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Sunlight and Vitamin D

Shining the Sunlight on Vitamin D for Older Adults

Deserving of focus is vitamin D, which is important for a number of functions, including maintaining bone health and decreasing risk of osteoporosis and osteomalacia, immune function, helping to maintain healthy skin, and maintaining muscle strength.

Severe vitamin D deficiency may cause bone and muscle pain in addition to weakness, which may mean exercise will be difficult and possibly painful (1). Everyday activities that maintain independence, such as brushing hair, or getting up from bed or a chair, can become too hard.

All of these factors therefore play a critical role in the quality of life and falls prevention in older adults.

Vitamin D occurs in two forms: one is produced by sunlight (i.e. ultraviolet [UV] radiation) exposure to the skin, and the other is found in food.

It has been speculated that it is difficult to obtain adequate vitamin D from the diet alone, therefore, factoring in some regular contact with sunlight, especially for those in care facilities and/or who have limited mobility, is a wise consideration.

The Sunshine Vitamin

Seasonal changes have been shown to have a significant effect on the production of this so-called “sunshine” vitamin by the skin, even in our generally sunny climate in Australia.

Vitamin D deficiency is more common in the winter months due to decreased sunlight, people spending less time outdoors and people wearing more clothing.

In older people, the efficiency of skin production of vitamin D from sunlight is also reduced, so they need to spend more time in the sun to store enough vitamin D for the winter months.

It should also be noted that glass and sunscreen reduces vitamin D production.

In summer, most Australian adults should be able to maintain adequate vitamin D levels during typical day-to-day outdoor activities (2). For example, a few minutes of mid-morning or mid-afternoon sun exposure to arms and hands (or equivalent area of skin) on most days of the week should be sufficient.

In late autumn and winter, time spent in the sun should be extended, such as by taking a walk or doing some gardening during the mid-morning or mid-afternoon.

Older adults are at particular risk of low or deficient vitamin D levels, due to a higher prevalence of the following with advancing age:

  • reduced efficiency of vitamin D production by the skin;
  • reduced mobility leading to reduced sunlight exposure; and
  • decreased appetite leading to decreased overall food intake.

Food Sources of Vitamin D

In Australia, fortified margarine appears to be the major dietary source of vitamin D, together with oily fish such as salmon, herring and mackerel, and eggs (3). Other oily fish such as tuna and sardines, white fish (barramundi, basa, hoki and king dory) (4), liver, egg yolks, cheese, full cream milk and butter also contain this vitamin.

Currently in Australia, vitamin D fortification is mandated for edible oil spreads (table margarine) and voluntary for modified and skim milks, powdered milk, yoghurts, cheese, and breakfast cereal (5).

Anyone who is suspected of not being able to obtain adequate regular sunlight exposure should try to have their vitamin D levels boosted through their diet.

An Accredited Practising Dietitian can assist with a nutritional assessment and practical advice.

Vitamin D supplementation is available but should only be considered once dietary measures have been exhausted and a blood test has confirmed the requirement, and should only be taken upon medical advice.

References:

Central Coast Local Health District, NSW Government. (2015) ‘Best Practice Food and Nutrition Manual for Aged Care’, Edition 2.1., accessed 18/09/18: http://www.cclhd.health.nsw.gov.au/wp-content/uploads/BestPracticeFoodandNutritionManualforAgedCareEdition2.1.pdf

Cancer Council Australia. ‘Position Statement – sun exposure and vitamin D – risks and benefits’, accessed 18/09/18: https://wiki.cancer.org.au/policy/Position_statement_-_Risks_and_benefits_of_sun_exposure#Sun_protection_and_vitamin_D

National Health and Medical Research Council, Australian Government. ‘Nutrient Reference Values for Australia and New Zealand: Vitamin D’, accessed 18/09/18: https://www.nrv.gov.au/nutrients/vitamin-d

Dietitians Association of Australia. (2017) Media release: ‘Our sunburnt country needs a dose of the sunshine vitamin’, accessed 18/09/18: https://daa.asn.au/wp-content/uploads/2016/05/Our-sunburnt-country-needs-a-dose-of-the-sunshine-vitamin-FINAL.pdf

Food Standards Australia New Zealand. (2016) ‘Vitamins and minerals added to food’, accessed 18/09/18: http://www.foodstandards.gov.au/consumer/nutrition/vitaminadded/Pages/default.aspx