FOOD ADDITIVES AS THERAPEUTIC AGENTS— AN ALTERNATIVE FUNCTION

III. FOOD ADDITIVES AS THERAPEUTIC AGENTS— AN ALTERNATIVE FUNCTION

A. Stabilisers and Thickeners

A number of materials used in food manufacture may fulfil more than one function. Typi- cal of these are some of the complex carbohydrates otherwise known both as soluble fibres and as effective stabilizing and thickening agents.

In recent years health aficionados have been promoting the beneficial effects of soluble fibre (18). In normal subjects, soluble dietary fiber can have a beneficial choles- terol-lowering effect, a fact highlighted by manufacturers of foods which are naturally high in soluble fiber. In non–insulin dependent diabetics, an additional postprandial reduction in blood glucose is observed. However, these beneficial effects are dose dependent, and it can be argued that large quantities of food rich in natural fiber would have to be consumed before any real benefits would be shown (The British Diabetic Association have recom- mended a minimum daily intake of 30 g of dietary fiber (19)).

An alternative approach relies on the use of polysaccharide gums such as guar, pectin, sodium alginate, and konjac glucomannan incorporated at appropriated doses in everyday consumer products such as bread or cereal. Some such ‘‘designer high-fiber foods’’ have been clinically tested for their therapeutic effect and results have been very positive.

1. Guar Gum This additive is a purified extract from the leguminous plant Cyamopsis tetragonoloba

(L.) Taub. It is composed mainly of the galactomannan polymer, which increases viscosity in the gut, causing a slowing in the absorption of carbohydrates and increased bile produc- tion (initiating cholesterol reduction). Work carried out using guar gum incorporated into bread points to an effective dosage of between 6 and 15 g/day (20), which is significantly below the British Diabetic Association’s minimum daily intake for dietary fiber, showing that incorporation into food increases the additive’s effectiveness.

Guar gum has also been used as a slimming aid; theoretically it swells in the stom- ach, giving a feeling of satiety and thus reducing the rate of food ingestion (21). However, due to the possibility of esophageal obstruction using guar gum, the Ministry of Agricul- ture, Fisheries and Foods (UK) in 1988 imposed limits on the use of guar gum tablets and capsules for slimming (22).

2. Konjac Glucomannan This polysaccharide gum is extracted from the plant called Amorphophallus konjac (K) 2. Konjac Glucomannan This polysaccharide gum is extracted from the plant called Amorphophallus konjac (K)

B. Lecithins

Lecithin in general is an approved food additive (E322 and FDA approved) for use as an emulsifier in margarine, chocolate, and bakery products. Commercially, it is predomi- nantly extracted from soya beans. Recently, research and marketing have been directed toward the development of lecithin fractions, with their own characteristic phospholipid composition (24). Similarly, in the health food sector lecithin is marketed as a natural emulsifier of fats, rich in choline and inositol. Claims are made which emphasize its role as a facilitator in the metabolism of fat. However, as yet there is no direct evidence which can link lecithin consumption with a reduction in heart disease (25).