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How we wish to be cited:
Björkegren K. Folate and cobalamin in dairy products [editorial]. Rondel 2004; 19. URL: http://www.rondellen.net

The classical picture of severe deficiency of cobalamin and/or folate is inhibition of cell division in prophase (1); the result is few big cells, macrocytes or megalocytes. The deficiency affects all tissues with dividing cells, producing anemia, infertility and thin vulnerable mucous membranes (1,2). In non-dividing cells, polyneuropaty due to defective maintenance of myelin sheaths is widely recognized (3). In a modern post-industrial society, deficiency states of cobalamin and folate are mainly a concern of primary health care; even preclinical deficiencies may produce infertility, miscarriages, and lesions of the fetus. However, elderly people provide the main part of deficiency patients (4). Since folate treatment may mask cobalamin deficiency, it is suggested that folate monotherapy is abandoned; every patient treated with folate should also be treated with cobalamin. Likewise, cobalamin deficiency should always be treated with both cobalamin and folate.

The nutritional physiologist Karin Arkbåge defended her theses at Ultuna (Uppsala), The National Agriculture University, in December, 2003. Her theses analysed folate, cobalamin, and folate-binding proteins in milk and dairy products. The main topics were bio-availability, process retention, and analysis of the vitamins. Now Karin Arkbåge works at the Center for Clinical Trials of Food in Uppsla, Sweden. Karin Björkegren elucidates the biomedical context of the dissertation of Arkbåge.

The debate on the importance of vitamin B12 and folate (vitamin B9) for the human being is still actual. Both B12 and B9 deliver units to the DNA synthesis and are dependent on each other. The human body cannot produce either B9 or B12; thus, the vitamins must be provided by the food. B12 and B9 are very important in new cell generation, for example in pregnancy (1-3).

As early as in the 1960’s, English researchers knew the unique role of folate in the development of the foetus. But it was not until the last decade that folate got big attention, because deficiency can cause infertility, early miscarriages, and foetal damage (1-3). Impaired cognition and dementia are also associated to B12 or folate deficiency (4, 5). Folic acid fortification already exists in several countries. In Sweden, we still discuss if we shall start to fortify the flour.

Dairy products constitute a difficult food matrix for analyses of B12 and B9. There is little reliable information about actual concentrations of the vitamins, and about which impact food processing techniques have on vitamin retention (6).

Milk and dairy products are good B12 and folate sources. Karin Arkbåge has in her dissertation (6) studied what happens to the vitamin contents during the manufacturing process from milk to "ready to consume" fermented products. She found that B12 was concentrated by a factor 5-8 during hard cheese making, while the vitamin content was reduced to one half in fermented milk and yoghurt that had been stored in refrigerator, compared to the original milk content. The concentration of folate was higher in yoghurt as well as in fermented milk and cheese compared to milk.

Another aim was to study folate bio-availability from milk and fermented milks using both an in vitro gastrointestinal model and a human model. Focus was on studying the nutritional role of bovine milk folate-binding proteins (FBP), which are suggested to have a positive impact on folate bio-availability. This has been discussed for a long time.

Karin Arkbåge now has shown that FBP in milk decreases folate gastrointestinal absorption. FBP does not change in pasteurised milk, but in fermented milks, which have been heated in much higher temperatures, there are no FBP.

The results of Karin Arkbåge´s studies also showed that both milk and yoghurt are suitable to be fortificated with folic acid, as 70-80% of the added vitamin was bioaccessible in the small intestines.