This is the new magic word in nutrition. There are many new terms introduced into the subject that are confusing to the newcomer - nutraceuticals, phytonutrients, phytofoods, functional foods. The implication is that these are extremely high powered nutrients but, of course, the evidence is largely anecdotal. These are associated nutrients, chemicals found with nutrients that appear to have synergistic effects with nutrients or augment their effect.
For years people have been consuming whole grains, lecithin, soya products, brewers yeast, spirulina and a range of other not so well known products. Among the various terms which we encounter subsumed under the heading phytonutrients, which are found in fruits and vegetables, we find flavonoids, cabbage factors (glucosinolates and indols), vitamin U (ubiquinone) was termed vitamin Q, tocopherol has always stayed as vitamin E. Many vitamin designations have been discontinued because no specific deficiency symptoms could be established. However it is claimed that recent research has elucidated certain classes of phytonutrients, based on similar protective functions, as well as individual, physical and chemical characteristics of the molecules, as vitamins.
Over forty years ago Dr Shelton said and wrote that we did not know all the chemicals in food that are important. They are still being discovered and will probably continue to be for some time.
Terpenes
These are found in green foods, soya products and grains and comprise one of the largest classes of phytonutrients. The carotenoids from which is derived beta-carotene, are probably the most widely noted. Terpenes are the anti-oxidants that protect lipids, body fluids and cells from assault by free radical oxygen species, including singlet oxygen, hydroxyl peroxide, super oxide, and similar radicals. Terpenoids are spread widely through vegetables and plants and are said to offer protection against reactive oxygen species (a free radical).
Carotenoids
This is a sub-class of the bright yellow or orange and red plant pigments found in vegetables such as tomatoes, parsley, pink grapefruit, oranges, spinach, red palm oil and of course carrots. Egg yolks are yellow because of carotenoids. The family actually includes two separate types of molecules. One type, the carotenes are chemically identified as 40 carbon tetraterpenes. They do not include specific chemical features like the hydroxyl or keto groups. The familiar member of this class is the molecule beta-carotene.
It is claimed that there are 600 naturally occurring carotenoids. Many think that carotenoids are precursors of vitamin A, in fact less than 10% have Vitamin A activity. These are the alpha, beta and epsilon carotenes.
Limonoids
Another terpene sub-class found especially in the peels of citrus fruit. It has been claimed that limonoids may be important chemo-preventive agents and that this sub-class of terpenes may be effective in the protection of lung tissue with a favourable influence on patients with chronic obstructive pulmonary disease.
PHYTOSTEROLS
Sterols are widespread in the plant kingdom, although yellow and green vegetables contain some quantity their seeds have the highest concentration so we find that seeds of pumpkins, yam, soya, rice, contain phytosterols which compete with dietary cholesterol for uptake in the intestine. Therefore it is claimed that they have the ability to block the uptake of cholesterol and to facilitate its elimination from the body.
A further claim for phytosterols is that they inhibit the development of tumours in colon, breast and prostate. As might be expected the mechanisms are poorly understood.
Phenols
It is well known that plants are protected from oxidative damage by phenols. The various colours of grapes, blue, reddish blue, violet etc. and the purple of eggplant are the result of their phenol content. Bilberries are high in phenolic anthocyanidins. It is claimed that these phenols have the ability in inhibit specific enzymes related to the evolution of inflammation. It is also said that they modify prostaglandin pathways protecting platelets from agglutinating.
Flavenoids
This phenol sub-class are said to enhance the effects ascorbate, (vitamin C). Flavenoids are numerous there being well over 1500 of them and widely distributed in plant foods. These present a marvellous field for the activities of the phyto-therapist. It is believed and claimed that their use is effective against allergies, inflammation, free-radicals, liver toxins, microbes, ulcers, viruses, tumours and goodness knows what. These are the saviours of the 21st century.
It is claimed that flavenoids block the angeotensin converting enzyme (ACE) that raises blood pressure, therefore we no longer need ACE inhibitors but I am inclined to think that the matter is much more complicated than this but it does tend to demonstrate that there are many more substances that are biologically important in food than the standard nutrients.
Flavenoids are also said to block enzymes that produce estrogens reducing the risk of estrogens related cancers. A mechanism is described by which the enzyme estrogens synthesase which facilitates the binding of oestrogen to receptors to certain cells of the body.
Anthocyanidins
Another group of flavenoids, technically called flavonals. They’re important in the development of strands of collagen, probably the most abundance protein in the body which is present throughout tendons, ligaments, facia, soft tissues, bone matrix. Anthocyanidins are water soluble they apparently can scavenge for free radicals which may be encountered in tissue fluids.
Catechins, Gallic Acids
These are still flavenoids and have important chemo-protective properties. Common among the catechins are certain esters called Gallic esters and named epicatechin (EC), Epicatechin Gallate (ECG) and Epigallaocatichim Gallate (EGCG). These are found noticeably in green tea – there’s one for the herbalists.
Isoflavoins
This nutrient belongs to the phenol sub-class and comes from legumes. Isoflavoins function much like flavenoids blocking enzymes. It is claimed, although I personally do not know the statistics, that people who consume diets rich in soya foods, rarely experience breast, uterine and prostate cancers. Better look into that!
Thiols
A sulphur containing class of photo-chemicals present in garlic and cruciferous vegetables, cabbage, turnips and members of the mustard family.
GLUCOSINOLATES
These are found in cruciferous vegetables. They have an effect on liver function, white blood cells and substances derived from blood cells called cytokins. These chemicals are said to be important in bio-transformation activities in the liver.
Allylic Sulphides
The most potent foods containing this particular sub-class of thiols are garlic, onions, leeks, shallots and chives. We have always noted that allylpropyl disulphide found in garlic and onions is the reason for the unpleasant odour and breath. It is argued that these foods like the cruciferous foods are important in liver detoxification enzyme systems.
Indoles
These interact with vitamin C which usually is found in the same food. It is claimed by the investigators that indole complexes bind chemical carcinogens and activate detoxification enzymes mostly in the gastro-intestinal tract.
Isoprenoids
These are said to neutralise free radicals. They have a long carbon side-chain to which they can anchor themselves to fatty membranes and any free radicals attempting to attach to the lipid membrane are secured by the carbon side chain and passed to antioxidants.
TOCOTRIENOLS AND TOCOPHEROLS
These occur naturally in grains and substantially in palm oil. Tocotrienols are said to inhibit breast cancer cell growth but their most widely accepted effect is as a cholesterol lowering substance.
LYPOIC ACID AND UNIQUINONE
This has been marketed as co-enzyme Q that, it is claimed, has important antioxidant properties, so much so that it is put at the top of the list of antioxidant.
All of the above phytochemicals have obviously been around a long time, it is just that as researchers investigate food more and more substances appear. It is almost like the physicists looking for particles. As we know every few years new particles are discovered and that’s obviously the way it is going to go on every few months, years or whatever, a new nutrient will be discovered or a new substance important in the body’s use of nutrients. We have to acknowledge that we are a long way from understanding the composition of food but we are learning. And one thing that stands out is that eating whole foods and a wide range of foods give us the best chance of being adequately and indeed well nourished.
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