Liver and Vitamin D: fact or fiction?Liz Williams, Renee Sobolewski, David Fraser

Food Standards Australia New Zealand, Canberra, ACT, 2610, Australia

Natural Sources Data origin µg per 100g food

Beef fillet, grilled Australian analysis 0.1

Cheese, cheddar Australian analysis 3.32

Chicken breast, grilled Australian analysis 0.12

Cod liver oil Borrowed (UK) 210

Egg Australian analysis 0.9

Liver, chicken, fried Australian analysis 0.27

Milk, regular fat Australian analysis 0.52

Salmon Atlantic, fillet, grilled Australian analysis 7.4

Fortified Foods Data origin µg per 100g food

Margarine spreads Australian analysis 4.5

Milk, reduced fat, fortified Label 2.24

Yoghurt, extra creamy, fortified Label 1.51

Mandatory Fortification with Vitamin D

Voluntary Fortification with Vitamin D

Australia Margarines & oil spreads

Dried milksModified milks & skim milkCheese & cheese productsYoghurtsDairy DessertsButter

United States

Milk & milk productsBreakfast cerealsBaked goodsMargarine and spreadsOrange juiceSoy products

United Kingdom MargarineOther spreadsBreakfast cereals

Boys

2-3 years

4.5

4

3.5

3

2.5

21.5

1

0.50

4-8 years 9-13 years 14-16 years

Girls

Total Children

Age in years

µg o

f vi

tam

in D

per

day

Australia PO Box 7186 Canberra BC ACT 2610 www.foodstandards.gov.auNew Zealand PO Box 10559 The Terrace Wellington 6036 www.foodstandards.govt.nz

Limitations of food composition dataAUSNUT 2007 contains the best available data for vitamin D concentrations in foods in

Australia, although the dataset is based on only a small set of Australian analyses. Wherever

analytical data was unavailable the most reasonable data for the foods where it was likely to

make a difference to nutrient intakes was obtained. For this reason, the vitamin D data should

still be interpreted with caution.

In general, there will always be limitations with food composition data. Nutrient data should

be regarded as approximations of the likely nutrient content of the food, beverage and

supplement to which they refer. This is because the nutrient composition of foods is

variable and dependent on a range of factors. There are inherent factors affecting nutrient

composition (e.g. the cultivar of a plant that is selected) and also factors associated with

variability in production, formulation and storage practices (14). Also the limitations associated

with method of analysis should be considered and are particularly relevant for vitamin

D. There is also some debate about the appropriate bioavailability factors to use when

estimating total vitamin D activity in a food from the different forms of the vitamin that may be

present (15).

References1. Food Standards Australia New Zealand. (2007). Australian Food,

Supplement & Nutrient Database 2007 for estimation of population nutrient intakes. Explanatory Notes.

2. Greenfield, H. And Southgate, DAT. (2003). Food composition data. Production, management and use, pp. 129-131. Rome, FAO.

3. Ball, GFM. (1998). Bioavailability and analysis of vitamins in foods. London, Chapman and Hall.

4. Holden, J.M. and Lemar, LE. (2008). Assessing vitamin D contents in foods and supplements: challenges and needs. Am J Clin Nutr 2008:88(suppl):551S-3S.

5. National Health and Medical Research Council. (2006) Nutrient Reference Values for Australia and New Zealand. Canberra.

6. Holick, M. (2001). Sunlight “D”ilemma: risk of skin cancer or bone disease and muscle weakness. Lancet 2001;357:4-6.

7. 2007 Australian National Children’s Nutrition and Physical Activity Survey – Main Findings. Publications Number: P3-4592, Commonwealth of Australia, Canberra.

8. Kids Eat Kids Play Survey. (2007). Food Standards Australia New Zealand, Canberra.

9. Food Standards Australia New Zealand (2007). AUSNUT 2007 – Australian Food Composition Tables. Canberra: FSANZ.

10. Nowson, CA, Diamond, TH, et al. Vitamin D in Australia. Issues and Recommendations. (2004). Australian Family Physician 33;133-138.

11. Food Standards Australia New Zealand. http://www.foodstandards.gov.au

12. United States Department of Agriculture. http://www.usda.gov

13. United Kingdom Food Standards Agency www.food.gov.uk

14. Pennington, JAT (2008). Applications of food composition data: Data sources and consideration for use. J Food Composition & Analysis, 21:S3-S21.

15. Valverde, J, Hayes M. (2010). EuroFoodChem XV: food for the future. The contribution of chemistry to improvement of food quality. Eur Food Res Technol 2010 230:687–691.

Table 1 Vitamin D Content in Food (9)

Vitamin D fortificationFortification of foods traces back to the need to address vitamin deficiencies. Various

diseases such as rickets can be linked to the lack of vitamin D. Vitamin D is also known

as the “Sunshine Vitamin”, as it is produced in the skin by exposure to sunlight. In today’s

society, many people have reduced sun exposure due to spending a large amount of time

indoors, wearing sunscreen when outdoors or wearing fully protective clothing, thereby

reducing formation of this vitamin (10). Vitamin D is not present in many foods that we

consume on a daily basis, so it was decided decades ago to fortify certain foods with this

vitamin. In Australia margarine was considered an appropriate choice, as it is consumed by

many people on a daily basis. Refer to Table 2 for a comparison of the range of foods fortified

with vitamin D in differing countries.

Table 2 Comparisons of vitamin D fortification in Australia, US and the UK (11,12,13)

IntroductionLiver is commonly reported as a good source of vitamin D in the diet. However, liver from terrestrial animals contains very little vitamin D as a result of hepatic catabolism. Fish liver, by contrast is a good source of vitamin D as the fatty acid ester is stored in the liver fat of fish.

AUSNUT 2007 is a nutrient database that was developed for estimating nutrient intakes from food, beverages and dietary supplements consumed as part of the 2007 National Children’s Nutrition and Physical Activity survey (Kids Eat, Kids Play).

AUSNUT 2007 contains Australia’s most comprehensive vitamin D dataset (1). The vitamin D dataset is a combination of Australian analytical data and where Australian data were not available, data has been derived using established data compilation techniques such as borrowed data from overseas food composition tables and imputation.

Challenges with developing a Vitamin D database for foods

Two forms of vitamin D are found in foods, cholecalciferol (D3) and ergocalciferol (D2). Vitamin D3 is the more widely distributed (e.g. in fish oils, fatty fish tissues, eggs, butter) and D2 occurs naturally in foods such as mushrooms (2). Estimates of the relative activities of cholecalciferol, ergocalciferol and their metabolites (25-hydroxycholecalciferol) vary.

Vitamin D in foods is found at a very low concentration, which makes its analysis difficult. Also, most food sources contain other lipids that tend to interfere with the analysis (3). Analysing different forms of vitamin D requires validated analytical methods and reference materials for vitamin D. Existing analytical methods have lacked specificity, sensitivity and precision. Developing a comprehensive analytical program for generating vitamin D data that are representative of the national food supply is costly because the chemistry is complex, food sampling and preparation is expensive, and compiling and estimating values is time consuming and detailed work (4).

Vitamin D intakes in the KEKP Survey 2007The estimated intakes for vitamin D were less than the adequate intakes (AIs) of 5 µg/day (5). Whilst these findings may suggest that a significant number of children may not be consuming sufficient vitamin D, a definitive conclusion cannot be reached. Vitamin D experts have reported that between 80-100% of our vitamin D is sourced from casual exposure to sunlight. However there is increasing recognition that a significant number of Australians and people from specific groups within the community are at risk of vitamin D deficiency (6).

Graph 1 Mean intake of vitamin D by age group and gender, KEKP2007 (7)

The Kids Eat Kids Play survey revealed that liver and liver containing products contributed only 0.02 % of the total vitamin D intake among survey participants. Margarine spreads contributed 4.3 % of the total vitamin D intake (8). This was due to the combined effect of the fortified levels of vitamin D in margarines and that they are widely consumed. Other major contributors were dairy milks (27.7%), multivitamin supplements (13.3%) and cheese (12.2%). Table 1 lists the vitamin D content of a number of foods as reported in AUSNUT 2007.