Total meats and total cancer.
Background: Dr. Hirayama examined the effects of a small amount of food groups in relation to a large amount of mortality end points in a Japanese cohort of
very large size. An extended review of his work was published as a book in 1990 (Hirayama T [3]). Data about this cohort is seldom included in current
systematic reviews about the relations mentioned. Dr. Hirayama published a lot of articles stating that vegetables and meats were related to
several disease end points, adjusted for age and sex. However, the book included one page showing effects after multivariate analysis including
cigarette smoking, meat, green-yellow vegetables, and alcohol. And this analysis showed that a large amount of previously published effects completely
changed when these variables were taken into account.
Since a) Dr. Hirayama himself only published sex, and age-adjusted results in the English language, b) the results were published as a book and not in a
peer-reviewed journal, and c) Dr. Hirayama was the only researcher examining this cohort, results from his cohort are debatable. Results will be presented
including effects from his work, but his work will not be included in the evidence for a possible effect.
Total cancer risk: Data was provided by 5 articles about 4 cohorts, including a total of 6,398 cases. A significant protective effect was found of vegetarianism vs
eating meat from pooled results of 2 cohorts (Key TJ [10]), including 3,033 cases (47% of all cases). No other associations were found. The average RR = 1.10 for
total meat consumption (excluding incomplete data from McCullough ML [9]).
Total cancer mortality: Data was provided by 9 articles about 6 cohorts, including a total of 16,916 cases. A strong significantly increased risk was found
in one cohort of very large size among men only. No other associations were found. The average RR = 1.25 for total meat consumption.
When results from one cohort with debatable results were excluded (Hirayama T [3]), effects were restricted to findings from 5 primarily vegetarian cohorts, including 2,176 cases.
No significant effects were found. RR's for meat consumption were < 1 in 3 cohorts (Chang-Claude J [2]), Key TJ [6], Key TJ [10]), and > 1 in the remaining 2
cohorts (Phillips RL [1], Appleby PN [5]). The average RR = 1.02 for total meat consumption.
Conclusion: A significant protective effect of vegetarianism against total cancer risk was found from pooled results of 2 cohorts, including 47% of all cases.
Suggestive evidence was found for an increased total cancer risk of total meat consumption (+ 10%). No associations were found with total cancer mortality.
Perspective: A significant protective effect (RR = 0.88) of vegetarians vs meat eaters was found from pooled results of 2 cohorts (Key TJ [10]). But the
effects size was stronger among fish eaters vs meat eaters (RR = 0.82; See extended table).
| Author | Cohort name | Cases | Relative Risk (RR) |
|---|---|---|---|
| 10) Key TJ (2009) | The EPIC-Oxford Cohort & The Oxford Vegetarian Study | 3,033 | RR = 0.88 (0.81-0.96) for vegetarians vs meat eaters. |
| 10) Benetou V (2008) | The EPIC-Greece Cohort | 851 | HR = 1.08 (0.99-1.17) per increment of 50 g meat/day. |
| 9) McCullough ML (2000) | The Health Professionals Follow-up Study | 1,661 | No association. |
| 4) Knekt P (1994) | The Finnish Mobile Clinic Health Survey | 853 | RR = 0.97 (0.80-1.17) for the highest vs lowest tertile of meat consumption. |
| Total number of cases: 6,398 | Average RR = 1.10 |
| Author | Cohort name | Cases | Relative Risk (RR) |
|---|---|---|---|
| 10) Key TJ (2003) | The EPIC-Oxford Study | 230 | DRR = 1.11 (0.82-1.51) for vegetarians vs nonvegetarians. |
| 6) Key TJ (1996) | The Health Food Shoppers Study | 451 | RR = 1.12 (0.93-1.35) for vegetarianism. |
| 5) Appleby PN (2002) | The Oxford Vegetarian Study | 367 | DRR = 0.90 (0.73-1.11) for vegetarians vs nonvegetarians. |
| 3) Hirayama T (1990) | No cohort name defined | 8,794 men, and 5,946 women | Men: RR = 1.46 (P = < 0.01) for meat consumption ≥ 4 times/week. Women RR = 0.98 (0.87-1.12) for meat consumption 0 vs ≥ 4 times/week. |
| 2) Chang Claude J (2005) | The German Vegetarian Study | 107 | RR = 1.04 (0.67-1.62 for vegetarians vs nonvegetarians. |
| 1) Phillips RL (1983) | The Adventist Health Study | 1,021 | MR = 1.07 (P = > 0.10) for the highest vs lowest tertile of meat consumption. |
| Total number of cases: 16,916 | Average RR = 1.25 |
| Author | Cohort name | Subjects | Years of follow-up | Cases | End point | Consumption of | Relative Risk (RR) | Adjustments | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 10) Key TJ (2009) | The EPIC-Oxford Cohort & The Oxford Vegetarian Study | 64,408 subjects aged 20-89. (UK) | 1980-1994 to 2006 (Oxford Vegetarian), and 1993-99 to 2006 (Epic-Oxford) | See variables | Total cancer incidence | Vegetarianism |
Smoking, alcohol consumption, BMI, physical activity level, and for women: parity, and oral contraceptive use. Stratified by sex and study/method of recruitment. |
10) Key TJ (2009) | The EPIC-Oxford Study | 52,706 men and women aged 20-89. | Including all surviving participants in The Oxford Vegetarian Study. (UK) 1993-99 to 2005 | 2,179 | Incidence of all malignant neoplasms | Vegetarian status |
IRR = 0.93 (0.83-1.04) for being a vegetarian vs nonvegetarian. |
Age as the underlying time variable, stratified by sex and method of recruitment. Adjusted for smoking. |
10) Benetou V. (2008) | The Greek segment of the EPIC Study. | 25,623 subjects (10,582 men, and 15,041 women). | (Greece) 7.9 | (1994-99 to 2007) 851 | (421 men, and 430 women) Total cancer risk (excluding nonmelanoma skin cancer) | Meat (not defined) | HR = 1.08 (0.99-1.17; No P-value) for an increment of 50 g/day. | Stratified by sex. Adjusted for age, years of schooling, smoking status, BMI, height, physical activity, ethanol intake, supplement use, and total energy intake. |
9) McCullough ML (2000) | The Health Professionals Follow-up Study | 38,622 men aged 40-75. | (USA) 8 | (1986-1994) 1,661? | Total cancer risk (all cancers except nonaggressive prostate cancer (< stage C and < grade 7) and nonmelanoma skin cancer) | Meats (defined as meat, poultry, fish, dry beans, eggs, and nuts) | Not associated with risk (no data shown). | Highest (10 points) vs lowest tertile (0 points) = 2.5-2.8 vs 0 servings/d respectively. Each component of the healthy food index was added individually into the multivariate model, adjusting for age, smoking, body mass index, alcohol intake, physical activity, total energy intake, and time period. |
4) Knekt P (1994) | The Finnish Mobile Clinic Health Survey | 9,990 men and women aged 15-99. | 24 | (1967-72 to 1991) 853 | All cancer incidence | Fried meat (all meat foods prepared by the pan-frying method [fried meat balls, pork and other meat fried in pieces, and steak were the most commonly consumed foods included]) |
RR = 0.97 (0.80-1.17) for the highest vs lowest tertile of consumption. | Amount specific data (Tertiles not defined): T1: RR = 1. T2: RR = 0.95 (0.80-1.12). T3: RR = 0.97 (0.80-1.17). Sex, age, smoking, geographical area, occupation, BMI, parity, intake of energy, other meats, cereals, potatoes, vegetables, fruits and berries, margarine, dairy products, fish and eggs. |
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