How Much Vitamin D Do You Need to Stay Healthy?
When you buy milk at the grocery store, chances are it’s been fortified with vitamin D. When you go outside, energy from sunlight helps your body manufacture its own supply of the nutrient. No matter how you get it, vitamin D helps you absorb calcium and build strong bones. Some studies have even suggested that vitamin D can protect against lung infections.
So it’s clear that we need vitamin D. But do we know how much we need?
In an editorial for the Journal of Adolescent Health, Professor Christian Warren (Brooklyn College) writes that there is no one perfect dosage for Vitamin D: Different people require different amounts. Medicine should take a global perspective that accounts for diversity in people and in their nutritional requirements rather than looking for a one-size-fits-all answer.
The editorial refers to a study in the same journal which found that countries differ in their vitamin D recommendations for adolescents. Much of this disagreement can be explained by looking at history, Warren says.
When early humans migrated out of Africa, they traveled to places with a variety of climates and different amounts of sunshine. A range of skin pigmentations evolved in different populations around the world. Diets varied tremendously by region as well. As a result, different groups of humans absorbed and processed varying amounts of vitamin D in different ways.
Modern migrations have added more complexity, as people have immigrated or been forcefully moved around the world. Even societal shifts between the country and the city have affected which demographics are most likely to develop vitamin D deficiencies.
All of these physical and societal factors add up to make each person’s unique profile. A child who identifies as black or of African descent on a medical intake form may have different medical needs than a pregnant Pakistani teenage immigrant, Warren says. But more importantly, neither of these individuals can be defined solely by race.
“So much training and clinical protocol are based on binary racial distinctions, but actual people do not line up neatly by color or race,” Warren writes.
Clinical genomics could someday provide personalized medical profiles, Warren says, but in the meantime we should encourage taking detailed histories of patients, and keep analyzing data to figure out the best practices when it comes to nutrition.