Sundt og sikkert

25. oktober 2007

Når det hævdes, at der mangler videnskabelig dokumentation om kosttilskud, vitaminer og mineraler, så er det måske værd at bemærke, at der findes over 480.000 offentliggjorte og videnskabeligt godkendte forskningsforsøg over kosttilskud eller indholdsstoffer brugt i kosttilskud, og størstedelen af disse har vist positiv virkning.

Der findes kun en lille håndfuld forsøg, der har vist negativ virkning, og disse kan generelt forbindes med høje doser eller syntetiske ingredienser som A-vitamin, betacaroten og E-vitamin.

Angående A-vitamin, er der ingen tvivl om, at meget høje doser af dette fedtopløselige vitamin kan være skadeligt og at en øvre grænse for indtagelse af dette vitamin er på sin plads.

Der findes 3 forsøg, som viser negativ effekt af betacaroten givet til syge patienter i højrisiko-grupper, men disse har alle benyttet syntetisk betacaroten, og ikke det kompleks af naturlige carotenoider, som findes i frugt og grøntsager, og som er potente cancerbekæmpende næringsstoffer. Ironisk nok vil disse ”naturlige carotenoider” blive forbudt af EUs Kosttilskudsdirektiv.

Endelig findes der fire negative forsøg vedrørende E-vitamin. Alle er udført med syntetisk E-vitamin, som kun omfatter et ud af de otte E-vitaminformer, der findes i naturen, og endda ændret i sin molekylestruktur til en såkaldt esterificeret form. Denne form for E-vitamin kaldes alfa-tocoferol, og er det eneste E-vitamin som EUs Kosttilskudsdirektiv tillader. Men denne form for E-vitamin nedsætter kroppens optagelse af gamma-tocoferol, som er en nøgle-antioxidantform af E-vitamin, som findes i fødekilder.

Dette er kun to af mange eksempler på, at EU kosttilskudsdirektiv derfor ikke vil kunne gavne borgerne i EU, men endda risikere at skade os.


Dr. Robert Verkerk, Alliance for Natural Health, Storbritannien.

(Redigeret af Claus Hancke)

E-vitamin eller falsk varebetegnelse

12. november 2004

Beregninger over gamle forsøg fører til påstand om øget dødelighed af antioxidanter og E-vitamin, men bygger i virkeligheden på forsøg med betakaroten.

For nylig publicerede forskere en undersøgelse om betakaroten, men kaldte det antioxidanter. Nu er der en ny undersøgelse af betakaroten, men denne gang kaldes det E-vitamin. Begge studier er såkaldte metaanalyser, dvs. beregninger over tidligere forskning.

De to studier hævder at vise, at hhv. antioxidanter og E-vitamin forøger dødeligheden, men de bygger faktisk begge på resultater af gamle forsøg med betakaroten. Siden 1994 har man vidst, at betakaroten kan medføre kræft og forhøjer dødeligheden hos i hvert fald mandlige rygere.

Den seneste metaanalyse stammer fra Johns Hopkins universitetet i USA. Her har man undersøgt dødeligheden i sammenlagt 19 gamle behandlingsforsøg med E-vitamin. Tilsyneladende forhøjede doser på over 400 enheder om dagen dødeligheden en smule, selv om den dog var nedsat i det forsøg, hvor dosis var højest (2.000 enh./dag). Der var 11 forsøg, hvor man brugte mere end 400 enheder om dagen. Ved lavere dosis var der tendens til nedsat dødelighed.

Af de 11 forsøg er det såkaldte Heart Protection Study (HPS) fra 2000 imidlertid langt det største. Faktisk så stort, at det helt dominerer udregningen. I HPS døde næsten dobbelt så mange som i alle de øvrige 10 forsøg tilsammen – og mere end fire gange så mange som i de øvrige forsøg med øget dødelighed. Problemet ved dette er, at i HPS bestod behandlingen foruden af E-vitamin af C-vitamin og betakaroten!

Man kan selvsagt ikke udtale sig om risikoen ved E-vitamin ud fra et forsøg, hvor man har brugt både E- og C-vitamin samt betakaroten. Man kan kun udtale sig om E- og C-vitamin samt betakaroten!

I det pågældende forsøg (HPS) brugte man i øvrigt syntetisk E-vitamin. Det består af otte forskellige kemiske forbindelser, hvoraf kun én findes i naturen. Det gør det jo endnu sværere at udtale sig om E-vitamin, som de fleste køber i naturlig form.

Man kan indvende meget andet mod den nye metaanalyse. Hvis man f.eks. arrangerer tallene bare en smule anderledes, men stadig rimeligt, forsvinder overdødeligheden helt. Det sker, hvis man ser bort fra den vildledende HPS-undersøgelse og medregner forsøg, der bruger over 300 enheder i stedet for kun over 400. Det ville være absolut plausibelt.

Dette og meget andet kan være grunden til, at flere uafhængige statistikere over for New York Times erklærede, at de ikke troede på konklusionen.

Man kan diskutere, om der er et reelt behov for disse undertiden vilkårlige opkog af gamle forsøg, som let fører til mistolkninger. Langt større er behovet for store undersøgelser af, om f.eks. en kombination af naturligt E- og C-vitamin forebygger åreforkalkning hos mennesker, der ikke er overvældende åreforkalkede i forvejen. Det er her, man kan forvente effekt, men disse forsøg er ikke foretaget.

Salget af E-vitamin er stigende i USA, hvor navnlig mange læger tager det. Kombinationen af E- og C-vitamin ses bl.a. som en konkurrent til de umådeligt dyre, men næsten uvirksomme, receptmidler mod Alzheimer. Ifølge en rapport tidligere i år – i øvrigt også fra Johns Hopkins – har brugere af begge disse vitaminer ca. 80 % nedsat risiko for at få Alzheimer – sammenlignet med dem, der kun får et af dem eller slet ingen.

Senest har desuden nobelpristageren Louis Ignarro på baggrund af egne forsøg kraftigt anbefalet samme kombination som forebyggelse mod åreforkalkning.
Vitalrådet.


Referencer:

1) Metaanalysis: High-dosage vitamin E supplementation may increase all-cause mortality. Ann Int Med 2004;142.
2) Bjelakowic G, Nikolova D, Simonetti R G, Gluud C. Antioxidant supplements for prevention of gastrointestinal cancers: a systematic review and meta-analysis. The Lancet 2004;364:1219-28.
3) Ignarro L J et al. “Long Term Beneficial Effects of Physical Training and Metabolic Treatment on Atherosclerosis in Hypercholesterolemic Mice. PNAS 2004 (May 24).
4) Zandi PP et al. Reduced risk of Alzheimer disaease in users of antioxidant vitamin supplements. Arch Neurol 2004;61:82-88.
5) Gina Kolata: Large Doses of Vitamin E May Be Harmful. New York Times 11.11.04.

www.annals.org
www.lancet.com
www.pnas.org
archneur.ama-assn.org
www.nytimes.com

A-vitamin og betacaroten forskningsreferencer

Januar 1999

1. Band P.R. et al. Treatment of Benign Breast Disease with Vitamin A. Prev Med 549-54, 1984.
2. Bendich A. Symposium conclusions: Biological actions of carotenoids. J Nutr 119: 112-5, 1989.
3. Bichler KH et al. Influence of vitamin A deficiency on the excretion of uromucoid and other substances in the urine of rats. Clin Nephrol 20:32-9, 1983.
4. Branowitz SA, Starrett B, Brookner AR. Carotene deficiency in HIV patients. AIDS 10; (1):115, 1996.
5. Burton GW, Ingold KU. Beta-carotene. An unusual type of lipid antioxidant. Scicnce 224: 569-573, 1984.
6. Cheraskin E, Ringsdorf WM, Medford FH. The ‘ideal’ daily vitamin A intake. Int J Vit Nutr Res 46: 11-13, 1976.
7. Chole Q. Vitamin A in the cochlea. Arch Otorhinolaryngol 124:379-82, 1978.
8. Comstock GW et al. Serum concentrations of alpha-tocopherol, beta-carotene, and retinol preceding the diagnosis of rheumatoid arthritis and systemic lupus erythematosus. Ann Rheum Dis 56: 323-5, 1997.
9. Connett JE, Kuller KH, Kjelsberg MO et al. Relationship between carotenoids and cancer. Cancer 64: 126-134, 1989.
10. Coutsoudis A, Bobat R, Coovadia H. The effects of vitamin-A supplementation on the morbidity of children born to HIV-infected women. Am J Public Health 85; (8):1076-81, 1995.
11. Delmas-Beauvieux M-C, Peuchant E, Couchouron A, et al. The enzymatic antioxidant system in blood and glutathione status in human immunodeficiency virus (HIV)-infected patients: Effects of supplementation with selenium or carotene. Am J Clin Nutr 64: 101-7, 1996.
12. DiMascio P, Murphy ME, Sies H. Antioxidant defense systems the role of carotenoids, tocopherols and thiols. Am J Clin Nutr 53: 194S-200S, 1991.
13. Eldred GE. Vitamins A and E in RPE lipofuscin formation and implications for age-related macular degeneration. Prog Clin Biol Res 314: 113-29, 1989.
14. Ferreira R et al. Antioxidant action of vitamins A and E in patients submitted to coronary bypass surgery. Vasc Surg 25: 191-195, 1991.
15. Gaby SK, Singh VN. Vitamin intake and health: A scientific review. New York: Marcel Dekker. p 29-57, 1991.
16. Gershoff SN, McGandy RB. The effects of vitamin A-deficient diets containing lactose in producing bladder calculi and tumors in rats. Am J Clin Nutr 34: 483, 1981.
17. Goodman DS. Vitamin A and retinoids in heath and disease. N Eng J Med 310: 1023-1031, 1984.
18. Hayes KC. Retinal degeneration in monkeys induced by deficiencies of vitamin E or A. Invest Ophthalmol Vis Sci 13:7:499-510, 1974.
19. Honkanen V et al. Vitamins A and E, retinol binding protein and zinc in rheumatoid arthritis. Clin Exp Rheumatol 7: 465-9, 1989.
20. Honkanen VEA et al. Serum cholesterol and vitamins A and E in juvenile chronic arthritis. Clin Exp Rheumatol 8: 187-91, 1990.
21. Liao CH, Erdman JW, Johnston PV. Dietary vitamin A deficiency and the immune system in a murine model of systemic lupus erythematosus. Nutr Res 16: 279-92, 1996.
22. Lohle E. The influence of chronic vitamin A deficiency on human and animal ears. Arch Otorhinolaryngol 234:167-73, 1982.
23. Mckeown LA. Beta carotene lifts CD4 counts. Study reported in Medical Tribune Feb. 25, p. 1. 1993.
24. Mobarhan S, Bowen P, Andersen B et al. Effects of beta-carotene repletion on beta-carotene absorption, lipid peroxidation, and neutrophil superoxide formation in young men. Nutr Cancer 14: 195-206, 1990.
25. Newbold PCH. Beta-carotene in the treatment of discoid lupus erythematosus. Br J Dermatol 95: 100-1, 1976.
26. Olson JA. Vitamin A. In: Present knowledge in nutrition. 7th edn. Washington DC: Intemational Life Sciences Press. p 109-119, 1996.
27. Oson JA. Provitamin A function of carotenoids. Thc conversion of B-carotene to Vitamin A. J Nutr 119: 105-108, 1989.
28. Paganini-Hill A, Chao A, Ross RK et al. Vitamin A, beta carotene and the risk of cancer. A prospective study. J Natl Cancer Inst 79: 443-448, 1987.
29. Palgi A. Association between dietary changes and morality rates; Israel 1949 to 1977; a trend-free regression model. Am J Clin Nutr 34: 1569-1583, 1981.
30. Prince MR, Frisoli JK. Beta-carotene accumulation in serum and skin. Am J Clin Nutr 1993; 57: 175-181, 1993.
31. Pryor WA. The antioxidant nutrients and disease prevention what do we know and what do we need to find out? Am J Clin Nutr 53: 391S-393S, 1991.
32. Riemersma RA, Wood DA, MacIntyre CCH, et al. Risk of angina pectoris and plasma concentrations of vitamins A, C and E and carotene. Lancet 337:1-5, 1991.
33. Romeo G. The therapeutic effect of vitamins A and E in neurosensory hearing loss. Acta Vitaminol Enzymol 7 Suppl:85-92, 1985.
34. Sahyoun NR et al. Carotenoids, vitamins C and E, and mortality in an elderly population. Am J Epidemiol 144:5:501-11, 1996.
35. Sappey C et al. Vitamin, Trace element and Peroxide status in HIV seropositive patients: Asymptomatic patients present a severe Carotene Deficiency. Clin Clim Acta 230:35-42, 1994.
36. Semba R, Graham N, Caiaffa W, et al. Increased Mortality associated with Vitamin A Deficiency during Human Immunodeficiency Virus type 1 infection. Arch Intern Med 153:2149-54, 1993.
37. Semba RD, Park S, Royal W, Griffin DE. Vitamin A deficiency and T-cell subpopulation in HIV-infected adults. Nutr Res 16:915-23, 1996.
38. Sommer A., West, KP. The duration of the effect of vitamin A supplementation. Am J Public Health 1997; 87: 467, 1997.
39. Salonen JT. Risk of cancer in relation to serum concentrations of selenium and vitamins A and E: matched case-control analysis of prospective data. Br Mcd J 1985, 290: 417-420, 1985.
40. Schauss AG. Beta-carotene and the incidence of lung cancer in Finnish male smokers. A critique. Q Rev Natural Med 191-195, 1994.
41. Seddon JM, Ajani UA, Sperduto RD, et al. Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. JAMA 272:1413-20, 1994.
42. Stahelin HB, Gey KB, Eichholzer M et al. Beta-carotene and cancer prevention. The Basel Study. Am J Clin Nutr 53: 265S-269S, 1991.
43. Street DA et al. Serum antioxidants and myocardial infarction: Are low levels of carotenoids and alpha-tocopherol risk factors for myocardial infarction? Circulation 90;3:1154-61, 1994.
44. Tang AM et al. Association between Serum Vitamin A and E levels and HIV-1 disease progression. AIDS 11:613-20, 1997.
45. Underwood BA. Was the ‘anti-infective’ vitamin misnamed? Nutr Rev 52: 140-143, 1994.
46. Vitale S et al. Plasma vitamin C, E and beta carotene levels and risk of cataract. Invest Ophthalmol Vis Sci 32:723, 1991.
47. Weisburger J. Nutritional approach to cancer prevention with emphasis on vitamins, antioxidants, and carotenoids. Am J Clin Nutr 53: S226-237, 1991.
48. Weisberger JH. Nutritional approach to cancer prevention with emphasis on vitamins, antioxidants, and carotenoids. Am J Clin Nutr 1995; 53: 226s.
49. Werler MA, Lammer EJ, Mitchell AA. Teratogenicity of high vitamin A intake. Letter. N Eng J Med 334: 1195, 1995.
50. White WS, Kim Cl, Kalkwarf HJ et al. Ultraviolet light-induced reduction in plasma carotenoid levels. Am J Clin Nutr 47: 879-883, 1988.
51. Willette W. Nutritional epidemiology. New York: Oxford University Press. p 292-310, 1990.
52. Ziegler RG. Vegetables, fruits and carotenoids and the risk of cancer. Am J Clin Nutr 53: 251S-259S, 1991.
Kilder
Joseph E. Pizzorno Jr., Michael T. Murrey & Melvyn R. Werbach.
1. Band P.R. et al. Treatment of Benign Breast Disease with Vitamin A. Prev Med 549-54, 1984.
2. Bendich A. Symposium conclusions: Biological actions of carotenoids. J Nutr 119: 112-5, 1989.
3. Bichler KH et al. Influence of vitamin A deficiency on the excretion of uromucoid and other substances in the urine of rats. Clin Nephrol 20:32-9, 1983.
4. Branowitz SA, Starrett B, Brookner AR. Carotene deficiency in HIV patients. AIDS 10; (1):115, 1996.
5. Burton GW, Ingold KU. Beta-carotene. An unusual type of lipid antioxidant. Scicnce 224: 569-573, 1984.
6. Cheraskin E, Ringsdorf WM, Medford FH. The ‘ideal’ daily vitamin A intake. Int J Vit Nutr Res 46: 11-13, 1976.
7. Chole Q. Vitamin A in the cochlea. Arch Otorhinolaryngol 124:379-82, 1978.
8. Comstock GW et al. Serum concentrations of alpha-tocopherol, beta-carotene, and retinol preceding the diagnosis of rheumatoid arthritis and systemic lupus erythematosus. Ann Rheum Dis 56: 323-5, 1997.
9. Connett JE, Kuller KH, Kjelsberg MO et al. Relationship between carotenoids and cancer. Cancer 64: 126-134, 1989.
10. Coutsoudis A, Bobat R, Coovadia H. The effects of vitamin-A supplementation on the morbidity of children born to HIV-infected women. Am J Public Health 85; (8):1076-81, 1995.
11. Delmas-Beauvieux M-C, Peuchant E, Couchouron A, et al. The enzymatic antioxidant system in blood and glutathione status in human immunodeficiency virus (HIV)-infected patients: Effects of supplementation with selenium or carotene. Am J Clin Nutr 64: 101-7, 1996.
12. DiMascio P, Murphy ME, Sies H. Antioxidant defense systems the role of carotenoids, tocopherols and thiols. Am J Clin Nutr 53: 194S-200S, 1991.
13. Eldred GE. Vitamins A and E in RPE lipofuscin formation and implications for age-related macular degeneration. Prog Clin Biol Res 314: 113-29, 1989.
14. Ferreira R et al. Antioxidant action of vitamins A and E in patients submitted to coronary bypass surgery. Vasc Surg 25: 191-195, 1991.
15. Gaby SK, Singh VN. Vitamin intake and health: A scientific review. New York: Marcel Dekker. p 29-57, 1991.
16. Gershoff SN, McGandy RB. The effects of vitamin A-deficient diets containing lactose in producing bladder calculi and tumors in rats. Am J Clin Nutr 34: 483, 1981.
17. Goodman DS. Vitamin A and retinoids in heath and disease. N Eng J Med 310: 1023-1031, 1984.
18. Hayes KC. Retinal degeneration in monkeys induced by deficiencies of vitamin E or A. Invest Ophthalmol Vis Sci 13:7:499-510, 1974.
19. Honkanen V et al. Vitamins A and E, retinol binding protein and zinc in rheumatoid arthritis. Clin Exp Rheumatol 7: 465-9, 1989.
20. Honkanen VEA et al. Serum cholesterol and vitamins A and E in juvenile chronic arthritis. Clin Exp Rheumatol 8: 187-91, 1990.
21. Liao CH, Erdman JW, Johnston PV. Dietary vitamin A deficiency and the immune system in a murine model of systemic lupus erythematosus. Nutr Res 16: 279-92, 1996.
22. Lohle E. The influence of chronic vitamin A deficiency on human and animal ears. Arch Otorhinolaryngol 234:167-73, 1982.
23. Mckeown LA. Beta carotene lifts CD4 counts. Study reported in Medical Tribune Feb. 25, p. 1. 1993.
24. Mobarhan S, Bowen P, Andersen B et al. Effects of beta-carotene repletion on beta-carotene absorption, lipid peroxidation, and neutrophil superoxide formation in young men. Nutr Cancer 14: 195-206, 1990.
25. Newbold PCH. Beta-carotene in the treatment of discoid lupus erythematosus. Br J Dermatol 95: 100-1, 1976.
26. Olson JA. Vitamin A. In: Present knowledge in nutrition. 7th edn. Washington DC: Intemational Life Sciences Press. p 109-119, 1996.
27. Oson JA. Provitamin A function of carotenoids. Thc conversion of B-carotene to Vitamin A. J Nutr 119: 105-108, 1989.
28. Paganini-Hill A, Chao A, Ross RK et al. Vitamin A, beta carotene and the risk of cancer. A prospective study. J Natl Cancer Inst 79: 443-448, 1987.
29. Palgi A. Association between dietary changes and morality rates; Israel 1949 to 1977; a trend-free regression model. Am J Clin Nutr 34: 1569-1583, 1981.
30. Prince MR, Frisoli JK. Beta-carotene accumulation in serum and skin. Am J Clin Nutr 1993; 57: 175-181, 1993.
31. Pryor WA. The antioxidant nutrients and disease prevention what do we know and what do we need to find out? Am J Clin Nutr 53: 391S-393S, 1991.
32. Riemersma RA, Wood DA, MacIntyre CCH, et al. Risk of angina pectoris and plasma concentrations of vitamins A, C and E and carotene. Lancet 337:1-5, 1991.
33. Romeo G. The therapeutic effect of vitamins A and E in neurosensory hearing loss. Acta Vitaminol Enzymol 7 Suppl:85-92, 1985.
34. Sahyoun NR et al. Carotenoids, vitamins C and E, and mortality in an elderly population. Am J Epidemiol 144:5:501-11, 1996.
35. Sappey C et al. Vitamin, Trace element and Peroxide status in HIV seropositive patients: Asymptomatic patients present a severe Carotene Deficiency. Clin Clim Acta 230:35-42, 1994.
36. Semba R, Graham N, Caiaffa W, et al. Increased Mortality associated with Vitamin A Deficiency during Human Immunodeficiency Virus type 1 infection. Arch Intern Med 153:2149-54, 1993.
37. Semba RD, Park S, Royal W, Griffin DE. Vitamin A deficiency and T-cell subpopulation in HIV-infected adults. Nutr Res 16:915-23, 1996.
38. Sommer A., West, KP. The duration of the effect of vitamin A supplementation. Am J Public Health 1997; 87: 467, 1997.
39. Salonen JT. Risk of cancer in relation to serum concentrations of selenium and vitamins A and E: matched case-control analysis of prospective data. Br Mcd J 1985, 290: 417-420, 1985.
40. Schauss AG. Beta-carotene and the incidence of lung cancer in Finnish male smokers. A critique. Q Rev Natural Med 191-195, 1994.
41. Seddon JM, Ajani UA, Sperduto RD, et al. Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. JAMA 272:1413-20, 1994.
42. Stahelin HB, Gey KB, Eichholzer M et al. Beta-carotene and cancer prevention. The Basel Study. Am J Clin Nutr 53: 265S-269S, 1991.
43. Street DA et al. Serum antioxidants and myocardial infarction: Are low levels of carotenoids and alpha-tocopherol risk factors for myocardial infarction? Circulation 90;3:1154-61, 1994.
44. Tang AM et al. Association between Serum Vitamin A and E levels and HIV-1 disease progression. AIDS 11:613-20, 1997.
45. Underwood BA. Was the ‘anti-infective’ vitamin misnamed? Nutr Rev 52: 140-143, 1994.
46. Vitale S et al. Plasma vitamin C, E and beta carotene levels and risk of cataract. Invest Ophthalmol Vis Sci 32:723, 1991.
47. Weisburger J. Nutritional approach to cancer prevention with emphasis on vitamins, antioxidants, and carotenoids. Am J Clin Nutr 53: S226-237, 1991.
48. Weisberger JH. Nutritional approach to cancer prevention with emphasis on vitamins, antioxidants, and carotenoids. Am J Clin Nutr 1995; 53: 226s.
49. Werler MA, Lammer EJ, Mitchell AA. Teratogenicity of high vitamin A intake. Letter. N Eng J Med 334: 1195, 1995.
50. White WS, Kim Cl, Kalkwarf HJ et al. Ultraviolet light-induced reduction in plasma carotenoid levels. Am J Clin Nutr 47: 879-883, 1988.
51. Willette W. Nutritional epidemiology. New York: Oxford University Press. p 292-310, 1990.
52. Ziegler RG. Vegetables, fruits and carotenoids and the risk of cancer. Am J Clin Nutr 53: 251S-259S, 1991.

Kilder
Joseph E. Pizzorno Jr., Michael T. Murrey & Melvyn R. Werbach.