Research by UFSCar in partnership with University College London (England) showed, for the first time, that obesity can cause a lack of vitamin D and not the other way around. In the study, participants who had abdominal obesity had a 36% greater risk of developing management and a 64% greater risk of vitamin D deficiency (image: Mohamed Hassan/Pixabay)
June 02, 2023
Maria Fernanda Ziegler | FAPESP Agency — A study carried out by a researcher from the Federal University of São Carlos (UFSCar), in partnership with University College London (England), showed, for the first time, that the accumulation of abdominal fat is a risk factor for vitamin insufficiency and deficiency D in people over 50 years old. Considered a hormone, D performs several functions in the body and its lack can lead to several problems, such as the absorption of calcium and phosphorus and the functioning of the immune system, for example.
“Both abdominal obesity and vitamin D deficiency are prevalent issues in the elderly population. However, with this study we show that it is abdominal fat that increases the risk of manifestation and vitamin D deficiency and not just the inverse relationship, as some studies have already demonstrated. We are not ruling out that D would lead to obesity, the vitamin is just demonstrating that the accumulation of abdominal fat is also a way to a lack of this vitamin,” he said. Tiago da Silva AlexandreProfessor 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. Research participants are part of the project English Longitudinal Study of Aging (ELSA), a longitudinal care study in England that collects multidisciplinary data from a representative sample of the English population. The contour analysis with the support from FAPESP.
To verify the physiological influence between the two factors, the researchers selected participants in 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 found that those who had abdominal obesity had a 36% greater risk of developing developed and 64% more risk of vitamin D deficiency, when compared to the group who did not have abdominal obesity”, says Alexandre.
In the study, people believed that vitamin D 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 explains that previous studies had already linked the lack of vitamin D with the development of obesity. “However, 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 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. That’s because it’s in the deepest layers of the skin that a precursor substance for vitamin D is stored. When the skin is exposed to the sun, its structure is modified and, through various metabolic processes, vitamin D is transformed into its active form, which circulates throughout the body and performs various functions.
Alexandre explains that, throughout the aging process, it is natural that it has caused changes in body composition, such as a 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 measures of abdominal infection, 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 change 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.
However, the study emphasizes, the accumulation of abdominal fat plays an important role in the “sequestration” of circulating vitamin D in the bloodstream. “When we analyze the fat cells of these people, it is possible to observe that the vitamin D enzymes are low. This happens because a vitamin D receptor (VDR) starts to capture the vitamin D that is in the bloodstream. This occurs as a way to compensate for the low level of enzymes in the fat cell. In a simplified way, it is as if the adipose tissue sequestered vitamin D. Which causes a lower bioavailability of vitamin D in blood tests, as we see. It is this process that will present a presentation or even a vitamin D deficiency”, explains Thais Barros Pereira da Silva, scientific initiation student and first author of the study.
Alexandre highlighted that the study reinforces the need for public policies for the prevention and confrontation of both obesity and vitamin D deficiency in speed. “We all know that prevention is easier than cure and we have shown that abdominal obesity can interfere with blood vitamin D concentrations, something that can have a number of health problems in the elderly,” he said.
The study Is abdominal obesity a risk factor for the incidence of vitamin D insufficiency and deficiency in older adults? Evidence from the ELSA study can be read at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9572900/.