It was a sunny summer this year, but vitamin D deficiency is diagnosed among Estonians regardless of the weather. Dr Irina Utenko, a laboratory doctor at SYNLAB, talks about what affects vitamin D absorption and when it is the right time to check your body’s summer stores.
“There is certainly hope that we will get enough vitamin D in the summer, but our daily testing shows that it is more likely that people in Estonia will continue to need to replenish their vitamin D stores,” says SYNLAB laboratory doctor Dr Irina Utenko.
She recommends assessing your body’s vitamin D stores over the summer at the end of September, beginning of October, or two to three weeks after returning from a trip in the sun. Sunshine is not enough if the body has an increased need for vitamin D. It is also a good idea to keep an eye on the reasons that may prevent absorption of the vitamin.
Higher vitamin D needs: pregnancy, breastfeeding and exercise
Pregnant women and breastfeeding mothers have a higher need for vitamin D, according to Dr Utenko, and should take regular vitamin D supplements to meet their body’s increased needs. According to a study by the University of Tartu entitled “Blood serum vitamin D levels in the second trimester of pregnancy affect pregnancy outcomes and maternal health”, low vitamin D levels are common among pregnant women in Estonia, and the main risk factors for this are carrying a pregnancy with low sun exposure during the calendar months, but also pre-pregnancy obesity. The level of vitamin D in the body influences the course of pregnancy and the health of the mother and baby. The study shows that the vitamin D stored in Estonia during the summer months is not sufficient for the winter period in our future mothers.
According to Dr Utenko, people who regularly engage in strenuous exercise could still have a higher vitamin D reserve to help the body cope better with stress.
Weaker synthesis of vitamin D in the skin on sun exposure
As humans age, the skin no longer synthesises vitamin D as efficiently and deficiencies are easy to develop. Melanin reduces the skin’s ability to synthesise vitamin D, which is why not only older people, but also people with darker skin, are less able to synthesise vitamin D, and why it is worth checking your reserves.
Causes of vitamin D deficiency after a hot summer are sometimes very commonplace and linked to our lifestyle. According to Dr Utenko, the healthiest time to be in the sun would be between 9:00-12:00 in the morning. But how many of us, especially on a weekday, actually take a breath of fresh air outdoors at this time? In addition, the synthesis of vitamin D in the skin can be affected by cloudy weather, air pollution or the use of sunscreens with a sun protection factor (greater than SPF8).
The causes of the deficit may be linked to a person’s wider health condition.
Absorption is more difficult in the case of diseases of the small intestine: coeliac disease, inflammatory bowel diseases, after gastric bypass surgery or when taking certain medicines. Vitamin D deficiency is also common in chronic alcoholism.
Vitamin D is a fat-soluble vitamin that is absorbed throughout the small intestine, while the reserve is stored in liver tissue and adipose tissue. “In an overweight person, therefore, the vitamin D reserve is high, but the body cannot easily absorb it from adipose tissue. If a person is losing weight, it is worth reviewing the vitamin D intake,” explains Dr Utenko.
Diet is an important determinant of absorption. Absorption is reduced by diets too high in fibre, by overindulging in coffee, and vegetarians tend to be deficient. It should be noted that other fat-soluble vitamins, such as vitamins A, E and K, compete for solubility in the small intestine and may also inhibit the solubility of vitamin D and hence absorption. It is therefore important to pay attention to your diet as a whole.
Apart from sunlight, people can get vitamin D from food or as a supplement. The main rich sources of vitamin D are most cooked fish (especially herring, salmon) and boiled eggs. Milk and dairy products fortified with vitamin D are suitable. According to Dr Utenko, vitamin D from food or taken in the form of a preparation is equally soluble in the small intestine. However, it should be noted that since vitamin D is fat-soluble, it is best taken with a meal that contains more fat. Useful fats include chia seeds, avocado, milk fat, which ensures better absorption.
Why do we talk so much about vitamin D today?
According to Dr Utenko, in the old days, vitamin D was known more as a children’s vitamin. This was because only some of its beneficial properties were known – the one that keeps bones and teeth in good condition. Scientific advances and new research over the past decades have given vitamin D a much broader meaning. Today, vitamin D is known to regulate more than 200 genes, making it essential for many physiological processes in the human body.
“Vitamin D not only regulates calcium and phosphate metabolism to keep bones and teeth in good condition, but also affects immune cells and insulin hormone synthesis in the pancreas, helps regulate blood pressure, blood clotting, nerve tissue function, helps keep muscles toned and improves performance. Low levels of vitamin D are now associated with an increased risk of diabetes, tumours, various infections, etc.,” explains Dr Utenko, adding that the vitamin’s role in preventing seasonal colds cannot be underestimated. Recent studies highlight the role of vitamin D in men’s health, as deficiency can lead to low testosterone levels. Links with different health indicators can be established by doctors based on tests.
