Phytonutrients Flashcards
Phytonutrients
Phytonutrients (phytochemicals) are chemical compounds produced by plants which are beneficial to human health and help prevent various diseases:
* Phytonutrients give foods taste, fragrance, colour and other characteristics.
* They promote health and fight disease.
* There are over 25,000 different phytonutrients.
* Phytonutrients are found in fruits, vegetables, tea, nuts, grains, beans, herbs and spices. These nutrients can be incorporated into one’s diet for their highly therapeutic properties.
Origins of phytonutrients
- All organic compounds are normally a by product of glycolysis or photosynthesis.
- All products have their own specific set of enzymes for production.
- These products can be divided into primary and secondary metabolites.
Primary metabolites
Are compounds necessary for plant survival such as carbohydrates,
proteins, lipids, enzymes and chlorophyll.
Secondary metabolites:
- Are synthesised by the plant in reaction to its environment an adaptive response.
- Evolve to facilitate the survival of the plant.
- Deter predators and protect from infection.
Roles of secondary
metabolites in plants
- Protection against herbivores, plant pathogens and against other plants.
- Protection against physical stressors such as ultraviolet light.
- Signals for communication and to attract pollinators
Roles of secondary metabolites in the human body
- Function as antioxidants (e.g. quercetin, abundant in red onions)
- Regulate the cell cycle.
- Increase detoxification of carcinogenic and other toxic compounds.
- Reduce DNA damage (e.g. lycopene in tomatoes)
- Mimic or interact with hormones and other body chemistry (e.g. lignans in flaxseeds can support oestrogen levels when low).
Difference in phytonutrients in plants can be due to
- Chemotype of plant.
- Soil and water conditions.
- Fungi and mycorrhizae.
- Insect friends and foes.
- Climate.
- Seasonal cycles.
- Variability of plant part.
- Bacteria, virus and pathogens.
- Humans and other
animals around them.
Dangerous phytonutrients
‒ Morphine: Comes for the opium poppy.
‒ Vinblastine: Comes from African violets.
‒ Digoxin: Found in foxglove.
Less harmful examples phytonutrients
- Solanine and chaconine alkaloids from the nightshade family. Excessive levels can be toxic as they possess anticholinesterase activity.
- Caffeine (an alkaloid) can be toxic in high doses. It has a strong effect on cognition,blood pressure, sleep and endurance.
- Phytates (found in beans, grains and legumes) may prevent the absorption of minerals (e.g. zinc, iron, calcium)
- However, this so called ‘anti-nutrient’ effect of phytates can be manifested only when large quantities of phytates are consumed.
Phytonutrient Types
Phenols and polyphenols
Terpenes
Phytosterols
Organosulphur compounds
Alkaloids
Phenol and polyphenol Types
Flavonoids
Phenolic Acids
Lignans
Stilbenes
Quinones
Tannins
Flavonoids
Quercetin, kaempferol, rutin, hesperidin, naringenin, catechins, anthocyanins, isoflavones.
Phenolic acids
Gallic acid (e.g. grapes ),
Caffeic acid (e.g. thyme, sage, sunflower seeds )
Salicylic acid (e.g. in white willow bark)
Lignans
Secoisolariciresinol (e.g. flaxseeds
Stilbenes
Resveratrol (e.g. grapes)
