Home > Classification of functional foods

Functional foods may be classified in various ways and can be identified/selected on the basis of their properties, clinical significance or composition. Some of the important criteria used for classifying functional foods are:

1. Food Source
2. Nutrient and Non-Nutrient Source
3. Organ/Organ System
4. Modifications in foods
5. Specific Foods
6. Mechanism of actions
7. Chemical Nature

1). Classification based on Food Source:

According to origin or food source, the Functional foods may be classified into plant, animal and microbial groups.

Plant-derived functional foods

Plant-derived functional foods are separated into primary and secondary metabolites; primary metabolites are plant compounds necessary for growth and include plant proteins, beta-glucans and omega-3 fatty acids. The secondary metabolites are not essential for growth, but are used for plant survival mechanisms and include phytoestrogens, antioxidants, vitamins, tocopherols, steroids and gamma-linolenic acid (GLA).

Animal-derived functional foods

Zoo chemicals, which are animal-derived functional foods, include omega-3 and omega-6 fatty acids, conjugated linolenic acid (CLA), small peptides, whey and casein, and glucosamine. Omega-3 fatty acids include alpha-linolenic, docosahexaenoic (DHA), and eicosapentaenoic (EPA) fatty acids whereas Omega-6 fatty acids include linoleic, gamma-linoleic, and arachidonic fatty acids.

Microbial functional foods

Microbial-derived functional foods include four groups of foods viz., Probiotics, Prebiotics, Symbiotic, and Synbiotics. Recently, a new food has been included and that is Postbitics.

Probiotics: Probiotics are the mono or mixed culture of living microorganisms, which when ingested in certain amounts, has a positive impact on host health, beyond conventional nutritional effects. These stimulate the growth of certain other bacteria in the colon, thus improve health. Bacteria most often used as probiotics are Lactobacilli and Bifidobacteria which can be given along with the fermented foods e.g., youghrt, fermented vegetables/ meat.

Prebiotics: Prebiotics are ingredients/ compounds that have a beneficial effect on microflora in the large intestine of the host e.g., fibre, fructo oligosaccherides, lactulose, sugar alcohols. Generally, they are carbohydrate that may be fermented in the large bowel and stimulate growth of potentiality beneficial Bifidobacteria. The most prevalent forms of prebiotics are nutritionally classed as soluble fiber.

Sybiotics and Synbiotics: Symbiotics contain probiotics and prebiotics combined randomly while synbiotics contain specific probiotics and prebiotics mixed together to benefit one another. Because the word alludes to synergism, this term should be reserved for products in which the prebiotic compound selectively favors the probiotic compound. For e.g., a product containing oligofructose and probiotic bifidobacteria would fulfill the definition.

Postbiotics: Postbiotics are the non-viable bacterial products or metabolic byproducts from probiotic microorganisms that have biologic activity in the host. General, postbiotics include bacterial metabolic byproducts, such as bacteriocins, organic acids, ethanol, diacetyl, acetaldehydes and hydrogen peroxide, but it is also found that certain heat-killed probiotics can also retain important bacterial structures that may exert biological activity in the host.

2). Non-Food Sources:

Apart from plant, animal and microbial sources there are non-food sources of nutraceuticals. Using modern fermentation methods, few nutraceuticals can also be produced. For example, amino acids and their derivatives have been produced by bacteria. Eicosapentaenioc acid produced by some algae and bacteria. But now using recombinant – genetic techniques, this EPA can also be produced by non –EPA producing bacteria.

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