Knowledge of vitamin D and perceptions and attitudes toward sunlight among Chinese middle-aged and elderly women: a population survey in Hong Kong

Physical and biological risk factors for vitamin D inadequacy are known; however, cultural- and population-specific behaviours and attitudes that influence these risk factors, particularly among Asian people, are less well documented. To understand more about prevailing attitudes and behaviour toward sunlight and knowledge of vitamin D among a population at greater risk of impaired vitamin D status, poor bone health and osteoporosis, we conducted a telephone interview survey of 547 middle-aged and elderly Chinese women living in Hong Kong.

All telephone interviews were conducted using the Computer Assisted Telephone Technique and target respondents were selected by random sampling. Interviews were conducted in Cantonese and eighteen main questions were asked pertaining to personal characteristics, perceptions, attitudes and behaviour toward sunlight, and knowledge about vitamin D.

The survey results showed that 62.3% (n = 341) did not like going in the sun and 66.7% of respondents spent an average of 6–10 hours indoors, between 6:30 am and 7:00 pm, during weekdays. However, 58% of people thought that they had enough exposure to sunlight. The majority had heard of vitamin D, but knowledge about the role and sources of vitamin D was low. Among those who knew that sunlight was a source of vitamin D, the majority spent less than 1 h in the sun in the past week (76.4% vs 23.6%, < 1 h in the sun in the past week vs > 1 h in the sun in the past week, chi-square p < 0.05). There were significantly more users of sunscreen products (75.5% vs 53.0%, p < 0.0001, sunscreen users vs non-users) and parasols (68.4% vs 43.7%, p < 0.0001, parasol users vs non-users) among respondents who knew that vitamin D was good for bone health and that sunlight was a source of vitamin D. Age, occupation, subjects who liked going in the sun were factors associated with awareness of vitamin D but age was the only predictive factor for giving correct answers to the actions and sources of vitamin D.

The survey revealed considerable ignorance and confusion about the role of sunlight in vitamin D production, and the function and sources of vitamin D. Attitudes and behaviour toward sunlight were largely negative and many took measures to avoid sunlight, particularly among younger (middle-aged) women who had good awareness of vitamin D.