This document presents a meta-analysis on the effects of various sources of animal protein on chronic diseases, highlighting that red and processed meats are associated with increased risks of diabetes, stroke, and colorectal cancer, while fish consumption is linked to decreased cardiovascular risks. Dairy shows mixed effects with benefits for certain conditions, but it is also associated with prostate cancer risk. The findings align with existing dietary guidelines but underscore the need for caution regarding high consumption levels of red and processed meats and the necessity for further research on protein source impacts.

1. Effects of sources of animal
protein on major chronic diseases.
Meta-analyses of prospective
cohorts.
Registered dietitian, M.Sc, MBA
Reijo Laatikainen
Aava Medical Center
Docrates Cancer Center
www.pronutritionist.net
www.tervevatsa.fi

2. Introduction
• This slide deck bases on recent meta-analyses of prospective cohorts
which are considered at least as important as surrogate marker
randomized studies.
• Small box depicts actual outcome (meta-regression). Red =risk is
increased, blue=no statistically significant change in risk and
green=risk is reduced
• Vertical line depicts confidence interval in each meta-analysis.
• Risk comparisons are formed by comparing the highest vs lowest
category of consumption (ie. quintiles, tertiles, thirds or so). Exception:
Red and processed meat (per 100g/50 g) and cardiovascular diseases.

3. 3

4. Red meat is associated with increased of
risk of diabetes, stroke and colorectal
cancer
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0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
1.60
1.70
1.80
1.90
2.00 Relative RIsk
(Vertical line: 95% CI)
1.10
1.02 1.00
1.19
1.09 1.00
Colorectal cancer Breast cancer Prostate cancer Type 2 Diabetes Stroke Coronary Heart disease
Stroke and CHD: Per 100 g/day, because comparison between lowest vs highest categories not given

5. 5

6. Processed meat is associated with
increased of diabetes, CHD, stroke and
colorectal cancer
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
1.60
1.70
1.80
1.90
2.00 Relative RIsk
(Vertical line: 95% CI)
Colorectal cancer Breast cancer Prostate cancer Type 2 Diabetes Stroke Coronary Heart disease
Colorectal cancer Breast cancer Prostate cancer Type 2 Diabetes Stroke Coronary Heart disease
Stroke and CHD: Per 50 g/day, because comparison between lowest vs. highest categories not given
1.17
1.00 1.05
1.51
1.15
1.42

7. 7

8. Fish is associated with decreased risk of
cardiovascular diseases
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
Relative RIsk
(Vertical line: 95% CI)
Colorectal cancer Breast cancer Prostate cancer Type 2 Diabetes Stroke Coronary Heart disease
0.93
1.03 1.01
1.15
0.87
0.79

9. 9

10. Eggs are associated with increased risk of
diabetes (for some peculiar reason)
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2 Relative RIsk
(Vertical line: 95% CI)
No meta-
analyses
available
Colorectal cancer Breast cancer Prostate cancer Type 2 Diabetes Stroke Coronary Heart disease
1.04
0.97
1.04 0.97
1.42
0.93 0.97

11. 11

12. Dairy is associated with decreased risk of
diabetes, CV diseases, breast and colorectal
cancer but also with increased risk of
prostate cancer
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2 Relative RIsk
(Vertical line: 95% CI)
Colorectal cancer Breast cancer Prostate cancer Type 2 Diabetes Stroke Coronary Heart disease
0.81 0.85
1.13
0.89 0.87
0.94

13. 13

14. There are no meta-analyses of
prospective cohorts available on white
meat.
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
However, individual cohorts most
often so neutrality of poultry. Also,
meta-analysis of colorectal adenomas
demonstrated neutrality of poultry
(Xu et al. 2014)
Colorectal cancer Breast cancer Prostate cancer Type 2 Diabetes Stroke Coronary Heart disease

15. Sources 1/2
Alexander DD, Morimoto LM, Mink PJ, Cushing CA. A review and meta-analysis of red and processed meat
consumption and breast cancer. Nutr Res Rev. 2010;23(2):349-65.
Alexander DD, Mink PJ, Cushing CA, Sceurman B.. A review and meta-analysis of prospective studies of red
and processed meat intake and prostate cancer. Nutr J. 2010;9:50.
Aune et al, Dairy products and colorectal cancer risk: a systematic review and meta-analysis of cohort
studies, ,Ann Oncol. 2012;23(1):37-45.
Chan DSM, Lau R, Aune D, et al. Red and Processed Meat and Colorectal Cancer Incidence: Meta-Analysis
of Prospective Studies. PLoS ONE. 2011;6(6):e20456
Chen GC, Lv DB, Pang Z, Liu QF. Red and processed meat consumption and risk of stroke: a meta-analysis
of prospective cohort studies. Eur J Clin Nutr. 2013 Jan;67(1):91-5.
Dong J et al. Dairy consumption and risk of breast cancer: a meta-analysis of prospective cohort studies.
Breast Cancer Res Treat. 2011;127(1):23-31
Gao D, Ning N, Wang C, Wang Y, Li Q, Meng Z, Liu Y, Li Q.Dairy products consumption and risk of type 2
diabetes: systematic review and dose-response meta-analysis.PLoS One. 2013 Sep 27;8(9):e73965
Leung Yinko SS, Stark KD, Thanassoulis G, Pilote L.Fish consumption and acute coronary syndrome: a
meta-analysis. Am J Med. 2014 Sep;127(9):848-57.e2
Micha R, Mozaffarian D. Unprocessed Red and Processed Meats and Risk of Coronary Artery Disease and
Type 2 Diabetes - An Updated Review of the Evidence. Atheroscler Rep. 2012:14;515-52
Qin LQ, Milk consumption is a risk factor for prostate cancer in Western countries: evidence from cohort
studies. Asia Pac J Clin Nutr. 2007;16(3):467-76.

16. Sources 2/2
Qin LQ, Xu JY, Han SF, Zhang ZL, Zhao YY, Szeto IM. Dairy consumption and risk of cardiovascular disease:
an updated meta-analysis of prospective cohort studies. Asia Pac J Clin Nutr. 2015;24(1):90-100
Shin JY, Xun P, Nakamura Y, He K. Egg consumption in relation to risk of cardiovascular disease and
diabetes: a systematic review and meta-analysis. Am J Clin Nutr. 2013;98(1):146-59.
Si R, Qu K, Jiang Z, Yang X, Gao P. Egg consumption and breast cancer risk: a meta-analysis. Breast Cancer.
2014 May;21(3):251-61
Szymanski KM, Wheeler DC, Mucci LA. Fish consumption and prostate cancer risk: a review and meta-
analysis. Am J Clin Nutr. 2010;92(5):1223-33.
Xie B, He H. No association between egg intake and prostate cancer risk: a meta-analysis. Asian Pac J
Cancer Prev. 2012;13(9):4677-81.
Xun P, Qin B, Song Y. Fish consumption and risk of stroke and its subtypes: accumulative evidence from a
meta-analysis of prospective cohort studies. Eur J Clin Nutr. 2012;66(11):1199-207.
Wu S1, Feng B, Li K, Zhu X, Liang S, Liu X, Han S, Wang B, Wu K, Miao D, Liang J, Fan D.
Fish consumption and colorectal cancer risk in humans: a systematic review and meta-analysis. Am J Med.
2012 Jun;125(6):551-9.e5.
Zheng Ju-Sheng, Hu Xiao-Jie, Zhao Yi-Min, Yang Jing, Li Duo. Intake of fish and marine n-3 polyunsaturated
fatty acids and risk of breast cancer: meta-analysis of data from 21 independent prospective cohort studies
BMJ 2013; 346 :f3706

17. Discussion 1/2
• Results are very well in line with recommendations of
World Cancer Research Fund (WCRF/AIRC expert report
2007), and with most international dietary guidelines
• Results are rather well in line with results of randomized
trials regarding Mediterranean Diet (Predimed, Lyon, Oslo
Diet Heart)
• Results are very well in line with the analysis of systematic
reviews and meta-analyses published between 1950-2013
(Fardet & Boirie 2013)

18. Discussion 2/2
• These data are not the ”final word”. Prospective cohorts
cannot show causality and various confounders can affect
results. However, no better data exists on the long term
effects of protein sources on health.
• Magnitude of effects is relatively small
• These data do not tell much about extreme users. One is
classified as a high user of eggs if consumption exceeds 7
eggs per week. This may dilute the actual effects.
• More randomized trials are needed to clarify the effects of
different animal protein sources on health, but none of this
data shows we should increase the intake of red or
processed meat at the population level.

19. What might explain effects of red and
processed meat?
• Excessive intake of heme iron
• Advanced glycation end products, AGE:s ↑
• Polycyclic aromatic hydrocarbons, PAH:s ↑
• N-nitroso compounds (NOC) and N-nitrosation ↑
• IGF-1↑
• Amount of bifidobacteria ↓. Amount of various bad bacteria ↑
• Salt
• Phosphates and other additives
• Induction of TMAO production in the gut (from choline & carnitine)
• Saturated fat
• Arachidonic acid
• Endotoxins (LPS) in minced and processed meat and increased LPS
production in gut
• Neu5gc
• Meat substitutes healthier choices of protein such as fish or plant protein
(less n-3 fatty acids, iodine, taurine & vitamin D)
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20. Why dairy might be healthier than red
and processed meat?
• Fermented dairy has beneficial effects on gut bacteria
• Natural ACE-inhibitors of fermented dairy products
• Anti-inflammatory effects of whey protein
• Vitamin K2 of cheese and fermented dairy
• Production of TMAO in the gut decreases (studies on
cheese)
• Production of butyrate increases in the gut (studies on
cheese)
• Dairy substitutes unhealthier animal protein sources (less
heme iron, less NOCs, less PAH, less neu5gc, less
arachidonic acid etc.)
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21. Wellcome aboard!
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Reijo Laatikainen, RD, MBA
Images bought and licensed from BigStockPhoto
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