Over 65? You might need 4,000 IU vitamin D daily for disease prevention

The older we get the less efficient we are at producing vitamin D

As we get older our bodies have less of the vitamin D precursor in our skin which means that we become less efficient at producing vitamin D through exposure to the sun. 

Research has shown that low vitamin D status is associated with cognitive decline, a decreased ability to perform activities of daily living and mortality. Vitamin D supplementation has also been shown to reduce the occurrence of acute respiratory tract infections by nearly 50% and improve survival rate after hip surgery. Therefore combating vitamin D deficiency is vitally important in preserving our health as we age.

There is a high prevalence of vitamin D among over 65's

Compounding the problem of not being able to produce as much vitamin D through skin exposure to the sun, elderly individuals also tend to live lifestyles that keep them indoors and lack access to information D education, as a result there is a high prevalence of vitamin D among the elderly.

Therefore recent research, published in the journal Osteoporosis International and reported on by the Vitamin D Council, sought to determine the dosage of vitamin D required to maintain optimal levels in individual over the age of 65.

A total of 305 individuals of age 65 and over were included in the study - the participants were able to walk, were living independently and were not supplementing with more than 400 IU vitamin D3 per day prior to taking part in the study.

The participants were randomly assigned to receive either 4000 IU of vitamin D3, 2000 IU of vitamin D3 or placebo every day for a period of one year.

The most accurate way to measure how much vitamin D is in your body is the 25-hydroxy vitamin D blood test. A level of 20 nanograms/milliliter to 50 ng/mL is considered adequate for healthy people. A level less than 12 ng/mL indicates vitamin D deficiency.

All participants had low levels of vitamin D at the start of the study, defined as less than 20 ng/ml. The time period over which the study was conducted allowed the participants to reach optimal vitamin D status which is defined as between 40 and 60 ng/ml.

The results were as follows:

• After 12 months:
  - vitamin D levels increased to 55 ng/ml in those who supplemented with 4,000 IU
  - vitamin D levels increased to 40.8 ng/ml among those who supplemented with 2,000 IU.
  - The placebo group’s vitamin D levels remained the same.
   
• Vitamin D levels significantly improved within one month of vitamin D supplementation in both supplement groups
   
• Between 6 and 12 months, the average 25(OH)D levels increased by 4.4 ng/ml and 2 ng/ml in the 4,000 IU and 2,000 IU supplement groups, respectively.
   
• Interestingly of the participants who were supplementing with vitamin D, the overall improvement in vitamin D status was decreased by ⅓ among overweight individuals and ⅔ in obese participants compared to those who were a normal weight.

The researchers concluded:

“After taking account of the typical average 70% compliance observed in long-term trials of vitamin supplements for disease prevention, the results of the present study suggest that daily doses of 4000 IU of vitamin D3 may be required to achieve the high plasma levels of 25(OH)D associated with the lowest risks of mortality in the observational studies.”