Medics have claimed that 99 per cent of Thai people who underwent blood tests for vitamin levels were found to be deficient in vitamin D - despite living in a hot country with year-round sun.

Doctor Rojanaree Thitisuwan, manager of Vejthani Hospital's checkup centre, said that the majority of people who were tested either work indoors or actively avoid sunlight in order to maintain pale skin.

As a result, the doctor had to provide supplementary vitamin D on a case-by-case basis due to the 'widespread' deficiency.

Rojanaree, citing a journal article from Mahidol University's Faculty of Medicine, said that city dwellers are more likely to suffer from Vitamin D deficiency compared to those in the countryside.

While people living in central Thailand were reportedly more susceptible to Vitamin D deficiency compared to those in the northeastern ricefields region.

Rojanaree said the study also found that younger citizens were more likely to avoid sunlight compared to older folks, echoing similar statistics in South Korea and Malaysia.

The doctor said that many people took part in indoor instead of outdoor exercises, depriving them of much-needed sunlight exposure.

They also avoid the sun in order to maintain pale skin, which socially is considered to be more attractive and a sign of a higher status in society. Many use umbrellas, sunhats, or a mosituriser that has sunblock elements.

The article was based on a study done by Mahidol University's Institute of Nutrition on the nutrition and development of Thai children aged 6 months to 12 years old 10 years ago.

The institute conducted a similar study this year, and found that the ratio of Thai children lacking Vitamin D has increased by 40% compared to a decade ago.

Mahidol University's Institute of Nutrition said it observed similar trends in Malaysia, Vietnam, and Indonesia.