Functional foods are at the forefront of nutrition science, offering benefits beyond basic sustenance. This article provides a comprehensive overview of functional foods: definition, classification, and benefits, tailored for students seeking to understand this evolving field.
What are Functional Foods? Definition and Related Concepts
Functional foods are healthy foods that resemble conventional foods, consumed as part of a usual diet, and are claimed to have physiological benefits such as health-promoting or disease-preventing properties beyond basic nutrient supply. The term was first introduced in Japan in the 1980s, referring to processed foods with ingredients aiding specific body functions. Japan even created a regulatory approval process for these, known as Foods for Specified Health Use (FOSHU), which bear a seal of approval from their Ministry of Health and Welfare.
While there isn't one universal statutory definition, many authorities and academic bodies agree that functional foods beneficially affect one or more target functions in the body, relevant to improved health and well-being or disease risk reduction. These are generally aimed at 'healthy' people for function improvement or long-term disease risk reduction, not disease treatment for 'sick' individuals.
Several terms are often linked with or interchanged with functional foods:
- Bioactive compounds: Naturally occurring chemical compounds from plants, animals, or marine sources that provide desired health/wellness benefits.
- Dietary supplements: Active ingredients added to food or consumed as pills, powders, or liquids, supplementing the diet without replacing a complete meal.
- Functional ingredients: Standardized and characterized preparations, fractions, or extracts containing bioactive compounds used by manufacturers in food.
- Medical foods: Formulated for dietary management of a specific disease or condition under physician supervision.
- Natural health products (NHP): Include homeopathic preparations, traditional medicines, vitamins, minerals, amino acids, essential fatty acids, and other botanical, animal, or microorganism-derived substances. They are generally sold in medicinal forms to diagnose, treat, prevent disease, or promote health.
- Nutraceutical: A substance, either a food or part of a food, that provides medical or health benefits, including disease prevention and treatment. They are derived from foods and can be consumed in various forms like pills or liquids.
Classifying Functional Foods: How They Are Modified
Functional foods can be classified based on their origin or how they are modified to enhance health benefits. This classification of functional foods helps understand their diverse forms and applications:
- Fortified Food Products: These are foods enriched with ingredients that positively influence diseases and health. Examples include calcium-fortified bread, ω-3 fortified breads, or phytosterol-fortified spreads.
- Liberated Foods: Foods processed to counteract anti-nutritional compounds, such as toxic compounds or food allergens.
- Improved Food Raw Materials: Raw materials enhanced by increasing specific components. This can be achieved by changing animal feed (e.g., eggs or meats high in ω-3 fatty acids, beef high in conjugated linoleic acid) or through post-harvest treatments (e.g., functional grapes with higher antioxidants developed by ultraviolet irradiation).
- Novel Foods: New varieties produced by genetic manipulation or selection that offer improved health benefits, like rice with high iron or B-vitamin content, or canola oil high in carotenoids.
- Probiotic and Prebiotic Foods: A significant category. Probiotics are live microorganisms that, when consumed in adequate numbers, confer a health benefit on the host (e.g., lactic acid bacteria, bifidobacteria in yogurt). Prebiotics are non-digestible food ingredients (like starches, dietary fibers, oligosaccharides) that beneficially affect the host by stimulating the growth or activity of beneficial bacteria in the colon (e.g., prebiotic bread).
It's important to note that natural traditional products like cranberry juice, which influences urinary tract infections, are not considered functional foods as such. However, if an isolated health-contributing ingredient from cranberry is added to another food to enhance health, the resulting food becomes a functional food.
Unpacking the Benefits: Specific Functional Food Categories and Their Roles
Understanding the various benefits of functional foods is crucial, as they are developed to address specific health problems and promote well-being. Here's a look at commodity-based developments:
Dairy-based Functional Foods
Milk is a rich source of calcium, crucial for preventing osteoporosis and potentially colon cancer. Beyond basic nutrients, milk contains bioactive elements like immunoglobulins, hormones, and peptides. Bioactive peptides derived from milk proteins can lower blood pressure, enhance immunity, and combat cardiovascular diseases. Examples include sour milk with blood pressure-lowering peptides (Calpis), hydrolyzed whey protein isolates (BioZate), and conjugated linoleic acid (CLA) from yogurt for weight reduction (Clarinol).
Probiotic dairy products, such as various brands of probiotic drinking yogurts (Actimel, Activia, Yakult), constitute a major section of dairy-based functional foods. Epidemiological studies link dairy intake with reduced risk of hypertension, stroke, and colorectal cancer.
Cereal-based Functional Foods
Cereals offer dietary insoluble fibers, which act as roughage, and water-soluble fibers like β-glucan and arabinoxylan. β-glucan, found abundantly in barley and oats, is known for lowering cholesterol and glycemic index. It's incorporated into nutrition bars, cereals, beverages, and baked products. Oligosaccharides in cereals also act as prebiotics, stimulating beneficial gut bacteria.
Whole cereals themselves are sources of phytochemicals that act as antioxidants, antiproliferatives, and carcinogen detoxifiers. Resistant starch, another functional fiber in cereals, contributes to fermentable carbohydrates for colonic bacteria, reducing bowel disease risk. Studies show whole grains and their fibers reduce cardiovascular disease and cancer risk, with wheat aleurone-rich foods decreasing LDL-cholesterol.
Flaxseed-based Functional Foods
Flaxseed (linseed) is a versatile nutritional ingredient rich in proteins, dietary fiber, polyphenolics, and essential fatty acids. It contains 51-55% α-linolenic acid (ALA), which inhibits cardiovascular disease, inflammation, blood pressure, cancer, skin diseases, and immune disorders. Phytoestrogens from flaxseed may also benefit menopausal symptoms, including osteoporosis. Flaxseed consumption has been shown to reduce total and LDL-cholesterol. It's often incorporated into breads, cereals, and muffins.
Tea-based Functional Foods
Tea is a major source of polyphenols, primarily catechins (e.g., epicatechins, epigallocatechin gallate) especially in green tea, accounting for 25-30% of its dry weight. These polyphenols offer antioxidant, anticarcinogenic, antibacterial, antifungal, antiviral, thermogenic, and blood glucose/lipid controlling properties. Green tea products like 'Sunphenon' are rich in natural catechins, and 'Mega-T' targets weight loss. Black tea, through oxidized catechins forming theaflavins and thearubigins, also possesses antioxidant, antimicrobial, anti-inflammatory, and anticancer activities. Tea consumption and its flavonoids have been linked to a reduced risk of lung cancer.
Fruits and Vegetables-based Functional Foods
Fruits and vegetables are rich in various phytochemicals that provide wide-ranging benefits. Berry fruits, for instance, are high in polyphenols like anthocyanins, flavonols, and phenolic acids, offering antioxidant activity. They can prevent cardiovascular diseases, cancer, diabetes, premature aging, and improve eyesight and brain function. Special fruit-juice mixtures, especially with berries, can significantly increase blood antioxidant capacity.
Red grapes and red wine contain resveratrol, a polyphenol known to be cardioprotective, anti-cancer, anti-inflammatory, and a modulator of lipid metabolism. UV irradiation can enhance resveratrol content in grapes. Lycopene, a natural carotenoid antioxidant in red fruits and vegetables (especially tomatoes), protects against oxidative stress, hypertension, atherosclerosis, and diabetes, and is linked to reduced risk of prostate, lung, and stomach cancer, and coronary heart disease. Combinations of lycopene with vitamins E, C, and β-carotene show superior antioxidant properties.
Soybeans are concentrated sources of isoflavones (genistein and daidzein), a class of phytoestrogens. Regular consumption of soy protein is associated with protection against hormone-dependent cancers, beneficial effects on cardiovascular diseases, osteoporosis, and menopausal symptoms, as well as lower total and LDL-cholesterol. The FDA permits health claims regarding soy protein's role in reducing heart disease risk.
Other examples include: β-carotene and glucosinolates from brassica vegetables linked to reduced cancer risk; carrot pomace extracts used for functional drinks; black carrots as sources of phenolic compounds for antioxidant and cancer prevention; garlic supplements for cardiovascular health; onion byproducts for antioxidant properties; asparagus byproducts for dietary fiber; and plant sterols/stanols in fortified foods to reduce total and LDL-cholesterol. Nuts, especially walnuts, are noted for high phenolic content and antioxidant activity, reducing heart disease risk.
Seafood-based Functional Foods
Seafood is an excellent source of ω-3 fatty acids (like DHA and EPA), antioxidants, and high-quality protein. Marine algae provide oils rich in DHA and polysaccharides acting as dietary fiber, offering benefits such as preventing CVD, antihypertensive, antioxidant, antiviral, and anticancer effects. Chitin and chitosan from crustaceans are used as dietary fiber, antimicrobial, antitumor, and hypocholesterolemic agents. Fish and fish oil consumption is linked to reduced colorectal and prostate cancer, and stroke risk.
Meat-based Functional Foods
Meat contains taurine, L-carnitine, creatine, CLA, and endogenous antioxidants. Modifications like adding 1% CLA to animal feed can reduce atherosclerosis and type 2 diabetes risk. Functional meat products incorporating nuts have shown to reduce CVD risk. Other additions include fish oil, vegetables, fiber, and soy.
Egg-based Functional Foods
Eggs enriched with ω-3 polyunsaturated fatty acids (e.g., 'Columbus' eggs) are important in preventing heart disease, atherosclerosis, thrombosis, and high blood pressure. Eggs can also be enriched with antioxidants, vitamins D, E, B12, folic acid, carotenoids, and selenium. These enriched eggs have shown to decrease plasma triglycerides and platelet aggregation.
Herb-based Functional Foods
Herbs are sources of functional ingredients. Curcumin, from turmeric, exhibits therapeutic potential for various conditions including Alzheimer's, Parkinson's, CVD, cancer, and diabetes, with GRAS status allowing its use in many foods. Cinnamon, with its methylhydroxy chalcone, aids glucose and lipid metabolism, beneficial for type 2 diabetes. Fenugreek galactomannan helps control blood sugar. Ginger contains gingerols and flavonoids with antioxidant activity. Other botanicals include chicory inulin-type fructans (prebiotic dietary fiber), rosemary extracts (antioxidant, antimicrobial), ginkgo, St. John's wort, and ginseng.
Vitamin-based Functional Foods
Vitamins also play a role. Vitamins B6, B12, D, and K can reduce the risk of CVD and osteoporosis, while vitamins C and E may help prevent colorectal carcinoma. These are often incorporated into fortified yogurts and milks.
The Functional Food Market: Research and Development
The market for functional foods is expanding rapidly, driven by growing consumer interest in general well-being and disease prevention. The leading market sections include dairy, bakery, confectionery, soft drinks, and baby foods. Products often target conditions like high blood pressure, cholesterol, blood sugar, and osteoporosis.
Key factors for success in this market include:
- Focus on general well-being and common health complaints.
- Effective mass distribution and market positioning.
- Clear and effective communication of health benefits to consumers.
- Extension of existing brand/food company credibility.
- Emphasis on taste, convenience, and appropriate pricing.
The global market for functional foods is projected to reach over 90.5 billion USD by 2013, with major markets in the U.S., Japan, and Europe. In Japan, FOSHU products like Econa cooking oil (cholesterol control) and Healthia green tea (catechin enriched) have high recognition rates. Countries like India are also seeing significant growth, particularly in probiotics.
Despite the growth, there's a recognized need for framed rules and longitudinal studies to scientifically prove health claims before launching products, a framework that is still lacking in many countries.
Challenges and Considerations for Functional Food Development
Developing successful functional foods requires careful consideration of food characteristics in tackling specific health problems and the contribution of specific food ingredients. Examples of food-health relationships include nutrient-dense foods for protein/fat/micronutrient deficiencies, low-energy/high-nutrient-density foods for physical inactivity, and pre/probiotic foods for food-borne illnesses. Furthermore, careful intake of some functional ingredients (e.g., iron, folic acid, herbal preparations) is crucial, as excess can lead to adverse health effects or mask symptoms.