New Delhi: Updated Endocrine Society guidelines released this week recommend that healthy adults refrain from testing for vitamin D or taking supplements until age 75 amid growing concerns about overuse of sunshine vitamin supplements and overdiagnosis of deficiency.
The guidelines call for limiting vitamin D supplementation above the recommended daily intake to certain risk groups, such as children aged 1 to 18 years to prevent rickets and reduce the risk of respiratory infections, and pregnant women to reduce the risk of maternal and fetal complications.
In the United States, the recommended daily intake of vitamin D for everyone ages 1 to 70 is 600 IU (international units), but for people age 70 and older, the recommended daily intake of this important vitamin is 800 IU.
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The guidelines, presented for the first time on June 3 at the Endocrine Society’s annual summit in the US, recommend supplementation with 25-hydroxyvitamin D. [25(OH)D] Giving vitamin D, the scientific name for vitamin D, to adults over 75 years of age reduces the risk of death and lowers the risk of type 2 diabetes in people with prediabetes.
Headquartered in the United States, the Endocrine Society is the largest and oldest scientific network of hundreds of endocrinology-related researchers worldwide and regularly publishes evidence-based recommendations on metabolism and endocrinology.
Vitamin D is a fat-soluble vitamin that is important for bone growth and development, increased resistance to certain diseases, and aiding in the absorption of calcium and phosphorus. The human body produces vitamin D naturally when exposed to direct sunlight, but it is also found in a limited number of foods, including oily fish, liver, and egg yolks.
This updated recommendation comes against the backdrop of various studies showing associations between serum vitamin D concentrations and a range of common diseases, including musculoskeletal, metabolic, cardiovascular, malignant, autoimmune and infectious diseases.
“There is growing epidemiological evidence showing an association between low levels of vitamin D and a number of diseases. Hence, in the guidelines, we sought to survey the literature to determine where the clinical trial evidence on this is,” Dr Marie B DeMay, professor of medicine at Harvard Medical School and lead author of the guidelines, told ThePrint in an email.
The researchers found no clinical trial evidence to support routine screening for vitamin D in the general population, obese individuals, or people with dark skin, nor was there clear evidence to define optimal target levels for disease prevention in the populations considered.
“The Committee therefore suggests against routine vitamin D testing in all populations considered,” the authors noted.
Read also: Vitamin D deficiency worsens in Indian cities as people hide from the sun
Interventions for specific subgroups
The Scientific Committee notes that due to the scarcity of natural food sources rich in vitamin D, empirical supplementation is possible in certain risk groups by combining fortified foods with vitamin D-containing supplements.
However, while the committee does not recommend routine vitamin D testing for healthy adults without an established indication, it also noted that these recommendations do not replace current daily vitamin D intakes or apply to people with an established indication for vitamin D treatment or testing.
The guidelines say more research is needed to determine optimal vitamin D levels for specific health benefits.
“Everyone should adhere to the daily intake recommended by the US Institute of Medicine (now the National Academy of Medicine). If the recommended intake cannot be achieved through diet, supplements should be used in certain risk groups,” DeMay told ThePrint.
Why India needs to see it in context
Several new studies in India suggest that the reference ranges used for vitamin D testing – which mimic those used in Western countries – may not be appropriate due to differences in ethnicity and skin pigmentation.
In most countries, a serum/plasma 25(OH)D concentration below 75 nmol/L (or 30 ng/ml) is considered vitamin D deficient, but a multicenter study by Indian researchers published last year found that according to this criteria, approximately 98% of Indians are vitamin D deficient, which may not reflect the actual situation.
These findings over the past few years have led to growing calls among clinicians and researchers to develop vitamin D reference values specific to the Indian population.
Some experts ThePrint spoke to said that while the latest guidelines contain important messages, they also have certain limitations.
Dr Mohit Sharma, senior endocrinology consultant at Amrita Hospital, Faridabad, said reliance on randomized controlled trials in populations who typically have adequate baseline 25(OH)D levels (31 ng/mL), for example, raises concerns.
“These studies may not adequately represent the benefits of vitamin D in populations with lower baseline levels and may underestimate the effectiveness of supplements,” he said.
Second, Sharma added that although the guidelines recommend supplementation for children, the elderly, pregnant women, and high-risk prediabetic patients, the optimal dose cannot be identified because there is considerable variation in the doses used in the included trials.
“The lack of precise dosing guidelines may limit the scope of the recommendations in clinical practice. The guidelines also dismiss routine 25(OH)D testing due to insufficient evidence for specific target levels. This stance may overlook the benefit of testing to identify individuals with undetected deficiencies, especially in populations at risk of low vitamin D levels due to genetic or lifestyle factors,” the endocrinologist explained.
He added that while the guidelines offer a practical approach to vitamin D supplementation, limitations in the evidence base, particularly regarding baseline 25(OH)D levels and dosing, suggest that more nuanced research and individualized clinical judgment is needed in practice.
(Editing by Nida Fatima Siddiqui)
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