daily and then be tested again after three months, after which dosage should be adjusted.
• Pregnant and nursing mothers should take at least 2,000 IU.
Types of Vitamin D
Not only is it important to take the right amount of vitamin D, it is also essential to take the right type. Vitamin D is actually a term that is used for five different vitamins (vitamin D1 to D5). The supplement that people need is vitamin D3, which is colecalciferol. Interestingly, however, prescription grade vitamin D is actually vitamin D2, which is ergocalciferol. This is a synthetic form and is much less effective. Luckily, most over the counter vitamin D is D3, which is what is needed.
It is also very important that you check which preparation you are actually taking. For instance, a lot of people will take cod liver oil supplements, as this also contains vitamin A. However, this vitamin can cancel out vitamin D, which means that you wouldn’t actually get your daily levels.
Studies on Vitamin D Dosages
A number of studies have taken place to figure out how much vitamin D someone should take, and it seems that the jury is still out. More and more scientists do agree that 1,000 IU is insufficient. A number of specific studies exist that most medical professionals base their opinions on. The table below highlights some of these studies.
|Organization||Year||IU Recommendation||Current Thoughts|
|Institute of Medicine’s Food and Nutrition Board||1977||2000||While most agree with the IU recommendation, they also feel that the research used to make that suggestion is old and possibly incorrect.|
|Creighton University Medical Center, Omaha, Nebraska||5000||This recommendation comes from Dr. Heaney, who is one of the biggest authorities on the vitamin.|
|Vitamin D Council||5000||This recommendation is for people who generally avoid sunlight.|
|Vitamin D Council – Dr. Cannell||5000||During fall and winter months.|
|Vitamin D Council – Dr. Cannell||2000||During spring and summer months.|
Some other tests have shown that:
• 104 African American patients with a vitamin D deficiency were given 2,000 IU per day for a year. 40% of them did not raise their levels sufficiently.
• Giving people 4,000 IU for six months did help to raise levels of vitamin D.
What Is the Right Level of Vitamin D?
It is recommended that people who suspect they have a deficiency should have a blood test to find out if they do indeed have a deficiency. This will also help to determine how much they should take in supplements. Again, a number of different schools of thought exist. It is believed that:
• Optimal levels are between 50 and 70 nanograms per milliliter (ng/ml).
• A deficiency is present when levels are lower than 15ng/ml, although some professionals consider the cut off to be 20ng/ml.
• The lowest level needed for vitamin D to have beneficial effects in terms of fighting cancer is 33 to 52ng/ml.
• A study showed that levels of between 29 and 38ng/ml help to fight certain types of cancer.
While having a vitamin D deficiency is bad for your overall health, having too much of it isn’t good either. Again, there is some debate as to how much is too much. Some of the ideas are:
• 2,000 IU per day is the upper limit, which is the official health position in this country.
• 1,000 IU per day is the upper limit, which is the official health position in the United Kingdom.
• Studies show that toxicity does not happen until levels of 40,000 IU per day are exceeded.
• A study in which elderly patients were given 5,000 IU per day for a year noted no adverse effects. In fact, by the end of the study, 92% had more an average of 29.6ng/ml in their plasma, up from 11.4ng/ml at the start.
• People with multiple sclerosis have been shown to benefit from 6,000 IU per day.
Official Recommendations for Vitamin D Intake
With so much confusion out there, it is perhaps no surprise that some people are confused about how much they should take. Officially, everyone between the age of 1 and 70, including pregnant and breastfeeding mothers, should take 600 IU per day. Those over the age of 70 should take 800 IU per day. However, as the table below shows, there are some specific health conditions that may be treated differently.
|Osteomalacia caused by anti-seizure drugs||2000|
|Cancer prevention||400 to 1,100|
|Prostate cancer||400 to 1,100|
|Heart disease||200 to 2,000|
|Cognition||528 to 9,000|
|Cystic fibrosis||800 to 2,000|
|Fall prevention||100 to 15,000|
|Fertility||400 to 50,000|
|Fibromyalgia||50,000 per week|
|Fracture prevention||200 to 1,370|
|Overactive parathyroid glands||400|
|High cholesterol||300 to 3,332|
|High blood pressure||400 to 8,571|
|Low parathyroid gland activity||50,000 to 200,000|
|Inflammatory bowel disease||1,000 to 1,200|
|Chronic kidney disease||400 to 100,000|
|Mood disorders||400 to 800|
|Increasing lifespan||400 to 500,000|
|Muscle strength||20 to 600,000|
|Muscle weakness or pain||100000|
|Osteoporosis||100 to 200,000|
|Osteoporosis and cystic fibrosis||800 to 1,600|
|Osteoporosis caused by drugs||200 to 800|
|Physical performance in the elderly||400|
|Pregnancy||400 to 600,000|
|Preventing respiratory tract infections||400 to 2,000|
|Respiratory infections||2,000 per kilogram of body weight|
|Rheumatoid arthritis||50,000 per week|
|Type 2 diabetes||400 to 200,000|
|Vitamin D deficiency||1000|
Recommendations have also been released for specific health conditions in children. Healthy children over the age of one should take 600 IU per day as standard. Babies up to 12 months should take 1,000. The table below shows the IUs for specific health conditions.
|Osteomalacia caused by anticonvulsant medication||2000|
|Cystic fibrosis||400 to 10,000|
|Osteoporosis with cystic fibrosis||800 to 1,600|
|Prevention of respiratory tract infections||300 to 1,200|
|Respiratory infections||100,000 once|
|Type 1 diabetes||2000|
|Viral infections||60,000 per week|
|Vitamin D deficiency||600,000 once|
It is vital, however, to only take the dosage as prescribed by a medical professional.
Resources and References:
The Truth About Vitamin D: How Much Vitamin D Do You Need? – Vitamin D dosage. (WebMD)
How Much Vitamin D Do You Really Need to Take? – Taking vitamin D supplements. (Mercola)
How Much Vitamin D Should You Take for Optimum Health? – Vitamin D supplementation. (Authority Nutrition)
Am I Getting Too Much Vitamin D? – Possible vitamin D overdose. (Vitamin D Council)
Vitamin D Factsheet for Consumers – Information on vitamin D for consumers. (NIH.gov)
Calcium and Vitamin D: What You Need to Know – Vitamin D and calcium for strong bones. (National Osteoporosis Foundation)