Vitamin D deficiency accumulated throughout the year can be partially or even completely corrected in some patients during the summer “but only if UVB exposure is sufficient; even in sunny areas, the deficiency may persist if there is sun protection, darker skin, obesity, advanced age, or habits that limit sun exposure,” José Esteban Jódar Gimeno, specialist in endocrinology and nutrition physician at University Hospital Quironsalud in Madrid, Spain, told El Médico Interactivo, part of the Medscape Professional Network.

The vitamin D deficiency currently observed may be due to the fact that modern lifestyles reduce cutaneous synthesis — due to factors such as more indoor time, less sun exposure, sunscreen use, skin aging, obesity, malabsorption, certain diseases, or the use of certain medications. Furthermore, the specialist explained, “In Europe, food fortification is limited and the diet provides little vitamin D, which maintains a high prevalence of insufficiency and deficiency.”

Balance

When it comes to striking a balance between sun exposure and vitamin D synthesis, the endocrinologist noted that this can be achieved through sensible, nonexcessive sun exposure, avoiding sunburn — because UVB radiation sufficient to produce vitamin D also increases the risk for skin cancer. The practical key is that synthesis depends on many factors, so the balance must be tailored to the individual and not based on a one-size-fits-all rule. In any case, one should aim for suberythemal exposure of about 15 minutes by exposing the arms, legs, or back outside of peak risk hours.

Recommended vitamin D levels have not been lowered. What has changed is the recognition that the level needed for bone health may differ from the higher levels sometimes proposed for nonskeletal benefits. For the general population, sufficiency is at least 20 ng/mL, while bone health targets are often set at 30 ng/mL, and some experts suggest 30-40 ng/mL for broader health benefits.

Lifestyle

Gimeno noted that maintaining adequate vitamin D levels through lifestyle involves a balance of sensible sun exposure, a diet with natural or fortified sources, healthy weight, and time spent outdoors. For about half the population, those measures are enough. For the rest, supplementation may be needed based on individual risk. Patients with obesity or reduced bioavailability often require higher doses to reach the same serum level.

Supplements are primarily indicated for people with a documented deficiency; at high risk, such as during pregnancy and lactation; those with malabsorption, obesity, chronic kidney disease; the elderly; people who have had falls, fractures, or osteoporosis; some patients with limited sun exposure; and groups at higher clinical risk for deficiency.

Meanwhile, the nonskeletal benefits are more evident in patients with true deficiency, not in the general population with adequate levels, where 25-hydroxyvitamin D levels exceed 30 ng/mL.

Duration of Treatment

Thus, to correct a deficiency, loading regimens or treatment lasting several weeks are used, followed by maintenance therapy. As detailed by Gimeno, the revised guidelines outline 6- or 8-week regimens for initial correction, followed by individualized maintenance. In patients with persistent risk or an uncorrectable underlying cause, treatment is typically prolonged or chronic, with adjustments based on levels and clinical context. “Something similar to what we do when treating hypothyroidism or any other endocrine deficiency,” noted Gimeno, who added that “we do need to correct deficiencies, but we don’t need to supplement everyone. The best strategy is to tailor treatment based on risk, baseline level, clinical goal, and the actual possibility of safe sun exposure.”

Gimeno disclosed no relevant financial relationship. 

This story was translated from El Médico Interactivo on Univadis, part of the Medscape Professional Network.