Canibais e Reis

Red Meat and Processed Meat Consumption and Cancer (pdf)
Dominik D. Alexander, PhD, MSPH. Senior Managing Epidemiologist. Health Sciences Practice, Exponent, Inc.

Abstract

This technical report summarizes the currently available epidemiologic evidence surrounding red meat and processed meat consumption and cancer. Although discussed herein, this report is not intended to systematically address all ofthe components of causation, such as dose-response or biological plausibility, between red or processed meat and specific types of cancer. Rather, the purpose of this report is to synthesize scientific information pertaining to the cancer types for which intake of meat has been evaluated, and to recapitulate some of the observed statistical associations between red or processed meat intake and cancer. In addition, the methodological, analytical, and biological complexity is underscored so the reader can recognize and appreciate the challenges scientists are faced with when interpreting a large body of scientific and medical literature.

 

Am J Clin Nutr. 2009 May;89(5):1402-9. Epub 2009 Mar 4.

Meta-analysis of animal fat or animal protein intake and colorectal cancer. (pdf)

Alexander DD, Cushing CA, Lowe KA, Sceurman B, Roberts MA.
Exponent Health Sciences, Wood Dale, IL, USA.

Abstract

BACKGROUND: In the recent World Cancer Research Fund/American Institute for Cancer Research report of diet and cancer, it was concluded that there is limited but suggestive evidence that animal fat intake increases the risk of colorectal cancer. Objective: To clarify this potential relation, we conducted meta-analyses across a variety of subgroups, incorporating data from additional studies. DESIGN: Analyses of high compared with low animal fat intakes and categorical dose-response evaluations were conducted. Subgroup analyses, consisting of evaluations by study design, sex, and tumor site were also performed. RESULTS: Six prospective cohort studies with comprehensive dietary assessments, contributing 1070 cases of colorectal cancer and approximately 1.5 million person-years of follow-up, were identified. The summary relative risk estimate (SRRE) for these studies was 1.04 (95% CI: 0.83, 1.31; P for heterogeneity = 0.221) on the basis of high compared with low intakes. When data from case-control studies were combined with the cohort data, the resulting SRRE was 1.15 (95% CI: 0.93, 1.42) with increased variability (P for heterogeneity = 0.015). In our dose-response analysis of the cohort studies, no association between a 20-g/d increment in animal fat intake and colorectal cancer was observed (SRRE: 1.02; 95% CI: 0.95, 1.09). In a separate analysis of 3 prospective cohort studies that reported data for animal protein or meat protein, no significant association with colorectal cancer was observed (SRRE: 0.90; 95% CI: 0.70, 1.15). CONCLUSION: On the basis of the results of this quantitative assessment, the available epidemiologic evidence does not appear to support an independent association between animal fat intake or animal protein intake and colorectal cancer.

 

[Proc Amer Assoc Cancer Res, Volume 45, 2004]. Epidemiology 1: Viral, Bacterial, and Dietary Exposures

Meat and fat intake and colorectal cancer risk: A pooled analysis of 14 prospective studies (pdf)

Eunyoung Cho, Stephanie A. Smith-Warner for the Pooling Project of Prospect Studies of Diet and Cancer Investigators. Brigham and Women’s Hospital and Harvard Medical School, Boston, MA and Harvard School of Public Health, Boston, MA

Abstract

Relatively high red meat and fat intakes have been hypothesized to increase the risk of colorectal cancer. However previous epidemiologic studies on meat and fat intake and colorectal cancer risk have been inconclusive. We therefore examined the association in a pooled analysis of the primary data from 14 prospective follow-up studies from North America and Europe. Meat and fat intake was assessed using a validated food-frequency questionnaire in each study at baseline. We calculated study-specific relative risks and pooled them using a random-effects model. During follow-up of 725,258 women and men over a maximum of 5 to 20 years in the studies, 7,743 incident cases of colorectal cancer were documented. Greater intake of either red meat (excluding processed meat) or processed meat was not related to colorectal cancer risk. The pooled multivariate relative risks (RRs) of colorectal cancer were 1.00 (95% CI 0.92-1.08) for each 90g(approximately 3 oz)/d increase of red meat and 1.05 (95% CI 0.96-1.15) for each 30g/d increase of processed meat. However, intake of poultry and seafood was related to a reduced risk of colorectal cancer (RR= 0.88 [95% CI 0.77-1.00] for each 90g/d increase, P value for heterogeneity=0.04). The RRs for colorectal cancer for each 45g/d increase were 0.92 (95% CI 0.83-1.02) for poultry and 0.91 (95% CI 0.83-0.99) for seafood. Intakes of total, saturated, monounsaturated, and polyunsaturated fats were not appreciably associated with colorectal cancer risk. In conclusion, these prospective data do not support a positive association between higher red meat and fat intake and colorectal cancer risk. Higher intake of poultry and fish may be associated with a lower risk of colorectal cancer.

 

J Natl Cancer Inst. 2008 Dec 3;100(23):1695-706. Epub 2008 Nov 25.

Fat, protein, and meat consumption and renal cell cancer risk: a pooled analysis of 13 prospective studies. (pdf)

Lee JE, Spiegelman D, Hunter DJ, Albanes D, Bernstein L, van den Brandt PA, Buring JE, Cho E, English DR, Freudenheim JL, Giles GG, Graham S, Horn-Ross PL, Håkansson N, Leitzmann MF, Männistö S, McCullough ML, Miller AB, Parker AS, Rohan TE, Schatzkin A, Schouten LJ, Sweeney C, Willett WC, Wolk A, Zhang SM, Smith-Warner SA.
Channing Laboratory, Brigham and Women’s Hospital, and Harvard Medical School, Boston, MA 02115, USA.

Comment in: J Natl Cancer Inst. 2008 Dec 3;100(23):1658-9.

Abstract

BACKGROUND: Results of several case-control studies suggest that high consumption of meat (all meat, red meat, or processed meat) is associated with an increased risk of renal cell cancer, but only a few prospective studies have examined the associations of intakes of meat, fat, and protein with renal cell cancer.

METHODS: We conducted a pooled analysis of 13 prospective studies that included 530,469 women and 244,483 men and had follow-up times of up to 7-20 years to examine associations between meat, fat, and protein intakes and the risk of renal cell cancer. All participants had completed a validated food frequency questionnaire at study entry. Using the primary data from each study, we calculated the study-specific relative risks (RRs) for renal cell cancer by using Cox proportional hazards models and then pooled these RRs by using a random-effects model. All statistical tests were two-sided.

RESULTS: A total of 1,478 incident cases of renal cell cancer were identified (709 in women and 769 in men). We observed statistically significant positive associations or trends in pooled age-adjusted models for intakes of total fat, saturated fat, monounsaturated fat, polyunsaturated fat, cholesterol, total protein, and animal protein. However, these associations were attenuated and no longer statistically significant after adjusting for body mass index, fruit and vegetable intake, and alcohol intake. For example, the pooled age-adjusted RR of renal cell cancer for the highest vs the lowest quintile of intake for total fat was 1.30 (95% confidence interval [CI] = 1.08 to 1.56; P(trend) = .001) and for total protein was 1.17 (95% CI = 0.99 to 1.38; P(trend) = .02). By comparison, the pooled multivariable RR for the highest vs the lowest quintile of total fat intake was 1.10 (95% CI = 0.92 to 1.32; P(trend) = .31) and of total protein intake was 1.06 (95% CI = 0.89 to 1.26; P(trend) = .37). Intakes of red meat, processed meat, poultry, or seafood were not associated with the risk of renal cell cancer.

CONCLUSIONS: Intakes of fat and protein or their subtypes, red meat, processed meat, poultry, and seafood are not associated with risk of renal cell cancer.

 

Obes Rev. 2010 Jul 21. [Epub ahead of print]

Red meat and colorectal cancer: a critical summary of prospective epidemiologic studies. (pdf)

Alexander DD, Cushing CA.
Exponent Inc. Health Sciences, Wood Dale, IL, USA.

Abstract

Summary Meat consumption and cancer has been evaluated in hundreds of epidemiologic studies over the past three decades; however, the possible role of this food group on carcinogenesis is equivocal. In this comprehensive review, the currently available epidemiologic prospective studies of red meat intake and colorectal cancer are summarized to provide a greater understanding of any potential relationships. Specifically, salient demographic, methodological and analytical information is synthesized across 35 prospective studies. Collectively, associations between red meat consumption and colorectal cancer are generally weak in magnitude, with most relative risks below 1.50 and not statistically significant, and there is a lack of a clear dose-response trend. Results are variable by anatomic tumour site (colon vs. rectum) and by gender, as the epidemiologic data are not indicative of a positive association among women while most associations are weakly elevated among men. Colinearity between red meat intake and other dietary factors (e.g. Western lifestyle, high intake of refined sugars and alcohol, low intake of fruits, vegetables and fibre) and behavioural factors (e.g. low physical activity, high smoking prevalence, high body mass index) limit the ability to analytically isolate the independent effects of red meat consumption. Because of these factors, the currently available epidemiologic evidence is not sufficient to support an independent positive association between red meat consumption and colorectal cancer.

 

Eur J Cancer Prev. 2010 Sep;19(5):328-41.

Processed meat and colorectal cancer: a quantitative review of prospective epidemiologic studies. (pdf)

Alexander DD, Miller AJ, Cushing CA, Lowe KA.
Exponent Inc. Health Sciences, Wood Dale, Illinois 60191, USA.

Abstract

A tremendous amount of scientific interest has been generated regarding processed meat consumption and cancer risk. Therefore, to estimate the association between processed meat intake and colorectal cancer (CRC), a meta-analysis of prospective studies was conducted. Twenty-eight prospective studies of processed meat and CRC were identified, of which 20 represented independent nonoverlapping study populations. Summary relative risk estimates (SRREs) for high versus low intake and dose-response relationships were calculated. The SRRE for high (vs. low) processed meat intake and CRC was 1.16 [95% confidence interval (CI): 1.10-1.23] for all studies. Summary associations were modified considerably by sex; the SRRE for men was 1.23 (95% CI: 1.07-1.42) and the SRRE for women was 1.05 (95% CI: 0.94-1.16), based on nine and 13 studies, respectively. Sensitivity analyses did not indicate appreciable statistical variation by tumor site, processed meat groups, or study location. The SRRE for each 30-gram increment of processed meat and CRC was 1.10 (95% CI: 1.05-1.15) based on nine studies, and the SRRE for each incremental serving of processed meat per week was 1.03 (95% CI: 1.01-1.05) based on six studies. Overall, summary associations were weak in magnitude (i.e. most less than 1.20), processed meat definitions and analytical comparisons were highly variable across studies, and isolating the independent effects of processed meat intake is difficult, given the likely influence of confounding by other dietary and lifestyle factors. Therefore, the currently available epidemiologic evidence is not sufficient to support a clear and unequivocal independent positive association between processed meat consumption and CRC.

 

Am J Epidemiol. 2003 Jul 1;158(1):59-68.

Meat, fat, and their subtypes as risk factors for colorectal cancer in a prospective cohort of women. (pdf)

Flood A, Velie EM, Sinha R, Chaterjee N, Lacey JV Jr, Schairer C, Schatzkin A.
Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD, USA.

Abstract

The authors investigated the association of intakes of meat and fat with colorectal cancer in a prospective cohort of women in the United States. Between 1987 and 1989, 45,496 women completed a 62-item National Cancer Institute/Block food frequency questionnaire, and during 386,716 person-years of follow-up, there were 487 incident cases of colorectal cancer. The authors used Cox proportional hazards regression to estimate relative risks and 95% confidence intervals for total meat, red meat, white meat, processed meat, and well-done meat intakes, as well as for total fat, saturated fat, and unsaturated fat. Relative risks for increasing quintiles of total meat and red meat consumption indicated no association with colorectal cancer (relative risk for high compared with low quintile = 1.10, 95% confidence interval: 0.83, 1.45) for red meat. For total fat, there was also no association with increasing quintiles of consumption (relative risk for high compared with low quintile = 1.14, 95% confidence interval: 0.86, 1.53). Additionally, none of the other subtypes of either meat or fat showed any association with colorectal cancer. This study provided no evidence of an association between either meat or fat (or any of their subtypes) and colorectal cancer incidence, but the authors cannot rule out the possibility of a modest association.

 

Cancer Causes Control. 1999 Oct;10(5):387-96.

Diet and risk of colorectal cancer in a cohort of Finnish men. (pdf)

Pietinen P, Malila N, Virtanen M, Hartman TJ, Tangrea JA, Albanes D, Virtamo J.
Department of Nutrition, National Public Health Institute, Helsinki, Finland.

Abstract

OBJECTIVES: Based on previous epidemiological studies, high fat and meat consumption may increase and fiber, calcium, and vegetable consumption may decrease the risk of colorectal cancer. We sought to address these hypotheses in a male Finnish cohort. METHODS: We analyzed data from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC Study) where 27,111 male smokers completed a validated dietary questionnaire at baseline. After an average of 8 years of follow-up, we documented 185 cases of colorectal cancer. The analyses were carried out using the Cox proportional hazards model. RESULTS: The relative risk (RR) for men in the highest quartile of calcium intake compared with men in the lowest quartile was 0.6 (95% CI 0.4-0.9, p for trend 0.04). Likewise, the intake of milk protein and the consumption of milk products was inversely associated with risk of colorectal cancer. However, intake of dietary fiber was not associated with risk, nor was fat intake. Consumption of meat or different types of meat, and fried meat, fruits or vegetables were not associated with risk. CONCLUSIONS: In this cohort of men consuming a diet high in fat, meat, and fiber and low in vegetables, high calcium intake was associated with lowered risk of colorectal cancer.

 

Br J Cancer. 2001 Aug 3;85(3):357-61.

Dietary fat, cholesterol and colorectal cancer in a prospective study. (pdf)

Järvinen R, Knekt P, Hakulinen T, Rissanen H, Heliövaara M.
Department of Clinical Nutrition, University of Kuopio, P.O. Box 1627, Kuopio, FIN-70211, Finland.

Abstract

The relationships between consumption of total fat, major dietary fatty acids, cholesterol, consumption of meat and eggs, and the incidence of colorectal cancers were studied in a cohort based on the Finnish Mobile Clinic Health Examination Survey. Baseline (1967-1972) information on habitual food consumption over the preceding year was collected from 9959 men and women free of diagnosed cancer. A total of 109 new colorectal cancer cases were ascertained late 1999. High cholesterol intake was associated with increased risk for colorectal cancers. The relative risk between the highest and lowest quartiles of dietary cholesterol was 3.26 (95% confidence interval 1.54-6.88) after adjusting for age, sex, body mass index, occupation, smoking, geographic region, energy intake and consumption of vegetables, fruits and cereals. Consumption of total fat and intake of saturated, monounsaturated, or polyunsaturated fatty acids were not significantly associated with colorectal cancer risk. Nonsignificant associations were found between consumption of meat and eggs and colorectal cancer risk. The results of the present study indicate that high cholesterol intake may increase colorectal cancer risk, but do not suggest the presence of significant effects of dietary fat intake on colorectal cancer incidence.

 

Cancer Sci. 2007 Apr;98(4):590-7.

Meat, fish and fat intake in relation to subsite-specific risk of colorectal cancer: The Fukuoka Colorectal Cancer Study. (pdf)

Kimura Y, Kono S, Toyomura K, Nagano J, Mizoue T, Moore MA, Mibu R, Tanaka M, Kakeji Y, Maehara Y, Okamura T, Ikejiri K, Futami K, Yasunami Y, Maekawa T, Takenaka K, Ichimiya H, Imaizumi N.
Department of Preventive Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.

Abstract

High intake of red meat has been associated with increased risk of colorectal cancer in Western countries. There has been much interest in the role of n-3 polyunsaturated fatty acids (PUFA) in colorectal cancer prevention, but epidemiological findings are limited and inconsistent. The objective of our study was to examine associations of meat, fish and fat intake with risk of colorectal cancer, paying particular attention to the subsite within the colorectum. Data were from the Fukuoka Colorectal Cancer Study, a population-based case-control study, covering 782 cases and 793 controls. Diet was assessed by interview, using newly developed personal-computer software for registering semiquantitative food frequencies. The intake of beef/pork, processed meat, total fat, saturated fat or n-6 PUFA showed no clear association with the overall or subsite-specific risk of colorectal cancer. There was an almost significant inverse association between n-3 PUFA and the risk of colorectal cancer; the covariate-adjusted odds ratio for the highest (median 3.94 g/day) versus lowest (median 1.99 g/day) quintile of energy-adjusted intake was 0.74 (95% confidence interval 0.52-1.06, trend P=0.050). The consumption of fish and fish products was similarly inversely related to the risk although the association was not statistically significant. These associations were more evident for distal colon cancer; adjusted odds ratio for the highest versus lowest quintile of n-3 PUFA intake was 0.56 (95% confidence interval 0.34-0.92, trend P=0.02). Our findings do not support the hypothesis that consumption of red meat increases colorectal cancer risk but do suggest that high intake of fish may decrease the risk, particularly of distal colon cancer.

 

Int J Cancer. 2009 May 15;124(10):2430-5.

Meat intake and meat preparation in relation to risk of postmenopausal breast cancer in the NIH-AARP diet and health study. (pdf)

Kabat GC, Cross AJ, Park Y, Schatzkin A, Hollenbeck AR, Rohan TE, Sinha R.
Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY 10461, USA.

Abstract

A number of studies have reported that intake of red meat or meat cooked at high temperatures is associated with increased risk of breast cancer, but other studies have shown no association. We assessed the association between meat, meat-cooking methods, and meat-mutagen intake and postmenopausal breast cancer in the NIH-AARP Diet and Health Study cohort of 120,755 postmenopausal women who completed a food frequency questionnaire at baseline (1995-1996) as well as a detailed meat-cooking module within 6 months following baseline. During 8 years of follow-up, 3,818 cases of invasive breast cancer were identified in this cohort. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI). After adjusting for covariates, intake of total meat, red meat, meat cooked at high temperatures, and meat mutagens showed no association with breast cancer risk. This large prospective study with detailed information on meat preparation methods provides no support for a role of meat mutagens in the development of postmenopausal breast cancer.

 

Cancer Detect Prev. 2009;32(5-6):340-51. Epub 2009 Mar 19.

Quantitative assessment of red meat or processed meat consumption and kidney cancer. (pdf)

Alexander DD, Cushing CA.
Exponent Health Sciences, 185 Hansen Court, Suite 100, Wood Dale, IL 60191, USA.

Abstract

OBJECTIVE: To conduct a quantitative assessment of red meat or processed meat consumption and kidney cancer. METHODS: We extracted data from 12 case-control studies, three cohort studies, and the Pooling Project of Diet and Cancer publication for which 13 international cohorts were evaluated. Random effects meta-analysis models were used to calculate summary relative risk estimates (SRRE) based on high vs. low intake values. Sensitivity and influence analyses were conducted, including assessments of heterogeneity. RESULTS: The SRRE for all studies that reported results for red meat (included variables labeled ‘red meat’ or single red meat items, such as beef, pork, or liver) was 1.12 (95% CI: 0.98-1.29; p-value for heterogeneity=0.015), and the SRRE using only data from prospective cohorts was 1.02 (95% CI: 0.91-1.15) with minimal heterogeneity (p=0.741). Similarly, in a meta-analysis of the five studies that simultaneously adjusted for smoking, BMI, and total energy intake, the SRRE for red meat was 1.02 (95% CI: 0.91-1.15). No significant association was observed in the meta-analysis of processed meat consumption (SRRE=1.07; 95% CI: 0.94-1.23), although a significant association was observed when only data from cohort studies were analyzed (SRRE=1.19; 95% CI: 1.03-1.37). CONCLUSIONS: Although many of the summary results were positive, all were weak in magnitude, most were not statistically significant, and associations were attenuated among studies that adjusted for key potential confounding factors. In summary, the findings of this meta-analysis are not supportive of an independent relation between red or processed meat intake and kidney cancer.

 

Am J Gastroenterol. 2005 Dec;100(12):2789-95.

Fat, fiber, meat and the risk of colorectal adenomas. (pdf)

Robertson DJ, Sandler RS, Haile R, Tosteson TD, Greenberg ER, Grau M, Baron JA.
Veterans Hospital, White River Junction, Vermont, and Department of Medicine, Dartmouth Medical School, Hanover, New Hampshire, USA.

Abstract

OBJECTIVE: The aim of this study was to determine the relationship between fat, fiber, and meat intake, and risk of colorectal adenoma recurrence. METHODS: We determined adenoma recurrence and dietary intake for 1,520 participants in two randomized trials: The Antioxidant Polyp Prevention Study and Calcium Polyp Prevention Study. Subjects underwent baseline colonoscopy with removal of all adenomas, and dietary intake was estimated with a validated semiquantitative food frequency questionnaire. Follow-up colonoscopy was performed 1 and 4 yr later. Pooled risk ratios for adenoma recurrence were obtained by generalized linear regression, with adjustment for age, sex, clinical center, treatment category, study, and duration of observation. RESULTS: In the total colorectum, fiber intake was weakly and nonsignificantly associated with a risk for all adenomas (RR quartile 4 vs quartile 1=0.85, 95% CI 0.69-1.05) and advanced adenomas (RR=0.88, 95% CI 0.54-1.44). Associations were stronger for adenomas in the proximal colon (RR=0.73, 95% CI 0.56-0.97) and some fiber subtypes (fruit and vegetable, grain). There was no association between fat or total red meat intake and risk of adenoma or advanced adenoma recurrence. However, when considering other meats, risk (quartile 4 vs quartile 1) for advanced adenoma was increased for processed meat (RR=1.75, 95% CI 1.02-2.99) and decreased for chicken (RR=0.61, 95% CI 0.38-0.98). CONCLUSION: The inverse associations between fiber intake and risk of adenoma recurrence we observed are weak, and not statistically significant. Our data indicate that intake of specific meats may have different effects on risk.

 

Eur J Clin Nutr. 2002 Mar;56 Suppl 1:S2-11.

Meat and cancer: meat as a component of a healthy diet.  (pdf)

Biesalski HK.
Department of Biological Chemistry and Nutrition, University Hohenheim, Stuttgart, Germany.

Abstract

Based on epidemiological studies it is assumed that meat, especially red meat, enhances risk for cancer, particularly of the colon, breast and prostate. Meat and meat products are important sources of protein, some micronutrients and fat. High fat intake has been blamed for correlation with different diseases, including cancer. Meat protein is reported to contribute to cancer formation. However, meat, including liver, is not only composed of fat and protein, it contains essential nutrients which appear exclusively in meat (vitamin A, vitamin B12) and micronutrients for which meat is the major source because of either high concentrations or better bioavailability (folate, selenium, zinc). In particular, vitamin A, folate and selenium are reported to be cancer-preventive, with respect to colon, breast and prostate cancer. Taken together, meat consists of a few, not clearly defined cancer-promoting and a lot of cancer-protecting factors. The latter can be optimized by a diet containing fruit and vegetables, which contain hundreds of more or less proven bioactive constituents, many of them showing antioxidative and anticarcinogenic effects in vitro.

 

Meat Science. Volume 70, Issue 3, July 2005, Pages 509-524.

Meat as a component of a healthy diet – are there any risks or benefits if meat is avoided in the diet? (pdf)

 

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H.-K. Biesalsk. Universität Hohenheim, Institut für Biologische Chemie und Ernährungswissenschaft, Garbenstrasse 30 70593 Stuttgart, Germany

Abstract

Meat is frequently associated with a “negative” health image due to its “high” fat content and in the case of red meat is seen as a cancer-promoting food. Therefore, a low meat intake, especially red meat is recommended to avoid the risk of cancer, obesity and metabolic syndrome. However, this discussion overlooks the fact, that meat is an important source for some of micronutrients such as iron, selenium, vitamins A, B12 and folic acid. These micronutrients are either not present in plant derived food or have poor bioavailability. In addition, meat as a protein rich and carbohydrate “low” product contributes to a low glycemic index which is assumed to be “beneficial” with respect to overweight, the development of diabetes and cancer (insulin resistance hypothesis). Taken together meat is an important nutrient for human health and development. As an essential part of a mixed diet, meat ensures adequate delivery of essential micronutrients and amino acids and is involved in regulatory processes of energy metabolism.

 

Am J Clin Nutr. 2009 Jul;90(1):1-10. Epub 2009 May 13.

Food sources of nitrates and nitrites: the physiologic context for potential health benefits. (pdf)

Hord NG, Tang Y, Bryan NS. Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI, USA. Comment in: Am J Clin Nutr. 2009 Jul;90(1):11-2.

Abstract

The presence of nitrates and nitrites in food is associated with an increased risk of gastrointestinal cancer and, in infants, methemoglobinemia. Despite the physiologic roles for nitrate and nitrite in vascular and immune function, consideration of food sources of nitrates and nitrites as healthful dietary components has received little attention. Approximately 80% of dietary nitrates are derived from vegetable consumption; sources of nitrites include vegetables, fruit, and processed meats. Nitrites are produced endogenously through the oxidation of nitric oxide and through a reduction of nitrate by commensal bacteria in the mouth and gastrointestinal tract. As such, the dietary provision of nitrates and nitrites from vegetables and fruit may contribute to the blood pressure-lowering effects of the Dietary Approaches to Stop Hypertension (DASH) diet. We quantified nitrate and nitrite concentrations by HPLC in a convenience sample of foods. Incorporating these values into 2 hypothetical dietary patterns that emphasize high-nitrate or low-nitrate vegetable and fruit choices based on the DASH diet, we found that nitrate concentrations in these 2 patterns vary from 174 to 1222 mg. The hypothetical high-nitrate DASH diet pattern exceeds the World Health Organization’s Acceptable Daily Intake for nitrate by 550% for a 60-kg adult. These data call into question the rationale for recommendations to limit nitrate and nitrite consumption from plant foods; a comprehensive reevaluation of the health effects of food sources of nitrates and nitrites is appropriate. The strength of the evidence linking the consumption of nitrate- and nitrite-containing plant foods to beneficial health effects supports the consideration of these compounds as nutrients.

 

Colorectal cancer: myths, facts and possibilities (pdf)

In this report we will look at some common myths about colorectal cancer (CRC); describe find-ings from the past decade of research that have countered those myths; and comment on what thefuture may hold.