Vitamin D helps the body absorb calcium and supports bone strength. Yet, according to the Cleveland Clinic, about 1 billion people worldwide lack vitamin D.
Women are slightly more affected than men, and the reasons go beyond simple diet or sun exposure.
Missed diagnosis
One major problem is that vitamin D deficiency is hard to detect.
Laura Acosta, a registered dietitian at the University of Florida, explains that low levels often cause no clear symptoms until the deficiency is severe.
Also read: As Trump nears 80, questions of legacy and health move into focus
Vitamin D tests are also not part of routine blood work and must be requested separately.
This means many women do not know their levels, even if they are at higher risk.
The original reporting notes that older women, pregnant women, people living in northern regions, and those with darker skin tones are more likely to be deficient because their bodies produce less vitamin D from sunlight.
More than bones
Vitamin D is best known for its role in bone health, especially since osteoporosis affects women far more often than men, according to a study published in Journal of Clinical Medicine Research.
Also read: Dietitian ate one apple a day for a week - this is how the body responded
However, recent research has widened the picture.
Clemens Bergwitz, an endocrinologist at Yale School of Medicine, says scientific studies increasingly link vitamin D to health areas unrelated to bones.
National Geographic cites studies suggesting vitamin D supplements may reduce the risk of autoimmune diseases and ease symptoms of multiple sclerosis.
These conditions affect women at much higher rates, highlighting gaps in how women’s health has been studied and treated.
Also read: Doctors: Laptop heat can cause skin damage
Practical response
Diet and sunlight alone are often not enough to maintain healthy vitamin D levels.
For this reason, experts quoted in National Geographic say supplements can be useful. Still, they warn against taking high doses without medical advice.
The key point, revealed through the reporting, is that better testing matters.
Blood tests can help ensure women get the right amount, avoiding both deficiency and excess.
Also read: How to drink your tea for the greatest health benefits, according to research
The issue is not only nutritional, but also about consistent preventive care.
Sources: National Geographic, Cleveland Clinic og Journal of Clinical Medicine Research.
Also read: This is what you can do to help prevent chronic kidney disease