Medical Hypotheses
5:825-34,
1979
SOME THOUGHTS 0~ THE EPIDEMIOLOGY OF CARDIOVASCULAR DISEASE, (WITH SPECIAL REFERENCE TO WOMEN "ON THE PILL"),ROLE OF ASCORBIC ACID C.A.B. Clemetson. The Methodist Hospital, 506 Sixth St., Brooklyn, N.Y. 11215, U.S.A. ABSTRACT Consideration of nine major factors predisposing to cerebral thrombosis, coronary thrombosis or thrombosis in the deep veins of the calf, reveals that these factors all have one thing in common. Estrogen administration, pregnancy, ageing, smoking,infection, trauma, surgery, soft water and winter season are all associated with a tendency towards decreased plasma ascorbic acid levels. Normally, ascorbic acid deficiency is thought of as causing a tendency towards hemorrhage rather than thrombosis, but it is here suggested that petechial hemorrhages under the endothelium of the blood vessels may precipitate thrombosis on the damaged endothelium. Is not blood coagulation the normal mechanism for the arrest of hemorrhage? Key Words:
ascorbic acid, cerebral thrombosis, contraceptives oral, estrogens, myocardial infarct, thromboembolism, vascular disease, water supply. INTRODUCTION
It has been known for some years that use of the combined estrogen-progestagen oral contraceptive pills is associated with an increased morbidity and mortality from thromboembolic disease (1,2,3,4). Other studies have shown that the use of these pills is associated with a significantly increased death rate from a wide range of vascular conditions, including acute myocardial infarction and cerebral thrombosis or hemorrhage (5,6,7). The excess mortality is reported as increasing with age, cigarette smoking and duration of oral contraceptive use. A large well controlled prospective study of high dosage diethylstilbestrol (5 mg daily) versus placebo in the treatment of men with carcinoma of the prostate (8) has also shown an increased death rate from heart disease and cerebrovascular accidents, which outweighed the benefits 05-a decreased death rate from prostatic cancer. These findings and other data have led to a general agreement that it is the estrogenic component of the birth control pills that causes the vascular problems and has resulted in the use of lower and lower doses of estrogen in the combined birth control pills in recent years. The mechanism by which estrogens predispose to thromboembolism is not known; several hematological changes have been reported in women taking the oral contraceptive pills, but it is dif825
ficult to assess the significance of these changes. Enhanced blood coagulability, increased blood viscosity, reduced blood cell filtrability, enhanced platelet adhesiveness and aggregation, a rise in clotting factors VII and X, an enhancement of fibrinolytic activity, a fall in antithrombin III activity and a low content of plasminogen activator in the walls of the veins were all discussed by Girdwood (9) when he rev ewed this subject in 1976, but no definite conclusions have been reached. Some authors have reported a slight reduction in the coagulation time of the blood of women "on the pill", as measured by the "Partial Thromboplastin Time" (P.T.T.) (10). However, it does not necessarily matter if the P.T.T. is reduced, just so long as the blood does not start to clot. The question is "What causes the coagulation mechanism to be initiated?" and not "How long does it take the blood to clot?". So we must look for changes in the endothelium or inner lining of the blood vessels, as first suggested by Armand J. Quick (11); we are particularly interested to know what deleterious Also, we need to effects estrogens may have on the endothelium. know whether other factors which increase the risk of death from cardiovascular disease could act by damaging the endothelium. We know that pregnancy predisposes to deep vein thrombosis and embolism; this condition is also well recognized as occurring after infection, trauma or surgery (12). There is evidence that the incidence of deep vein thrombosis is higher in the cold half of the year (13). There is also evidence that deaths from all forms of cardiovascular disease are higher in soft water areas than in hard water areas (14). HYPOTHESIS Could there be anything in common between the nine seemingly unrelated factors, namely estrogen ingestion, pregnancy, ageing, smoking, infection, trauma, surgery, soft water and winter season, all of which seem to predispose to cardiovascular disease and thrombosis? Strangely enough, there is one thing that all these factors They all can or do decrease the ascorbic acid concenhave in common. tration in the blood. This is particularly important because ascorbic acid is essential for the health and integrity of the vascular endothelium.
It is generally believed that low levels of ascorbic acid in the blood are of little consequence and that no problem arises until all ascorbic acid has disappeared, when frank scurvy becomes evident; however, there are reasons for believing that this is not true; ascorbic acid deficiency has been shown to predispose to atherosclerosis (15); moreover, serious vascular accidents may suddenly occur as a result of ascorbic acid deficiency in subjects who appeared to be perfectly healthy (16); sudden deaths occur long before the development of scurvy (17); the evidence for these statements will be discussed later in this paper. 826
Ascorbic acid deficiency is normally considered as a cause of hemorrhage rather than thrombosis; however, clotting is the normal mechanism for the arrest of hemorrhage, so small subendothelial hemorrhages could well be the precipitating cause of thrombosis. now be considered.
Each of the nine epidemiological factors will
1. Estrogens. It is paradoxical that, on the one hand, women, losing their ovarian function, become more prone to coronary heart disease and, on the other hand, estrogen administration increases the risk of this disease. Some authors have suggested that the reason for this is that natural estrogens are beneficial and synthetic ones are harmful to the blood vessels; however, it seems far more likely that estrogens are like all other hormones, being harmful in deficiency or excess and being beneficial in correct replacement dosage. Small amounts of estrogen may be considered as having a direct beneficial effect on the blood vessels, for they increase the capillary strength of menopausal women (18,19). The harmful effect of estrogens on the blood vessels is almost certainly due to the high potency and/or dosage of the estrogens used in oral contraceptive pills kvhichis necessary to inhibit ovulation. This harm may well be an indirect effect, for estrogen is known to reduce the ascorbic acid content of the blood in guinea pigs and in rats (20,21,22 there is evidence that this may in part be due to decreased tubular reabsorption of ascorbic acid (23), but it may also be due to the marked increase in the plasma concentration of the copper protein ceruloplasmin, which is an ascorbate oxidase (24,25). Plasma total copper and ceruloplasmin levels are markedly increased in women taking estrogens or estrogen-containing oral contraceptive pills (26,27). The plasma and platelet ascorbic acid levels of women "on the pill" are correspondingly decreased (28,29,30). y The estrogens of pregnancy have a similar 9 effect in fncr~~~i~~":he copper content of the blood plasma (31,32,33). Presumably this high blood copper or ceruloplasmin level and other factors, such as the active transfer of ascorbic acid from mother to fetus (34), account for the progressive fall in the plasma ascorbic acid level during pregnancy (35,36). Several workers have shown that the plasma and 3. A ein white blood ccl p9' ascorbic acid levels decrease progressively with increasing age (37,38). causes levels in the method
4. Smoking_. It is well established that cigarette smoking a reduction in both the plasma and the leukocyte ascorbic acid (37,39,40). This may be a direct effect of the carbon particles lung, for powdered charcoal is used in a standard analytical for oxidizing ascorbic acid to its dehydro-form (41). 827
5. Infection. Both acute and chronic infectious diseases cause an increase in the ceruloplasmin concentration of the blood (42); this may account for the decreased ascorbic acid levels observed following infection (43). 6. Trauma. Various forms of stress have been shown to reduce the adr?%%il%corbic acid level. This is almost certainly a direct effect of ACTH. However, there is also a general effect of trauma on ascorbic acid metabolism (45), which may be related to the fact that hemolysis rapidly destroys ascorbic acid -in vitro (46). 7. Surgery. Decreased plasma ascorbic acid levels have been observed following surgery (47). This may in part be due to leukocytic transport of ascorbic acid to the area of the wound where it is needed for healing. 8. Soft water. It has been found that death rates for all forms of cardiovascular disease are higher in soft water areas than in hard water areas throughout the United States, the United Kingdom and Japan where it has been studied (14). The cause of this problem is not known, as no offending substance has been isolated from the water in the soft water reservoirs. However, in soft water areas, the first water drawn from copper pipes in the morning may contain up to two parts per million of copper and the cupric ion is a potent catalyst for the oxidation of ascorbic acid and may destroy ascorbic acid before it can be absorbed from the lumen of the jejunum (48). In hard water areas, this problem does not arise because the water pipes are coated by an inner lining of "fur". 9. Not only does deep vein thrombosis occur Winter season. more commonly during the cold half of the year (13), it has also been shown that ischemic heart disease occurs more frequently in the winter (49). These findings may be related to the seasonal variations of plasma (50) and leukocyte (51) ascorbic acid levels, presumably due to a lower vitamin C intake in winter, as reported in Great Britain (52). Indeed, a correlation between a low ascorbic acid consumption and a high incidence of myocardial infarction in winter has previously been suggested by Spittle (53). Thus, the nine main factors predisposing to deep vein thrombosis and other cardiovascular diseases, all can or do decrease the ascorbic acid level of the blood. But the reader will say that this is irrelevant unless it can be shown that ascorbic acid deficiency predisposes to cardiovascular disease in humans. We rarely see scurvy nowadays but it has been produced experimentally by Krebs (16), who studied ten healthy volunteers, aged twenty-one to thirty-four years, on a vitamin C free diet. I quote from his report.
828
"Some important abnormalities were observed in single cases. One man developed effusions into both knee joints and ecchymoses of the leg during the 30th week of deprivation after a long walk, Another was taken ill 4 weeks later, 19 h after heavy physical exercise. He had severe pain in the lower sternal region, and became dyspnoeic and cyanosed. The pulse was rapid and the blood pressure low. The clinical picture was that of an acute cardiac emergency. He was immediately admitted to hospital and dosed with vitamin C. The lower sternal pain, which at first had increased in intensity, passed off after 9 h. The electrocardiogram showed high ST levels in leads I and II. A radiogram of the chest showed no abnormality. Eighteen days later another deprived volunteer complained of a sudden constrictive pain in the chest. Physical examination revealed a systolic murmur which had not been heard before, and the electrocardiogram showed a partial heart-block, the P-R interval being 0.32 sec. Before the experiment the electrocardiogram had been normal with a P-R interval of 0.20 sec. It was thought necessary to treat this volunteer immediately with large doses of vitamin C. The chest pain and the systolic murmur disappeared within 24 h, but during the following months the P-R interval showed variable periods between 0.13 and 0.32 sec. depending on posture, breathing, administration of drugs, and other factors." The older records of scurvy contain many references to sudden death. James Lind (17), in 1753, wrote: "Persons that appear to be but slightly scorbutic, are apt to be suddenly and unexpectedly seized with some of its worse symptoms. Their dropping down dead upon an exertion of their strength, or change of air, is not easily foretold.". These incidents occur at a stage when occasional skin petechiae are the main clinical manifestation of scurvy and general fitness still appears to be fairly good. We can only conjecture as to whether it is a subendothelial hemorrhage or a hemorrhage followed by thrombosis in one of the coronary arteries that caused these heart attacks. Moreover, we may wonder whether thromboembolism may not have occurred in some of those who suddenly "dropped down dead". Follis, in 1942, reported sudden deaths in three infants with scurvy and concluded, on autopsy, that they died of heart failure (54). Shafar (55) reports rapid reversion of electrocardiographic changes, like those of myocardial infarction, after treatment in two cases of scurvy. One wonders what would have happened 829
to these patients if they had not been diagnosed as scurvy and treated with ascorbic acid, for Hume et al (56) report a further fall in leukocyte ascorbic acid to scorbutic levels after myocardial infarction. Perhaps the most significant experiment of all is that of Willis (15) who showed that ascorbic acid deficiency causes atherosclerosis in guinea pigs within fifteen days even at normal blood cholesterol levels. It seems that cholesterol is deposited under the endothelium when it has been damaged by the petechial hemorrhages of scurvy. Thus, we may think of atherosclerosis as an aberrant form of wound healing in blood vessels. In this context, it is interesting to note that Boyd (57), in his "Textbook of Pathology", observed atherosclerosis even in young persons who died following one of the acute infectious fevers. While L-ascorbic acid is essential as a vitamin and has only beneficial effects, it is unstable in aqueous solutions and is readily oxidized in the presence of traces of copper to form dehydroascorbic acid which is toxic, causing hypertension (58) and diabetes (59) when injected into rats. Moreover, ascorbic acid has recently been shown to become mutagenic in the presence of traces of copper (60). It is therefore essential that ascorbic acid should be formulated with one of the "capillary active" bioflavonoids, such as rutin, quercetin or catechin, which act as indirect antioxidants for ascorbic acid by virtue of chelating heavy metal catalysts (61). CONCLUSION It is therefore proposed that a large controlled study should be conducted to find out whether the inclusion of 200 mg of ascorbic acid and 200 mg of rutin in each combined oral contraceptive pill will prevent the development of the cardiovascular problems. REFERENCES 1.
Inman WHW, Vessey MP. Investigation of deaths from pulmonary, coronary, and cerebral thrombosis and embolism in women of child-bearing age. British Medical Journal 1:193, 1968.
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Vessey MP, Doll R. Investigation of relation between use of oral contraceptives and thromboembolic disease. British Medical Journal 1:199, 1968.
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Sartwell PE, Masi AT, Arthes FG, Greene GR, Smith HE. Thromboembolism and oral contraceptives: an epidemiologic case-control study. American Journal of Epidemiology 90:365, 1969.
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Markush RE, Seigel DG. Oral contraceptives and mortality trends from thromboembolism in the United States. American Journal of Public Health 59:418, 1969.
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Mann JI, Inman WHW. Oral contraceptives and death from myocardial infarction. British Medical Journal 2:245, 1975.
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Mann JI, Vessey MP, Thorogood M, Doll R. Myocardial infarction in young women with special reference to oral contraceptive practise. British Medical Journal 2:241, 1975.
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Veterans Administration Co-operative Urological Research Group. Treatment and survival of patients with cancer of the prostate. Surgery, Gynecology and Obstetrics 124:1011, 1967.
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Quick AJ. Oral contraception and coagulability. British Medical Journal 1:1604, 1963.
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Nixon WCW. Venous thrombosis in obstetrics and gynaecology. Bulletin de la Societe Royale Belge de Gynecologie et d'obstetrique 25:321, 1955.
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Lawrence JC, Xabregas A, Gray L, Ham JM. Seasonal variation in the incidence of deep vein thrombosis. British Journal of Surgery 64:777, 1977.
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Schroeder HA. Municipal drinking water and cardiovascular death rates. Journal of the American Medical Association 195:81, 1966.
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Willis GC. An experimental study of the intimal ground substance in atherosclerosis. Canadian Medical Association Journal 69:17, 1953.
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Krebs HA. The Sheffield experiment on the vitamin C requirement of human adults. Proceedings of the Nutrition Society 12:237, 1953.
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Lind J. 1757.
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Clemetson CAB, Blair LM, Reed DH. Estrogens and capillary strength. American Journal of Obstetrics and Gynecology 83:1261, 1962.
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Clemetson CAB, Blair L, Brown AB. Capillary strength and the menstrual cycle. Annals of the New York Academy of Sciences 93:277 (Art. 7), 1962.
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Mesonyi 3. The influence of sex hormones on the vitamin C content of the adrenals and liver of the guinea pig. Hoppe-Seyler's Zeitschrift fur Physiologische Chemie 242:158, 1936.
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di Martini E, Marrubini G, Silo N. Action of ovarian hormones on the ascorbic acid content of the adrenals, liver and uterus. Archivio di Fisiologia 50:94, 1950.
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Saroja N, Mallikarjuneswara VR, Clemetson CAB. Effect of estrogens on ascorbic acid in the plasma and blood vessels of guinea pigs.
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Selkurt EE, Talbot LJ, Houck CR. The effect of the administration of estrogen on the mechanism of ascorbic acid excretion in the dog. American Journal of Physiology 140:260, 1943.
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Humoller FL, Mockler MP, Holthaus JM, Mahler DJ. Enzymatic Journal of Laboratory and Clinical properties of ceruloplasmin. Medicine 56:222, 1960.
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Osaki S, McDermott JA, Frieden E. dase activity of ceruloplasmin. 239:3570, 1964.
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Johnson NC, Kheim T, Kountz WB. Influence of sex hormones on total serum copper. Proceedings of the Society for Experimental Biology and Medicine 102:98, 1959.
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Kalesh DG, Mallikarjuneswara VR, Clemetson CAB. Effect of estrogen-containing oral contraceptives on platelet and plasma ascorbic acid concentrations. Contraception 4:183, 1971.
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Briggs M, Briggs M. Vitamin C requirements Nature 238:277, 1972.
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Rivers JM, Devine MM. oral contraceptives. 25:684, 1972.
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Johnson NC. Study of copper and zinc metabolism during pregnancy. Proceedings of the Society for Experimental Biology and Medicine 108:518, 1961.
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De Jorge FB, Delascio D, Antunes ML. Copper and copper oxidase concentrations in the blood serum of normal pregnant women. Obstetrics and Gynecology 26:225, 1965.
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O'Leary JA, Novalis GS, Vosburgh GJ. in normal and abnormal gestations. 28:112, 1966.
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Raiha N. On the placental transfer of vitamin C. Scandinavica 45:l (Supplementurn 155), 1958.
35.
Darby WJ, McGanity WJ, Martin MP, Bridgforth E, Densen PM, Kaser MM, Ogle PJ, Newbill JA, Stockell A, Ferguson ME, Touster 0, McClellan GS, Williams C, Cannon RO. The Vanderbilt cooperative Journal of Nutrition study of maternal and infant nutrition. 51:565, 1953.
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Javert CT. Decidual bleeding in pre nancy. Annals of the New York Academy of Sciences 61:700 (Art. 33 , 1955.
37.
Brook M, Grimshaw JJ. Vitamin C concentration of plasma and leukocytes as related to smoking habit, age and sex of humans. American Journal of Clinical Nutrition 21:1254, 1968.
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and oral contraceptives.
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Denson KW, Bowers EF. The determination of ascorbic acid in white blood cells. A comparison of w.b.c. ascorbic acid and phenolic acid excretion in elderly patients. Clinical Science 21:157, 1961.
39.
Pelletier 0. Vitamin C and cigarette smokers. New York Academy of Sciences 258:156, 1975
40.
Calder JH, Curtis RC, Fore H. Comparison of vitamin C in plasma Lancet 1:556, 1963. and leukocytes of smokers and non-smokers.
41.
Roe JH, Kuether CA. The determination of ascorbic acid in whole blood and urine through the 2, 4,-dinitrophenylhydrazine derivative of dehydroascorbic acid. Journal of Biological Chemistry 147:399, 1943.
42.
Lahey ME, Gubler CJ, Cartwright GE, Wintrobe MM. Studies on copVII Blood copper in pregnancy and various pathoper metabolism. logic states. Journal of Clinical Investigation 32:329, 1953.
43.
Goldsmith GA. Human requirements for vitamin C and its use in clinical medicine. Annals of the New York Academy of Sciences 92:230 (Art. I), 1961.
44.
Sayers MA, Sayers G, Woodbury LA, The assay of adrenocorticotropic hormone by the adrenal ascorbic acid depletion method. Endocrinology 42:379, 1948.
45.
Perry MO. Care of the Trauma Patient. Book Company, 1966.
46.
Kellie AE, Zilva SS. The catalytic oxidation of ascorbic acid. Biochemical Journal 29:1028, 1935.
47.
Crandon JH, Lennihan R, Mikal S, Reif AE. Ascorbic acid economy Annals of the New York Academy of Sciences in surgical patients. 92:246 (Art. l), 1961.
48.
Mystkowski EM. The oxidation of ascorbic acid in the presence Biochemical Journal 36:494, 1942. of copper.
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Dunnigan MG, Harland WA. Seasonal incidence and mortality of Lancet 2:793, 1970. ischaemic heart disease.
50.
Roine P, Koivula L, Pekkarinen M, Rissanen A. Vitamin C intake International and plasma level among aged people in Finland. Journal for Vitamin and Nutrition Research 44:95, 1974.
51.
Schorah CJ, Zemroch PJ, Sheppard S, Smithells RW. Leukocyte ascorBritish Journal of Nutrition 39:139, bic acid and pregnancy. 1978.
52.
Vitamin C intakes in Great Britain. Editorial. 27:139, 1969.
53.
Spittle CR. 1970.
54.
Follis RH. Sudden death in infants with scurvy. Pediatrics 20:347, 1942.
Vitamin C and myocardial
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Shafar J. Rapid reversion of electrccardiographic abnormalities after treatment in two cases of scurvy. Lancet 2:176, 1967.
56.
Hume R, Weyers E, Rowan T, Reid DS, Hillis WS. Leukocyte asccirbic British Heart acid levels after acute myocardial infarction. Journal 34:238, 1972.
57.
Boyd W. A Textbook of Pathology, London, 1938.
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Patterson JW, Mastin DW. Some effects of dehydroascorbic acid on the central nervous system. American Journal of Physiology 167:119, 1951.
59.
Patterson JW. The diabetogenic effects of dehydroascorbic and dehydroisoascorbic acids. Journal of Biological Chemistry 183:81, 1950.
60.
Stich HF, Karim J, Koropatnick J, Lo L. bic acid. Nature 260:722, 1976.
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Clemetson CAB, Andersen L. Plant polyphenols as antioxidants for ascorbic acid. Annals of the New York Academy of Sciences 136:339 (Art. 14), 1966.
a34
3rd ed. p. 438.
Henry
KimptGn,
Mutagenic action of ascor-
5:825-34,
1979
SOME THOUGHTS 0~ THE EPIDEMIOLOGY OF CARDIOVASCULAR DISEASE, (WITH SPECIAL REFERENCE TO WOMEN "ON THE PILL"),ROLE OF ASCORBIC ACID C.A.B. Clemetson. The Methodist Hospital, 506 Sixth St., Brooklyn, N.Y. 11215, U.S.A. ABSTRACT Consideration of nine major factors predisposing to cerebral thrombosis, coronary thrombosis or thrombosis in the deep veins of the calf, reveals that these factors all have one thing in common. Estrogen administration, pregnancy, ageing, smoking,infection, trauma, surgery, soft water and winter season are all associated with a tendency towards decreased plasma ascorbic acid levels. Normally, ascorbic acid deficiency is thought of as causing a tendency towards hemorrhage rather than thrombosis, but it is here suggested that petechial hemorrhages under the endothelium of the blood vessels may precipitate thrombosis on the damaged endothelium. Is not blood coagulation the normal mechanism for the arrest of hemorrhage? Key Words:
ascorbic acid, cerebral thrombosis, contraceptives oral, estrogens, myocardial infarct, thromboembolism, vascular disease, water supply. INTRODUCTION
It has been known for some years that use of the combined estrogen-progestagen oral contraceptive pills is associated with an increased morbidity and mortality from thromboembolic disease (1,2,3,4). Other studies have shown that the use of these pills is associated with a significantly increased death rate from a wide range of vascular conditions, including acute myocardial infarction and cerebral thrombosis or hemorrhage (5,6,7). The excess mortality is reported as increasing with age, cigarette smoking and duration of oral contraceptive use. A large well controlled prospective study of high dosage diethylstilbestrol (5 mg daily) versus placebo in the treatment of men with carcinoma of the prostate (8) has also shown an increased death rate from heart disease and cerebrovascular accidents, which outweighed the benefits 05-a decreased death rate from prostatic cancer. These findings and other data have led to a general agreement that it is the estrogenic component of the birth control pills that causes the vascular problems and has resulted in the use of lower and lower doses of estrogen in the combined birth control pills in recent years. The mechanism by which estrogens predispose to thromboembolism is not known; several hematological changes have been reported in women taking the oral contraceptive pills, but it is dif825
ficult to assess the significance of these changes. Enhanced blood coagulability, increased blood viscosity, reduced blood cell filtrability, enhanced platelet adhesiveness and aggregation, a rise in clotting factors VII and X, an enhancement of fibrinolytic activity, a fall in antithrombin III activity and a low content of plasminogen activator in the walls of the veins were all discussed by Girdwood (9) when he rev ewed this subject in 1976, but no definite conclusions have been reached. Some authors have reported a slight reduction in the coagulation time of the blood of women "on the pill", as measured by the "Partial Thromboplastin Time" (P.T.T.) (10). However, it does not necessarily matter if the P.T.T. is reduced, just so long as the blood does not start to clot. The question is "What causes the coagulation mechanism to be initiated?" and not "How long does it take the blood to clot?". So we must look for changes in the endothelium or inner lining of the blood vessels, as first suggested by Armand J. Quick (11); we are particularly interested to know what deleterious Also, we need to effects estrogens may have on the endothelium. know whether other factors which increase the risk of death from cardiovascular disease could act by damaging the endothelium. We know that pregnancy predisposes to deep vein thrombosis and embolism; this condition is also well recognized as occurring after infection, trauma or surgery (12). There is evidence that the incidence of deep vein thrombosis is higher in the cold half of the year (13). There is also evidence that deaths from all forms of cardiovascular disease are higher in soft water areas than in hard water areas (14). HYPOTHESIS Could there be anything in common between the nine seemingly unrelated factors, namely estrogen ingestion, pregnancy, ageing, smoking, infection, trauma, surgery, soft water and winter season, all of which seem to predispose to cardiovascular disease and thrombosis? Strangely enough, there is one thing that all these factors They all can or do decrease the ascorbic acid concenhave in common. tration in the blood. This is particularly important because ascorbic acid is essential for the health and integrity of the vascular endothelium.
It is generally believed that low levels of ascorbic acid in the blood are of little consequence and that no problem arises until all ascorbic acid has disappeared, when frank scurvy becomes evident; however, there are reasons for believing that this is not true; ascorbic acid deficiency has been shown to predispose to atherosclerosis (15); moreover, serious vascular accidents may suddenly occur as a result of ascorbic acid deficiency in subjects who appeared to be perfectly healthy (16); sudden deaths occur long before the development of scurvy (17); the evidence for these statements will be discussed later in this paper. 826
Ascorbic acid deficiency is normally considered as a cause of hemorrhage rather than thrombosis; however, clotting is the normal mechanism for the arrest of hemorrhage, so small subendothelial hemorrhages could well be the precipitating cause of thrombosis. now be considered.
Each of the nine epidemiological factors will
1. Estrogens. It is paradoxical that, on the one hand, women, losing their ovarian function, become more prone to coronary heart disease and, on the other hand, estrogen administration increases the risk of this disease. Some authors have suggested that the reason for this is that natural estrogens are beneficial and synthetic ones are harmful to the blood vessels; however, it seems far more likely that estrogens are like all other hormones, being harmful in deficiency or excess and being beneficial in correct replacement dosage. Small amounts of estrogen may be considered as having a direct beneficial effect on the blood vessels, for they increase the capillary strength of menopausal women (18,19). The harmful effect of estrogens on the blood vessels is almost certainly due to the high potency and/or dosage of the estrogens used in oral contraceptive pills kvhichis necessary to inhibit ovulation. This harm may well be an indirect effect, for estrogen is known to reduce the ascorbic acid content of the blood in guinea pigs and in rats (20,21,22 there is evidence that this may in part be due to decreased tubular reabsorption of ascorbic acid (23), but it may also be due to the marked increase in the plasma concentration of the copper protein ceruloplasmin, which is an ascorbate oxidase (24,25). Plasma total copper and ceruloplasmin levels are markedly increased in women taking estrogens or estrogen-containing oral contraceptive pills (26,27). The plasma and platelet ascorbic acid levels of women "on the pill" are correspondingly decreased (28,29,30). y The estrogens of pregnancy have a similar 9 effect in fncr~~~i~~":he copper content of the blood plasma (31,32,33). Presumably this high blood copper or ceruloplasmin level and other factors, such as the active transfer of ascorbic acid from mother to fetus (34), account for the progressive fall in the plasma ascorbic acid level during pregnancy (35,36). Several workers have shown that the plasma and 3. A ein white blood ccl p9' ascorbic acid levels decrease progressively with increasing age (37,38). causes levels in the method
4. Smoking_. It is well established that cigarette smoking a reduction in both the plasma and the leukocyte ascorbic acid (37,39,40). This may be a direct effect of the carbon particles lung, for powdered charcoal is used in a standard analytical for oxidizing ascorbic acid to its dehydro-form (41). 827
5. Infection. Both acute and chronic infectious diseases cause an increase in the ceruloplasmin concentration of the blood (42); this may account for the decreased ascorbic acid levels observed following infection (43). 6. Trauma. Various forms of stress have been shown to reduce the adr?%%il%corbic acid level. This is almost certainly a direct effect of ACTH. However, there is also a general effect of trauma on ascorbic acid metabolism (45), which may be related to the fact that hemolysis rapidly destroys ascorbic acid -in vitro (46). 7. Surgery. Decreased plasma ascorbic acid levels have been observed following surgery (47). This may in part be due to leukocytic transport of ascorbic acid to the area of the wound where it is needed for healing. 8. Soft water. It has been found that death rates for all forms of cardiovascular disease are higher in soft water areas than in hard water areas throughout the United States, the United Kingdom and Japan where it has been studied (14). The cause of this problem is not known, as no offending substance has been isolated from the water in the soft water reservoirs. However, in soft water areas, the first water drawn from copper pipes in the morning may contain up to two parts per million of copper and the cupric ion is a potent catalyst for the oxidation of ascorbic acid and may destroy ascorbic acid before it can be absorbed from the lumen of the jejunum (48). In hard water areas, this problem does not arise because the water pipes are coated by an inner lining of "fur". 9. Not only does deep vein thrombosis occur Winter season. more commonly during the cold half of the year (13), it has also been shown that ischemic heart disease occurs more frequently in the winter (49). These findings may be related to the seasonal variations of plasma (50) and leukocyte (51) ascorbic acid levels, presumably due to a lower vitamin C intake in winter, as reported in Great Britain (52). Indeed, a correlation between a low ascorbic acid consumption and a high incidence of myocardial infarction in winter has previously been suggested by Spittle (53). Thus, the nine main factors predisposing to deep vein thrombosis and other cardiovascular diseases, all can or do decrease the ascorbic acid level of the blood. But the reader will say that this is irrelevant unless it can be shown that ascorbic acid deficiency predisposes to cardiovascular disease in humans. We rarely see scurvy nowadays but it has been produced experimentally by Krebs (16), who studied ten healthy volunteers, aged twenty-one to thirty-four years, on a vitamin C free diet. I quote from his report.
828
"Some important abnormalities were observed in single cases. One man developed effusions into both knee joints and ecchymoses of the leg during the 30th week of deprivation after a long walk, Another was taken ill 4 weeks later, 19 h after heavy physical exercise. He had severe pain in the lower sternal region, and became dyspnoeic and cyanosed. The pulse was rapid and the blood pressure low. The clinical picture was that of an acute cardiac emergency. He was immediately admitted to hospital and dosed with vitamin C. The lower sternal pain, which at first had increased in intensity, passed off after 9 h. The electrocardiogram showed high ST levels in leads I and II. A radiogram of the chest showed no abnormality. Eighteen days later another deprived volunteer complained of a sudden constrictive pain in the chest. Physical examination revealed a systolic murmur which had not been heard before, and the electrocardiogram showed a partial heart-block, the P-R interval being 0.32 sec. Before the experiment the electrocardiogram had been normal with a P-R interval of 0.20 sec. It was thought necessary to treat this volunteer immediately with large doses of vitamin C. The chest pain and the systolic murmur disappeared within 24 h, but during the following months the P-R interval showed variable periods between 0.13 and 0.32 sec. depending on posture, breathing, administration of drugs, and other factors." The older records of scurvy contain many references to sudden death. James Lind (17), in 1753, wrote: "Persons that appear to be but slightly scorbutic, are apt to be suddenly and unexpectedly seized with some of its worse symptoms. Their dropping down dead upon an exertion of their strength, or change of air, is not easily foretold.". These incidents occur at a stage when occasional skin petechiae are the main clinical manifestation of scurvy and general fitness still appears to be fairly good. We can only conjecture as to whether it is a subendothelial hemorrhage or a hemorrhage followed by thrombosis in one of the coronary arteries that caused these heart attacks. Moreover, we may wonder whether thromboembolism may not have occurred in some of those who suddenly "dropped down dead". Follis, in 1942, reported sudden deaths in three infants with scurvy and concluded, on autopsy, that they died of heart failure (54). Shafar (55) reports rapid reversion of electrocardiographic changes, like those of myocardial infarction, after treatment in two cases of scurvy. One wonders what would have happened 829
to these patients if they had not been diagnosed as scurvy and treated with ascorbic acid, for Hume et al (56) report a further fall in leukocyte ascorbic acid to scorbutic levels after myocardial infarction. Perhaps the most significant experiment of all is that of Willis (15) who showed that ascorbic acid deficiency causes atherosclerosis in guinea pigs within fifteen days even at normal blood cholesterol levels. It seems that cholesterol is deposited under the endothelium when it has been damaged by the petechial hemorrhages of scurvy. Thus, we may think of atherosclerosis as an aberrant form of wound healing in blood vessels. In this context, it is interesting to note that Boyd (57), in his "Textbook of Pathology", observed atherosclerosis even in young persons who died following one of the acute infectious fevers. While L-ascorbic acid is essential as a vitamin and has only beneficial effects, it is unstable in aqueous solutions and is readily oxidized in the presence of traces of copper to form dehydroascorbic acid which is toxic, causing hypertension (58) and diabetes (59) when injected into rats. Moreover, ascorbic acid has recently been shown to become mutagenic in the presence of traces of copper (60). It is therefore essential that ascorbic acid should be formulated with one of the "capillary active" bioflavonoids, such as rutin, quercetin or catechin, which act as indirect antioxidants for ascorbic acid by virtue of chelating heavy metal catalysts (61). CONCLUSION It is therefore proposed that a large controlled study should be conducted to find out whether the inclusion of 200 mg of ascorbic acid and 200 mg of rutin in each combined oral contraceptive pill will prevent the development of the cardiovascular problems. REFERENCES 1.
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