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Food fortification as a means to increase vitamin D intake

Published online by Cambridge University Press:  18 April 2016

Suvi T. Itkonen*
Calcium Research UnitDepartment of Food and Environmental SciencesDivision of NutritionUniversity of Helsinki 00014 University of HelsinkiHelsinki, Finland
Christel Lamberg-Allardt
Calcium Research UnitDepartment of Food and Environmental SciencesDivision of NutritionUniversity of Helsinki 00014 University of HelsinkiHelsinki, Finland
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Letters to the Editor
Copyright © The Authors 2016 

Soininen et al. ( Reference Soininen, Eloranta and Lindi 1 ) recently reported about vitamin D intake, serum 25-hydroxyvitamin D (25(OH)D) concentration, determinants of 25(OH)D and risk factors for serum 25(OH)D<50 nmol/l in Finnish children. The authors draw conclusions that 80 % of the children did not meet the current recommendation for vitamin D intake from food and supplements and 20 % had serum 25(OH)D concentrations <50 nmol/l. This may cause concern about the adequacy of the vitamin D status at northern latitudes. The study and its results are potentially interesting, but the authors have misled the reader to some extent by not stressing that the data collection was carried out between the years 2007–2009. At the time of the study, a decree on general vitamin D fortification had been adopted in 2002( 2 ). It stated that the vitamin D levels for fluid milk products (with exception of organic products) and respective lactose-free milk and soya- and cereal-based drinks should be 0·5 µg/100 g and for spreadable fats 10 µg/100 g. These levels were, however, much lower than the present ones.

Studies and reports about the efficacy of that fortification level( 2 ) on vitamin D intake and 25(OH)D concentrations in different population groups in Finland were already carried out in 2000s( Reference Laaksi, Ruohola and Ylikomi 3 Reference Lehtonen-Veromaa, Mottonen and Leino 7 ). The main message of these studies was that, although the 25(OH)D concentrations and vitamin D intake mainly tended to increase because of the fortification, a significant percentage of the subjects remained with inadequate vitamin D status in all age groups. From that point of view, the study of Soininen et al. ( Reference Soininen, Eloranta and Lindi 1 ) does not provide any new data, as this has already been reported in children and adolescents as well( Reference Piirainen, Laitinen and Isolauri 5 , Reference Lehtonen-Veromaa, Mottonen and Leino 7 , Reference Tylavsky, Cheng and Lyytikäinen 8 ). The results of those earlier studies from the 2000s led to the discussion on new recommendations on fortification levels in 2010.

In April 2010, The National Nutrition Council launched a new recommendation that the fortification levels should be doubled to 1·0 µg/100 g for all fluid milks and respective products and to 20 µg/100 g for spreadable fats( 9 ). These recommendations were based on simulations on the effect of fortification. Especially the dairy industry responded immediately and almost all fluid milk products were fortified, with the exception of ecological products. Soininen et al. ( Reference Soininen, Eloranta and Lindi 1 ) discuss this, but they still seem to hide this fact from their conclusions. They do not point out that nowadays, since 2010, the range of vitamin D content in dairy products in Finland has increased because of the new fortification policy. In addition, a wide selection of vitamin D-fortified products, not only fluid milk and spreads, are currently on the market. Some fluid milk products contain even 2 µg vitamin D/100 g and, for example, a number of yogurts may have the same amount( Reference Itkonen, Erkkola and Skaffari 10 ).

Thus, it is probable that this later fortification has had a positive impact on the vitamin D intake and status among Finnish children, especially among those who consume fluid milk products. This has been reported in adults, whose mean vitamin D intake now is about 10 µg, and close to 40–50 % of it comes from fortified milk products( Reference Raulio, Hyvärinen and Virtanen 11 ). Moreover, the supplementation recommendations for children and adolescents have been increased and extended to cover the whole year since 2011( 12 ). Consequently, the conclusion of the authors that many children need more vitamin D from food or supplements to reach sufficient serum 25(OH)D concentrations in northern latitudes is drawn from outdated data, which is a serious flaw in the interpretation of it. These actions have already been taken in 2010, and what we need is new data from the time after that. The Physical Activity and Nutrition in Children (PANIC) study is an ongoing trial, and the second 2-year follow-up was carried out in 2009–2011. Thus, we wonder why the authors have not presented new data after the year 2010 fortification, because they seem to have it already( 13 ).

Further, the results of the Soininen et al. ( Reference Soininen, Eloranta and Lindi 1 ) study have a significant and serious methodological problem, which subsequently weakens the conclusions regarding vitamin D status. The analytical assay used for 25(OH)D, the LIAISON® 25OHD Total assay (DiaSorin Inc.), has been shown to have a negative bias in external analyses, for example, DEQAS (Vitamin D External Quality Assessment Scheme, Reference Carter 14 ). Thus, the 25(OH)D data are flawed and make subsequent analyses worthless. This is a common problem with 25(OH)D, which causes bias in the result assays( Reference Carter 15 ). This is extremely important to understand when vitamin D status cut-off values are reported and used. During the last few years, the Vitamin D Standardization Programme (VDSP) has been initiated by National Institute of Health, with the aim to standardise commercial assays against two reference laboratories using National Institute of Standards and Technology reference material( Reference Binkley and Sempos 16 ). An important focus of the VDSP is on standardising the measurement of 25(OH)D in national health and nutrition surveys around the world by recalibrating 25(OH)D values from past surveys( Reference Cashman, Kiely and Kinsella 17 , Reference Cashman, Dowling and Škrabáková 18 ). As the assay used is of such importance in reporting vitamin D status in populations, it is astonishing that the authors do not even mention any external quality control system.


The authors thank Dr Maijaliisa Erkkola for her comments on the letter. There was no funding. S. T. I. and C. L.-A. wrote the letter.


1. Soininen, S, Eloranta, A-M, Lindi, V, et al. (2016) Determinants of serum 25-hydroxyvitamin D concentration in Finnish children: the Physical Activity and Nutrition in Children (PANIC) Study. Br J Nutr 115, 10801091.Google Scholar
2. Ministry of Trade and Industry of Finland. Regulation 917/2002 about adding of vitamins and some other substances to foodstuffs. FINLEX (Kauppa- ja teollisuusministeriön asetus 917/2002 vitamiinien ja eräiden muiden aineiden lisäämisestä elintarvikkeisiin (In Finnish). 020 917 (accessed February 2016).Google Scholar
3. Laaksi, IT, Ruohola, JP, Ylikomi, TJ, et al. (2006) Vitamin D fortification as public health policy: significant improvement in vitamin D status in young Finnish men. Eur J Clin Nutr 60, 10351038.Google Scholar
4. Lamberg-Allardt, C & Viljakainen, H, a Working Group (2006) Follow-up study on the vitamin D status in the Finnish population 2002 and 2004. Reports of the Ministry of Social Affairs and Health, Finland (D-vitamiinitilanteen seurantatutkimus 2002-2004) (In Finnish with English summary). (accessed February 2016).Google Scholar
5. Piirainen, T, Laitinen, K & Isolauri, E (2007) Impact of national fortification of fluid milks and margarines with vitamin D on dietary intake and serum 25-hydroxyvitamin D concentration in 4-year old children. Eur J Clin Nutr 61, 123128.Google Scholar
6. Välimäki, V-V, Löyttyniemi, E & Välimäki, MJ (2007) Vitamin D fortification of milk products does not solve hypovitaminosis D in young Finnish men. Eur J Clin Nutr 61, 493497.Google Scholar
7. Lehtonen-Veromaa, M, Mottonen, T, Leino, A, et al. (2008) Prospective study on food fortification with vitamin D among adolescent females in Finland: minor effects. Br J Nutr 100, 418423.Google Scholar
8. Tylavsky, FA, Cheng, S, Lyytikäinen, A, et al. (2006) Strategies to improve vitamin D status in northern European children: exploring the merits of vitamin D fortification and supplementation. J Nutr 136, 11301134.CrossRefGoogle ScholarPubMed
9. National Nutrition Council (2010) Report of vitamin D working group (Valtion ravitsemusneuvottelukunta. D-vitamiinityöryhmän raportti), April (in Finnish) (accessed February 2016).Google Scholar
10. Itkonen, ST, Erkkola, M, Skaffari, E, et al. (2016) Development and validation of an interview-administered FFQ for assessment of vitamin D and calcium intakes in Finnish women. Br J Nutr 115, 11001107.Google Scholar
11. Raulio, S, Hyvärinen, H & Virtanen, S (2015) Vitamin D status improving in Finland. (Suomalaisten D-vitamiinitilanne parantumassa). Suomen Lääkärilehti 70, 4111414 (In Finnish with English summary).Google Scholar
12. National Nutrition Council (2014) Finnish Nutrition Recommendations – Health from Food (Suomalaiset ravitsemussuositukset – Terveyttä ruoasta). Helsinki: Juvenes Print; (In Finnish).Google Scholar
13. University of Eastern Finland (2006) PANIC Study website. (accessed February 2016).Google Scholar
14. Carter, GD (2011) Accuracy of 25-hydroxyvitamin D assays: confronting the issues. Curr Drug Targets 12, 1928.Google Scholar
15. Carter, GD (2012) 25-Hydroxyvitamin D: a difficult analyte. Clin Chem 58, 486488.Google Scholar
16. Binkley, N & Sempos, CT, Vitamin D Standardization Program (2014) Standardizing Vitamin D assays: the way forward. J Bone Miner Res 29, 17091714.Google Scholar
17. Cashman, KD, Kiely, M, Kinsella, M, et al. (2013) Evaluation of Vitamin D standardization program protocols for standardizing serum 25-hydroxyvitamin D data: a case study of the program’s potential for national nutrition and health surveys. Am J Clin Nutr 97, 12351242.Google Scholar
18. Cashman, KD, Dowling, KG, Škrabáková, Z, et al. (2015) Standardizing serum 25-hydroxyvitamin D data from four Nordic population samples using the Vitamin D Standardization Program protocols: shedding new light on vitamin D status in Nordic individuals. Scand J Clin Lab Invest 75, 549561.Google Scholar