account for many poor surgical resuits. Even in full-blown spinal stenosis, often with positive myelographic findings, 15% of patients respond quickly and completely and another 15% are sufficiently improved that an operation is no longer considered (unpublished data, 1978). However, long-term follow-up data are lacking. The contributions by chiropractors are not going unnoticed in certain orthopedic circles, although, ironically, the North American Academy of Manipulative Medicine excludes chiropractors while admitting just about everyone else. Letters such as Dr. Draper's serve no useful purpose, and the Canadian Medical Association's publication of such material helps perpetuate the dual loyalty forced on patients toward chiropractors and doctors. One of the reasons that physiotherapists across Canada are striving to gain the right to see patients without medical referral is because they know the benefits of manipulative treatment better than do doctors. I suggest that the Canadian Medical Association invite members of the chiropractic profession, especially those from Belgium and Switzerland, to write an editorial for the Journal to promote cooperation and to disseminate some very useful information for the good of all. GORDON E. POTFER, MB, BS
#222-3600 Park Ave. Montreal, PQ
References 1. KIRKALDY-WILLIS WH: Five common back disorders: how to diagnose and treat them. Geriatrics 33: 32, Dec 1978 2. KIRK.ALDY-WILLIS WH, HILL RJ: A
more precise diagnosis for low-back pain. Spine 4: 102, Mar/Apr 1979
Body iron status associated with tea consumption To the editor: Recent reports have called attention to the interference with absorption of nonheme dietary iron by tea.14 This effect has been ascribed to the formation of insoluble tannate complexes in the gut.1 It has been suggested that tea and other tannin-containing beverages contribute to the pathogenesis of iron deficiency if dietary iron consists largely of nonheme sources.
The effect of tannin on nonheme
iron absorption is greater when ascorbic acid intake is low.' Valberg and colleagues' have concluded that "if 'normality' requires more than small amounts of storage iron to meet physiologic needs, then our results have demonstrated that iron deficiency was present in 20% to 40% of native Canadian children, adolescents and nonpregnant women of reproductive age". Other researchers have also expressed concern regarding the body iron status of Canadian Inuit and Indian people.89 Low intake of heme iron or dietary shifts or both have been noted as being major causative factors in the low iron status of Inuit and Indian populations. Tea ingestion by Canadian Indians is substantial from infancy to old age. Tea is often steeped for long periods and it frequently remains in the same container all day.1' The steeping time will influence the amount of tannic acid extracted.11 Farkas1' has observed that infants may start drinking tea at 2 to 3 months of age and that by 6 months to 2 years of age it is common practice. Tea is frequently given two to three times daily. Although it may be given undiluted, it is usually diluted with water, milk and sugar. (It has been noted that milk binds with tannic acid,1' but the relation between such binding and the interference of tannic acid with iron absorption has not been explored.) Drinking of tea, whether diluted or undiluted, by preschool-aged and school-aged children is common, and tea intake by adolescents is popular. Women drink about 10 cups of tea a day and men about 5 cups a day. A cup can measure from 300 to 480 ml. Hargreaves" has observed that, of 1883 randomly selected Canadian children, 18% of the nonnative children and 85% of the native children drank tea. Of the latter group 79% drank three or more cups of tea a day. In view of the serious implications of tea intake by Canadian Indian people for body iron status, and also of caffeine intake14 for thiamin status,1' high priority should be given to future research in this area. It is vital that programs be
706 CMA JOURNAL/SEPTEMBER 22, 1979/VOL. 121
developed aimed at reducing tea consumption among Canadian native people. CAROL SPINDELL FARKAS, B SC, MN ED
Adjunct lecturer Department of man-environment studies University of Waterloo Waterloo, Oat.
References 1. DISLER PB, LYNCH SR, TORRANCE
JP, et al: The mechanisms of the inhibition of iron absorption by tea. S Air J Med Sci 40: 109, 1975 2. DISLER PB, LYNCH SR, CHARLTON
RW, et a!: The effect of tea on iron absorption. Gut 16: 193, 1975 3. DERMAN D, SAYERS M, LYNCH SR,
et al: Iron absorption from a cerealbased meal containing cane sugar fortified with ascorbic acid. Br J Nutr 38: 261, 1977 4. DE ALARCON PA, DONOVAN M-E,
FORBES GB, et al: Iron absorption in the thalassemia syndromes and its inhibition by tea. N Engi J Med 300: 5, 1979 5. VALBERG LS, BIRKETT N, HAIST J,
6.
7.
8.
9. 10.
et al: Evaluation of the body iron status of native Canadians. Can Med Assoc 1 120: 285, 1979 SCHAEFER 0: Changing dietary patterns in the Canadian north: health, social and economic consequences. I Can Diet Assoc 38: 17, 1977 DEs.i I, LEE M: Nutritional status of British Columbia Indians. III. Biochemical studies at Ahousat and Anaham reserves. Can I Public Health 62: 526, 1971 GOLDThORPE W: Malnutrition in Sioux Lookout Zone Indians 19701974, in Nutrition of Indian and Eskimo Children, HAWORTH J (ed), Second Ross Conference on Pediatric Research, Montreal, 1975, p 67 CooDiN F, DILLING L, HAWORTH J: The Cross Lake study, ibid, p 62 FARKAS CS: Tea intake among northern Canadian Indian populations: consideration of potential health implications. Presented at Canadian Physical Anthropology Conference, Niagara-on-the-Lake, Nov 1978
11. SINCLAIR
12. 13.
14.
15.
H,
HOLLINGSWORTH
D
(eds): Hutchinson's Foods and the Principles of Nutrition, Edward Arnold, London, 1969, p 481 MORTON JF: Tea and milk (C). Science 204: 908, 1979 HAROREAvES JA: Fluoride in teas and tea drinking by Canadian children (abstr). I Dental Res 57: Jan 1978 FARKAS CS: Caffeine intake and p0tential effect on health of a segment of northern Canadian indigenous people. mt I Addict 14: 27, 1979 Idem: Potential for and implications of thiamine deficiency in northern Canadian Indian populations affected by mercury contamination. Ecology Food Nutr 8: 11, 1979
#222-3600 Park Ave. Montreal, PQ
References 1. KIRKALDY-WILLIS WH: Five common back disorders: how to diagnose and treat them. Geriatrics 33: 32, Dec 1978 2. KIRK.ALDY-WILLIS WH, HILL RJ: A
more precise diagnosis for low-back pain. Spine 4: 102, Mar/Apr 1979
Body iron status associated with tea consumption To the editor: Recent reports have called attention to the interference with absorption of nonheme dietary iron by tea.14 This effect has been ascribed to the formation of insoluble tannate complexes in the gut.1 It has been suggested that tea and other tannin-containing beverages contribute to the pathogenesis of iron deficiency if dietary iron consists largely of nonheme sources.
The effect of tannin on nonheme
iron absorption is greater when ascorbic acid intake is low.' Valberg and colleagues' have concluded that "if 'normality' requires more than small amounts of storage iron to meet physiologic needs, then our results have demonstrated that iron deficiency was present in 20% to 40% of native Canadian children, adolescents and nonpregnant women of reproductive age". Other researchers have also expressed concern regarding the body iron status of Canadian Inuit and Indian people.89 Low intake of heme iron or dietary shifts or both have been noted as being major causative factors in the low iron status of Inuit and Indian populations. Tea ingestion by Canadian Indians is substantial from infancy to old age. Tea is often steeped for long periods and it frequently remains in the same container all day.1' The steeping time will influence the amount of tannic acid extracted.11 Farkas1' has observed that infants may start drinking tea at 2 to 3 months of age and that by 6 months to 2 years of age it is common practice. Tea is frequently given two to three times daily. Although it may be given undiluted, it is usually diluted with water, milk and sugar. (It has been noted that milk binds with tannic acid,1' but the relation between such binding and the interference of tannic acid with iron absorption has not been explored.) Drinking of tea, whether diluted or undiluted, by preschool-aged and school-aged children is common, and tea intake by adolescents is popular. Women drink about 10 cups of tea a day and men about 5 cups a day. A cup can measure from 300 to 480 ml. Hargreaves" has observed that, of 1883 randomly selected Canadian children, 18% of the nonnative children and 85% of the native children drank tea. Of the latter group 79% drank three or more cups of tea a day. In view of the serious implications of tea intake by Canadian Indian people for body iron status, and also of caffeine intake14 for thiamin status,1' high priority should be given to future research in this area. It is vital that programs be
706 CMA JOURNAL/SEPTEMBER 22, 1979/VOL. 121
developed aimed at reducing tea consumption among Canadian native people. CAROL SPINDELL FARKAS, B SC, MN ED
Adjunct lecturer Department of man-environment studies University of Waterloo Waterloo, Oat.
References 1. DISLER PB, LYNCH SR, TORRANCE
JP, et al: The mechanisms of the inhibition of iron absorption by tea. S Air J Med Sci 40: 109, 1975 2. DISLER PB, LYNCH SR, CHARLTON
RW, et a!: The effect of tea on iron absorption. Gut 16: 193, 1975 3. DERMAN D, SAYERS M, LYNCH SR,
et al: Iron absorption from a cerealbased meal containing cane sugar fortified with ascorbic acid. Br J Nutr 38: 261, 1977 4. DE ALARCON PA, DONOVAN M-E,
FORBES GB, et al: Iron absorption in the thalassemia syndromes and its inhibition by tea. N Engi J Med 300: 5, 1979 5. VALBERG LS, BIRKETT N, HAIST J,
6.
7.
8.
9. 10.
et al: Evaluation of the body iron status of native Canadians. Can Med Assoc 1 120: 285, 1979 SCHAEFER 0: Changing dietary patterns in the Canadian north: health, social and economic consequences. I Can Diet Assoc 38: 17, 1977 DEs.i I, LEE M: Nutritional status of British Columbia Indians. III. Biochemical studies at Ahousat and Anaham reserves. Can I Public Health 62: 526, 1971 GOLDThORPE W: Malnutrition in Sioux Lookout Zone Indians 19701974, in Nutrition of Indian and Eskimo Children, HAWORTH J (ed), Second Ross Conference on Pediatric Research, Montreal, 1975, p 67 CooDiN F, DILLING L, HAWORTH J: The Cross Lake study, ibid, p 62 FARKAS CS: Tea intake among northern Canadian Indian populations: consideration of potential health implications. Presented at Canadian Physical Anthropology Conference, Niagara-on-the-Lake, Nov 1978
11. SINCLAIR
12. 13.
14.
15.
H,
HOLLINGSWORTH
D
(eds): Hutchinson's Foods and the Principles of Nutrition, Edward Arnold, London, 1969, p 481 MORTON JF: Tea and milk (C). Science 204: 908, 1979 HAROREAvES JA: Fluoride in teas and tea drinking by Canadian children (abstr). I Dental Res 57: Jan 1978 FARKAS CS: Caffeine intake and p0tential effect on health of a segment of northern Canadian indigenous people. mt I Addict 14: 27, 1979 Idem: Potential for and implications of thiamine deficiency in northern Canadian Indian populations affected by mercury contamination. Ecology Food Nutr 8: 11, 1979
![[Effect of green tea or green tea extract consumption on body weight and body composition; systematic review and meta-analysis].](/assets/img/hold.png)
