Our diet is omnivorous and consists of a wide variety of plants, fungi and many branches of the animal kingdom as well as yeasts and bacteria of various sorts. The basis of our health and longlevity is closely related to the biochemical diversity of the foods we eat.
From our gatherer-hunter origins, we have inherited a degree of dependence on the molecular diversity of other species around us and have reaped particular benefits from the phytochemicals associated with the wide variety of plants and berries derived from a diverse gatherer diet.
In fact the diversity of our foodstuffs has in many ways declined, as is shown in falling diversity both of the genetic diversity of foodstuffs and the number of different fruits, plants and berries commonly consumed. For example traditional fruit have shrunk from the hundreds to little more than ten. The worl'd cereal production depends on just three species. Furthermore it has become possible in the modern world of consumer outlets for diets to develop a degree of uniformity, which can result in deficiences of many beneficial biodynamic substances in food.
Protection against premature ageing, mutagenicity and cancer is dependent to a significant extent on prudent diversity of food intake and particularly on adequate intake and diversity of fruit and vegetables, because of the many phytochemicals and vitamins they contain. Overall the effects of smoking on lung cancer, the course of HIV and the deleterious effects of alcohol all appear to be significantly reduced given adequate dietary care.
Principal Dietary Components of Food
The traditional major components of the diet are regarded as being carbohydrates, fats and proteins, along with certain vitamins or cofactors, however there is a growing recognition that there are both a wide spectrum of other beneficial biodynamic molecules which are protective to welfare and long life and that there are also hidden in our food natural toxins which are a potential threat to health and which we should learn to be wary of.
Our principal energy source is carbohydrates, so named because their chemical formula (CH2O)n is equivalent to hydrated carbon. Sucrose is a dimer consisting of glucose and fructose joined. Although each ofthese monomers is safe to eat and indeed our metabolic energy is driven by glucose the dimer sucrose places a stress on our pancreatic enzymes. On the right amylopectin illustrates how starches are complex chains or trees of linked glucose molecules. Such large polysaccharides are less strain to digest and even help to protect against the effects of mild diabetes in the case of oats.
The fats are generally a variety of esters or organic salts of fatty acids. The long-chain fatty acid oleic acid with one kinked double bond (half-way down) illustrates the hydrocarbon nature of fats, which give them 5 to 7 times as much energy per weight as carbohydrates. Such non-polar molecules are frequently also part of the cell membrane as part of the lipid molecules which are fatty at one end and ionic at the other. The non-polar steroid cholesterol (below), an excess of which is associated with blockings of the coronary and other arteries in heart disease is also a membrane component.
The proteins are exceedingly diverse molecules which constitute all the enzymes and receptors and much of the structural molecules in the body. They are composed of 20 different amino acids which can be linked to form a vast variety of chemically active substances. Our diet requires a full complement of amino acids to rebuild all the enzumes for our bodies to function. Some amino acids permit unique reaction types and a deficiency of these can lead to serious illness. Methionine and lysine are sometimes deficient in plant proteins.
Polar neutral amino acids have a variety of specific chemical types. Two are the amides of the acids, two are alcoholic, one has SH bonds (as does non-polar methionine). Tyrosine provides a carbolic OH and tryptophan an indole group.
The principal vitamins are biodynamic molecules which generally have a catalytic or electrochemical role which cannot be performed by existing proteins by themselves. A variety of minerals including Zn, Mn, Mg, Co, Se, I, Fe also function in this way. Because some of these substances are ubiquitous particularly in the diverse human food intake, we have become unable to synthesize these products ourselves (except for the case of vitamin D and sunlight which is it's principal source from cholesterol and other steroids. Humans can no longer make vitramin C unlike rats who can synthesize their own.
Several vitamins catalyse very specific essential metabolic or electrochemical reactions which become inhibited unless we ingest aminimum daily requirement of these substances.
Vitamins and their coenzyme forms
Type Coenzyme or active form Function promoted
Thiamin Thiamin pyrophosphate (TPP) Aldehyde-group transfer
Riboflavin Flavin mononucleotide (FMN) Hydrogen-atom (electron) transfer
Flavin adenine dinucleotide (FAD) Hydrogen-atom (electron) transfer
Nicotinic acid Nicotinamide adenine dinucleotide (NAD) Hydrogen-atom (electron) transfer
Nicotinamide adenine dinucleotide phosphate (NADP) Hydrogen-atom (electron) transfer
Pantothenic acid Coenzyme A (CoA) Acyl-group transfer
Pyridoxine Pyridoxal phosphate Amino-group transfer
Biotin Biocytin Carboxyl transfer
Folic acid Tetrahydrofolic acid One-carbon-group transfer
Vitamin B12 Coenzyme B12 1,2 shift of hydrogen atoms
Lipoic acid Lipoyllysine Hydrogen-atom and acyl-group transfer
Ascorbic acid Cofactor in hydroxylation
Vitamin A 11-cis-Retinal Visual cycle
Vitamin D 1,25-Dihydroxycholecalciferol Calcium and phosphate metabolism
Vitamin E Antioxidant
Vitamin K Prothrombin biosynthesis
Thiamine is involved in aldehyde group transfer. The highlighted hydroxethyl group detaches to form acetaldehyde CH3CHO.
Riboflavin is capable of picking up two hydrogen atoms at the two bare nitrogen atoms in the central and right-hand heterocycles, thus being involved in reversible redox reactions in electron transport and in flavoenzymes. They are thus essential in resperation and the oxidation of fatty acids, pyruvate and amino acids. Sometimes they have additional metal ion factors.
The very ancient nature of these substances is indicated by their frequent pairing with nucleotides that make up the units of RNA. These nucleotide cofactors as illustrated by NAD nicotinamide adenine dinucleotide (left) and Vitamin B12 (right), which has two adenines linked over a cobalt containing corrin ring, similar to the prophyring rings of heme and chlorophyll. It is believed these may be ancient molecular fossils from the RNA era before the development of the genetic code which defines protein sequneces and thus may constitute relics of the original RNA-based metabolism.
Pantothenic acid is used as the coupling molecule to
form coenzyme A another nucleotide coenzyme which is likewise
essential in the citric acid cycle to carry acetyl (generally
This indicates the citric acid cycle may too date from before genetic translation.
Pyroxidine enzymes are extremely versatile, functioning in a large number of different enzymatic reactions in which amoni acids or amino groups are transformed or transferred. Biotin is similarly capable of transferring a carboxyl group by picking it up at the lower NH group. Egg white binds biotin so tightly that it can cause a deficiency of biotin. Lipoic acid has reversible sulf-hydryl groups which are coenzymes in oxidation-reduction reactions.
Tetrahydrofolic acid, the active form of folic acid is able to pick up and transfer methyl and formyl groups at its N5 and N10 and to form cyclic products to both in one-carbon transfers in the metabolism of amino acids, and nucleotide bases. Folic acid is particularly necessary in pregnancy.
Vitamin C (ascorbic acid) is a strong reducing agent which is active in making hydroxyl transfers in its oxidized form. It is present at high concentration (1 mg/100 ml blood plasma) in all animal tissues. It functions are not completely elucidated. It does hydroxylate proline but other metabolites can substitute. It is the first of the vitamins which are known to have an anti-mutagenic activity in association with protecting against attack by hydroxyl radicals arising from aqueous oxidations.
Vitamin D in its various forms is generated from 7 dehydro-cholesterol by the action of sunlight on skin. This is our major source of the vitamin so we require adequate sunlight exposure without suffering unlta-violet damage. It is also present in fish liver, but is rare in the rest of the diet. It is essential for bone metabolism and calcium uptake. Vitamin essentially functions as a hormone secreted in precursor form by the kidney in respose to signals concerning calcium levels. It becomes inactive requiring dietary supplement when too little sunlight falls on human skin.
Vitamin E has been slow to be recognised as a vitamin because its deficiency syndrom remains obscure. It lack causes infertility in rats. Like vitamin C it is a significant anti-oxidant and works synergetically with vitamin C in the non-polar environment of the membrane, where it inhibits oxidation of unsaturated fatty acids. It is notably present in the germs of grain. Vitamin E has recently been found in dises of around 70 mg/day to reduce cancer of the prostate by up to 40% (Feb 98)
Vitamin A and lycopene are likewise non-polar molecules which are known to have an anti-oxidant protective value. Lycopene from tomatoes is known to protect against prostate cancer through its strong anit-oxidant action. Vitamin A has a role in the repair of the epithelial lining of lung tissues. People consuming half a cup of carrots a day were found to have only a seventh the rate of lung cancer of those who didn't, although this may involve other synergetic dietary correlations. More recently vitamin A on its own has been shown to increase incidence of cancer by up to 29%, so it appears any protective action happens only in association with other substances possibly including bioflavonoids.
This situation has become clearer with the discovery that Falcarinol ((3S,9Z)-heptadeca-1,9-diene-4,6-diyn-3-ol) in carrots and red ginseng is believed to reduce the risk of developing cancer, as a research team from the University of Newcastle upon Tyne discovered in February 2005.
The anti-cancer properties of carrots are more potent if the vegetable is not cut up before cooking, research shows. Scientists found "boiled before cut" carrots contained 25% more of the anti-cancer compound falcarinol than those chopped up first.
Capsaicin in chilli (left) causes apostosis (cell death) by triggering mitochondria in cancer cells
Circumin in turmeric (right) has a similar effct on apostosis of oesophageal cancer cells.
Articles of the Value of Phytochemicals in Food
Salicylates are found widely in plants as a defence against insect attack. Organic vegetables consequently contain up to 50 times as much and these substances, along with asprin have demonstrated anti-cancer potential:
In addition to the three anti-oxidant viatmins mentioned above, there are a variety of other small active biodynamic molecules present in particular foods which have a variety of anti-oxidant and hence anti-aging, or anti-cancer properties.
One partucularly important group of such molecules are the bioflavonoids, a diverse group of monomers dimers and polymers of a polyphenolic nature. It is estimated that in the normal diet, bioflavonoids form the principal anti-oxidants. It is estimated that the mutagenic effacts of oxygen are up to 2000 mutations per cell per day. The body has a variety of peroxidase and other enzymes to counteract the effects of peroxide and other free radical products of oxidation as well as repair enzymes, but depends on additional anti-oxidant substances to reduce this mutational load, which is itself a significant part of the aging process.
Catechins occur in tea, quercetin in red wine red onions and also tea. These are both anti-oxidant and anti-cancer, although quercetin is believed to also be mutagenic to some degree. Green tea is believed to reduce lung cancer rates by 40%. Hop bioflavinoids are also prominent in beer and repress cancer growth. Reports of cancer rates 20 times lower have come from areas e.g. in China where red onions are frequently eaten. Such polyphenolic substances are also known to be good for heart disease and to reduce blood thickening and protect against heart disease. Proanthocyanidin dimers are assocated with a variety of berry fruits and nuts, as are the related natural anthocyanin pigments. They occur prominently in pine bark and grape pips. The dimers are an order of magnitude more effective as anti-oxidants and may be pivotal in protecting against the mutagenic effects of free ferric ions.
Resveratrol a closely-related molecule present in grape juice and red wine also merits investigation as a potential cancer chemo-preventive agent. It has been found in at least 72 species including mulberries, peanuts and grapes. It is thought to be one of a class called phytoalexins, produced by plants when they are stressed by fungal attack.
It has recently been discovered to both trigger the sirtuin switch causing significant extension of ife in yeast, worms, and now fish, in the same way caloric restriction (near starvation) can do. It also appears able to arrest cancer at several stages of development while not being toxic to healthy cells.
Allicin (diallylthiosulfinate) of garlic is an example of the sulphur-containing small molecules in garlic and onion. It is known to reduce cholesterol. These substances are also known to be antibacterial. In garlic allicin exists as a dimer wheras in onion the reactive monomer becomes the factor causing eye watering.
Allium vegetables, such as onion and garlic, are best prepared by leaving them for 10 minutes after chopping them up before heating them in a pan. This allows an enzyme called alliinase, which is destroyed by heating, to work on sulphur compounds in the vegetables and turn them into diallyl sulphides, which are known to have an anti-cancer effect and are not destroyed by heat.
Glucosinolate, glucoraphanin and sinigrin
Glucosinolates are present notably in brassicas, where they dispaly a variety of anti-cancer properties. The sinigrin of Brussels sprouts is converted to allyl isothiocyanate from the glucosinolate in the above reaction byremoving the glucose ring. Sinigrin causes small polyps in the large intestine to self-destruct and the effect occurs even with intermittent consumption. A similar glucosinolate in broccoli, glucoraphanin, which breaks down into an isothiocyanate called sulphoraphane, complementing sinigrin, stops or slows the genetic damage before it happens (New Scientist 21/28 Dec 1996 46). Brassicas also contain anti-carcinogenic indoles.
Sulforaphane and isothiocyanate.
Conjugated linoleic acid present in full fat milk may also protect against melanomia, leukemia as well as cancers of the breast, colon, ovaries and prostate. CLA is found in dairy products including milk, yoghurt cheese and meat from ruminants. The avergae US diet contains about 1g of CLA a day. 3.5g a day are needed to benefit. Adding corn oil to cows diet can increase CLA from 2 mg/g to 4.5 mg/g (New Scientist 16 Nov 96 p8).
rumenic c9, t11 conjugated linoleic acid
CLAs were discovered accidentally by researchers looking for mutagens in beef. In 1979, researchers from the University of Wisconsin applied a beef extract to mice skin. The mice were then exposed to a strong carcinogen. When the researchers counted the number of tumors developed by the mice 16 weeks later, they found, to their surprise, that the mice exposed to the beef extract had 20% fewer tumors. The identity of this anti-carcinogen was not discovered till almost a decade later in 1987. Micheal Pariza, the scientist who discovered CLA, later remarked that "few anticarcinogens, and certainly no other known fatty acids, are as effective as CLA in inhibiting carcinogenesis in these models."Researchers have also found that the cis-9, trans-11 form of CLA can reduce the risk for cardiovascular disease and help fight inflammation.
Soya beans contain two substances of significance, phytosterols, which reduce cholesterol absorbtion and may help to prevent colon cancer, and isoflavones such as genistein, which may offset the effects of estrogen in breast and ovarian cancer. And has been found to prevent vascularization of a number of cancers.
Limonene in citrus fruits also helps produce enzymes that flush out cancer-causing substances. A component of the pectin in citrus fruits also has anti-cancer properties agains prostate cells inhibiting their binding to blood vessels.
γ-linolenic acid is a prostaglandin precursor which is believed ot facilitate the prostaglandin metabolism in pre-menstrual tension.
Natural Food Toxins
Many natural food substances contain a variety of toxins which can be poisonous or can induce long-term harm. The cyanides in cassava and the solanine of potatoes and the neuro and hepatotoxins of the sago palm are well know examples. Those presented here are ones which may cause mutagenic effects in less-detected ways.
There are a variety of natural carcinogens in particular foodstuffs in addition to any foreign substances such as insecticides. These foods should be treated with caution consequently:
Canavanine in alfalfa sprouts and broad beans is a non-coded amino acid which substitutes for arginine (see above) to form a less basic amino acid which can become incorrectly incorporated into DNA-binding proteins in the place of arginine, causing them to bind incorrectly, resulting in impaired gene activation and promotion. This can cause a variety of deleterious secondary effects including lupus erythematosis syndrome - an autoimmune condition against nucleic acids - and possibly cancer.