Vitamin D deficiency in Australia and New Zealand: what are the dietary options?

Abstract

Measurement of serum vitamin D levels in population samples has revealed unexpectedly high prevalence of vitamin D deficiency among children, adults, the elderly and other vulnerable groups in Australia and New Zealand. The new Nutrient Reference Values report has established dietary recommendations for vitamin D of between 5 and 15 [micro]g/day, depending on age. Dietary intakes of vitamin D in Australia typically fall in the range of 2-3 [micro]g/day, below intakes in comparable countries. Dietary intake of vitamin D is currently dependent on consumption of a few key foods, notably margarine and oily fish. Current models of healthy eating do not deliver the recommended amounts of vitamin D and need review. Consideration should be given to the range of foods fortified with vitamin D, which is currently limited. Higher dietary intakes of vitamin D in overseas countries have been achieved through the fortification of margarine, milk and breakfast cereals. Increased voluntary fortification of dairy products with vitamin D would be a safe and simple means of increasing vitamin D intakes in Australasia in the short term. The relatively high dietary recommendation for vitamin D for elderly people cannot be met through the existing food supply and supplementation appears to be a desirable option for many.

Key words: food supply, fortified food, nutrition education, vitamin D deficiency.

INTRODUCTION

Vitamin D deficiency emerged during the industrial revolution in northern Europe and then the USA. At the beginning of the twentieth century, the vitamin D deficiency disease rickets was epidemic among urbanised young children on both sides of the Atlantic Ocean. (1) The problem in European and North American children largely subsided as the effects of sunlight on endogenous vitamin D production became understood, cod liver oil was given to children and vitamin D was isolated and added to staple foods as a public health measure in some countries. Until recently, the incidence of rickets in Australia appears to have been greatly limited by children's ready access to sunlight. (2)

Several important developments have rekindled interest in vitamin D. First, health authorities have advised the general public to reduce sun exposure and to use ultraviolet (UV)-screening skin lotions to lower the risk of skin cancer. Sunscreens with a sun protection factor (SPF) of 15 reduce the capacity of the skin to produce vitamin D by about 98%. Second, vitamin D status of communities can now be quantified through measurements of serum vitamin D, rather than by counting the cases of rickets. The Working Group of the Australian & New Zealand Bone & Mineral Society, the Endocrine Society of Australia and Osteoporosis Australia proposed that the normal serum 25-OH vitamin D concentration is over 50 nmol/L. (3) Vitamin D deficiency was defined in the following terms (amounts of serum 25-OH vitamin D): 25-50 nmol/L for mild deficiency; 12.5-25 nmol/L for moderate deficiency and <12.5 nmol/L for severe deficiency.

Third, mild vitamin D deficiency has been shown to lead to a compensatory secondary increase of parathyroid hormone; is associated with high bone turnover and is an important risk factor for osteoporosis and fractures. (4) Moderate deficiency is associated with reduced bone density, high bone turnover and increased risk of hip fracture in the elderly (5) and severe deficiency with osteomalacia in adults. Finally, noncalcaemic roles for vitamin D have been hypothesised. Some epidemiological studies have shown associations of high latitudes (less sunlight) and some cancers, type 1 diabetes and multiple sclerosis. The discovery of vitamin D receptors in most human cell types suggests a wider role for vitamin D. (6)

VITAMIN D DEFICIENCY IN AUSTRALASIA

The prevalence of vitamin D deficiency appears to be much higher in Australia and New Zealand than previously thought. (3) In a Tasmanian study conducted in winter, 68% of 16-year-old boys were found to have serum concentrations of 25-OH vitamin D less than 50 nmol/L. (7) A cross-sectional study of women with a median age of 46 years conducted in Geelong found that 43% had mild or moderate vitamin D deficiency during winter. (8) Marginal vitamin D deficiency has also been observed among younger adults in south-east Queensland. (9) In New Zealand, the recent National Children's Nutrition Survey found that 31% of children aged 5-14 years had serum 25-OH vitamin D concentrations of less than 37.5 nmol/L, with 4% less than 17.5 nmol/L. (10) Similar results were observed in adults. (11) These two studies highlight that, outside high-risk groups, mild vitamin D deficiency is largely a seasonal problem.

Dark skin and ethnic and religious practices that limit exposure to sunlight increase the risk of vitamin D deficiency. (12) In both New Zealand studies, Pacific Island and Maori peoples were at higher risk of deficiency than subjects of European origin. (10,11) Among veiled and/or dark-skinned pregnant women in Melbourne, 80% were found to have serum 25-OH vitamin D concentrations below 22.5 nmol/L. (13) Over the last decade, a steady increase in the number of cases of rickets has been observed in major teaching hospitals in Sydney, with a doubling between 2002 and 2003. (14) The increasing number of migrants from North Africa, Middle Eastern and Asian countries, many of which are characterised by high prevalence of vitamin D deficiency is thought to underpin the increasing prevalence of rickets. Nozza et al. found that 81% of mothers with babies that have been diagnosed with rickets have serum concentrations of 25-OH vitamin D of 25 nmol/L or less. (15)

House-bound and institutionalised elderly people are at high risk of vitamin D deficiency A study in Hobart reported that 67% of 109 elderly patients consecutively admitted to a short-stay geriatric ward had serum 25-OH vitamin D concentrations less than 28 nmol/L. (16) In the same study, vitamin D deficiency was also observed in 17% of a sample of 52 community-dwelling elderly subjects. Deficiency was common among elderly residents of hostels and nursing homes in Sydney, with 86% of females and 68% of males having serum concentrations less than 28 nmol/L. (17) There were similar findings in a West Australian study. (18) Diamond et al. observed sub-clinical vitamin D deficiency (<50 nmol/L) in 63% of patients admitted with hip fractures compared with 25% in controls. (19)

These reports and the lack of any reports of hypervitaminosis D suggest that the distributions of serum vitamin D in Australia and New Zealand are displaced from the ideal, exposing both populations to mild vitamin D deficiency and vulnerable groups to moderate deficiency

DIETARY RECOMMENDATIONS

While most countries have had recommended dietary intakes for vitamin D for many years, this has not been the case in Australia and New Zealand. (20) In 1991, a National Health & Medical Research Council committee concluded: 'Recommendations for vitamin D are not considered necessary unless people are housebound or always indoors since the vitamin status of Australians is determined predominantly by exposure to UV light from the sun ...'. In a less prominent part of the report: 'Those who are housebound or the elderly in nursing homes could benefit from an oral intake of 10 [micro]g vitamin D per day if they are not exposed for 1-2 hours per week to direct sunlight in summer'. (21) In light of recent developments, public policy settings are now being reevaluated and options to improve vitamin D status considered.

Nutrient reference values

New Nutrient Reference Values for Australia and New Zealand have recently been established by the National Health & Medical Research Council and the New Zealand Ministry of Health. One of the major changes is the establishment of a general recommendation for dietary vitamin D. (22) The recommended nutrient intakes or Adequate Intakes (AIs) for vitamin D, which assume minimal exposure to sunlight, are: 5 [micro]g/day for infants, children and adults 50 years of age or less; 10 [micro]g/day for adults 51-70 years of age and 15 [micro]g/day for adults >70 years of age.

The rationale for the recommendation of 5 [micro]g/day for infants is that human milk is a poor source of vitamin D and unlikely to meet needs beyond early infancy. (23,24) An intake of 5 [micro]g/day is thought to be sufficient through childhood, adolescence and early middle age. However, with increasing age, the potential to produce vitamin D in the skin under the action of ultraviolet light is diminished and this is reflected in the higher AI for older adults up to 70 years of age. In elderly adults (>70 years), there is a fourfold decrease in the capacity to produce vitamin D compared with young adults and therefore a substantial increase in the dietary requirement. (25) These new Australia New Zealand dietary recommendations for vitamin D mirror the 1997 recommendations for the USA and Canada. (26)

DIETARY SOURCES AND INTAKES OF VITAMIN D

Very few foods naturally contain vitamin D and intake from dietary sources accounts for a minority of the daily requirement. The vitamin D supply in the Australian and New Zealand diets is narrowly based, suggesting that intakes by individuals are highly dependent on the consumption of specific foods. Table 1 lists the vitamin D content of the major food sources, although these should be considered approximate as there is no official database for vitamin D content in Australian and New Zealand foods. All natural sources of vitamin D are foods of animal origin: oily fish is a moderate source; dairy fat and egg yolks contain small amounts and meat contains more vitamin D than previously thought. (28) In Australia but not New Zealand, all table margarines are fortified with vitamin D, making it a good source. Dairy products fortified with vitamin D are becoming increasingly available and have the potential to become significant sources.

Estimating dietary intakes of vitamin D is difficult because of limited data on the vitamin D content of foods. Nevertheless, two comparable estimates of Australian intakes have been derived from different dietary surveys. Data from a Commonwealth, Scientific Industrial Research Organisation (CSIRO) National Dietary Survey, reported by Nowson and Margerison indicated that dietary intakes of vitamin D in Australia are low, approximately 2.0-2.2 [micro]g/day for women and 2.6-3.0 [micro]g/day for men. (29) The highest decile of vitamin D intake for men was only 5.6 [micro]g/day. Margarine was the best source of vitamin D, providing almost half the total dietary intake in both men and women. Canned fish and eggs provided approximately 16% and 10% of the vitamin D in the Australian diet, respectively. Very similar intakes of vitamin D, falling in the range 2.0-2.4 [micro]g/day for men and women, were estimated by Food Standards Australia New Zealand. (30) Both estimates are approximately half the newly established Al for vitamin D for infants, children and younger adults. Lower intakes of vitamin D (1.2 [micro]g/day) were estimated among women in the Geelong Osteoporosis Study, although the relative contributions of foods to non-supplement dietary intakes of vitamin D were comparable to the studies mentioned previously: margarine 50%, fish 31% and eggs 13%. (8)

ACHIEVING THE AIs FOR VITAMIN D

The establishment of new dietary recommendations for vitamin D begs a number of questions: Are the new AIs attainable with the existing food supply? Do nutrition education tools encourage adequate intakes of vitamin D? Should additional fortification of staple foods be considered in Australia and New Zealand? How will the vitamin D requirements of vulnerable groups, especially the elderly be met?

Vitamin D levels in healthy diets

Over the last two decades, several models of healthy eating have been developed in Australia and these have sought to balance the provision of essential nutrients with the prevention of chronic diseases, such as cardiovascular disease and obesity. However, the previous lack of a dietary recommendation for vitamin D ensured little consideration was given to its provision in these models. Also, the restriction of dietary fat in these healthy eating concepts has had the unintended consequence of limiting the vitamin D content of recommended diets. The low level of vitamin D in healthy diets was recently highlighted in a dietary modelling exercise in which six low saturated fat diets ranging in energy from 6000 to 11 000 kJ were modelled, based on the Australian Guide to Healthy Eating but excluding margarine. (31) Five of the six diets contained less than or equal to 1.8 [micro]g of vitamin D and the mean was only 1.3 [micro]g (range 0.1-3.3 [micro]g), which fell below typical intakes in. Australia and well below the AI for vitamin D (50 years of age or less) of 5.0 [micro]g/day. In three of the diets, the content of vitamin D was less than or equal to one-tenth of this lower AI. The appreciable vitamin D in the other three diets was largely because of the inclusion of a single serve of a good source of vitamin D, for example salmon. Total energy of the diets had little relation with vitamin D content.

Further examples of how well-intentioned dietary advice may have compromised vitamin D status include the increasing use of olive oil in preference to margarine, low egg consumption because of cholesterol concerns, reticence to recommend increased intakes of fish because of sustainability concerns and advocacy of extended breastfeeding. Nevertheless, it is unlikely that typical Australian or New Zealand diets ever provided the new AIs for vitamin D, especially those for older age groups.

Implications for nutrition education

Nutritionists now face a challenge to reconcile healthy eating advice with the new dietary recommendations for vitamin D. Inevitably the roles of meat, full-fat dairy foods, fish and eggs will need to be reconsidered, together with the roles of vitamin D-fortified foods such as margarine and selected dairy products. However, continuing high rates of coronary heart disease (32) and relatively high mean blood cholesterol concentrations of the populations of both Australia (33) and New Zealand (34) will preclude a change to dietary recommendations in relation to saturated fat, thereby limiting the options relating to full-fat dairy products. Although use or nonuse of table margarine probably has the single most significant effect on dietary vitamin D intake, the positioning of margarine in some food guides is ambiguous and requires clarification. The role of eggs in healthy diets has been under review recently and dietary recommendations relating to eggs are now less restrictive than a decade ago. If increased consumption of fish is not to be recommended on sustainability grounds, alternative options for the supply of vitamin D will need to be considered, which inevitably raises the issue of the further fortification of the food supply with vitamin D. In a recent editorial, Skeaff and Green wrote: 'The recent discovery that our food supply does not provide all the necessary vitamins and minerals to prevent deficiency (e.g. ... vitamin D) will challenge many nutritionists and dietitians who have long argued that a varied diet provides all the nutrient requirements we need. Clearly a re-evaluation of this assumption is needed'. (35)

Food fortification

In 2002, Nowson and Margerison concluded that ... 'it is probably an unrealistic expectation that most people will achieve dietary vitamin D intakes of 5-10 [micro]g/day with current fortification practices in Australia'. (29) In these circumstances, several questions need to be addressed: Should further fortification of food with vitamin D be considered? Should the range of foods fortified with vitamin D be extended? Are there safety implications?

Fortification with vitamin D is only likely to be an effective public health strategy if staple foods are fortified. Although fortification practices vary considerably around the world, the most commonly fortified foods are margarine and milk. In Canada there is mandatory fortification of both margarine and milk. In the USA, vitamin D is a GRAS (generally regarded as safe) ingredient, although there are strict controls on the categories of food in which it can be used and the levels of use. Unlike Canada, fortification in the USA is not mandatory Fluid milk and breakfast cereals are the predominant vehicles for fortification and some orange juice is also fortified. Typical intakes of vitamin D in the USA fall in the range of 5-10 [micro]g/day, (36-38) substantially above intakes in Australia. In some European countries, some margarines, dairy products and cereals are fortified with vitamin D, whereas other countries have no mandatory fortification and limited use of optimal fortification. Cereals provide approximately 30% of the vitamin D in the diets of men and women aged 65 years and above in the UK, where vitamin D intakes average 3.8 and 3.3 [micro]g/day, respectively, in this age group. (39)

Nowson and Margerison have estimated that countries in which both milk and margarine are fortified with vitamin D show 2-3 [micro]g/day higher dietary intakes than those in which either of these foods is fortified. (29) Thus, if all milk was fortified with vitamin D in Australia, mean intakes could rise from approximately 2-3 [micro]g/day to 4-6 [micro]g/day, still well below the AI for adults aged 51-70 years. Nevertheless, such a move would be likely to generally meet the AI for younger groups. A proposal for mandatory fortification of milk may not be welcomed by industry and its costs and benefits would need thorough investigation. However, under current food regulations, voluntary fortification with vitamin D is permitted in a range of dairy products including yoghurts and reduced-fat and skim milks, and fortified products are currently on the market. Increased voluntary fortification of these products would be a simple step towards increasing the level of vitamin D in the food supply. In time, a broadening of the range of foods fortified with vitamin D, for example to include bread and/or breakfast cereals, and the amount of vitamin D added to these foods may need to be considered if the needs of all at-risk groups are to be met. This will require dietary modelling based on a recent national dietary survey.

The safety margin for increased fortification of foods in Australia and New Zealand appears to be very wide. There were no adverse effects observed in a randomised controlled trial in which 25 [micro]g/day and 100 [micro]g/day of vitamin D were provided to 30 subjects over six months. (40) In the Nutrient Reference Values report, an uncertainty factor was applied and a safe Upper Level of Intake of 80 [micro]g/day was agreed for children over the age of one year and all adults. (22) This is approximately 30-fold higher than the current Australian intake.

Supplementation with vitamin D

Achieving the AI for adults over 70 years of age of 15 [micro]g/day is not feasible through diet with the existing food supply. Nor would it be achievable should there be mandatory fortification of milk at some time in the future, which suggests a more pharmacological approach may be required for house-bound and institutionalised elderly adults if their vitamin D needs are to be met. Five options for supplementation could be considered:

* A daily multivitamin, providing at least 5 [micro]g vitamin D at low cost.

* Daily provision of existing supplements, which provide 25 [micro]g ergocalciferol plus calcium at a cost of 24 cents per capsule. a new supplement produced in Australia contains only vitamin D and costs 13 cents per capsule.

* A large oral dose (2500 [micro]g) of vitamin D provided every four months, as used by Trivedi et al. (41)

* A large oral dose of vitamin D provided annually which is currently being trialled in a five-year study in Geelong.

* An annual injection of 15 000 [micro]g vitamin D. Although this preparation has not yet been approved by the Therapeutic Goods Association it has been tested in 50 Sydney patients with osteoporosis. (42) Serum 25-OH vitamin D was normalised to an average of 114 nmol/L.

A recent meta-analysis indicated that vitamin D supplementation reduced the risk of hip fractures in institutionalised elderly subjects, (43) which suggests that supplementation is a useful strategy Although supplementation is clearly efficacious in addressing vitamin D deficiency, the equity and practicality of large-scale vitamin D supplementations need to be fully considered. Whereas supplementation may have a place in controlled environments, such as nursing homes, it has limited potential in free-living subjects, especially those with low awareness of the issues, restricted access to health care and limited financial means.

CONCLUSION

The prevalence of sub-clinical vitamin D deficiency in Australia and New Zealand is relatively high. New dietary recommendations for vitamin D from the National Health & Medical Research Council are now in place, but against these AIs of 5-15 [micro]g/day, depending on age, the usual Australian diet provides only 2-3 [micro]g/day. Current models of healthy eating do not deliver the recommended amounts of vitamin D and need review. Unlike the situation in the USA, Canada, UK and Europe, there is only limited fortification of foods with vitamin D in Australia and New Zealand and, consequently, average dietary intakes of vitamin D are substantially below intakes in those countries. Increased voluntary fortification of yoghurts and some reduced-fat milks up to the levels permitted by current Australian and New Zealand food regulations would seem to be desirable and would certainly be safe. Regular use of such products is to be encouraged in all age groups. Mandatory fortification of milk with vitamin D deserves consideration but would require changes to food regulations. Elderly housebound or institutionalised people are at high risk of deficiency and probably require vitamin D supplementation if their high dietary requirements are to be met.

REFERENCES

1 Backstrand JR. The history and future of food fortification in the United States: a public health perspective. Nutr Rev 2002; 60: 15-26.

2 Clements FW. A History of Human Nutrition in Australia. Melbourne: Longman Cheshire, 1986.

3 Working Group of the Australian and New Zealand Bone and Mineral Society, Endocrine Society of Australia and Osteoporosis Australia. Vitamin D and adult bone health in Australia and New Zealand: a position statement. Med J Aust 2005; 182: 281-5.

4 Lindsay R, Cosman F. Osteoporosis. In: Kapper DL, Braunwold E, Fauci AS, Hauser SL, Longo DL, Jameson JL, eds. Harrison's Principles of Internal Medicine, 16th edn. New York: McGraw Hill, 2005; 2268.

5 Weatherell M. A meta-analysis of 25 hydroxyvitamin D in older people with fracture of the proximal femur. N Z Med J 2000; 113: 137-40.

6 Holick MF. Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers and cardiovascular disease. Am J Clin Nutr 2004; 80: 1678S-88S.

7 Jones G, Dwyer T, Hynes KL, Parameswaran V, Greenaway TM. Vitamin D insufficiency in adolescent males in Southern Tasmania: prevalence, determinants, and relationship to bone turnover markers. Osteoporos Int 2005; 16: 636-41.

8 Pasco JA, Henry MJ, Nicholson GC, Sanders KM, Kotowicz MA. Vitamin D status of women in the Geelong Osteoporosis Study: association with diet and casual exposure to sunlight. Med J Aust 2001; 175: 401-5.

9 McGrath JJ, Kimlin MG, Saha S, Eyles DW, Parisi AV. Vitamin D insufficiency in south-east Queensland. Med J Aust 2001; 174: 150-51.

10 Rockell JE, Green TJ, Skeaff CM et al. Season and ethnicity are determinants of serum 25-hydroxyvitamin D concentrations in New Zealand children aged 5-14 y. J Nutr 2005; 135: 2602-8.

11 Skeaff CM, Green TJ. Serum 25-hydroxyvitamin D status of New Zealand adolescents and adults. Asia Pac J Clin Nutr 2004; 13: S47.

12 Weisberg P, Scanlon KS, Li R, Cogswell ME. Nutritional rickets among children in the United States: review of cases reported between 1986 and 2003. Am J Clin Nutr 2004; 80: 1697S-705S.

13 Grover SR, Morley R. Vitamin D deficiency in veiled or dark-skinned pregnant women. Med J Aust 2001; 175: 251-2.

14 Robinson PD, Hogler W, Craig ME et al. The re-emerging burden of rickets: a decade of experience from Sydney. Arch Dis Child 2006; 91: 564-8.

15 Nozza JM, Rodda CP. Vitamin D deficiency in mothers of infants with rickets. Med J Aust 2001; 175: 253-5.

16 Inderjeeth CA, Nicklason F, Al-Lahham Y et al. Vitamin D deficiency and secondary hyperparathyroidism: clinical and biochemical associations in older non-institutionalised Southern Tasmanians. Aust N Z J Med 2000; 30: 209-14.

17 Sambrook PN, Cameron ID, Cumming RG et al. Vitamin D deficiency is common in frail institutionalised older people in northern Sydney. Med J Aust 2002; 176: 560.

18 Flicker L, Mead K, MacInnis RJ et al. Serum vitamin D and falls in older women in residential care in Australia. J Am Geriatr Soc 2003; 51: 1533-8.

19 Diamond T, Smerdely P, Kormas N, Sekel R, Vu T, Day P. Hip fracture in elderly men: the importance of sub-clinical vitamin D deficiency and hypogonadism. Med J Aust 1998; 169: 138-41.

20 IUNS Committee 1/5. Recommended dietary intakes around the world. Nutr Abstr Rev 1983; 53: 939-1015, 1075-119.

21 Fraser DR, Vitamin D. In: Truswell AS, Dreosti IE, English RM, Rutishauser IHE, Palmer N, eds. Recommended Nutrient Intakes: Australian Papers. Sydney: Australian Professional Publications, 1990; 149-55.

22 Commonwealth Department of Health and Ageing (Aust), Ministry of Health (NZ), National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand. Canberra: Commonwealth of Australia, 2004.

23 Nakao H. Nutritional significance of human milk vitamin D in neonatal period. Kobe J Med Sci 1988; 34: 121-8.

24 Specker BL, Tsang RC, Hollis BW. Effect of race and diet on human-milk vitamin D and 25-hydroxyvitamin D. Am J Dis Child 1985; 139: 1134-7.

25 Holick MF, MacLaughlin JA, Wortsman J. Age, vitamin D and solar ultraviolet. Lancet 1989; 2: 1104-5.

26 Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Washington, DC: National Academy Press, 1997.

27 Holland B, Welch AA, Unwin ID, Buss DH, Paul AA, Southgate DAT. McCance and Widdowson's The Composition of Foods (Fifth edition). Cambridge: The Royal Society of Chemistry, 1991.

28 Hill TR, O'brien MM, Cashman KD, Flynn A, Kiely M. Vitamin D intakes in 18-64-y-old Irish adults. Eur J Clin Nutr 2004; 58: 1509-17.

29 Nowson CA, Margerison C. Vitamin D intake and vitamin D status of Australians. Med J Aust 2002; 177: 149-52.

30 Australia New Zealand Food Authority (ANZFA). Review of Vitamins and Minerals Standard. Canberra: ANZFA, 1999. Proposal 16.6.

31 Shrapnel B, Baghurst K. Adequacy of essential fatty acid, vitamin D and vitamin E intake: implications for the 'core' and 'extras' food group concept of the Australian Guide to Healthy Eating. Nutr Diet (in press).

32 Australian Institute of Health and Welfare. Heart, Stroke and Vascular Diseases: Australian Facts 2004. AIHW Cat No. CVD-27. Canberra: AIHW, 2004.

33 Australian Institute of Health and Welfare. Diabetes: Australian Facts 2002. AIHW Cat No. CVD 20 (Diabetes Series No. 3). Canberra: AIHW, 2002.

34 Skeaff CM, Mann JI, McKenzie J, Wilson NC, Russell DG. Declining levels of total serum cholesterol in adult New Zealanders. N Z Med J 2001; 114: 131-4.

35 Skeaff M, Green T. Do we need more food fortification. Nutr Diet 2004; 61: 71-2.

36 McKenna MJ. Differences in vitamin D status between countries in young adults and the elderly. Am J Med 1992; 93: 69-77.

37 Calvo MS, Whiting SJ, Barton CN. Vitamin D fortification in the United States and Canada: current status and data needs. Am J Clin Nutr 2004; 80: 1710S-16S.

38 Moore C, Murphy MM, Keast DR, Holick MF. Vitamin D intake in the United States. J Am Diet Assoc 2004; 104: 980-83.

39 Finch S, Doyle W, Lowe C et al. National Diet and Nutrition Survey: People Aged 65 Years and Over. Volume 1: Report of the Diet and Nutrition Survey. London: Department of Health, 1998.

40 Vieth R, Chan PC, MacFarlane GD. Efficacy and safety of vitamin D3 intake exceeding the lowest observed adverse effect level. Am J Clin Nutr 2001; 73: 288-94.

41 Trivedi DP, Doll R, Khaw KT. Effect of four-monthly oral vitamin [D.sub.3] (cholecalciferol) supplementation on fractures and mortality in men and women living in the community: a randomised double blind controlled trial. BMJ 2003; 325: 469-75.

42 Diamond TH, Ho KWK, Rohl PG, Meerkin M. Annual intramuscular injection of a megadose of cholecalciferol for treatment of vitamin D deficiency: efficacy and safety. Med J Aust 2005; 183: 10-12.

43 Bischoff-Ferrari HA, Willett WC, Wong JB, Giovannucci E, Dietrich T, Dawson-Hughes B. Fracture prevention with vitamin D supplementation: a meta-analysis of randomized controlled trials. JAMA 2005; 293: 2257-64.

William SHRAPNEL (1) and Stewart TRUSWELL (2)

(1) Shrapnel Nutrition Consulting Pty Ltd, Beecroft, and (2) The University of Sydney, Sydney, New South Wales, Australia

W. Shrapnel, GDipNutrDiet, MHP, Director

S. Truswell, AO, DSc, FRCP, FFPH, Emeritus Professor of Human Nutrition

Correspondence: W. Shrapnel, 10 Blackwood Close, Beecroft, NSW 2119, Australia. Email: [e-mail]

Table 1 Vitamin D content of foods ([micro]/100 g)

Herrings, kippers (a)         22.0-25.0
Canned salmon, tuna (a)       4.0-13.0
White fish, prawns (a)        Trace
Margarine (b)                 10.0
Egg (a)                       1.8
Butter (a)                    1.4
Cheddar cheese (a)            0.3
Milk (a)                      0.03
Liver (a)                     0.5-1.1
Lean meat (c)                 0.5-0.9
Fruit, vegetables, nuts (a)   Nil
Olive oil, vegetable oil (a)  Nil

(a) Data taken from Holland et al., (27) with permission.
(b) Industry data.
(c) Data taken from Hill et al., (28) with permission.