On 2016 May 10, Ramune Jacobsen commented:

On behalf of: Jacobsen R, Abrahamsen B, Bauerek M, Holst C, Jensen CB, Knop J, Raymond K, Rasmussen LB, Stougaard M, Sørensen TI, Vaag AA, Heitmann BL and the D-tect group (The Research Unit for Dietary Studies at the Parker Institute and the Institute of Preventive Medicine, Frederiksberg and Bispebjerg Hospital, The Capital Region, Denmark). In the published paper we describe the design of a Danish societal experiment, the “D-tect study”. Among others, the D-tect study takes advantage of the mandatory vitamin D fortification policy implemented in Denmark, in which we used onset and termination of the vitamin D fortification of margarine to examine the possible effect of food fortification on the risk of adverse health outcomes among individuals from birth through adulthood (Jacobsen R, 2013). Based on official documentation from the Nordic Council of Ministers (1), the commencement of vitamin D fortification was 1961. However, we have recently uncovered new evidence that makes this onset date less secure, and suggests that mandatory fortification may have started even before World War II, for both vitamin A and D (2-4). While this new research weakens our confidence in the onset date of the vitamin D margarine fortification, all data sources we have come across confirms that the date of termination of the mandatory margarine fortification with 50 IU D-vitamin per 100 g margarine was June 1985 (5). Furthermore, the new evidence suggests a change in fortification policies related to mandatory vitamin A fortification around 1961 (an additional 25% vitamin A was added to margarine raising amounts from 20 iu to 25 iu per g margarine) (6). It is feasible that the addition of vitamin A may have programming effects related to both neurodevelopment, immune function and growth (Zhang X, 2009,van de Pavert SA, 2014,Wang YZ, 2009) like those from vitamin D, and that effects seen around initiation, for instance as those we saw in relation to birth weight (Jensen CB, 2015, Jensen CB, 2014), may potentially be explained by the extra vitamin A from fortification (Yassai MB, 1989, Ghebremeskel K, 1994, Tolba AM, 1998). We regret that we had not identified this information prior to study commencement. However, we now have access to analytic epidemiology in order to directly explore links between neonatal vitamin D status and risk of adverse health outcomes, as we have been able to directly measure 25 hydroxyvitamin D concentrations in neonatal dried blood spots over the years of interest. In light of the potential that food supplementation with vitamin D can differentially impact on neonatal and adult health outcomes, we will continue to use the best available evidence to explore this area of research. References: 1.Haraldsdóttir J & Thaarup S: Tilsætning af vitaminer & mineraler til levnedsmidler. Nordisk Ministerråd. 1989; 2.Lov om tilvirkning og forhandling af margarine m.m (Bek. af lov om tilvirkning og forhandling af margarine m.m ). Nr. 229 af 28. juni 1937; 3.Bekendtgørelse angaaende Vitaminvirkning i Margarine. Nr. 247 af 28. juli 1937; 4.Bekendtgørelse om vitaminvirkning i margarine. Nr. 258 af 27. juni 1952; 5.Bekendtgørelse om margarine m.v. Nr. 197 af 20. maj 1985; 6.Bekendtgørelse om vitaminvirkning i margarine. Nr. 344 af 5.december 1961.

On 2016 May 10, Ramune Jacobsen commented:

On behalf of: Jacobsen R, Abrahamsen B, Bauerek M, Holst C, Jensen CB, Knop J, Raymond K, Rasmussen LB, Stougaard M, Sørensen TI, Vaag AA, Heitmann BL and the D-tect group (The Research Unit for Dietary Studies at the Parker Institute and the Institute of Preventive Medicine, Frederiksberg and Bispebjerg Hospital, The Capital Region, Denmark). In the published paper we describe the design of a Danish societal experiment, the “D-tect study”. Among others, the D-tect study takes advantage of the mandatory vitamin D fortification policy implemented in Denmark, in which we used onset and termination of the vitamin D fortification of margarine to examine the possible effect of food fortification on the risk of adverse health outcomes among individuals from birth through adulthood (Jacobsen R, 2013). Based on official documentation from the Nordic Council of Ministers (1), the commencement of vitamin D fortification was 1961. However, we have recently uncovered new evidence that makes this onset date less secure, and suggests that mandatory fortification may have started even before World War II, for both vitamin A and D (2-4). While this new research weakens our confidence in the onset date of the vitamin D margarine fortification, all data sources we have come across confirms that the date of termination of the mandatory margarine fortification with 50 IU D-vitamin per 100 g margarine was June 1985 (5). Furthermore, the new evidence suggests a change in fortification policies related to mandatory vitamin A fortification around 1961 (an additional 25% vitamin A was added to margarine raising amounts from 20 iu to 25 iu per g margarine) (6). It is feasible that the addition of vitamin A may have programming effects related to both neurodevelopment, immune function and growth (Zhang X, 2009,van de Pavert SA, 2014,Wang YZ, 2009) like those from vitamin D, and that effects seen around initiation, for instance as those we saw in relation to birth weight (Jensen CB, 2015, Jensen CB, 2014), may potentially be explained by the extra vitamin A from fortification (Yassai MB, 1989, Ghebremeskel K, 1994, Tolba AM, 1998). We regret that we had not identified this information prior to study commencement. However, we now have access to analytic epidemiology in order to directly explore links between neonatal vitamin D status and risk of adverse health outcomes, as we have been able to directly measure 25 hydroxyvitamin D concentrations in neonatal dried blood spots over the years of interest. In light of the potential that food supplementation with vitamin D can differentially impact on neonatal and adult health outcomes, we will continue to use the best available evidence to explore this area of research. References: 1.Haraldsdóttir J & Thaarup S: Tilsætning af vitaminer & mineraler til levnedsmidler. Nordisk Ministerråd. 1989; 2.Lov om tilvirkning og forhandling af margarine m.m (Bek. af lov om tilvirkning og forhandling af margarine m.m ). Nr. 229 af 28. juni 1937; 3.Bekendtgørelse angaaende Vitaminvirkning i Margarine. Nr. 247 af 28. juli 1937; 4.Bekendtgørelse om vitaminvirkning i margarine. Nr. 258 af 27. juni 1952; 5.Bekendtgørelse om margarine m.v. Nr. 197 af 20. maj 1985; 6.Bekendtgørelse om vitaminvirkning i margarine. Nr. 344 af 5.december 1961.