Having a large waist circumference and lacking vitamin D are connected

If you have a large waist circumference, you are more likely to have low blood levels of vitamin D, according to a study that was presented at the annual meeting of the European Society of Endocrinology (ESE) in Barcelona in 2018. The researchers therefore suggest that overweight individuals with a large waist circumference have their vitamin D levels measured, as this may help prevent many of the health problems that are linked to low vitamin D levels, including such things as an increased risk of infections, cardiovascular disease, osteoporosis, winter depression, blood sugar irregularities, diabetes, autoimmune diseases, and cancer.

Overweight is a problem of epidemic proportions that is believed to cause 2.8 million deaths annually worldwide. Overweight is not just a result of consuming too many calories. In many cases, people have unstable blood sugar levels and are unable to reach satiety. Scientists have talked about a link between low blood levels of vitamin D and overweight but have not looked closer at what type of fat the overweight individuals had, or the ratio between the different kinds of fat.
In the new study, Rachida Rafiq and her colleagues from VU University Center and Leids University Center in Holland, studied the matter by looking closer at a large, Dutch epidemiological study of obesity, where they measured body fat and abdominal fat (also known as visceral fat) in the participants. The fat measurements were then compared to levels of vitamin D in the blood. The scientists adjusted for different confounding factors such as chronic disease, alcohol consumption, and physical activity and found that the total amount of fat and the amount of abdominal fat were linked to vitamin D levels in the blood. They could see that greater abdominal fat was associated with lower vitamin D status.
The researchers did not screen for actual vitamin D deficiency in their study, but their results suggest that too much body fat – especially if you have a large waist circumference with too much abdominal fat – increases the risk of lacking vitamin D, and that can make you an easier target for a number of related diseases such as infections, cardiovascular disease, osteoporosis, winter depression, blood sugar disturbances, diabetes, autoimmune diseases, and cancer.

WHO´s classification of abdominal obesity in adult Europeans
Gender	Waist circumference (cm)	Health risk
Men	Higher than 94	Increased
	Higher than 102	Significantly increased
Women	Higher than 80	Increased
	Higher than 88	Significantly increased

What causes the relation?

The scientists now plan to investigate the underlying reason for the strong relation between vitamin D, overweight, and enlarged waist circumference. Is it lack of vitamin D that predisposes for overweight? Does an elevated fat percentage sequester a person’s vitamin D reserves? Or does being overweight make it difficult for a person to convert vitamin D into its active form – the form that is measured in the blood? The scientists are still unable to make final conclusions about the relation between overweight, fat deposits, and vitamin D levels in the blood, yet studies seem to hold certain answers.

Lack of vitamin D increases the risk of overweight, metabolic syndrome, and type 2 diabetes

An earlier study from Sao Paulo in Brazil has demonstrated that women older than 50 years of age are more likely to have problems with their blood sugar, weight, cardiovascular disease, and metabolic syndrome, if they also lack vitamin D. Metabolic syndrome is a very common insidious metabolic disorder characterized by insulin resistance, elevated blood pressure, elevated blood lipid levels, enlarged waist circumference, and an increased risk of type 2 diabetes. If you want to control your blood sugar balance and lose weight, it is not enough to eat less and exercise, you also need to make sure to get enough vitamin D.

An estimated one billion people worldwide lack vitamin D, a nutrient that we primarily get through sun exposure. Apparently, there is a link between the modern lifestyle with too much indoor activity and overweight.

How does vitamin D affect our blood sugar, appetite, and overweight?

Most cells in the body have vitamin D receptors. According to earlier studies, vitamin D has several mechanisms of action that can explain its effect on blood sugar and overweight. The researchers refer to the fact that vitamin D increases insulin sensitivity, which is a determining factor for cells and their ability to take up sugar from the bloodstream.
Scientists have also discovered vitamin D receptors in the hypothalamus of the brain, which is a gland that controls the nervous system and hormone system. It is already known that hypothalamus has a role in regulating our appetite and metabolism, and according to a scientist named Stephanie Sisley, both vitamin D and the hypothalamus have an important role in controlling our weight and blood sugar.

We all need sufficient amounts of vitamin D to help us produce effective insulin

Official recommendations for vitamin D – and our actual need for the nutrient

The reference intake (RI) level for adults (in Denmark) is five micrograms. Many researchers claim that the actual need for vitamin D is much higher than that. Their recommendations vary from 30-100 micrograms daily, and that is an amount, which one can easily synthesize on a sunny day during the summer. People with dark skin, or older people with thin skin do not produce vitamin D as effectively, however. The same is the case with overweight individuals and diabetics, who produce less vitamin D and have difficulty with utilizing the nutrient properly.
In the winter period, it is necessary to take a vitamin D supplement, as even a balanced and healthy diet only provides limited quantities of this vitamin. Vitamin D is lipid-soluble, which means that we get the best effect of the vitamin by taking a supplement that contains vitamin D in some sort of vegetable oil

References

European Society of Endocrinology. Larger waistlines are linked to higher risk of vitamin D deficiency. ScienceDaily May 2018

Scott LaFee. Vitamin D Deficiency Linked to Greater Risk of Diabetes. UC San Diego Health. April 2018

Plasma 25-hydroxyvitamin concentration and risk of type 2 diabetes and pre-diabetes. 12-year cohort study. PLoS One 2018

Eneida Boteon Schmitt et al. Vitamin D deficiency is associated with metabolic syndrome in postmenopausal women. Maturitas 2018

Sisley SR et al. Hypothalamic Vitamin D Improves Glucose Homeostasis and Reduces Weight. Diabetes 2016

Pernille Lund. Sådan får du styr på dit blodsukker og din vægt. Ny Videnskab 2013