Australia is renowned for its sunny climate and outdoorsy, beach-loving lifestyle, however its population is – paradoxically – deficient in vitamin D. Approximately one in four Australian adults has inadequate levels of the ‘sunshine vitamin’, with the highest rates of deficiency measured in winter in people living in Victoria and the ACT (49 per cent respectively). In Western Australia, in winter, 28 per cent of the population has a vitamin D deficiency.
Vitamin D deficiency in winter by state and territory, 2011- 2012. (Source: Australian Health Survey: Biomedical results for nutrients.)
The body needs vitamin D to absorb calcium and promote bone growth, and low levels of vitamin D can result in soft bones in children (rickets) and fragile bones in adults (osteomalacia). Vitamin D may also be important for immunity against bacteria and viruses, and low levels of vitamin D are linked to obesity.
Ultraviolet radiation from the sun triggers the production of vitamin D in the skin, however it’s also the main cause of skin cancer, which has led to people reducing their exposure to sunlight by spending less time outdoors, and covering up with clothing and sunscreen when they are in the sun. Others at risk of vitamin D deficiency are elderly people, those with naturally darker skin, and breastfed babies of mothers who have low levels of vitamin D.
While sunlight is the best source of vitamin D, a team of scholars from the School of Public Health, including Dr Lucinda Black, and Master of Dietetics students Rachel Cheang and Eleanor Dunlop, have completed a pilot study on food as an alternative source of the sunshine vitamin. The study, funded by the Western Australian Department of Health, has returned some very encouraging results.
Student, Rachel Cheang, said that for people who are vitamin D deficient, and concerned about the implications of ultraviolet radiation, dietary sources are an excellent option to consider.
“If you struggle to get enough sun exposure during the day, especially over winter, try to eat healthy, whole foods that contain vitamin D. Foods like oily fish, such as salmon, tuna and mackerel, meat, some dairy foods and mushrooms contain vitamin D, and give us a host of other important nutrients,” Ms Cheang said.
Some foods are an excellent alternative source of vitamin D.
Both eggs and white fish are also an excellent source of vitamin D, as Eleanor Dunlop’s research has demonstrated. A 100 gram serve of cooked white fish, such as barramundi, basa, hoki or king dory, provides around half (43 to 60 per cent) of the daily adequate intake of vitamin D for Australians aged 1 to 50 years.
“Based on our findings, either two eggs, or one egg and one serve of white fish (depending on the species), may allow many Australians to get their vitamin D intake for the day. The vitamin D content of many other Australian foods is unknown, so more work needs to be done to collect this information,” Ms Dunlop said.
Research lead, Dr Lucinda Black, said the results from the pilot were enlightening and her team hoped to extend the study to identify further food sources of vitamin D.
“We don’t know how much vitamin D is in many foods, so we don’t know if we should be fortifying more products to ensure people are getting enough,” Dr Black said.
The team presented their research at the Dietitians Association of Australia’s National Conference in Hobart in May, and their paper ‘Vitamin D3 and 25-hydroxyvitamin D3 content of retail white fish and eggs in Australia Eleanor Dunlop, Judy Cunningham, Jill L. Sherriff, Robyn M. Lucas, Heather Greenfield, Jayashree Arcot, Norbert Strobel, Lucinda J. Black’ has been published in Nutrients.
*The infographic used in this story can be found at the Australian Bureau of Statistics site.