Earlier studies have found a link between low selenium and overweight, but only few and limited studies have investigated this connection in children. Therefore, Chinese researchers wanted to take a closer look, and selenium levels in nail clippings give a rather accurate picture of the body’s general selenium status. Selenium deficiency is common in many parts of the world, including parts of China and Europe.
The growing number of overweight children in the world is viewed as one of the most serious threats to our health in the 21st century. It increases the risk of type 2 diabetes and a host of different lifestyle diseases early in life. There are many complex factors involved in overweight such as genetics, diet, behavior and environment.
The main reason why people become overweight is that they consume more calories from food and beverage than the amount of calories burned with physical activity, and the excess calories are then stored as fat. Handling overweight is a matter of burning calories effectively, and in order to do that, we need a number of vitamins and minerals such as selenium that are involved in a large number of enzyme processes.
Overweight causes oxidative stress in the body – and vice versa
Overweight normally leads to excess fat around the bowels. Visceral fat, as this unhealthy type of fat is called, generates an excess of inflammatory molecules and free radicals. Normally, the immune defense handles inflammation swiftly and effectively, but when a person becomes overweight, the large concentration of visceral fat turns into chronic inflammation that a person does not feel, but which creates oxidative stress in the body. This condition can easily get out of hand and increase the risk of insulin resistance, further weight gain, and metabolic syndrome that is an early stage of type 2 diabetes.
Various antioxidants are our only defense against free radicals. Earlier laboratory studies suggest that selenium plays a particularly important role by fueling powerful antioxidants and active selenoproteins.
Only few studies have looked into the relation between infant selenium status and body weight. Scientists have measured children’s selenium status by means of urine samples, but these only provide a temporary picture. In contrast, nail clippings show a person’s selenium status over the past 6-12 months. Even though this is an easy and effective way to compare children’s selenium status and overweight, the Chinese study is the first to use this method.
Children with normal weight tend to have more selenium in their fingernails
The Chinese study involved 62 overweight children and 65 children of normal weight, all of whom were aged 7-13 years and lived in Shanghai. Their overweight was rated according to a special scale for children, simply because the normal BMI scale only applies to people who have reached full growth.
The children’s fingernails were cut and stored in plastic boxes, until the selenium content had been analyzed. The scientists could see that children of normal weight had more selenium in their fingernails compared with overweight children, although the difference was not statistically significant. Nonetheless, the researchers say that there can easily be an inverse relation between selenium content in fingernails and overweight in Chinese children.
Earlier studies show a link between selenium status and weight
The new study supports earlier studies but not all of them. One study of Egyptian children showed that those who were overweight had lower selenium concentrations than peers of normal weight. The same was the case in studies from Poland, Spain, and United States, where scientists compared overweight children with children of normal weight.
Selenium’s role in weight regulation
Selenium fuels 25-30 different selenium-dependent proteins (selenoproteins) that function as enzymes and antioxidants. Every cell in the body depends on the presence of these selenoproteins. Cellular energy turnover is controlled by coenzyme Q10 and cannot run smoothly without selenium. The thyroid hormones work by channeling oxygen into the cells, and in order for these hormones to be activated, the body needs a type of selenoproteins called deiodinases.
Selenium is a constituent of a variety of antioxidants, namely GPX (glutathione peroxidase 1-6) that protect the body against free radicals and oxidative stress. Furthermore, selenium supports different proteins that repair cellular damage caused by oxidative stress and other irritants.
In other words, selenium helps to reduce a variety of those inflammatory mechanisms that have a cumulative effect in overweight. That way, selenium lowers the risk of overweight in children.
How do we get selenium?
We mainly get selenium from seafood, offal, eggs, dairy products, and Brazil nuts. Still, a large number of Europeans are not getting enough selenium, because the soil is stripped of its nutrients and because our diets have changed. Selenium supplements can compensate for the shortcoming. It is best to take organic selenium yeast with a variety of different selenium compounds, which provides the same natural variation as one gets from eating a balanced diet with many different selenium sources.
Pay attention other nutrients and your lifestyle
There are also studies that show that too little vitamin D, chromium, magnesium, and calcium may increase the risk of overweight and type 2 diabetes, because these nutrients are involved in the body’s turnover of carbohydrate and fat (macronutrient metabolism). It is essential to make sure that you consume calcium and magnesium in the right balance. Too much calcium at the expense of magnesium tends to cause inflammation.
Many children could lower their risk of overweight by eating healthier diets with more whole grain, fruit, and vegetables and by limiting their intake of sugar and sweets. Also, it is essential to be physically active and get plenty of sunshine and fresh air.
Xu, Renying et al. Fingernail selenium levels in relation to the risk of obesity in Chinese children: A Cross-sectional study. Medicine, March 2018
Fujita K et al. Systemic oxidative stress is associated with visceral fat accumulation and the metabolic syndrome. Circ. J 2016
Yves Rayssiguier et al. Magnesium deficiency and metabolic syndrome: stress and inflammation may reflect calcium activation. John Libbey Eurotext 2010
Diabetikere mangler ofte D-vitamin. Diabetes.dk 2013
Pernille Lund. Sådan får du styr på dit blodsukker og din vægt. Ny Videnskab 2013
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