Koreans are at a growing risk of vitamin D deficiency due to increased hours spent indoors, a report showed Thursday.

According to a report by the state-run Health Insurance Review and Assessment Service, the number of patients suffering from diseases caused by vitamin D deficiency surged more than eightfold from 1,008 in 2007 to 10,006 in 2011. Medical costs to treat related diseases also jumped nearly 6.5 times.

The report showed that the proportion of patients the aging population has surged in recent years while the rate among children under age 9 has substantially decreased.

The proportion of patients aged between 0 and 9 declined from 34.5 percent in 2007 to 17.6 percent last year. The proportion of patients aged 50 and over rapidly increased to 49.1 percent in 2011 from 31.4 percent in 2007, the report said.

Low levels of vitamin D can increase the risk of poor bone health including rickets in young children and osteomalacia in seniors, doctors say.

When the level of vitamin D decreases, bones can become soft and deformed. As bones weaken, legs begin to bow due to the pressure imposed by weight.

Vitamin D deficiency has become a public health concern particularly in Korea and Japan due to their geographic location and urban life.

“Recent surveys showed that Korea and Japan had the highest rate of people with lower levels of vitamin D because there is not much sunlight due to their relatively northern latitude and that many people live in metropolitan areas. Frequent use of sunscreen products in two countries has contributed in the growing risk of vitamin D deficiency,” said Lim Sung-kil, an internal medicine doctor at Yonsei Severance Hospital in Seoul.

Having low vitamin D levels in the body is quite a serious health matter as studies have found a deficiency to be related to cancers, heart and autoimmune diseases, diabetes, multiple sclerosis and depression, Lim said.

“Vitamin D is an important nutrient in our body because it contributes to building our immune system. Studies found that children with a lack of vitamin D suffer from flu quite often,” Lim said.

Doctors recommend exposure to the sun during lunch time or enjoying outdoor activities as much as one can during the winter. Most vitamin D intake comes from direct sunlight on skin. The human body synthesizes vitamin D in reaction to light.

Deficiency in the sunshine vitamin can also be treated simply by taking supplements and eating foods with vitamin D including cod liver oil, salmon, mackerel, tuna fish, milk and egg.

“Sunbathing and outdoor activities are the best ways to increase the level of vitamin D in the human body,” said Park Hee-jeon, an orthopedics doctor at Wonju Christian Hospital. “Many would find difficulties with playing outside during the cold winter, but remember that we can only absorb a limited amount of vitamin D from food,” he said.

It is important for breastfeeding mothers to have balanced meals containing an optimal level of vitamin D to make sure their babies also receive enough of the vitamin, Park added.

By Cho Chung-un (christory@heraldcorp.com)