Phytonutrients Notes

Phytonutrients

• Phytonutrients are biologically active compounds in plant foods that can positively or negatively alter human health.
• They are also known as phytochemicals or nontraditional nutrients.
• These compounds are usually present in plants for defense and survival.
• Phytonutrients is a more descriptive term, implying favorable nutritional properties.

Biological Responsiveness

• The body's response to phytonutrients suggests they could be regarded as pharmaceuticals due to their role in managing clinical conditions.
• Individual variation impacts bioavailability and responsiveness to phytonutrient intake.
  • Factors include gender, age, epigenetics, personal behavior, and gut microbiota.
• The extensive number of phytonutrients allows for the development of functional foods for specific psychological or pathological needs.

Classification of Phytonutrients

• Classification is difficult because plants contain various chemical and functional classes of compounds.
• One class of phytonutrients may have several functions, while a particular function may be provided by more than one class.

Phenolics (Polyphenols)

• Found only in plants and certain fungal species; not synthesized by animals or humans.
• Types of Polyphenols:
  • Phenolic Acids:
    • Hydroxybenzoic acids (e.g., Ellagic acid, Gallic acid)
      • Found in strawberry, raspberry, grape juice, and pomegranate juice.
    • Hydroxycinnamic acids (e.g., Caffeic acid, Chlorogenic acid, Ferulic acid)
      • Found in apples, blueberries, cranberries, cherries, orange, lemon, grapefruit, spinach, coffee, tea, cider.
      • Caffeic acid and chlorogenic acid have demonstrated antioxidant activity in vitro.
      • They may inhibit the formation of mutagenic, carcinogenic, and nitrozo compounds.
  • Flavonoids:
    • Most abundant polyphenol in the diet.
    • Found in vegetables, fruits, tea, and coffee.
    • Chief biological effects are due to antioxidant activity and ability to scavenge free radicals.
  • Stillbenes:
    • The most well-studied is Resveratrol.
      • Found predominantly in grape skin and seeds, grape juice, and red wine.
      • Benefits include anti-inflammatory, anticarcinogenic, cardioprotective, vasorelaxant, phytoestrogenic, and neuroprotective effects.
  • Lignans:
    • Found in a wide variety of plant foods, including flax seeds, sesame seeds, sunflower seeds, pumpkin seeds, whole grains (rye, oats, barley), fruits (especially berries), and vegetables.
    • When ingested, they can be metabolized by intestinal bacteria to mammalian lignans (enterodiol and enterolactone).
    • These can mimic some of the effects of estrogens.
    • Individual differences in the metabolism of lignans influence their biological activities and health effects.

Health Benefits of Phenolics

• Prevention of blood clots.
• Reduction of blood sugar levels.
• Lowering heart disease risk.
• Promotion of brain function.
• Improvement of digestion.
• Protection against some cancers.
  *Foods high in phenolics include berries, pomegranate, red capsicum, spinach, and beetroot.

Lignans as Phytoestrogens

• Phytoestrogen: A class of nonsteroidal compounds of plant origin or metabolically derived from plant precursors.
• Hundreds of foods contain phytoestrogens.
• Three classes of phytoestrogens:
  • Isoflavones:
    • Found in legumes, with soybeans and soy products being the major dietary source.
  • Lignans:
    • Found in high-fiber foods such as whole grains, flax seeds, and sesame seeds.
  • Calmestans:
    • Highest amount found in alfalfa and clover sprouts.
• After consumption of isoflavones, lignans, and calmscens enzymatic metabolic conversions occur in the gut resulting in the formation of heterocyclic phenols.
• These compounds structurally resemble estrogen and have weak estrogenic activity.
• They are all selective estrogen receptor modulators (SERMs), each with its profile of action.
• SERMs are defined as compounds that behave like estrogen agonists in certain tissues and like antagonists in others.
• Because phytoestrogens act as SERMs, there is interest in their potential role in helping to manage menopausal symptoms and reducing the risk associated with reproductive cancers.

Types of Phytonutrients

• Isoflavonoids:
  • Found particularly in legumes, soy, lentils, chickpeas.
  • Have important antimicrobial activities.
  • Genistein and dead scene display estrogenic activity.
• Carotenoids:
  • Branch into provitamin A and nonprovitamin A.
    • Provitamin A: α-carotene, β-carotene, and β-cryptoxanthin.
    • Nonprovitamin A: Lycopene, lutein, zeaxanthin.
  • Most abundant and widespread pigments responsible for many of the brilliant red, orange, and yellow colors of edible fruits, vegetables, and flowers, as well as the colors of certain animals.
  • Leafy greens can also be good sources of carotenoids, but chlorophyll masks their colors.
  • Major carotenoids: α-carotene, β-carotene, lycopene, β-cryptoxanthin, lutein, and zeaxanthin.
  • Biological effects include antioxidant, immune enhancement, anti-mutagenic, and anticarcinogenic properties.
  • Antioxidant property of carotenoids could contribute to the reduction of oxidative stress, lipid pre-oxidation, and free radical damage.
  • Zeaxanthin and lutein can help retard some of the destructive process due in macular degeneration.
  • Carotenoids are a class of naturally occurring pigments synthesized by plants, algae, and photosynthetic bacteria.
  • Responsible for the yellow, orange, and red colors of many fruits and vegetables (red capsicum, carrots, apricots, tomatoes).
  • Play essential functions in photosynthesis and photoprotection in plants.
  • Humans and animals cannot synthesize carotenoids and must obtain them through diet.
  • Some carotenoids can be converted into vitamin A by the body if needed.
  • Carotenoids are highly lipophilic and are usually located inside cell membranes.
  • High regular carotenoid intake is positively associated with reducing the risk of cardiovascular disease and prostate cancer.

Isothiocyanates and Indoles

• Found in vegetable foods.
• Give the pungent or sharp flavor and odor associated with mustard, radish, watercress, broccoli, and Brussels sprouts.
• Biological effects include goitrogenic, antibacterial, antifungal, and antiprotozoal actions.

Organosulfur Compounds

• Two main types:
  • Glucosinolates:
    • Present in brassicae vegetables such as broccoli and cabbage.
    • Converted into bioactive indoles and isothiocyanates when plant cells are crushed (chopping or chewing) and the enzyme myrosinase is released.
    • Actions include up generation of phase two liver detoxification enzymes, anticarcinogenic effects, and potential benefits on estrogen metabolism.
  • Allellic sulfur compounds:
    • Present in Lillet K vegetables such as onion and garlic.
    • Allicin is produced when fresh garlic is chopped or crushed, giving the recognizable smell of fresh garlic.
    • Allicin is unstable and readily changes into a series of other sulfur compounds such as dialylidysulfide.
    • Several studies show that this compound is protective against colorectal cancer and cardiovascular diseases.

Plant Sterols (Phytosterols)

• Plant-derived sterols that are similar in structure to cholesterol.
• Best sources include sesame, linseed, corn, soy, and peanuts.
• Help to lower circulating cholesterol by inhibiting the incorporation of cholesterol into micelles in the gastrointestinal tract and decreasing cholesterol absorption.
• Potentially reduce the risk of CVD (cardiovascular disease).
• There is increasing evidence that reintroducing plant foods that provide phytosterols into the modern diet can improve serum lipid profiles and reduce the risk of inflammation, blood sugar dysregulation, and cardiovascular disease risk.
• Hunter-gatherer diets likely provided as much as 1000 mg per day.
• Modern dietary intake is estimated to vary from 150 to 400 mg per day.
• Foods high in phytosterols include wheat germ, canola oil, peanuts, almonds, and olive oil.
• Care needs to be taken in sourcing, storing, using, and consuming foods or oils extracted from plants high in phytosterols to avoid any negative consequences from oxidation.

Other Phytonutrients

• Phenolic alkaloids:

  • Found in oats.
  • Have antioxidant and anti-inflammatory properties and thereby protect against atherosclerosis.
  • Oats may have a protective effect against colon cancer.

• Curcumin:

  • Main bioactive compound in turmeric.
  • Has antioxidant and anti-inflammatory properties.
  • Studies indicate it can prevent and treat a variety of conditions such as atherosclerosis, cystic fibrosis, arthritis, certain cancers, dementia, and Alzheimer's.

• Chlorophylls:

  • Pigments found abundantly in plants, with dark green leafy vegetables being the richest source.
  • The basic structure of chlorophyll is a porphyrin ring similar to that of heme in hemoglobin, although the central atom on chlorophyll is magnesium instead of iron.
  • Chlorophyll is traditionally used as an oral supplement to reduce fecal odor.

• Plants use chlorophyll to trap light needed for photosynthesis.

• Little is currently known about bioavailability and metabolism chlorophyll.

• Chlorophyll may have cancer-protective effects by forming tight molecular complexes with carcinogenic compounds such as polyaromatic hydrocarbons, heterosilic amines, and aflatoxins interfering with their absorption.