Older adults suffering vitamin D deficiency need higher remedial doses than younger adults, according to a new research review.
The study, Correcting poor vitamin D status: Do older adults need higher repletion doses of vitamin D3 than younger adults?, concluded that: “The doses and total time for repleting older adults with vitamin D3 appeared to be greater than for younger adults, in part due to the lower starting baseline vitamin D status.”
Oral supplementation
To ensure almost all patients receive sufficient vitamin D, a daily dose of 125 mcg (5000 IU) is required for older people, aged 65 and above, while for younger patients, below the age of 65, a rate above 50 mcg (2000 IU) was sufficient.
The results applied whether Vitamin D was taken daily or as a bolus oral supplementation. Adults classed as deficient were those with levels of 25-hydroxyvitamin D less than 75 nmol/L.
The researchers further concluded that several regimens, such as loading with a high dose (12500 mcg) of vitamin D3 and then giving 1250 mcg monthly, provide enough vitamin D3 for most patients to achieve and maintain 25(OH)D levels at or above 75 nmol/L.
According to the research review, a promising loading regimen is to provide calcidiol (25(OH)D) itself.
Since information on repletion with vitamin D2 has been published recently, the researchers decided to focus on the use of vitamin D3 from dietary supplements, prescriptions for large oral doses, and bolus dosing or injections.
Most published dosing regimens failed to achieve 75 nmol/L in almost all subjects, whether young adults (below 65 years) or older adults (above 65 years).
The authors, Susan Whiting, College of Pharmacy and Nutrition, University of Saskatchewan, Canada, and Mona Calvo, US Food and Drug Administration, noted many differences among studies, including baseline levels, endpoints, study duration, and compliance.
Adverse effects
All the studies reviewed reported that subjects were free of adverse effects, indicating that the vitamin D3 protocols were safe during the observed dosing periods.
Meanwhile, the researchers noted that: “Vitamin D insufficiency and deficiency is at epidemic proportions worldwide. In temperate countries more than half of the population is at risk and worldwide, even in tropical countries, vitamin D deficiency is a very serious concern due to changes in living and working conditions.”
Vitamin D has been shown convincingly to have many functions beyond its role in calcium and bone health, they added.
In addition to maintaining normal blood levels of calcium and phosphorus, Vitamin D aids in the absorption of calcium, helping to form and maintain strong bones. Recently, research also suggests vitamin D may provide protection from osteoporosis, hypertension, cancer, and several autoimmune diseases.
Source: Molecular Nutrition and Food Research
Title: Correcting poor vitamin D status: Do older adults need higher repletion doses of vitamin D3 than younger adults?
Authors: S. Whiting, M.Calvo
Seniors with higher blood levels of vitamin D are also likely to have better physical function, suggests a new study that suggests higher recommended levels may be needed to ensure muscle health.
Physical function was highest in people with the highest blood levels of 25-hydroxyvitamin D (25(OH)D) – the storage form of the vitamin in the body – while lower levels were associated with poorer physical function, scientists from Wake Forest University told attendees at the Experimental Biology 2010 meeting in Anaheim yesterday.
The study does not prove causality, however. Indeed, since we make vitamin D on exposure to sunlight, it is possible that people with better physical function have higher levels simply because they were able to get outside more often.
If future trials support the hypothesis that higher vitamin D may increase physical function in the elderly then increases in recommended intakes may be needed, said researchers led by Dr Denise Houston.
“Current dietary recommendations are based primarily on vitamin D’s effects on bone health,” she explained. “It is possible that higher amounts of vitamin D are needed for the preservation of muscle strength and physical function as well as other health conditions.
“However, clinical trials are needed to definitively determine whether increasing 25-hydroxyvitamin D concentrations through diet or supplements has an effect on these non-traditional outcomes,” added Dr Houston.
Vitamin D is well known to support muscle function, and the science supporting the link is sufficiently robust to have merited a positive opinion from the European Food Safety Authority’s (EFSA) Panel on Dietetic Products, Nutrition and Allergies (NDA).
The Panel concluded that “a cause and effect relationship has been established between the dietary intake of vitamin D and contribution to the normal function of the immune system and healthy inflammatory response, and maintenance of normal muscle function”.
Study details
Dr Houston and her co-workers analysed data from 2,788 people with an average age of 75. Blood levels of 25(OH)D were measured at the start of the study, two years later, and then again after four years. These levels were then related to the physical function of the participants, measured by a variety of tests including how quickly they could walk 6 metres, how quickly they could rise from a chair five times, and how well they maintained their balance when asked to adopt a challenging position.
Data showed that people with the highest levels of vitamin D levels had better physical function. On the other hand, of the people with the lowest physical function 90 per cent of them had insufficient or deficient levels of vitamin D, said the researchers.
Science grows
In addition to the EFSA nod of approval, science continues to emerge to support the muscle-benefits of the vitamin, including a recent study from McGill University in Canada found that insufficient blood levels of vitamin D may be associated with the accumulation of fat in muscle tissue, leading to lower muscle strength.
The findings were said to be the first to show a clear link between vitamin D levels and the accumulation of fat in muscle tissue, and were published in the Journal of Clinical Endocrinology and Metabolism (doi:10.1210/jc.2009-2309).
Data presentation
Dr Houston presented as part of the scientific program of the American Society for Nutrition at the Experimental Biology 2010 meeting in Anaheim. NutraIngredients has not seen the full data.
The researchers were affiliated with Wake Forest University, the University of Georgia, University of Pittsburgh, University of California, San Francisco, University of Tennessee, VU University, Amsterdam, and the National Institute on Aging.