Dr. Michele Jones investigates the difference between the natural and synthetic forms of this versatile vitamin, and examines how manufacturers are communicating both the benefits and the fundamental differences between the two.
Vitamin E has long been recognised as an important part of a balanced, nutritious diet. However, recent market research has indicated that there is a lack of understanding in relation to the various forms of vitamin E that are available, leading to confusion for the consumer. The fact that synthetic vitamin E is not chemically identical to naturally sourced vitamin E is not always realised. Many manufactured "synthetic" vitamins have exactly the same molecular configuration as the "natural" form: the "synthetic" molecules are the same and behave in exactly the same way as the "natural" molecules. Consequently there is no difference in the effectiveness of these vitamins. This is not so for vitamin E. It is the only vitamin for which there is a chemical and biological distinction between "natural" and "synthetic".
Recent consensus indicates that natural vitamin E is utilised by the body in preference to the synthetic vitamin E isomers. In practice, this is seen as a more effective initial retention of natural vitamin E over the synthetic forms and with time, by the presence of a consistently higher natural to synthetic ratio in many body tissues. What this means is that natural-source vitamin E has a higher bioavailability than synthetic. Also, with increasing consumer preference for naturally derived foods, natural-source vitamin E is ideally placed to meet current consumer expectations.
Natural-source vitamin E (d-alpha-tocopherol) is derived from vegetable oils, primarily from soya beans, corn, rapeseed and sunflower. The vitamin E found in nature is correctly known as d-alpha -tocopherol or RRR-alpha-tocopherol, but other natural forms known as beta-, gamma- and delta-tocopherol also exist.
This is the natural form of alpha-tocopherol whereas natural-source vitamin E is a single stereoisomer of tocopherol, synthetic chemically manufactured vitamin E (dl-alpha-tocopherol or all-rac-alpha-tocopherol) is a mixture of eight diastereoisomers in equal proportions. Only one of these, 12.5 per cent of the total mixture, is the d-alpha-tocopherol that is identical to natural-source vitamin E. The other seven stereoisomers have different molecular configurations and lower biological activities.
There are four naturally occuring tocopherols: alpha, beta, gamma and delta — usually referred to collectively as "mixed tocopherols". Alpha-tocopherol is by far the main type of vitamin E found in the human body. Natural-source vitamin E capsules generally contain d-alpha tocopherol and/or mixed tocopherols. The synthetic alternatives contain dl-alpha-tocopherol. The 'd' and 'dl' signify the single stereoisomer and the mixture of 8 synthetically derived isomers, respectively.
In the U.S., the Institute of Medicine (IOM) recommended recently that, for dietary purposes, vitamin E activity should be expressed as milligrams of d-alpha-tocopherol. However, commercial products are required by U.S. law to be labelled in IU (international units). IUs, recognised by the Food Chemicals Codex, refer to the activity of the alpha-tocopherol form of vitamin E in pregnant rodents. While beta, gamma and delta tocopherols carry significantly less IU activity there is emerging evidence to suggest that they may confer additional health benefits.
As already discussed, there are differences in the molecular structures of natural-source and synthetic vitamin E. These differences affect how the vitamin is treated by the body and in turn, its biological availability. Numerous studies support the following differences between natural-source and synthetic vitamin E:
- Both natural source vitamin E and synthetic vitamin E are absorbed in the body indiscriminately. However, after absorption, a protein in the liver recognizes the natural d-alpha-tocopherol and gives it priority over the synthetic form.
- As a result of the preferential retention of natural-source vitamin E by the liver compared with synthetic vitamin E, only 50 per cent of the synthetic form is treated as natural. The remainder of synthetic vitamin E is excreted more quickly.
- Owing to this discriminatory process natural d-alpha-tocopherol is retained better than the synthetic form. To compensate for its lower retention, a person would have to ingest, by weight, approximately twice the amount of synthetic vitamin E to match the activity of the natural form, and possibly more. A recent study has demonstrated that pregnant women transfer natural-source vitamin E to their babies approximately three times more efficiently than synthetic vitamin E.
- Natural-source vitamin E products are the same as the vitamin E found in the food supply and consequently, in the human body. Even though d-alpha-tocopherol has the highest biological activity of the four d-isomers, recent studies indicate that the beta, gamma and delta tocopherols may confer additional benefits that were previously unknown. At the present time, synthetic vitamin E is only available as dl-alpha tocopherol. Only natural-source vitamin E products can be formulated to contain the entire combination of alpha, beta, gamma and delta tocopherols found in food.
Whilst not a revolutionary new discovery, increased scientific and media attention has led to vitamin E continuing to strengthen its appeal to health conscious and proactive consumers in many countries around the world.
However, given the many differences in culture and traditional healthcare practice, the task of actually communicating the benefits of vitamin E to a European audience remains complex. The Spanish and Italians, for example, continue to rely on the advice of physicians for healthcare advice, whereas in the UK there is a growing trend towards developing a similar mass market for vitamins and minerals to that seen in the United States. There are currently widely differing national regulations but within the European Union the process of harmonisation relating to vitamins and minerals is underway.
In terms of raising consumer awareness, the recent publication of a report from the US Institute of Medicine served an important dual purpose: Firstly, the report highlighted the many potential health benefits associated with higher intakes of vitamin E, such as helping to maintain cardiovascular health and supporting the immune system. Secondly, and perhaps more significantly, the report was the first to give scientific recognition to the difference in bioavailability between the natural and the synthetic forms.
This was the first time that a scientific consensus had concluded that there is a 2:1 difference in activity between natural vitamin E, listed on labels as 'd-alpha-tocopherol' and the synthetic 'dl-alpha-tocopherol'.
Understanding how consumers perceive vitamin E and the reasons for supplemental incorporation into their diets are key areas of interest to many manufacturers. A study carried out by C&R Research provides a valuable insight into consumer attitudes towards vitamin E. In terms of serious disease, the findings of this survey showed that the majority of interviewees took vitamin E for its health promoting benefits in areas relating to heart disease, cancer and 'brain functioning' diseases such as Alzheimer's.
However, when it comes to identifying the difference between natural and synthetic vitamin E, many consumers are not familiar with the correct terminology and as a result, may assume that they are taking "natural" when in reality it is "synthetic". It is this specific communication that formed the focus of a high profile, promotional test market campaign carried out in Chicago, USA initiated by ADM in conjunction with Walgreens and GNC stores. The campaign specifically focused on promoting the d-Alpha (natural-source) terminology and the difference in bioavailability between the natural and synthetic forms. Consumer research carried out prior to the campaign showed a clear lack of understanding; only 6.3 per cent of respondents specifically looked for 'd-Alpha' on the ingredients label to ensure purchase of natural-source vitamin E. However, of those who did buy the natural form, 39.4 per cent mentioned that: "natural vitamin E is more effective than synthetic." A 20 per cent increase in volume sales of its natural-source vitamin E as a direct result of this test market promotion was reported.
In certain foods, adverse processing and/or storage conditions may lead to large oxidative losses. In many food products light, heat, alkaline pH and the presence of certain metals, primarily iron and copper, can lead to a reduced nutrient content and impaired flavour. Vitamin E can protect, fortify or enrich a variety of food products and can be incorporated easily into food supplements and food systems, including baked goods, cereals, spreads and dairy products.
In order to obtain the optimum health benefits associated with vitamin E, intakes in the range 200 and 800 IU per day have been suggested. However, it is almost impossible to consume this amount from dietary sources alone. Additionally, foods containing relatively high levels of vitamin E are also high in fat, making it difficult for the health conscious consumer to take in higher amounts without increasing fat intake. Supplements are therefore a very practical alternative. Any form of vitamin E is beneficial but the argument for natural-source vitamin E in terms of bioavailability is becoming stronger as the amount of supporting evidence continues to increase.
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