FeedMagazine
From EFSA'S Work

Vitamins as feed additives

Casimir Funk (1884 – 1967) could not have imagined what resonance he would trigger when over a hundred years ago (1911) he introduced the melodious and vowel-rich word “vitamins” to denote various vital organic compounds. He erroneously assumed that the nutritional contents, which had been researched since the end of the 19th century, contained amino groups, so that he considered “vitamins” a justified word to express “amines for life”.

At the beginning, for example the B-vitamins were given numbers in the sequence of their discovery, such as e.g. vitamin B1 for aneurin/thiamine; vitamin B2 for riboflavin; vitamin B3 for niacin; vitamin B4 for choline; vitamin B5 for pantothenic acid, vitamin B6 for pyridoxine etc. As analysis skills and knowledge of the physiological significance of these substances improved further, many of them lost the “vitamin status”, as it could not be documented that they possessed essential effect(s). This finding applies for instance to betaine, L-carnitine (Vit. BT), inositol, laetrile (Vit. B17), L-carnitine, methyl-methionine sulfonium chloride (Vitamin U), orotic acid (Vit. B13), pangamic acid (Vit. B15), taurine, ubiquinone (Q10), and with limitations to choline as well.

From the scientific standpoint, 13 vitamins (vitamin A, C, D, E, K, B1, B2, B6, B12, as well as folic acid, biotin, niacin and pantothenic acid) are currently considered to be essential. This means that they cannot be synthesised in the body (although that does not apply for vitamin D, and in the case of vitamin C it applies only for a few species, including humans). In other words they must be consumed with the diet as vitamins or pro-vitamins (e.g. beta-carotene as provitamin for vitamin A) and exercise a physiological function.

However, the status “vitamin-like” substances does not prevent various manufacturers from offering these substances on the market with special effects under specific conditions, both for food-supplying animals and for pets (and humans). All these substances are appraised by the FEEDAP Panel of EFSA with regard to their safety for humans, animals and the environment, as well as for their effectiveness.

In the past years, the FEEDAP Panel has repeatedly considered applications for various vitamins and vitamin-like compounds. Extensive discussion under the aspect of consumer protection was conducted above all when setting upper limits for vitamin A. Vitamin A is stored in high quantities in the liver of animals. With consideration given to several scientific opinions by the EFSA NDA Panel (Panel on Dietetic Products, Nutrition and Allergies) and extensive animal trials on the accumulation of vitamin A in the liver, milk and eggs, the FEEDAP Panel proposed various maximum levels for vitamin A in feeds, depending on the animal species and category (for example EFSA Journal 2008, 873, 1-81; EFSA Journal 2013, 11: 3037), which were subsequently taken over by the EU Commission – though regrettably not completely.

Another example of a critical assessment is the way in which a vitamin D3 metabolite that is metabolically very active is handled. Leaves of Solanum glaucophyllum or “waxy-leaf nightshade” growing in South America contain considerable quantities of the metabolite 1.25-dihydroxycholecalciferol (1.25(OH)2D3) with vitamin D activity. In human and animal metabolism, this metabolite only occurs through activation of vitamin D in the liver and subsequently in the kidney. It then possesses a hormone character, especially as concerns control of the Ca and P metabolism. In dairy cows, the substance certainly possesses the potential for helping to help avoid milk fever. The problem is finding a practicable dosing scheme. The scientific opinion of the FEEDAP Panel (see EFSA-Journal 2015; 13: 3967) provides various answers, but also offers suggestions for future research approaches on the topic of Solanum glaucophyllum. Whereas the formulation of maximum levels for vitamin A focused mainly on consumer protection, the high dosage levels of vitamin D revolve chiefly around animal welfare and animal health.

Another topic is the stability of the vitamins during storage, in vitamin-mineral substance premixes, in compound feed and during pelletizing. It becomes apparent here, for example, that vitamin K3 (above all menadione sodium bisulphite; MSB) is not very stable in vitamin mineral premixes, which led to a recommendation of storage periods of less than one month (EFSA Journal 2014, 12(1)3532).

In FEEDAP opinions on the assessment of additives, yes/no answers, comparative or relative statements are deliberately avoided – although they would certainly be expedient. This rules out misuse of opinions by applicants for advertising purposes, as well as unconscious and unwanted participation of the Panel as advisor/umpire in a “contested” market.

There have been hardly any problems in connection with consumer protection so far with regard to water-soluble vitamins and vitamin-like compounds. Water-soluble vitamins are only stored in the body in small quantities or are secreted with milk and eggs. On the other hand, overdoses are of no benefit to either the farm animal or the farmer.

This finding also applies to the vitamin supplements added to drinker water, as the feed is generally supplemented sufficiently with the corresponding vitamins and uptake via water can hardly be estimated from the start due to various influencing factors (temperature, animal species, category, performance level, water content of the feedstuff etc.). Administering vitamins via drinker water is only expedient if the total content in the feed is known or vitamins have not been added to the feed at all. Both situations are unlikely in feeding practice.

The observance of maximum levels enters into question when, as in the example of vitamin A, exposure of consumers can rise above a reasonable level.
The Authors
The authors – (Gerhard Flachowsky and Jürgen Gropp) – are long-serving members of the EFSA Panel on Additives and Products or Substances in Animal Feed (FFEDAP). They report on the work of the FEEDAP Panel. The articles contain personal views and representations, not those of EFSA or the EU. Consequently they do not necessarily coincide with the viewpoints of EFSA or the EU. Consequently they do not necessarily coincide with the viewpoints of EFSA or the EU. As experts working on behalf of EFSA, the authors are subject to certain confidentiality obligations.
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