Vitamin D, a fat-soluble vitamin, is dissolved and stored in fats, specifically retained by adipocytes, the cells of adipose tissue. According to a study by Azzam et al. in 2019, a direct link was found between high levels of body fat and vitamin D deficiencies in the blood. This implies that the more adipose tissue retaining vitamin D, the more vitamin D intake is required to maintain adequate blood levels.
People who are overweight or obese need two to three times more vitamin D to achieve the same blood concentrations as those with a lower percentage of fat. This is an important factor when considering vitamin D supplementation.
Reducing body fat percentage can help release vitamin D stored in adipocytes. For example, 40 kilos of fat can be equivalent to 2000 days of intake of the recommended daily allowance of vitamin D, either through diet or supplementation. However, maintaining an energy deficit for so long is impractical.
Historically, in summer, with more sunshine and plenty of food, vitamin D was stored as fat to make up for future deficits. In winter, with less sunshine and less food, this stored fat was used, releasing vitamin D into the blood.
Nowadays, we do not need to wait for winter to increase the levels of vitamin D stored in fat. Physical exercise is an efficient alternative. Engist et al., in 2019, showed that an exercise session, through its lipolytic effect, can significantly increase serum vitamin D concentrations.
Solar exposure is crucial for vitamin D synthesis, as only 50% of ingested vitamin D is absorbed, while vitamin D synthesised by solar exposure has a higher bioavailability and half-life. In addition, insufficient magnesium levels may hinder vitamin D metabolisation.
Marta Valls - CEO Metabolic Nutrition
EN