There is increasing interest of Americans in the problem of aging, which prompts them to search for remedies against age-related diseases and senescence. Clearly, it is a natural desire of humans to be active as long as possible and fully enjoy their lives. The great current interest in the problem can be explained by several reasons. On the one hand, the number of elderly people in the USA is rapidly increasing. A large group of people born in the years of the birth boom are now coming to an age when they have to face health problems. On the other hand, in an economically well-developed country, many people take care of their health and are ready to spend a pretty sum of money to maintain it. And, finally, the scientific advances allow people to be optimistic as to the possibility of extending their lifespan.
Be it as it may, but in response to the growing demand of Americans for remedies against senile diseases, a great number of specialized shops offer a great many of dietary supplements. You can hardly find any drug-store in the USA which would have no section selling various anti-aging drugs.
Another thing is how efficient and safe all this stuff is. Scientists are very cautious about giving an unambiguous answer, although they admit that some of the products have a certain favorable effect. Probably, it would not be an exaggeration to say that science is still on the threshold of understanding the physical and biochemical processes of senescence. Further research is needed to answer the questions: What is the cause of senescence, and how can this process be prevented or slowed down?
According to the present-day views, many diseases that develop in individuals of advanced age as well as the general physiological and mental disorders are largely caused by free radicals (very reactive molecules with unpaired electrons). Free radicals are formed due to chronic infection or tobacco smoke, or the action of some other external factors. They are also inevitably produced in normal metabolic processes, where the lipids and carbohydrates we consume are cleaved to release energy necessary for the organism.
Being very reactive, free radicals can induce damage to cells and their DNA. Estimations show that every cell in a human body may experience daily up to 10,000 “bites” by free radicals wandering in the organism, as a result of which the cell will either mutate or die, depending on how severely the cell is “bitten” and how soon it can “heal the wound”.
Professor Denam Harman from the College of Medicine at the University of Nebraska considers free radicals to be aggressive “debris” of molecules that trigger biochemical processes to develop cardiac abnormalities, hypertension, cancer, cataract, diabetes, as well as Parkinson’s and Alzheimer’s diseases in elderly persons. However, as Prof. Harman and colleagues note, free radicals are responsible not only for induction of diseases but also, at least partially, for aging.
As many investigators believe, aging is due to multiple free radical attacks at the cellular DNA. After being attacked a single time, the cell recruits “a repair team” to rapidly repair the DNA lesion. However, the team fails to efficiently repair all of the lesions induced by free radicals. The cell continues to live and function even with poorly repaired lesions.
Cells can counteract the effect of free radicals for a long time and repair DNA lesions due to defense mechanisms operating in every human organism. Each of these mechanisms produces antioxidant molecules, which neutralize free radicals by donating electrons to them. As Pamela Starke-Reed from the National Institute on Aging in Bethesda, Maryland, says, each antioxidant acts in its own way and only in a particular cell compartment.
It should be noted that these defense systems are efficient only against free radicals produced naturally inside a human organism and fail to protect from free radicals abundantly produced in the organism by ionizing radiation or entering the organism with tobacco smoke. Moreover, the production of particular antioxidants in an organism depends on the presence of particular chemical elements in the organism. For example, some antioxidants can be produced only in the presence of copper, zinc and manganese ions, whereas others require iron or selenium ions. In other words, the proper functioning of the defense systems depends on the availability of particular elements in our diet.
Perhaps, in the future, scientists would be able to alter genes such that the human organism could be able to produce antioxidants required. For now, the only way to keep the defense systems of organisms functioning in a proper way is to supply them with the necessary chemical elements.
According to Denam Harman, the dietary supplements that contain primarily vitamins C and E, beta-carotene, and selenium can neutralize the free radicals that overcame the defense barrier of the organism.
Almost all scientists dealing with the aging problem share a viewpoint that the above compounds are very beneficial. However, there is no consensus as to which compound and in what amount should be taken in excess of the daily diet. Some scientists do not recommend the intake of any dietary supplement. Basically, there exist vitamin consumption standards calculated by the US National Academy of Sciences, according to which the female standard dosage of vitamin C is 75 mg per day, and the male standard dosage is 90 mg per day. Cigarette smokers should additionally consume 35 mg of vitamin C per day.
The mentioned organism’s demands for vitamin C can be well satisfied by using dietary fruits and vegetables (citruses, strawberry, potato, etc.). For instance, one glass of orange juice contains 100 mg of vitamin C. The maximum allowable dosage is considered to be 2000 mg, while an overdosage may cause stomach disorder.
A daily dosage of vitamin E for males and females is 15 mg (22 international units, IU), which can also be provided through a well-balanced diet. Vitamin E is found in sufficient amounts in nuts, cereals, beans, and liver. The maximum allowable dosage is 1000 mg, whereas an overdosage is associated with the risk of cerebral thrombosis and internal hemorrhage, since vitamin E possesses an anticoagulant activity.
It is believed that a daily requirement of an individual for selenium is 55 mg, which he or she receives from fish, liver, meet, and cereals. An overdosage may cause selenosis, which manifests itself in the loss of hair and thickening of nails.
A group of medical experts advising to the US National Academy of Sciences in evaluating human vitamin allowance were very careful with respect to beta-carotene, as no unambiguous data are available on this vitamin so far. Head of the advisers, Professor Norman Krinsky from the Tufts University Medical Center noted in this respect: “Although many investigations show a relationship between the diet rich in antioxidant-containing products (various fruits and vegetables) and the decline in the cases of some chronic diseases, we cannot yet state with certainty that it is antioxidants that exert a beneficial therapeutic effect”.
Professor Krinsky belongs to a group of specialists who are not inclined to take any premature decisions and to overestimate the anti-aging effect of the above dietary antioxidants. His inferences are based on compelling and unambiguous evidence obtained in experiments with humans rather than with animals.
Professor Harman, a Krinsky’s opponent, advocates large intakes of antioxidants. Although Harman admits that “nobody actually knows what the optimal dosage is”, he recommends the daily dosage of vitamin E and C to be 200-400 IU and 1500-2000 mg, respectively. He also recommends an intake of beta-carotene at a dosage of 25,000 IU at two-day intervals and two 50-mg selenium capsules per day, one in the morning and the other in the evening.
Nevertheless, Prof. Harman is not sure whether such vitamin additives can slow down the aging process: “Nobody knows this”. Some beneficial effects were obtained only for animals, whereas the respective experiments on humans receiving dietary antioxidants at high doses are in progress.
Jeffrey Blumberg, Chief of the Antioxidant Research Laboratory at the Tufts University in Boston, also recommends vitamins as supplements to a well-balanced diet. He believes that “a high-quality diet is very essential if you want to remain young for long. It is very important that your diet includes products containing vitamins C, E, and beta-carotene”. He considers it to be necessary that dietary supplements contain a complex of vitamins and minerals, since they reduce the risk of many diseases and compensate for vitamin deficiency in the diet. Prof. Blumberg notes that because of malnutrition, the daily calorie intake of many elderly individuals is about 1200 instead of the normal 2000, which clearly demonstrates the necessity of taking vitamin supplements. Prof. Blumberg recommends a daily vitamin dosage of 2.4 mg vitamin B12, 10-15 mg vitamins E and D, and 400 mg vitamin B6. Calcium should also be included in the diet.
There is much controversy as to the intake of vitamin E. In 1996 the journal Lancet published an investigation which showed that regular intakes of vitamin E can reduce the risk of cerebral thrombosis. Four years later, an article published in the New England Journal of Medicine presented evidence which argued the above theory. Many-year examinations of 2545 females and 6996 males showed that the percentage of cardiac abnormalities, cerebral thromboses, and cardiac lethalities was approximately the same in persons fed with vitamin E and those who received placebos. Does it mean that vitamin E is not an essential supplement?
Not in the least. Although being unable to prevent the development of cardiac disorders, vitamin E proved to be a good antioxidant reducing the risk of some other diseases. Investigations performed at Tufts University with elderly persons (age 65 and older) who received vitamin E at a daily dosage up to 200 IU showed that vitamin E favorably affects the immune system (the activity of cells of the immune system increased by 65%).
Promising results were obtained by a research group headed by Michael Grandman from the University of California, San Diego. The patients with Alzheimer’s disease, who received vitamin E as a dietary supplement, required hospitalization less frequently than those who took no supplements. “Vitamin E seems to be able to prevent the development of the worst symptoms of Alzheimer’s disease”, says Grandman.
Scientists believe that one of the more effective applications of antioxidants is their use for cancer treatment. Over the recent decade more than 50 investigations have been performed on the possible use of beta-carotene in cancer prevention and cure and more than 40 investigations dealing with the use of vitamin C for the same purpose. Further studies are needed to develop a better understanding of the dosage and forms of intake of dietary antioxidants.
Scientists from Cornell University, Ithaca, consider that the intake of 100 g of fresh apple is equivalent to the intake of 1500 mg of vitamin C. They also maintain that vitamins E and C used in combination can exert a beneficial effect. The studies performed by a group headed by Prof. Rue Hai Lew showed that a combination of phytochemical substances exerted a substantial antioxidant and antitumor effect.
Laboratory experiments indicated that extracts obtained from the apple rind and pulp are effective in slowing down the proliferation of tumor cells in individuals with large intestine cancer by 43 and 29%, respectively. Still more impressive results were obtained in the studies of patients with liver cancer: the apple extracts inhibited the proliferation of tumor cells by 57 and 40%, respectively.
These findings, which confirm the known fact that the apple is a valuable dietary product, will most likely be scenically taken by the scientists who are inclined to think that vitamins used only in megadoses may have an effect. Doctor Chris Renna, one of the ardent advocates of this concept, gives recommendations to many movie stars. Following her recommendations, the 59-year-old actor Nick Nolte, well-known from the “48 Hours” and “Another 48 Hours” movies is going not only to get rid of his pernicious habits (drug and alcohol abuse) but also to rejuvenate.
The actor takes daily as many as 60 capsules with vitamins C and E and microelements (such as chromium, zinc, calcium, and magnesium) and does regular vitamin injections. His diet includes bilberry to keep good eyesight, gingko biloba to protect against cerebral diseases, and aspirin to protect against the development of cardiac disorders. Nick Nolte admits that he already begins to feel rejuvenated.
In the final analysis, time will show what it would be like.
Vladimir Rogachev (ITAR-TASS correspondent)