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Diet and colorectal cancer mortality: secular trends over 30 years in 15 European countries
CANCER LETTERS
ELSEVIER
Cancer
Letters
114 (1997)
247-2.50
Diet and colorectal cancer mortality: secular trends over 30 years in 15 European countries Olov H. Holmqvist Swedish Meat
Research
Institute,
P.O. Box 504, S-244 Kiivlinge,
Sweden
Abstract Many western European countries have increased consumption of meat and fat conspicuously from 1961 to 1990 according to FAO ‘food disappearance’ data. These trends within countries compare well with intake data obtained by weighing and questionnaires. For three countries more meat and fat is combined with small changes in plant foods, but nevertheless standardized mortalities from colorectal cancer drop. For nine countries meat, fat and plant foods increase and mortalities drop. For two countries, there is moderately more meat, fat and plant foods increase, and in one there is drastically more meat and a high consumption of plant foods, associated with rising mortalities. Overall, there is no consistent pattern. 0 1997 Elsevier Science Ireland Ltd. Keywords:
Cancer; Colorectal; Mortality; Diet; Trends; Epidemiology
1. Source and quality of data
2. Selection of food items and countries
Food disappearance data for Europe from 1961 to 1990 were recently published [ 11. Their value may be criticized as they may not reflect what is actually eaten. In 1959-1960 food intakes were investigated for the ‘Seven Countries Study’ by the then best available methods [2,3], and for cohorts from three European countries follow-ups 30 or 31 years later by weighing and through questionnaires have been published [d-6]. This allows for trends to be compared obtained by the two methods for 11 food items. Agreement is found in all cases. As for mortalities, quality of data is less controversial, e.g. they were used after critical analysis of drawbacks in the World Health Organization’s (1990) presentation of the current state of knowledge [7].
Meat and fat were selected as hypothetical promotors and vegetables, cereals and fruits as hypothetical inhibitors. Fat is given as energy percent, and other items as kg per person and year. Eggs and alcohol were excluded as data may be unreliable because some production and consumption may not be included in official statistics. Homegrown fruits and vegetables may similarly blur these trends, but are included here as deemed relevant per se, and as trends fitted those obtained in the seven countries study [46]. Sugar and fish were excluded as they were deemed less important and salt was not available. Dairy products were excluded as the source does not separate milk from cheese, and these differ by five to ten times in calcium content. Eastern European countries were excluded as other factors may have deteriorated over the period such as
0304-3835/97/$17.00 0 1997 Elsevier PIZ SO304-3835(97)04674-O
Science
Ireland
Ltd. All rights reserved
O.H. Holmyvist
248
/ Cuncrr
ixttrcv
health care, environmental pollutants and stress, especially during the 1980s with its political upheaval. Four countries were excluded as consumption trends were not consistent. In total 15 countries remained as part of the study (Table 1).
3. Trends in diets and mortalities All countries have increase their consumption of meat and fat, and many have increased it a lot. In Austria, France and Switzerland drastic increases in
Table Critical
I14 ( 1997) 247--2X
conjunction with less cereals, and only moderately more vegetables and fruits, are associated with lower mortalities. In nine countries meat, fat and plant foods have increased in conjunction with dropping mortalities. In Norway and Finland the increases have been more meat from low to moderate, more vegetables and fruits from low to moderate, less cer eals and more fat associated with rising mortalities. In Spain drastically more mea{ and fat have been con sumed, more vegetables and fruits going from high to higher and less cereals, associated with increasing mortality.
I foods consumed
and premature
Meat
Austria
SMR in colorectal
Fat
cancer in lY61 and approx.
Cereals
30 years later
Fruits
-.-
Vegetables
Colorectal cancer SMR <65/l O6
1961
1990
-____ 1970
1986
1961
1990
1961
1990
1961
1990
1961
66
93
36
42
13s
88
135
150
65
74
79
Belgium
61
95
42
46
108
99
62
131
84
Denmark
61
98
,4?
44
I02
IO1
50
6Y
,?O
Finland
35
64
3h
3Y
1 38
96
42
96
I8
France
73
95
3i
38
132
47
86
I 3h
Germany
66
96
38
39
89
II’
112
Peak (year) 105
92
(1975)
(1991) 79 (1987) 103 (19Yli 54 11991) 6X (1w.N
106 (1978)
91 (1990)
103 112
54
Last war)
48 81
Greece
21
72
33
37
167
149
160
212
90
227
30
34 (1978)
34 (1990)
Ireland
58
87
35
37
IS2
123
38
71
40
65
111
131 (1970)
106 (1990)
Italy
31
85
30
36
1no
I60
102
136
127
172
68
88 (1977)
Netherlands
44
78
42
41
107
67
64
139
16
78
80
70 (1989) 73
Norway
38
50
40
39
101
Ilh
60
98
47
5x
60
(1999 90
Spain
22
92
31
3x
145
100
16
140
1.17
160
52
Sweden
51
60
37
37
71
x3
61
102
3-J
67
14
Switzerland
56
83
39
43
139
97
139
127
75
86
82
C’K
69
72
40
41
109
95
Sh
II
SY
83
Foods as kg/person
and year; fat as energy
percent;
SMR
as standardized
mortalities
III
-
per 10’ under 65 years of age
.-
(1990) 60 (19X9) 71 (1989) 61 (1991) 94 (1991)
O.H. Holmqvist
/ Cancer
4. Discussion A recent exhaustive review of 33 prospective or case control studies [8] investigating the relation diet-colon cancer found positive associations for meat or meat products in ten cases, and negative associations in two. As for fat, positive associations were found in nine cases for saturated or animal fat, and one negative association. For meat and fat no associations were found in other cases. Negative associations were found for vegetables overwhelmingly in ten cases, and for fruits and cereals in three, with no positive associations for any of these. Fiber and vitamin A or C were also frequently found to associate negatively. Taken together, this indicates possible adverse effects from fat and perhaps meat, and protective for plant foods, especially vegetables. These results do no quite fit the trend data presented here. Most strikingly, Austria, Switzerland and France increased both their fat and meat consumption from moderate to high over 30 years, changed consumption of plant foods slightly, but premature colorectal mortalities nevertheless dropped. In most countries (nine) meat, fat and plant foods increased and mortalities dropped. In Finland and Norway mortalities rose, meat increased but only to moderate levels, and fat went to high. Cereals rose in Norway, but dropped in Finland, especially rye, a traditionally important cereal in Finland. Spain is the third country with rising mortalities. Meat and fat rose very much, vegetables and fruit going to very high levels. In Belgium both meat and fat reached extraordinary levels, bur mortalities dropped. Hence, when observing trends in all 15 countries, no general pattern is discernible. Correlations between changes in mortalities versus changes in a meat/vegetable ratio (as absolute or relative changes) give coefficients ranging from 0.14 to 0.24, indicating a weak association. There can be several explanations for the differences with cohort or migrant studies [9]. Firstly, poor quality of data in national trends. However, questionnaires in conjunction with weighing seem to yield the same results [4-61. Another may be as yet incompletely explored confounding, e.g. meat and fat may be associated with a rising standard of living, involving less physical work. Early detection and surgical treatment may blur a dietary connection. The time
Letters
114 (1997)
247-2.50
249
required for an adenoma to develop into a cancer may be as long as 30 years, but is typically around lo- 15 years [lo], and a trend period of 30 years as in the present report may be too short to capture the resulting sequel diet-cancer. Moreover, dietary changes in a population may appear first in the young, whereas deaths occur in the old. These difficulties may here be alleviated by the use of ageadjusted data under 65 years of age. Finally, cohort studies test long-term effects from what is assumed to be a constant dietary pattern, characterized once, a principal structural difference from the trend studies. In conclusion, a diet-colorectal cancer mortality connection seems difficult to demonstrate at the level of national populations. Measurable effects at this level are desirable in order to validate the population strategy.
References [II L21
[31
141
[51
[61
I71
World Health Organization (1995) Food and Health Indicators, Version 3. WHO Regional Office for Europe, Nutrition Unit, Copenhagen. Kromhout, D., Keys, A., Aravanis, C., Buzina, R., Fidanza, F., Giampoli, S., Jansen, A., Menotti, A., Nedeljkovic, S., Pekkaxinen, M., Simic, B.S. and Toshima, H. (1989) Food patterns in the 1960s in seven countries, Am. J. Clin. Nutr., 49,889-894. Keys, A., Aravanis, C., Van Buchem, F.S.F.P., Blackbum, H., Buzina, R., Djordjevic, B.S., Dontas, A.S., Fidanza, F., Karvonen, M.J., Kimura, N., Menotti, A., Nedeljkovic, S., Puddu, V., Punsar, S., and Taylor, H.L. (1981) Lance& ii, 5861. R&&en, L., Mutanen, M., Pekkanen, J., Laitinen, S., Koski, K., Halonen, S., Kivinen, P., Stengkd, J. and Nissinen, A. (1992) Dietary intake of 70- to 89-year-old men in eastern and western Finland, J. Intern. Med., 232, 305-312. Huijbregts, P.P.C.W., Feskens, E.J.M. and Kromhout, D. (1995) Dietary patterns and cardiovascular risk factors in elderly men: the Zutphen elderly study, Int. J. Epidemiol., 34313-320. Alberti-Fidanza, A., Paolacci, C.A., Chiuchiu, M.P., Coli, R., Fruttini, D., Verducci, G. and Fidanza, F. (1994) Dietary studies on two rural Italian population groups of the seven countries study. 1. Food and nutrition intake at the thirty-first year follow-up in 1991, Eur. J. Clin. Nutr., 48, 85-91. IARC (1990)Cancer: Causes, Occurrence and Control. IARC Scientific Publication No. 100, pp. 31-52. Editors: L. Tomatis, A. Aitio, N.E. Day, E. Heseltine, J. Kaldor, A.B. Miller, D.M. Parkin and E. Riboli. International Agency for Research on Cancer, Lyon, France.
[SJ Potter. J.D., Slattery, IML., Bostick, R.M. aod Gapstur, S.M. (1993) Colon cancer: a review of the epidemiology, Epidemiol. Rev., 15, 499-545. [9] Thomas, D.3. and Karagas, M.R. (1987) Cancer in first and second generation Americans. Cancer Res., 47. 577 l-5776.
j 101 Muto. .I‘., Bussey. H.J.R. and Morson, B.C. (1975) The evolution of cancer of the colon and rectum. Cancer, 36. 225 I 2270.
ELSEVIER
Cancer
Letters
114 (1997)
247-2.50
Diet and colorectal cancer mortality: secular trends over 30 years in 15 European countries Olov H. Holmqvist Swedish Meat
Research
Institute,
P.O. Box 504, S-244 Kiivlinge,
Sweden
Abstract Many western European countries have increased consumption of meat and fat conspicuously from 1961 to 1990 according to FAO ‘food disappearance’ data. These trends within countries compare well with intake data obtained by weighing and questionnaires. For three countries more meat and fat is combined with small changes in plant foods, but nevertheless standardized mortalities from colorectal cancer drop. For nine countries meat, fat and plant foods increase and mortalities drop. For two countries, there is moderately more meat, fat and plant foods increase, and in one there is drastically more meat and a high consumption of plant foods, associated with rising mortalities. Overall, there is no consistent pattern. 0 1997 Elsevier Science Ireland Ltd. Keywords:
Cancer; Colorectal; Mortality; Diet; Trends; Epidemiology
1. Source and quality of data
2. Selection of food items and countries
Food disappearance data for Europe from 1961 to 1990 were recently published [ 11. Their value may be criticized as they may not reflect what is actually eaten. In 1959-1960 food intakes were investigated for the ‘Seven Countries Study’ by the then best available methods [2,3], and for cohorts from three European countries follow-ups 30 or 31 years later by weighing and through questionnaires have been published [d-6]. This allows for trends to be compared obtained by the two methods for 11 food items. Agreement is found in all cases. As for mortalities, quality of data is less controversial, e.g. they were used after critical analysis of drawbacks in the World Health Organization’s (1990) presentation of the current state of knowledge [7].
Meat and fat were selected as hypothetical promotors and vegetables, cereals and fruits as hypothetical inhibitors. Fat is given as energy percent, and other items as kg per person and year. Eggs and alcohol were excluded as data may be unreliable because some production and consumption may not be included in official statistics. Homegrown fruits and vegetables may similarly blur these trends, but are included here as deemed relevant per se, and as trends fitted those obtained in the seven countries study [46]. Sugar and fish were excluded as they were deemed less important and salt was not available. Dairy products were excluded as the source does not separate milk from cheese, and these differ by five to ten times in calcium content. Eastern European countries were excluded as other factors may have deteriorated over the period such as
0304-3835/97/$17.00 0 1997 Elsevier PIZ SO304-3835(97)04674-O
Science
Ireland
Ltd. All rights reserved
O.H. Holmyvist
248
/ Cuncrr
ixttrcv
health care, environmental pollutants and stress, especially during the 1980s with its political upheaval. Four countries were excluded as consumption trends were not consistent. In total 15 countries remained as part of the study (Table 1).
3. Trends in diets and mortalities All countries have increase their consumption of meat and fat, and many have increased it a lot. In Austria, France and Switzerland drastic increases in
Table Critical
I14 ( 1997) 247--2X
conjunction with less cereals, and only moderately more vegetables and fruits, are associated with lower mortalities. In nine countries meat, fat and plant foods have increased in conjunction with dropping mortalities. In Norway and Finland the increases have been more meat from low to moderate, more vegetables and fruits from low to moderate, less cer eals and more fat associated with rising mortalities. In Spain drastically more mea{ and fat have been con sumed, more vegetables and fruits going from high to higher and less cereals, associated with increasing mortality.
I foods consumed
and premature
Meat
Austria
SMR in colorectal
Fat
cancer in lY61 and approx.
Cereals
30 years later
Fruits
-.-
Vegetables
Colorectal cancer SMR <65/l O6
1961
1990
-____ 1970
1986
1961
1990
1961
1990
1961
1990
1961
66
93
36
42
13s
88
135
150
65
74
79
Belgium
61
95
42
46
108
99
62
131
84
Denmark
61
98
,4?
44
I02
IO1
50
6Y
,?O
Finland
35
64
3h
3Y
1 38
96
42
96
I8
France
73
95
3i
38
132
47
86
I 3h
Germany
66
96
38
39
89
II’
112
Peak (year) 105
92
(1975)
(1991) 79 (1987) 103 (19Yli 54 11991) 6X (1w.N
106 (1978)
91 (1990)
103 112
54
Last war)
48 81
Greece
21
72
33
37
167
149
160
212
90
227
30
34 (1978)
34 (1990)
Ireland
58
87
35
37
IS2
123
38
71
40
65
111
131 (1970)
106 (1990)
Italy
31
85
30
36
1no
I60
102
136
127
172
68
88 (1977)
Netherlands
44
78
42
41
107
67
64
139
16
78
80
70 (1989) 73
Norway
38
50
40
39
101
Ilh
60
98
47
5x
60
(1999 90
Spain
22
92
31
3x
145
100
16
140
1.17
160
52
Sweden
51
60
37
37
71
x3
61
102
3-J
67
14
Switzerland
56
83
39
43
139
97
139
127
75
86
82
C’K
69
72
40
41
109
95
Sh
II
SY
83
Foods as kg/person
and year; fat as energy
percent;
SMR
as standardized
mortalities
III
-
per 10’ under 65 years of age
.-
(1990) 60 (19X9) 71 (1989) 61 (1991) 94 (1991)
O.H. Holmqvist
/ Cancer
4. Discussion A recent exhaustive review of 33 prospective or case control studies [8] investigating the relation diet-colon cancer found positive associations for meat or meat products in ten cases, and negative associations in two. As for fat, positive associations were found in nine cases for saturated or animal fat, and one negative association. For meat and fat no associations were found in other cases. Negative associations were found for vegetables overwhelmingly in ten cases, and for fruits and cereals in three, with no positive associations for any of these. Fiber and vitamin A or C were also frequently found to associate negatively. Taken together, this indicates possible adverse effects from fat and perhaps meat, and protective for plant foods, especially vegetables. These results do no quite fit the trend data presented here. Most strikingly, Austria, Switzerland and France increased both their fat and meat consumption from moderate to high over 30 years, changed consumption of plant foods slightly, but premature colorectal mortalities nevertheless dropped. In most countries (nine) meat, fat and plant foods increased and mortalities dropped. In Finland and Norway mortalities rose, meat increased but only to moderate levels, and fat went to high. Cereals rose in Norway, but dropped in Finland, especially rye, a traditionally important cereal in Finland. Spain is the third country with rising mortalities. Meat and fat rose very much, vegetables and fruit going to very high levels. In Belgium both meat and fat reached extraordinary levels, bur mortalities dropped. Hence, when observing trends in all 15 countries, no general pattern is discernible. Correlations between changes in mortalities versus changes in a meat/vegetable ratio (as absolute or relative changes) give coefficients ranging from 0.14 to 0.24, indicating a weak association. There can be several explanations for the differences with cohort or migrant studies [9]. Firstly, poor quality of data in national trends. However, questionnaires in conjunction with weighing seem to yield the same results [4-61. Another may be as yet incompletely explored confounding, e.g. meat and fat may be associated with a rising standard of living, involving less physical work. Early detection and surgical treatment may blur a dietary connection. The time
Letters
114 (1997)
247-2.50
249
required for an adenoma to develop into a cancer may be as long as 30 years, but is typically around lo- 15 years [lo], and a trend period of 30 years as in the present report may be too short to capture the resulting sequel diet-cancer. Moreover, dietary changes in a population may appear first in the young, whereas deaths occur in the old. These difficulties may here be alleviated by the use of ageadjusted data under 65 years of age. Finally, cohort studies test long-term effects from what is assumed to be a constant dietary pattern, characterized once, a principal structural difference from the trend studies. In conclusion, a diet-colorectal cancer mortality connection seems difficult to demonstrate at the level of national populations. Measurable effects at this level are desirable in order to validate the population strategy.
References [II L21
[31
141
[51
[61
I71
World Health Organization (1995) Food and Health Indicators, Version 3. WHO Regional Office for Europe, Nutrition Unit, Copenhagen. Kromhout, D., Keys, A., Aravanis, C., Buzina, R., Fidanza, F., Giampoli, S., Jansen, A., Menotti, A., Nedeljkovic, S., Pekkaxinen, M., Simic, B.S. and Toshima, H. (1989) Food patterns in the 1960s in seven countries, Am. J. Clin. Nutr., 49,889-894. Keys, A., Aravanis, C., Van Buchem, F.S.F.P., Blackbum, H., Buzina, R., Djordjevic, B.S., Dontas, A.S., Fidanza, F., Karvonen, M.J., Kimura, N., Menotti, A., Nedeljkovic, S., Puddu, V., Punsar, S., and Taylor, H.L. (1981) Lance& ii, 5861. R&&en, L., Mutanen, M., Pekkanen, J., Laitinen, S., Koski, K., Halonen, S., Kivinen, P., Stengkd, J. and Nissinen, A. (1992) Dietary intake of 70- to 89-year-old men in eastern and western Finland, J. Intern. Med., 232, 305-312. Huijbregts, P.P.C.W., Feskens, E.J.M. and Kromhout, D. (1995) Dietary patterns and cardiovascular risk factors in elderly men: the Zutphen elderly study, Int. J. Epidemiol., 34313-320. Alberti-Fidanza, A., Paolacci, C.A., Chiuchiu, M.P., Coli, R., Fruttini, D., Verducci, G. and Fidanza, F. (1994) Dietary studies on two rural Italian population groups of the seven countries study. 1. Food and nutrition intake at the thirty-first year follow-up in 1991, Eur. J. Clin. Nutr., 48, 85-91. IARC (1990)Cancer: Causes, Occurrence and Control. IARC Scientific Publication No. 100, pp. 31-52. Editors: L. Tomatis, A. Aitio, N.E. Day, E. Heseltine, J. Kaldor, A.B. Miller, D.M. Parkin and E. Riboli. International Agency for Research on Cancer, Lyon, France.
[SJ Potter. J.D., Slattery, IML., Bostick, R.M. aod Gapstur, S.M. (1993) Colon cancer: a review of the epidemiology, Epidemiol. Rev., 15, 499-545. [9] Thomas, D.3. and Karagas, M.R. (1987) Cancer in first and second generation Americans. Cancer Res., 47. 577 l-5776.
j 101 Muto. .I‘., Bussey. H.J.R. and Morson, B.C. (1975) The evolution of cancer of the colon and rectum. Cancer, 36. 225 I 2270.