INTRODUCTION TO FUNCTIONAL FOODS AND NUTRACEUTICALS
Classification of Functional Foods and Nutraceuticals
Objectives: After studying this module, the student shall be able to:
• classify functional foods
• identify different groups of functional foods
• illustrate functional foods from different classifications
Introduction:
The number of purported nutraceutical substances is in the hundreds, and some of the
most common known substances include carotenoids, polyphenols, fibers, curcumin,
and allyl sulfur compounds. In light of a long and ever growing list of nutraceutical
substances, organization systems are needed to allow for easier understanding and
application. This is particularly true for academic instruction, as well as product
formulation by food companies. Depending upon one’s interest and/or background, the
appropriate organizational scheme for nutraceuticals can vary. Whether it is for
UGC PG MOOC on Functional Foods and Nutraceuticals
Module 2: Classification of Functional Foods and Nutraceuticals
academic instruction, clinical trial design, functional food development, or dietary
recommendations, nutraceutical factors can be organized in several ways. In the
present module, we shall study different types of classifications of functional foods and
nutraceuticals.
Classification of Functional Foods and Nutraceuticals
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
A. Classification based on Food Source
According to origin or food source, the Functional foods may be classified into
plant, animal and microbial groups and has been depicted in Figure1.
2
UGC PG MOOC on Functional Foods and Nutraceuticals
Module 2: Classification of Functional Foods and Nutraceuticals
Classification of Functional Foods according to Food Sources
Food Non Food
sources Sources
Plant Animal Microbial
Derived Derived Foods
Probiotics Prebiotics Synbiotics Postbiotics
Figure 1: Classification of functional foods according to food source
a. 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).
b. Animal-derived functional foods
Zoochemicals, 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.
3
UGC PG MOOC on Functional Foods and Nutraceuticals
Module 2: Classification of Functional Foods and Nutraceuticals
c. 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.
i. 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.
ii. 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.
iii. 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
4
UGC PG MOOC on Functional Foods and Nutraceuticals
Module 2: Classification of Functional Foods and Nutraceuticals
product containing oligofructose and probiotic bifidobacteria would fulfill
the definition.
iv. 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.
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.
B. Classification based on Nutrient and Non Nutrient Components
From the nutritional viewpoint, they can be categorized as nutrients and non
nutrients and has been presented in Table 1.
Table 1: Classification of Functional foods based on nutrients and non nutrients
components
Nutrient Non nutrients
Lipids Fibre: insoluble and soluble fibre
N3 fatty acids Phenolic Compounds: Phenolic
Conjugated fatty acids acids, Flavonoids, catechins and
Vitamins Tannins
Folates Non digestible oligosaccherides:
Vitamin E Fructans, Galacto oligosaccharides,
Carotenoids: b-carotene and isomaltos oligosaccharides, Xylo
alpha carotene oligosaccharides
5
UGC PG MOOC on Functional Foods and Nutraceuticals
Module 2: Classification of Functional Foods and Nutraceuticals
Vitamin c Phytosterols
Minerals Glucosinolates
Selenium Carotenoids: Lutein, cryptoxanthine
Lycopene
Organosulphur Compounds
C. Classification based on Organ/Organ System
Another classification is by the target organ/system benefitted. This is of clinical
significance especially with respect to treatment and management of various
diseases. Examples of functional foods, on the basis of their beneficial impact on
different organ system, have been presented in Table 2.
Table 2: Classification of functional foods according to organ/organ system
SN Organ/organ system Food Component
1. Gastrointestinal tract Prebiotics, soluble and insoluble fibres, Probiotics,
Polyphenols, Phytate
2. Cardiovascular system N-3 fatty acids, Polyphenols, Micronutrients,
Soluble fibre
3. Kidney Fructans
4. Immune System Prebiotics, Probiotics, Nutrients, n-3 fatty acids,
polyphenols
5. Skeletal system Fructans
D. Classification According to Modifications in Foods
Some foods are naturally functional and do not require much modification whereas
others do. Foods may be made functional by:
1. Elimination of components e.g. toxins or allergenic proteins
6
UGC PG MOOC on Functional Foods and Nutraceuticals
Module 2: Classification of Functional Foods and Nutraceuticals
2. Increasing the concentration of natural component e.g. fortification
3. Addition of components with beneficial effects e.g. non vitamin antioxidants.
4. Addition of beneficial microbes e.g. some yeasts, bacteria.
5. Replacement of a component, usually a macronutrient e.g. fat replaced with
modified or emulsified carbohydrates. And
6. Enhancement of bioavailability of components.
According to modifications done the foods are classified as:
1. Fortified foods
2. Enriched foods
3. Enhanced foods
4. Altered foods
Fortified foods are foods fortified with additional nutrients e.g. vitamin fortified milk
and Calcium-fortified orange juice. These nutrients which are fortified are present in
foods but are not in appreciable amounts.
Enriched foods are foods with added new nutrients or components not normally
found in a particular food e.g. folic acid enriched breads, butter with phytochemicals,
probiotics etc.
Altered products are foods from which harmful components has been removed,
reduced or replaced with another substance with beneficial effects.E.g. fibers as fat
replacers in high fat products.
7
UGC PG MOOC on Functional Foods and Nutraceuticals
Module 2: Classification of Functional Foods and Nutraceuticals
Enhanced commodities are foods in which one of the components has been
naturally enhanced through special growing conditions, new feed composition,
genetic manipulation or otherwise. Examples are eggs with increased omega 3 fatty
acids content achieved by altered chicken feed, Conjugated linoleic acid enriched
milk achieved by feed manipulation etc.
E. Classification based on Nutraceutical Factors in Specific Foods
This classifiction is more appropriate when there is interest in a particular
nutraceutical compound or related compounds. There are several nutraceutical
substances that are found in higher amounts in specific foods or food families such
as capsaicinoids are found primarily in pepper fruit, and allyl sulfur (organosulfur)
compounds are chiefly concentrated in onions and garlic. The nutraceuticals that
are considered exceptional to certain foods or food families have been presented in
Table 3.
Table 3: Foods with Higher Content of Specific Nutraceutical Substances
SN Nutraceutical
Foods of Remarkably High Content
Substance/Family
1. Allyl sulfur compounds Onions, garlic
2. Isoflavones (e.g., genestein,
Soybeans and other legumes,
daidzein)
3. Onion, red grapes, citrus fruit, broccoli,
Quercetin
Italian yellow squash
4. Capsaicinoids Pepper fruit
5. EPA and DHA Fish oils
6. Lycopene Tomatoes and tomato products
7. Cruciferous vegetables
Isothiocyanates cauliflower, cabbage, garden cress, bok
choy, broccoli, Brussels sprouts and
8
UGC PG MOOC on Functional Foods and Nutraceuticals
Module 2: Classification of Functional Foods and Nutraceuticals
similar green leaf vegetables
8. Β-Glucan Oat bran
9. CLA Beef and dairy
10. Resveratrol Grapes (skin), red wine
11. Β-Carotene Citrus fruit, carrots, squash, pumpkin
12. Carnosol Rosemary
13. Catechins Teas, berries
14. Adenosine Garlic, onion
15. Cabbage, broccoli, cauliflower, kale,
Indoles
brussels sprouts
16. Curcumin Turmeric
17. Ellagic acid Grapes, strawberries, raspberries, walnuts
18. Anthocyanates Red wine
19. 3-n-Butyl phthalide Celery
20. Cellulose Most plants (component of cell walls)
21. Lutein, zeaxanthin Kale, collards, spinach, corn, eggs, citrus
22. Psyllium Psyllium husk
23. Monounsaturated fatty acids Tree nuts, olive oil
24. Inulin, Fructooligosaccharides
Whole grains, onions, garlic
(FOS)
25. Lactobacilli, Bifidobacteria Yogurt and other dairy
26. Catechins Tea, cocoa, apples, grapes
27. Lignans Flax, rye
9
UGC PG MOOC on Functional Foods and Nutraceuticals
Module 2: Classification of Functional Foods and Nutraceuticals
F. Classification based on Mechanism of Action
This system groups nutraceutical factors together, irrespective of food source,
based upon their proven or assumed physiological properties. Among the
classes are anticarcinogenic, antioxidant, anti-inflammatory, antibacterial,
osteoprotective, and so on. This classification would be helpful to an individual
who is genetically predisposed to a particular medical condition , researchers are
trying to develop potent functional foods for such persons or planning diet and
product developer to develop a new functional food. The different groups of
nutraceuticals according to proven properties are as follows:
• Nutraceuticals having anticancer properties include components such as
capsaicin, genestein,daidzein, α- Tocotrienol and γ –Tocotrienol, Conjugated
Linoleic acid , Lactobacillus acidophilus, Sphingolipids, Limonene, diallyl sulfide,
Ajoene, α-Tocopherol, Enterolactone, glycyrrhizin, Equol, Curcumin, ellagic acid,
Luetin, Carnosol and L. bulgaricus.
• Positive Influence on Blood Lipid profile: β- Glucan, γ-Tocotrienol, δ-
Tocotrienol, MUFA,Quercetin, ω -3 PUFAs, Resveratrol, tannins, β-Sitosterol,
saponins, guar and pectin.
• Antioxidant activity: Conjugated Linoleic acid, Ascorbic acid, β- Carotene,
Polyphenolics, Tocopherols, Tocotrienols, Indole -3- carbonol, α-Tocopherol,
10
UGC PG MOOC on Functional Foods and Nutraceuticals
Module 2: Classification of Functional Foods and Nutraceuticals
Ellagic acid, Lycopene, Lutein, Glutathione, Hydroxytyrosol, Lutolin, Oleuropein,
Catechins, Gingerol, Chlorogenic acid, Tannins
• Antiinflammatory: linolenic acid, EPA, DHA, GLA(Gamma-linolenicacid),
capsaicin, Quercetin and Curcumin.
• Osteogenetic or Bone protective nutraceuticals: CLA, Soy protein,
Genesetin, daidzein, Calcium, Casein phospopeptides,
FOS(fructooligosaccharides), Inulin.
G. Classification of nutraceuticals based on chemical nature
This classification permits nutraceuticals to be categorized under
molecular/elemental groups. This preliminary model includes several large groups,
which then provide a bases for subclassification or subgroups, and so on. One way
to group nutraceuticals grossly is as follows:
• Isoprenoid derivatives
• Phenolic substances
• Fatty acids and structural lipids
• Carbohydrates and derivatives
• Amino acid-based substances
• Microbes
11
UGC PG MOOC on Functional Foods and Nutraceuticals
Module 2: Classification of Functional Foods and Nutraceuticals
• Minerals
a. Isoprenoid Derivatives (Terpenoids)
Isoprenoids and terpenoids are terms used to refer to the same class of molecules.
These substances are one of the largest groups of plant secondary metabolites. Many
popular nutraceutical families comes under this group such as carotenoids, tocopherols,
tocotrienols, simple terpenes and saponins. This group is also referred to as isoprenoid
derivatives because isoprene is the principal building block molecule which is
synthesized from acetyl coenzyme A (CoA).
b. Phenolic Compounds
Phenolic compounds are also considered secondary metabolites. The base for family of
molecules is a phenol structure, which is a hydroxyl group on an aromatic ring. From
this structure, larger molecules are formed viz., anthocyanins, coumarins, isoflavones,
flavonones, flavonols, tannins, and lignin.
c. Carbohydrates and Derivatives
Ascorbic acid (Vitamin C) is the glucose derivative and functions as an antioxidant.
Many plants produce some oligosaccharides which functions as prebiotic substances.
Several plant polysaccharide families are not readily available energy sources for
humans as they are resistant to secreted digestive enzymes. These polysaccharides
are grouped together along with lignin to form one of the most recognizable
nutraceutical families — dietary fibers. The nonstarch polysaccharides are further
divided into homogeneous and heterogeneous polysaccharides, as well as into soluble
and insoluble substances.
d. Fatty Acids and Structural Lipids
Fatty acids and/or their derivatives include the ω-3 PUFA found in higher amounts in
plants, fish, and other marine animals, and conjugated linoleic acid (CLA) produced by
bacteria in the ruminants.
12
UGC PG MOOC on Functional Foods and Nutraceuticals
Module 2: Classification of Functional Foods and Nutraceuticals
e. Amino Acid-Based
This group includes intact protein (i.e., soy protein), polypeptides, amino acids, and
nitrogenous and sulfur amino acid derivatives. A few amino acids are also being
investigated for their nutraceutical potential now a days. Among these amino acids is
arginine, ornithine, taurine, and aspartic acid. Arginine has been considered to be
cardioprotective since it is a precursor molecule for the vasodilating substance nitric
oxide (NO). Also, arginine may reduce atherogenesis. The nonprotein amino acid
taurine may also have blood pressure-lowering as well as antioxidant properties. Other
examples are isothiocyanates, indole-3-carbinol, allyl sulfur compounds, and
capsaicinoids. Another nutraceutical amino acid-derived molecule is folic acid, which is
believed to be cardioprotective by minimizing homocysteine levels. Other members of
this group would include the tripeptide glutathione and choline.
f. Microbes (Probiotics)
Other groups of nutraceuticals include molecules or elements, whereas probiotics
includes live bacteria. A good probiotic must be resistant to acid conditions of the
stomach, bile, and digestive enzymes normally found in the human gastrointestinal
tract; able to colonize the human intestine; be safe for human consumption; and have
scientifically proven efficacy. Among the bacterial species recognized as having
functional food potential are Lactobacillus acidophilus, L. plantarum, L. casei,
Bifidobacterium bifidum, B. infantis, and Streptococcus salvarius subspecies
thermophilus. Some yeasts have been noted as well, including Saccharomyces
boulardii.
g. Minerals
Several minerals have been recognized for their nutraceutical potential and thus have
been included under functional foods. Among the most evident is calcium with relation
to bone health, colon cancer, and perhaps hypertension and cardiovascular disease.
Potassium has also been found to reduce hypertension and thus improve
cardiovascular health. A couple of trace minerals have also been found to have
nutraceutical potential such as copper, selenium, manganese, and zinc. All these trace
13
UGC PG MOOC on Functional Foods and Nutraceuticals
Module 2: Classification of Functional Foods and Nutraceuticals
minerals have antioxidant property. Copper, zinc, and manganese are components of
superoxide dismutase (SOD) enzymes, whereas selenium is a component of
glutathione peroxidase. Certainly more research is required in the area of trace
elements in view of their metabolic relationships to other nutrients and the potential for
toxicity.
Let us summerize
Thus we have seen the classification of functional foods and nutraceuticals according to
source/origin, nutrient/non nutrient, organ/organ system, modifications in foods, specific
functional components, mechanism of action and chemical nature of food. According to
source or origin, functional foods are classified as plant foods, animal foods and
microbial foods. According to nutrient and nutrient, functional foods are classified as
nutrient viz., lipids, Vitamins and minerals. According to organs, functional foods have
been classified according to beneficial effects on Gastrointestinal tract, Cardiovascular
system, Kidney: Immune System and Skeletal system. According to modifications, the
foods are classified as: Fortified foods, Enriched foods, Enhanced foods and Altered
foods. According to mechanism of action, they are classified as antioxidant,
antibacterial, antihypertensive, antihypercholesterolemic, antiaggregate, anti-
inflammatory, anticarcinogenic and osteoprotective. According to chemical nature of
foods nutraceuticls have been classified as Isoprenoid derivatives, Phenolic
substances, Fatty acids and structural lipids, Carbohydrates and derivatives, Amino acid-
based substances, Microbes and Minerals.
References
1. Arai, S., Vattem, D., & Kumagai, H. (2016). Functional Foods-History and
Concepts. In D. A. Vattam, & M. Vatsala, Functional Foods, Nutraceuticals and
Nautral Products, Concepts and Applications, Lancaster,Pennsylvania,U.S.A.:
DEStech Publications Inc., 1-18.
14
UGC PG MOOC on Functional Foods and Nutraceuticals
Module 2: Classification of Functional Foods and Nutraceuticals
2. Kerry, R. G., Patra, J. K., Gouda, S., Park, Y., Shin, H., & Das, G. (2018).
Benefaction of Probiotics for Human Health: A Review. Journal of Food and Drug
Analysis, 927-939.
3. Wildman, R., & Kelley, M. (2007). Nutraceuticals and Functional Foods. In R.E.C.
Wildman, Handbook on Nutraceuticals and Functional Foods (pp. 1-22). Taylor
and Francis Group: CRC Press.
4. http://egyankosh.ac.in/bitstream/123456789/33348/1/Unit-11.pdf accessed on 12
June 2018
5. https://youtu.be/gCeSLR5PFIc accessed on 2nd April 2019
6. https://image.shutterstock.com/image-photo/assortment-dairy-products-milk-
cheese-450w-243530956.jpg accessed on 5th June 2019.
7. https://image.shutterstock.com/image-photo/healthy-food-clean-eating-selection-
450w-722718097.jpg accessed on 5th June 2019.
8. https://image.shutterstock.com/image-photo/composition-vegetables-fruits-
wicker-basket-450w-88218493.jpg accessed on 5th June 2019.
9. https://image.shutterstock.com/image-photo/vintage-still-life-vegetables-450w-
66376402.jpg accessed on 5th June 2019.
15