Abdominal fat increases the risk of vitamin D deficiency – 02/06/2023 – Equilibrium

A study carried out by researchers from UFSCar (Federal University of São Carlos), in partnership with University College London (England), showed, for the first time, that the accumulation of abdominal fat is a risk factor for insufficiency and vitamin D deficiency in people over 50 years of age.

Considered a hormone, vitamin D performs several functions in the body and its lack can lead to problems, such as in the absorption of calcium and phosphorus and in the functioning of the immune system, for example.

“Both abdominal obesity and vitamin D insufficiency and deficiency are prevalent issues in the elderly population. However, with this study we show that it is abdominal fat that increases the risk of vitamin D insufficiency and deficiency and not just the inverse relationship, as some studies had already shown. We are not ruling out that vitamin D would lead to obesity, just demonstrating that the accumulation of abdominal fat is also a way for the lack of this vitamin”, says Tiago da Silva Alexandre, professor of Gerontology at UFSCar and author of the study published in the journal Nutrients.

The work involved analyzing a database of 2,459 Britons aged over 50 followed for four years. The research participants are part of the project “English Longitudinal Study of Aging” (Elsa, in English), a longitudinal study conducted in England that collects multidisciplinary data from a representative sample of the English population. The analysis was supported by FAPESP.

To verify the correlation between the two factors, the researchers selected participants from the Elsa project who were over 50 years old and had normal levels of vitamin D (greater than 50 nmol/L). The participants were divided into two groups: one formed with people with little abdominal fat and the other with fat accumulation in the abdomen (waist circumference greater than 102 cm for men and greater than 88 cm for women).

“When evaluating the vitamin D index of these individuals four years after the first data collection, we verified that those who presented abdominal obesity had 36% more risk of developing insufficiency and 64% more risk of vitamin D deficiency, when compared to the group who didn’t have abdominal obesity”, says Alexandre.

In the study, people considered to have vitamin D insufficiency had rates between 30 and 50 nmol/L of the substance in the bloodstream, while deficiency was configured for those who had less than 30 nmol/L of vitamin D.

reduction of receptors

Alexandre states that previous studies had already linked the lack of vitamin D with the development of obesity.

“However, they are studies based on body measurement index (BMI) measures, which use weight and height data, give a global analysis of obesity and are very imprecise. However, the question that remains is how so many countries with high or low solar incidence have a very high prevalence of vitamin D deficiency. The answer is because there is a high prevalence of obesity”, says the researcher.

Obtaining vitamin D is mainly through sunlight. This is because it is in the deepest layers of the skin that a hormone precursor substance is stored. When the skin is exposed to the sun, its structure is modified and, through various metabolic processes, the vitamin is converted into its active form, which then circulates throughout the body and performs various functions.

Alexandre points out that, throughout the aging process, it is natural for changes to occur in body composition, such as greater accumulation of fat in the abdomen region, for example. In addition, it is also common for there to be a decrease in the thickness of the skin and, consequently, a lower availability of the precursor substance of vitamin D in the epidermis, as well as a lower capacity for synthesis of the active form of this vitamin.

“For this reason, in our study, we used measurements of abdominal circumference, which is a practical and accessible measure that verifies the accumulation of fat in the abdomen and is more accurate than BMI, for example”, he says.

Another modification pointed out with aging is the decrease in the number of vitamin D receptors in body tissues, which makes it difficult to capture this circulating vitamin in the body.

Alexandre points out that the study reinforces the need for public policies to prevent and cope with vitamin D deficiency, both in obese people and in old age. “We all know that prevention is easier than cure and we have proven that abdominal obesity can interfere with the concentrations of vitamin D in the blood, something that can trigger a series of health problems in the elderly”, he indicates.