Major Classes of Phytonutrients

Carotenoids

• Of all the phytonutrients, we probably know the most about carotenoids, the red, orange and yellow pigments in fruits and vegetables
• The carotenoids most commonly found in vegetables (and in plasma) are listed in the nest slide along with common sources of these compounds
• Fruits and vegetables that are high in carotenoids appear to protect humans against certain cancers, heart disease and age related macular degeneration

Flavonoids

• Polyphenol compounds are natural components of a wide variety of plants; they are also known as secondary plant metabolites.
• Food sources rich in polyphenols include onion, apple, tea, red wine, red grapes, grape juice, strawberries, raspberries, blueberries, cranberries, and certain nuts
• The average polyphenol / flavonoid intake in the U.S. has not been determined with precision, in large part, because there is presently no U.S. national food database for these compounds. It has been estimated that in the Dutch diet a subset of flavonoids (flavonols and flavones) provide 23 mg per day. It is thought that the Standard American Diet gives us 1 -3 mg per day.
• Polyphenols can be classified as non-flavonoids and flavonoids. The flavonoids quercetin and catechins are the most extensively studied polyphenols relative to absorption and metabolism.

Inositol Phosphates (phytates)

• Inositol, (of which the most prominent naturally occurring form is myo-inositol), is a carbocyclic polyol that plays an important role as the structural basis for a number of secondary messengers in eukaryotic cells, including inositol phosphates, phosphatidylinositol (PI) and phosphatidylinositol phosphate (PIP) lipids.
• It is found in many foods, in particular, in cereals with high bran content, nuts, beans, and fruit, especially cantaloupe melons and oranges.
• Inositol is not considered a vitamin itself because it can be synthesised by the body.
• Myo-Inositol was classified as a member of the vitamin B complex (often referred to as vitamin B8), but was found to be synthesized by the human body (thus, declassifying it as a vitamin).
• Inositol as the basis for a number of signalling and secondary messenger molecules, is involved in a number of biological processes, including:
  • Insulin signal transduction
  • Cytoskeleton assembly
  • Nerve guidance
  • Intracellular calcium (Ca2+) concentration control
  • Cell membrane potential maintenance
  • Serotonin activity modulation
  • Breakdown of fats and reducing blood cholesterol
  • Gene expression
• Clinical Implications
  • Patients suffering from clinical depression generally have decreased levels of inositol in their cerebrospinal fluid
  • Some preliminary results of studies on inositol supplements show promising results for people suffering from problems such as bulimia, panic disorder, obsessive-compulsive disorder, and unipolar and bipolar depression
  • Myo-inositol has been found in a single double-blind study to significantly reduce the symptoms of obsessive-compulsive disorder (OCD) with effectiveness equal to SSRIs and virtually without side-effects.
  • In a double-blind, controlled trial, myo-inositol was superior to fluvoxamine for decreasing the number of panic attacks and had fewer side effects
  • A double-blind, placebo-controlled study of depressed patients showed that a high dose of inositol (12 grams daily) resulted in significant improvement of symptoms, with no changes noted in liver, kidney, or hematological function.[
  • D-chiro-inositol (DCI) has been found in two double-blind studies to be an effective treatment for many of the clinical hallmarks of polycystic ovary syndrome (PCOS), including insulin resistance, hyperandrogenism, and oligo-amenorrhea.
  • Studies from in vitro experiments, animal studies, and limited clinical experiences, claim that inositol may be used effectively against some types of cancer, in particular, when used in combination with phytic acid.
  • According to some reports, Inositol strengthens the cells of the hair helping it to retain moisture. It is available orally and is an ingredient in some shampoo formulas.

Lignans (phytoestrogens)

• The lignans are a group of chemical compounds found in plants, particularly in flax seed.
• Lignans are one of the major classes of phytoestrogens, which are estrogen-like chemicals and also act as antioxidants. The other classes of phytoestrogens are the isoflavones, and coumestans.
• Plant lignans are polyphenolic substances derived from phenylalanine.
• When part of the human diet, some lignans are metabolized to form mammalian lignans known as enterodiol (1) and enterolactone (2) by intestinal bacteria. Lignans that can be metabolized to form mammalian lignans are pinoresinol, lariciresinol, secoisolariciresinol, matairesinol, hydroxymatairesinol, syringaresinol and sesamin.

Isothiocyanates and Indoles

• Isothiocyanates are sulphur-containing phytochemicals.
• Different molecules belong to this group, such as the Isothiocyanates
• Isothiocyanates combat carcinogens by neutralizing them, reducing their poisonous effect and stimulating the secretion of carcinogens of carcinogens. Isothiocyanates act by inhibition of cell proliferation and induction of apoptosis.
• Help to lower harmful effects of estrogens
• Studies have shown that isothiocyanates help to prevent lung cancer and esophageal cancer. Isothiocyanates can also lower the risk of other cancers, including gastrointestinal cancer.
• Isothiocyanates can be found in cruciferous vegetables such as broccoli, cauliflower, kale, turnips, collards, Brussels sprouts, cabbage, radish, turnip and watercress.
• Glucosinolates are precursors of isothiocyanates. When the raw vegetables are chewed the plant cells are broken and an enzyme (myrosinase) hydrolyses the glucosinolates into isothiocyanates.

Phenols and Cyclic Compounds

• Phenols are found in almost all fruits, vegetables, grains and green tea
• They act as antioxidants, preventing blood clots, inflammation, and may also activate enzymes that fight cancer.
• The outstanding phytonutrient feature of phenols is their ability to block specific enzymes that cause inflammation.

Saponins

• The name saponin is derived from the Latin word ’sapo’, which means the plant that consists of frothing agent when diluted in aqueous solution.
• Saponins are basically phyto-chemicals which are found in most of the vegetables, beans and herbs.
• The well known sources of saponins are soybeans, peas, and some herbs with the names that indicate foaming properties such as soapwort, soapberry, soapbark and soap root.
• Saponins are also found in tomatoes, spinach, onions and garlic. They help to stimulate the immune system and lower circulating levels of fats. Saponins aid in blocking the absorption of dietary cholesterol and excreting it from the body. They may help prevent disease and some cancers.
• A prominent structural relationship is found between saponins and steroid hormones, vitamin D and cardio actives.
• As a result, this has added to the commercial interest for the synthesis of such medicine by saponin like, for the synthesis of the contraceptive hormones, the use of dioscin in the yams (Dioscorea spp.).
• It was formerly discarded in Western Medicine (as was considered to be figment of imagination), it was later recognized to be worthy in many cases.
• The contents of a triterpenoid saponin is widely implicated in Aralia manshurica, Chai Hu (Bupleurum chinense), Dang Gui (Angelica sinensis), ginseng, or in Chinese Ren Shen (Panax ginseng), Hu Mu (Aralia chinensis), jujube, or in Chinese Da Zao (Zizyphus jujuba), licorice, or in Chinese Gan Cao (Glycyrrhiza uralensis), Siberian ginseng (Eleutherococcus senticosus), Yuan Zhi (Polygala tenuifolia), Wu Wei Zi (Schizandra chinensis).
• Recent studies have illustrated saponins effects which have been beneficial on the control of blood cholesterol levels, bone health, cancer, and support of the immune system. Saponins are found to have numerous health benefits.

Sulfides and Thiols

• Garlic and onions are the most potent members of this thiol subclass, which also includes leeks, shallots and chives.
• The allylic sulfides in these plants are released when the plants are cut or smashed.
• Once oxygen reaches the plants' cells, various bio-transformation products are formed. Each of these appears to have tissue specificity.
• As a group, allylic sulfides appear to possess antimutagenic and anticarcinogenic properties as well as immune and cardiovascular protection.
• They also appear to offer anti-growth activity for tumors, fungi, parasites, cholesterol and platelet/leukocyte adhesion factors.
• Garlic and onions, like their cruciferous relatives, can also activate liver detoxification enzyme systems. Specific allylic sulfides block the activity of toxins produced by bacteria and viruses.