Functional foods are food items that provide health benefits beyond basic nutrition. Their health benefits include reducing or minimising the risks of certain diseases.
The functional foods are grouped as:
These are life micro-organisms that are found in fermented vegetables and cultured milk such as yoghurt. They include strains of lactic acid bacteria, Saccharomyces, streptococcus and lactococcus spp.
They are believed to reduce irritable bowel syndrome, lactose intolerance, inflammatory bowel syndrome, cancer, allergens, kidney stones and vaginal infections.
These are non-digestible food components that promote the growth of beneficial intestinal micro-flora. They include soy-oligosaccharides, inulin, fructo-oligosaccharides and lactulose.
They protect the intestinal lining against pathogens, enhance mineral absorption in the large intestines and reduce diabetes mellitus.
Examples of prebiotics are onions, whole grains, garlic, honey, leeks, bananas, fortified foods and beverages. Garlic contains allicin and allyl sulfides which are converted to a sulfur-containing (responsible for the characteristic pungent flavour of garlic) compounds by allicinase when garlic is crushed.
Garlic reduces cardiovascular diseases and inhibits growth of Helicobacter pylori, which causes ulcers.
Polyunsaturated fatty acids
These are fatty acids with more than 18 carbons in their chain with two or more double bonds.
They can either be omega-3 or omega-6 fatty acids (3 and 6 denotes the position of the first double bond from the methyl end).
Examples of these fatty acids are eicosapentanoic, docosahexanoic and alpha linoleic. The major sources of fatty acids are fish such as salmon, tuna, trout, sardines, flounder and halibut.
They lower the levels of low density lipoproteins (bad fats) and increase levels of high density lipoproteins (good cholesterols).
In children, omega-3 fatty acids promote growth of the neural system which later improves their learning ability, improves their immune systems, maturation of sensory systems and rapid growth.
Other benefits are, reduces chances of getting rheumatoid arthritis, hypertension, colorectal and prostate cancer, osteoporosis, depression, skin disorders and attention deficit hyperactivity.
They are natural water soluble pigments found in flowers, leaves and fruits of plants. Examples of flavonoids are anthocyanin and flavanols such as catechins, epigallocatechins and epigalocatechin galletes found in green tea.
They are either red, violet or colourless. Flavonoids are found in tea, chocolate, apples, cocoa and grapes while anthocyanin is found in beetroots, berries, cherries and red grapes.
The benefit of flavonoids is realised when they are polymerised into condensed tannins and hydrolysable tannins, which act as free radical acceptors and chain breakers in our body.
They are also known as cellular antioxidants. They have the following benefits to the body: antiviral, antitoxin, anti-fungal, antibacterial, anti-allergenic and anti-inflammatory effects.
It is a plant-based protein obtained from soybeans and has a larger percentage of the eight essential amino acids. Foods rich in soy proteins are soy nuts, tempeh, miso, tofu and those enriched with soybeans.
Bio-availability of soy proteins can be enhanced by fermentation to reduce the levels of protein inhibitors. They are used to replace animal proteins which have a higher fat content.
Eating soy protein reduces low density lipoprotein, risks of heart diseases, getting colon and prostate cancer.
These are fat-soluble pigments found in foods such as orange fleshed sweet potatoes, pumpkins, carrots, spinach, tomatoes and cantaloupe. Examples of carotenoids are lycopene, lutein and beta-carotene.
Beta-carotene is a precursor of Vitamin A and neutralises free radicals in the body. Lycopene found in processed tomato products, tomatoes, watermelon, red and pink grape fruits is believed to reduce prostate cancer while lutein, a major pigment in the eye retina, is an anti-oxidant that enhances eye health.
They are reduced calorie carbohydrates that are added to foods to improve the taste and texture. They include malitol, sorbital, xylitol erythritol and isomalt.
They are used as sugar replacers in candies, ice cream, chewing gums and baked goods.
They have low glycemic index hence can help reduce diabetes and insulin response. They do not cause tooth decay.
Polyols are naturally found in fruits and vegetables.
Examples of these fruits are apples, blackberries, cherries, lychee, plums, pears, apricots, and vegetables such as cauliflower, snow peas and celery. On the other hand, polyols can also be made artificially and used as low-calorie sweeteners.
This is a group of non-digestible carbohydrates that pass through the small intestines without being broken down.
However, these foods are fermented in the colon by intestinal micro-flora to release volatile fatty acids such as butyrate, which are the major source of energy to colonic cells and have both anti-inflammatory and anti-carcinogenic benefits to the colon.
Some of these dietary fibres include cellulose, hemi-cellulose, lignin, resistant starch, pectin and gums which are found in bran, leafy vegetables, beans, squash, cabbage, mushrooms, oranges and berries.
Dietary minerals and vitamins
Minerals are the chemical elements found in food that the body needs for growth and health. Vitamins are organic compounds which are needed in small quantities to sustain life.
Examples of minerals and their health benefits are calcium together with Vitamin D which minimise osteoporosis.
Calcium alone reduces kidney stones and colorectal cancer. Magnesium reduces chances of getting heart diseases and hypertension while iodine is essential in the synthesis of thyroid hormone.
Retinoid, a form of Vitamin A is important in clear vision, niacin prevents insulin depend diabetes, folic acid reduces birth complications.
Most green vegetables and dairy products are the best sources of vitamins and some minerals.
Chia: Its seeds have lots of fatty acids than any other known plant. They are loaded with magnesium, iron, calcium, and potassium.
Sukuma wiki: This tough vegetable is high in nutrition, providing more antioxidants than most of other classes of greens.
Broccoli: This food is packed with vitamins, minerals, disease-fighting compounds, and the fibre essential in any diet.
Tea: It has a natural remedy for everything from cancer to heart disease. It also has Epigallocatechin gallate, a chemical that slows irregular cell growth, which could potentially help prevent the growth of some cancers.
Ginger: A natural remedy for coughs, stomach upsets and other inflammation.
The writers are based at the Department of Dairy Food Science and Technology, Egerton University.