The anti-oxidant vitamins are electron donors capable of decreasing the number of
free radicals in the body, blood, spaces within tissues, and even within cells where
they are the most dangerous. The mechanism for this has been worked out. Free
radicals are usually multi-atom chemical substances which have lost an electron and
become ionized, although some minerals can also exist as free radicals. The free
radicals can take up electrons from any location where they can be easily accessed.
Remembering that nitrogenous compounds (proteins) are highly unstable, they provide
excellant electron donors for free radicals to ‘steal’ electrons from.
This, of course, breaks a peptide bond (the chemical reaction breaking the peptide
bond is an oxidation reaction, and the free radical is reduced), producing two
polypeptides (without the biological significance which made them proteins in the
first place). If the proteins were structural, then structural damage results
requiring repair using available amino acids. If the proteins were enzymatic, the
enzymatic function ceases sooner than expected, and may compromise whatever function
would have been supplied had the enzymatic function continued. The alternative to the
damaging effects of free radicals is for an anti-oxidant (such as Vitamin C, Vitamin
E, or beta-carotene) to intercept the free radical, reduce it (preventing damage),
but this also oxidizes the vitamin (or other anti-oxidant) thereby destroying the
anti-oxidant. This also explains why Vitamins A, C and E are needed on a daily basis
rather than weekly as for most nutrients. Tobacco and tobacco smoke [first-hand or
second-hand] contain “substances known to the State of California…”
which can be absorbed into the blood from the lining of the respiratory system as
well as the lining of the digestive system [not limited to the intestines] and
which are very effective free radicals, so tobacco users [including
‘smokeless’ tobacco products, and even most products used to aid smoking
cessation] require more Vitamin A, C, and E than do non-smokers (but non-smoking
requires not inhaling second-hand smoke). There is little doubt that these processes
(damage due to free radicals, and the capability of anti-oxidants to disable the free
radicals) actually occur in living tissues.
The claim that anti-oxidants can repair damage due to oxidation of essential chemicals can not be explained as easily as the protective role of anti-oxidants. Most of the mechanisms for causing the repair of the damage caused by free radicals involve known metabolic processes, so the anti-oxidant would have to be a co-enzyme for that particular metabolic process in order for the anti-oxidant to assist in the repair [not drive, read “cause,” the repair]. The role of Vitamin C in lessening the symptoms of the common cold would have to be the reduction of bacterial or viral toxins by the anti-oxidant properties of the Vitamin C [assuming, these toxins behave as free radicals]. This could serve, at best, to lower the toxin concentration, and therefore the amount of damage inflicted by the toxins. Assuming that the role of Vitamin C in preventing the symptoms of the common cold is true [not a good assumption] rather than an example of the placebo effect [a much better assumption], the mechanism of action would have to be the reduction of critical biochemicals in the bacteria or viruses (there are about 3,000 such bacteria and viruses) responsible for the common cold; and this has not been shown to happen in a living organism. Two minerals, Zinc and Selenium have been cited as minerals with anti-oxidant properties which could be effective in relieving cold symptoms. Unfortunately, if either of these minerals were to have this effect, the mineral would be oxidized from its atomic state [no charge on the atom] to a free radical, which in turn could inflict damage somewhere else. Since both Zinc and Selenium can easily become charged ions (a.k.a. free radicals), they happen to be rather toxic [Selenium, for example, is the active ingredient in ‘loco weed,’ which produces severe psychosis (brain chemistry) problems for cattle; Selenium also causes (pg. 23-9 in the text) abnormal brain function (irritability) in Humans].
We have already met the French Paradox (last lecture): the French eat delicious flaky pastries made with animal lard, and filled with dairy-based fillings, providing too much cholesterol and saturated fats [and should exhibit a high incidence of artherosclerosis], but are heart-healthy. They also drink too much [mostly wine, usually red wine]. So, we wondered, does drinking red wine allow them to completely ignore the USDA's food guide pyramid? without consequences? Since red wine appears to exhibit a greater effect than do the white wines, and red wines are made from grapes with skins, and white wines are made from grapes with the skins removed, the obvious place to look for the active ingredient is in the skins. When we examined the grapes skins, we found a high concentration of anti-oxidants, such as reveratrol (see any of the Roizen & Oz books, and look up either red wine or reveratrol in the index). Similarly, the Italians consume large amounts of pasta made with animal fats (and whole grains) plus lots of tomato-based sauces & olive oil (an Ω-3 oil) [not to mention drinking more wine than most American health professionals consider reasonable], and remain heart healthy. Tomatoes turn out to be high in anti-oxidants, but at lower density then in grape skins. Turning our attention to the two large populations with the highest life expectancies [age at which 50% of the same aged population can be expected to die (a concept borrowed from the Insurance Industry)], Japan and Hong Cong, we find that they consume very large quantities of green vegetables which have been cooked quickly in hot Ω-3 oils [stir frying using a wok] so they remain crisp even after cooking and, more importantly, retain virtually all their nutrients [American-style over-cooked vegetables have most of the nutrients ‘cooked out’ of them], plus lots of Ω-3 fish (white fish). The darker green vegetables have the highest anti-oxidant density of all vegetables. The common feature of these diets is high anti-oxidants and Ω-3 oils. The obvious hypothesis is that the combination of anti-oxidants and Ω-3 oils cause the heart health needed to achieve long life expectancies and long life spans. Current research is testing this hypothesis.
The popularity of the anti-oxidants led to similar claims for many other
plant-derived chemicals [given the catchy name phyto-chemicals]. Phyto-chemicals were [and still are] heavily
promoted by Herbalists. The Ethnobotanists (the Botany discipline which studies
“Folk remedies” from regional plants), Nutritionists and medical
researchers interested in wellness are currently examining the phytochemicals to
determine if the health claims for them are justified. Their results thus far have
been sufficiently encouraging that the phytochemicals have become credible enough to
start appearing in Nutrition textbooks and lectures. However, all of the research thus
far (and it is currently “inconclusive”) suggests that the phytochemicals
taken as food (dark green leafy vegetables, cruciferous vegetables [broccoli,
cauliflower, brussel sprouts]) provide a far greater benefit than do the plant
extracts taken as supplements in tablet form. Some of the supplement tablets show no
positive benefits, while others show only slight effects [below statistical
significance]. Some authors are now speculating that the phytochemicals will
eventually be added to the list of nutrient classes important to optimal Human
functioning. Although I am not surprised that the benefits of phytochemicals are
higher from food than from tablets, I am not prepared to accept the phytochemicals as
nutrients [until more research supports the health benefit claims for the
phytochemicals]. I would also like to see some explanation of the physiological
mechanisms by which they work.
The phytochemicals technically include all chemicals found in plants: the pigments & accessory pigments, enzymes & co-enzymes, hormones & hormone-like substances, cellulose & lignin in cell walls, the toxins that protect plants from insect [and other animals] damage & fungal diseases of plants, and even DNA. In practice, most of the “phytochemicals” with proposed health benefits are pigments, accessory pigments, enzymes, and co-enzymes [but a few are toxins]. One group of phytochemicals which are claimed to “speed up your metabolism” as a means of losing weight without changing either your eating or exercise habits are the co-enzymes of the electron transport system (where energy is finally captured as ATP). These claims are highly seductive, but your mitachondrial DNA includes all of the genes for all of these co-enzymes, and as a result every mitachondrion you own already has all the co-enzymes it needs (or can use); you could speed up your metabolism by growing more mitachondria [but you have to wait until the “Weight Management 2” lecture to find out how to do this].
footnote: the Welch's ads promoting their Concord grape juice cite reports from the USDA in support of their claims. You need to know that the USDA publishes pamphlets written by individuals not employed by the USDA, and not fact-checked by USDA personnel. The individual who wrote the pamphlets cited by Welch's is Welch's [the IRS promulgated regulations allowing treatment of corporations as individuals for tax purposes, because the IRS can tax income only of individuals; this regulation also causes corporations to be treated as individuals by all Federal agencies]. The pamphlets describing the anti-oxidant properties of concord grape juice were neither written by nor endorsed by the USDA, but merely published by the USDA. This statement does not say anything about the accuracy of the information in the pamphlet, only the nature of the source of the pamphlet. Since Concord grape juice is made from grapes with skins included, the anti-oxidant levels are probably very high.
Technically, all food from agricultural sources is genetically modified,
because we have been using selective breeding to ‘improve’ food organisms
for at least 5,000 years. According to an article in Science, “Maize [corn]
was domesticted from Balsas teosinte (Zea mays ssp parviglumis ~9000 years
ago, resulting in a wide variety of [different breeds]” (Jean-Philippe Vielle-Calzada,
et al. The Palomero Genome Suggests Metal Effects on Domestication, Science
vol 326 [20 November 2009]: p. 1078) This pushes the time frame for selective breeding
4,000 years further back than previous estimates!
However, the opponents of “genetically modified”' foods
are actually referring to genetic engineering, where beneficial genes from one species
are spliced into the genome of another species. For example, some plants which were
not Vitamin C sources have been genetically engineered to produce Vitamin C. The
opposition to genetically engineered foods seems to have become a issue after a
reporter in Europe used the expression “franken-tomatoes” to describe a
genetically engineered tomato. This was, of course, a reference to Mary Shelly's
famous book about a mad scientist who created a monster in his laboratory [the
monster was not ‘Frankenstein;’ the mad scientist was Dr. Frankenstein; in
fact, the monster had no name], and conjured up images that struck fear in the minds
of some readers. Thus far, most of the genetic engineering accomplishments have been
to add the ability to produce toxins for the control of insect pests. You should know
that one of the most effective insecticides known is nicotine. Because the physiology
of insect external respiration (breathing) is different from that of vertebrates,
nicotine causes respiratory arrest in insects. A very effective means of getting rid
of household ants is to put tobacco in a jar filled with water, and make a ‘sun
tea’ from the tobacco. This “tea” can be sprayed around the foundation
of the house, and ants entering or leaving the house will absorb the nicotine through
their feet [I told you tobacco toxins can be absorbed through ‘unusual’
surfaces], and go into respiratory arrest. The down side is that this pesticide
application has to be repeated if it rains. I have successfully gotten rid of ants
over a three year period by this treatment. [this is intended to be useful trivia].
There is no evidence that GM foods are unsafe, but little credible evidence that they are safe [since the ability to produce toxins has been added to food plants]. I doubt that the controversy over GM foods will go away in most of your life times.
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© 2004-2010 TwoOldGuys
revised: 16 Aug 2010