Experts Explain Why Many Israelis Lack Vitamin D Despite Abundant Sunlight

Dr. Maya Rozman addresses the common question of why many people in sunny Israel still suffer from vitamin D deficiency. She explains that vitamin D is difficult to obtain from food alone, as few foods naturally contain significant amounts. The recommended daily intake for adults up to age 70 is 600 international units (IU), increasing to 800 IU for those over 70, combining diet and supplements under limited sun exposure assumptions.

Sun exposure needed to produce vitamin D varies widely depending on factors such as season, time of day, UVB intensity, skin tone, age, clothing, and duration outdoors. Darker skin requires longer exposure, and older adults produce less vitamin D in their skin. Exposure through windows or cars is ineffective since glass blocks UVB rays. Excessive sun exposure does not increase vitamin D production indefinitely but raises risks of skin aging, spots, and cancer.

Groups at higher risk for deficiency include people who rarely go outside, those who cover most of their skin, individuals with darker skin, the elderly, obese people, and those with certain digestive, liver, or kidney diseases or on specific medications. Vegans and vegetarians who avoid fish also face nutritional challenges and should verify their intake of fortified products.

Regarding supplementation, Dr. Rozman emphasizes that there is no universal dose. The need depends on age, diet, sun exposure, health conditions, medications, and blood test results. Doctors may prescribe higher doses temporarily for deficiency followed by maintenance doses. The upper safe limit for daily intake in adults is 4,000 IU unless otherwise directed. Overconsumption, usually from supplements, can cause elevated blood calcium, nausea, weakness, thirst, kidney stones, and potentially kidney damage.

Dr. Rozman advises against self-prescribing supplements or copying others' doses, highlighting the importance of medical guidance and monitoring.