(NaturalHealth365) When it comes to vitamin D, medical doctors, dietitians and researchers all seem to agree. Not only is the “sunshine vitamin” indispensable for strong bones and teeth, immune system function and heart health, but it also can help prevent serious diseases, including cancer. But, when it comes to recommendations for vitamin D supplementation, confusion and contradiction reign.

Fortunately, a new study provides valuable information about just how much vitamin D to take in order to reach optimal levels. Keep reading to learn more.

Current vitamin D recommendations vary wildly

According to the Institute of Medicine, 4,000 IU daily is the tolerable upper level of intake – defined as the highest level that would be unlikely to cause harm to nearly all adults. However, the Vitamin D Council recommends that adults take 5,000 IU of the vitamin a day.

Meanwhile, a naturopathic practitioner might advise dosages in the area of 8,000 IU of vitamin D a day, depending on the individual’s history and lifestyle, while The Endocrine Society Practice Guidelines maintain that adults can safely take up to 10,000 IU a day – more than double what the IOM advises as the safe upper level.

Although these bewildering variances can certainly make it hard to arrive at the right vitamin D dosage, a brand-new scientific study published in Dermatoendocrinology is helping to clarify the matter.

Specific variables dictate the body’s response to vitamin D

The year-long study involved 3,882 participants, with an average age of 60. 27.5 percent were obese, 37 percent were overweight, 35.5 percent had normal BMI, and less than 1 percent were underweight – roughly similar to a breakdown of the general population.

The participants were told to take vitamin D3, also known as cholecalciferol – the same form produced by the body in response to sunshine. The average dosages of vitamin D increased throughout the year – from 2,106 IU to 6,767 IU – and the participants’ average vitamin D levels increased from 34.8 nanograms per milliliter to 50.4ng/ml.

Healthy levels of vitamin D are defined as 40 ng/ml or above, while under 20 ng/ml is considered a deficiency.  Levels of 50 ng/ml to 80 ng/ml are considered optimal.

The researchers found that changes in levels depended on dosage, body mass index, and vitamin D levels at the beginning of the study. For example, they found that as body weight rose, response to vitamin D became less. In other words, obese participants required the largest amount of supplementation to reach sufficient levels, with normal-weight and underweight participants requiring the least.

Researchers also found that people with vitamin D deficiencies experienced greater increases in vitamin D levels than those who had sufficient levels of the vitamin to begin with.

And, researchers were able to determine which dosages were effective for increasing levels.

People with normal body mass index needed 6,000 IU of cholecalciferol (D3) a day to reach levels over 40 ng/ml. Overweight individuals needed 7,000 IU daily to reach the same level, while obese participants needed 8,000.

The team also noted that they saw no evidence of side effects or vitamin D toxicity, indicated by hypercalcemia – or excessive calcium in the blood – fatigue, lack of appetite, abdominal pain, frequent urination and excessive thirst.

Warning: Vitamin D deficiency raises risk of Alzheimer’s disease

According to recent research, those with levels of vitamin D lower than 10 ng/ml have a 122 percent higher risk of Alzheimer’s disease. Other conditions associated with poor vitamin D status include Parkinson’s disease, multiple sclerosis, cancer, depression and respiratory infections.

In addition, a recent study shows that people with vitamin D levels below 20 ng/ml are at increased danger of muscle injury, including hernias and strains.

And, just as deficiencies can cause susceptibility to disease, raising levels to optimal have a protective effect.

Studies have shown that a vitamin D level of 40 ng/ml or higher is associated with a 67 percent lower risk of developing cancer – when compared to under 20 ng/ml. Ironically, 20 ng/ml is what has been recommended as sufficient by the Institute of Medicine since 2010.

In other studies, researchers found that the risk of colorectal cancer and prostate cancer are reduced by 30 to 50 percent when vitamin D status is improved.

Vitamin D supplementation is as effective as a flu shot

When it comes to warding off acute respiratory infections and flu, vitamin D – which produces over 200 antimicrobial peptides – is a proven ally.

In a recent study at Queen Mary University in London, researchers found that regular cholecalciferol (D3) supplementation was as effective as a flu shot when it came to protecting against risk of acute respiratory infection.

A simple blood test can help you determine if – like 40 percent of Americans – you’re at risk of vitamin D deficiency. Vitamin D can be obtained through sunlight – at least 20 minutes several times a week – or taken as a supplement. You can also obtain vitamin D from free-range eggs, wild-caught cold-water fish and organic soy and mushrooms.

However, for optimal protection against disease, supplementation with cholecalciferol (D3) may be necessary.

Vitamin D2, the form derived from plants and found in fortified foods, is believed to be not as beneficial as vitamin D3, which is approximately 87 percent more potent when it comes to raising and maintaining vitamin D concentrations in the body.

As the study shows, correct dosage depends on body weight – as well as lifestyle habits, health history and even genetics. To create a regimen that’s right for you, check with your own healthcare provider.

Bottom line: ensuring that you have adequate levels of vitamin D3 just might be one of the most important things you can do to protect your health – and your life.

Sources for this article include:

NIH.gov