Jump to content

JAMA weighs in on the plant vs animal protein debate.

Recommended Posts

JAMA weighs in on plant protein vs animal protein. It seems the conclusion is meat eggs only bad if you stray from healthy lifestyle.




So eat your red meat as long as your not a smoker, fat or an alcoholic etc. hmm... So why would it especially effect people with one or more unhealthy lifestyle factors. I am brainstorming this but not getting it.

Link to comment
Share on other sites



So eat your red meat as long as your not a smoker, fat or an alcoholic etc.


And as long as you don't care about the sh*tty treatment of animals, and are willing to eat your own children ☺.


From the article you linked to, being obese, a smoker or a heavy drinker weren't the only unhealthy characteristics that seemed to make red meat bad for mortality (my emphasis):


More careful analysis revealed that the association of animal protein intake with an elevated mortality risk only applied to participants with at least one factor associated with an unhealthy lifestyle -- being either obese or underweight, heavy alcohol consumption, a history of smoking, or physical inactivity. In fact, the association disappeared in participants with a healthy lifestyle. 


So why would it especially effect people with one or more unhealthy lifestyle factors. I am brainstorming this but not getting it. 


Well, the article you point to has one explanation:


Analysis based on specific sources of protein indicated that the animal-protein-associated mortality risk applied primarily to processed and unprocessed red meats, which include both beef and pork products, and not to protein from fish or poultry.

"While we expected we might find the associations to be weaker in the healthy lifestyle group, we did not expect them to completely disappear," says Song. "But when we looked deeper into the data, we found that -- at similar levels of animal protein intake -- those in the unhealthy lifestyle group consumed more red meats, eggs and high-fat dairy, while the healthy lifestyle group consumed more fish and poultry. So we suspect the different sources of animal protein between the two groups may contribute to the stronger results in the unhealthy lifestyle group."


Here is the relevant paragraph in the discussion from the free full text of the paper [1] the article refers to:


Interestingly, in this study, we found that the association of animal and plant protein with mortality varied by lifestyle factors, and any statistically significant protein-mortality associations were restricted to participants with at least 1 of the unhealthy behaviors, including smoking, heavy alcohol intake, overweight or obesity, and physical inactivity. Several reasons may explain these findings. First, given the remaining variation of health behaviors across protein intake categories in the unhealthy-lifestyle group, residual confounding from lifestyle factors may contribute to the observed protein-mortality associations. However, our results are robust to adjustment for a wide spectrum of potential confounders and the propensity score. Second, our results suggest that the adverse effects of high animal protein intake and beneficial effects of plant protein may be enhanced by other unhealthy lifestyle choices and become evident among the subgroup of individuals with these behaviors who may already have had some underlying inflammatory or metabolic disorders. Finally, as shown in Table 3, participants with a similar intake and with and without a healthy lifestyle demonstrated distinct profiles of protein sources. Those with unhealthy lifestyles consumed more processed and unprocessed red meat, whereas the healthy-lifestyle group consumed more fish and chicken as animal protein sources, suggesting that different protein sources, at least in part, contributed to the observed variation in the protein-mortality associations according to lifestyle factors. This hypothesis is supported by our substitution analysis results. Although substituting plant foods for various animal foods was associated with a lower mortality, red meat, especially processed red meat, showed a much stronger association than fish and poultry, which themselves were not associated with mortality (eTable 6 in the Supplement). In fact, protein from certain fish, such as cod, has been suggested to improve the lipid profile, glycemic control, and insulin sensitivity.


In other words, the authors offer three possible explanations for why red meat + unhealthy lifestyle practices → increased morality:

  • Red meat is bad for everyone, and people with unhealthy lifestyle practices tend to eat more of it, and less of the (somewhat) healthier animal proteins, like fish poultry and plants.
  • Red meat may look bad because of residual confounders - i.e. people who eat more read meat have other unhealthy lifestyle practices that the authors couldn't/didn't control for. They discount this one.
  • If you engage in other unhealthy behaviors that tend to increase inflammation (e.g. smoking, being obese), the cholesterol, saturated fat, and/or TMAO-boost resulting from red meat consumption may result in damage to your arteries that might not occur (at least as much) in a state of low systemic inflammation. For example, eating red meat and/or other animal products is known to raise LDL cholesterol. By depleting antioxidant defenses or increasing glycemia, smoking or other unhealthy behaviors likely causes the elevated LDL cholesterol to become oxidized and/or glycated, and therefore more damaging to arteries.




[1] JAMA Intern Med. Published online August 01, 2016. doi:10.1001/jamainternmed.2016.4182


Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality


Mingyang Song, MD, ScD1,2; Teresa T. Fung, ScD2,3; Frank B. Hu, MD, PhD2,4,5; Walter C. Willett, MD, DrPH2,4,5; Valter D. Longo, PhD6,7; Andrew T. Chan, MD, MPH1,5,8; Edward L. Giovannucci, MD, ScD


Free full text: http://archinte.jamanetwork.com/article.aspx?articleid=2540540




Importance  Defining what represents a macronutritionally balanced diet remains an open question and a high priority in nutrition research. Although the amount of protein may have specific effects, from a broader dietary perspective, the choice of protein sources will inevitably influence other components of diet and may be a critical determinant for the health outcome.
Objective  To examine the associations of animal and plant protein intake with the risk for mortality.
Design, Setting, and Participants  This prospective cohort study of US health care professionals included 131 342 participants from the Nurses’ Health Study (1980 to end of follow-up on June 1, 2012) and Health Professionals Follow-up Study (1986 to end of follow-up on January 31, 2012). Animal and plant protein intake was assessed by regularly updated validated food frequency questionnaires. Data were analyzed from June 20, 2014, to January 18, 2016.
Main Outcomes and Measures  Hazard ratios (HRs) for all-cause and cause-specific mortality.
Results  Of the 131 342 participants, 85 013 were women (64.7%) and 46 329 were men (35.3%) (mean [sD] age, 49 [9] years). The median protein intake, as assessed by percentage of energy, was 14% for animal protein (5th-95th percentile, 9%-22%) and 4% for plant protein (5th-95th percentile, 2%-6%). After adjusting for major lifestyle and dietary risk factors, animal protein intake was weakly associated with higher mortality, particularly cardiovascular mortality (HR, 1.08 per 10% energy increment; 95% CI, 1.01-1.16; P for trend = .04), whereas plant protein was associated with lower mortality (HR, 0.90 per 3% energy increment; 95% CI, 0.86-0.95; P for trend < .001). These associations were confined to participants with at least 1 unhealthy lifestyle factor based on smoking, heavy alcohol intake, overweight or obesity, and physical inactivity, but not evident among those without any of these risk factors. Replacing animal protein of various origins with plant protein was associated with lower mortality. In particular, the HRs for all-cause mortality were 0.66 (95% CI, 0.59-0.75) when 3% of energy from plant protein was substituted for an equivalent amount of protein from processed red meat, 0.88 (95% CI, 0.84-0.92) from unprocessed red meat, and 0.81 (95% CI, 0.75-0.88) from egg.
Conclusions and Relevance  High animal protein intake was positively associated with mortality and high plant protein intake was inversely associated with mortality, especially among individuals with at least 1 lifestyle risk factor. Substitution of plant protein for animal protein, especially that from processed red meat, was associated with lower mortality, suggesting the importance of protein source.
PMID: Not available
Link to comment
Share on other sites



Just so we're not missing the forest for the trees: one thing that I think people may overlook in our focus on the red meat → increased mortality angle of this study is the overarching result - namely that animal protein was associated with a higher mortality risk than vegetable protein. The most interesting figure from the free full text was this one, showing estimated magnitude of the beneficial effects on mortality of replacing various forms of animal protein with plant protein:




As you can see, animal proteins of all kinds were worse than plant proteins for all-cause mortality, and all the major causes of death, including CVD, cancer and "other", even after controlling for a plethora of potential confounders (listed in the caption).


From the abstract, it appears the effect was pretty substantial, particularly for processed and unprocessed red meat and eggs:


[T]he HRs for all-cause mortality were 0.66 (95% CI, 0.59-0.75) when 3% of energy from plant protein was substituted for an equivalent amount of protein from processed red meat, 0.88 (95% CI, 0.84-0.92) from unprocessed red meat, and 0.81 (95% CI, 0.75-0.88) from egg.


So for all you egg lovers, that translates into an almost 20% lower likelihood of dying simply by replacing one egg per day with healthy plant protein. A similar substitution of plants for 1oz per day of red or processed meat results in a 12% and 33% reduction in mortality risk, respectively.


So stop eating the damn animals already...



Link to comment
Share on other sites

So stop eating the damn animals already...


Well not for health reasons, necessarily. I mean there may be excellent reasons to avoid animal products, like ethical, or environmental (most persuasive to me, personally), but health is not one of them. If it were, then we'd expect vegan diets to lead to the longest lifespans, and I don't think most studies show that - it appears that pescetarian, and various flavors of vegetarian are at the top of the heap, and vegan almost never. That said, I don't know if it has any relevance for people who are in our position - health fanatics; odds are that if you are as careful as we are here about the totality of our health practices, you will live about as long on almost any carefully constructed diet - omnivore, vegetarian, pescetarian, vegan etc. - I don't think small amounts of fish or even occasional eggs are going to make a lick of difference to our health/lifespan. 


But at the end of the day, I don't even put lifespan as the top of my priority stack. I think it's quite justifiable to sacrifice some lifespan if the sacrifice leads to a lessening of a great evil (suffering of animals and destroying the environment etc.). Therefore even if it transpires - as I believe it to be the case - that veganism is suboptimal from a health POV, the appeal of veganism is undiminished, IMHO.

Link to comment
Share on other sites



But at the end of the day, I don't even put lifespan as the top of my priority stack. I think it's quite justifiable to sacrifice some lifespan if the sacrifice leads to a lessening of a great evil (suffering of animals and destroying the environment etc.). Therefore even if it transpires - as I believe it to be the case - that veganism is suboptimal from a health POV, the appeal of veganism is undiminished, IMHO.


Well said Tom! To back up your point about a low-animal product diet being as healthy as a strict vegan diet, here is the data from the clean-living 7th Day Adventists on all-cause mortality [1] (discussed here) and cancer mortality [2] (discussed here) by diet pattern:


                                             Cancer Mortality (Men)     All-Cause Mortality (Men & Women)

Non-vegetarians                                1.00                                      1.00

Semi-vegetarians                               1.09                                      0.92

Pesco-vegetarian                               0.87                                      0.81

Lacto-ovo-vegetarians                        0.91                                      0.91

Vegans                                              0.79                                      0.85


So vegans win by a bit in avoiding cancer, but fish-eaters win by a bit overall, although the confidence intervals for both diets are nearly completely overlapped for both cancer mortality and all-cause mortality.


Interestingly, if DHA consumption is a proxy for (fatty) fish intake, the pesco-vegetarian Adventists weren't eating that much (fatty) fish. From Table 3 of PMID 23988511 (discussed here), the pesco-vegetarian Adventists had an average dietary DHA intake of 187 mg/day. That is the equivalent of about 1/7 of a 3oz serving of atlantic salmon per day, or about one servings of fatty fish per week. They probably also ate some non-fatty fish without much DHA, but it still look like the pesco-vegetarian Adventists don't eat a whole lot of fish. No wonder they live a long time.


So based on the best data available on clean-living westerners like most of us, it is close to a wash for health and longevity whether you eschew animal products altogether and go vegan or include a small amount of fish as a pesco-vegetarian. Ethically and for the health of the planet, I (obviously) think a strong case can be made for avoiding eating animals altogether.





[1] JAMA Intern Med.. 2013 Jul 8;173(13):1230-8.. doi: 10.1001/jamainternmed.2013.6473.

Vegetarian dietary patterns and mortality in Adventist Health Study 2.
Orlich MJ(1), Singh PN, Sabaté J, Jaceldo-Siegl K, Fan J, Knutsen S, Beeson WL,
Fraser GE.
Author information:
(1)School of Public Health, Loma Linda University, Loma Linda, CA 92350, USA.
Comment in
JAMA Intern Med.. 2014 Jan;174(1):168-9.
JAMA Intern Med.. 2014 Jan;174(1):169.
JAMA Intern Med.. 2013 Jul 8;173(13):1238-9.
Dtsch Med Wochenschr.. 2013 Sep;138(39):1930.
IMPORTANCE: Some evidence suggests vegetarian dietary patterns may be associated
with reduced mortality, but the relationship is not well established.
OBJECTIVE: To evaluate the association between vegetarian dietary patterns and
DESIGN: Prospective cohort study; mortality analysis by Cox proportional hazards
regression, controlling for important demographic and lifestyle confounders.
SETTING: Adventist Health Study 2 (AHS-2), a large North American cohort.
PARTICIPANTS: A total of 96,469 Seventh-day Adventist men and women recruited
between 2002 and 2007, from which an analytic sample of 73,308 participants
remained after exclusions.
EXPOSURES: Diet was assessed at baseline by a quantitative food frequency
questionnaire and categorized into 5 dietary patterns: nonvegetarian,
semi-vegetarian, pesco-vegetarian, lacto-ovo-vegetarian, and vegan.
MAIN OUTCOME AND MEASURE: The relationship between vegetarian dietary patterns
and all-cause and cause-specific mortality; deaths through 2009 were identified
from the National Death Index.
RESULTS: There were 2570 deaths among 73,308 participants during a mean follow-up
time of 5.79 years.. The mortality rate was 6.05 (95% CI, 5.82-6.29) deaths per
1000 person-years.. The adjusted hazard ratio (HR) for all-cause mortality in all
vegetarians combined vs nonvegetarians was 0.88 (95% CI, 0.80-0.97).. The adjusted
HR for all-cause mortality in vegans was 0.85 (95% CI, 0.73-1.01); in
lacto-ovo-vegetarians, 0.91 (95% CI, 0.82-1.00); in pesco-vegetarians, 0.81 (95%
CI, 0.69-0.94); and in semi-vegetarians, 0.92 (95% CI, 0.75-1.13) compared with
nonvegetarians.. Significant associations with vegetarian diets were detected for
cardiovascular mortality, noncardiovascular noncancer mortality, renal mortality,
and endocrine mortality.. Associations in men were larger and more often
significant than were those in women.
CONCLUSIONS AND RELEVANCE: Vegetarian diets are associated with lower all-cause
mortality and with some reductions in cause-specific mortality.. Results appeared
to be more robust in males.. These favorable associations should be considered
carefully by those offering dietary guidance.
PMCID: PMC4191896
PMID: 23836264


[2] Cancer Epidemiol Biomarkers Prev. 2013 Feb;22(2):286-94. doi:

10.1158/1055-9965.EPI-12-1060. Epub 2012 Nov 20.

Vegetarian diets and the incidence of cancer in a low-risk population.

Tantamango-Bartley Y(1), Jaceldo-Siegl K, Fan J, Fraser G.

Author information:
(1)Department of Epidemiology and Biostatistics, Loma Linda University, School of
Public Health, Loma Linda, CA 92350, USA. ytantamango@hotmail.com

BACKGROUND: Cancer is the second leading cause of death in the United States.
Dietary factors account for at least 30% of all cancers in Western countries. As
people do not consume individual foods but rather combinations of them, the
assessment of dietary patterns may offer valuable information when determining
associations between diet and cancer risk.
METHODS: We examined the association between dietary patterns (non-vegetarians,
lacto, pesco, vegan, and semi-vegetarian) and the overall cancer incidence among
69,120 participants of the Adventist Health Study-2. Cancer cases were identified
by matching to cancer registries. Cox proportional hazard regression analysis was
conducted to estimate hazard ratios, with "attained age" as the time variable.
RESULTS: A total of 2,939 incident cancer cases were identified. The multivariate
HR of overall cancer risk among vegetarians compared with non-vegetarians was
statistically significant [hr, 0.92; 95% confidence interval (CI), 0.85-0.99] for
both genders combined.
 Also, a statistically significant association was found
between vegetarian diet and cancers of the gastrointestinal tract (HR, 0.76; 95%
CI, 0.63-0.90). When analyzing the association of specific vegetarian dietary
patterns, vegan diets showed statistically significant protection for overall
cancer incidence (HR, 0.84; 95% CI, 0.72-0.99) in both genders combined
 and for
female-specific cancers (HR, 0.66; 95% CI, 0.47-0.92). Lacto-ovo-vegetarians
appeared to be associated with decreased risk of cancers of the gastrointestinal
system (HR, 0.75; 95% CI, 0.60-0.92).
CONCLUSION: Vegetarian diets seem to confer protection against cancer.
IMPACT: Vegan diet seems to confer lower risk for overall and female-specific
cancer than other dietary patterns. The lacto-ovo-vegetarian diets seem to confer
protection from cancers of the gastrointestinal tract.

PMCID: PMC3565018
PMID: 23169929

Link to comment
Share on other sites

  • 6 months later...

This is another analysis of the health of different kinds of vegetarians versus different kinds of non-vegetarians.



A collaborative analysis of data from the first five studies listed in Table 1, published in 1999, found no significant difference in death rates between vegetarians and non-vegetarians for cancers of the stomach, colorectum, lung, breast or prostate( 20 ). This analysis did not examine overall cancer mortality, but a subsequent analysis of mortality in AHS-2 found no significant difference in overall cancer mortality between vegetarians and non-vegetarians( 41 ).

For cancer incidence, information on site-specific cancer incidence comes from a pooled analysis of nearly 5000 incidence cancers using data from the EPIC-Oxford and Oxford Vegetarian studies( 42 ). In this analysis, the non-vegetarians were subdivided into meat eaters and fish eaters (who ate fish but not meat) and incidence rates compared across the three diet groups. Significant heterogeneity of risk between the diet groups were found for the following cancers: stomach cancer, with lower risk in vegetarians (relative risk and 95 % CI compared with meat eaters 0·37, 0·19, 0·69); colorectal cancer, with lower risk in fish eaters (0·66, 0·48, 0·92) but not in vegetarians; cancers of the lymphatic and hematopoietic tissues, with lower risk in vegetarians (0·64, 0·49, 0·84), largely due to a significantly lower risk of multiple myeloma in vegetarians (0·23, 0·09, 0·59). There were no significant differences in incidence rates for other common cancers sites including the breast and prostate. Overall cancer incidence rates were significantly lower in both fish eaters (relative risk and 95 % CI compared with meat eaters 0·88, 0·80, 0·97) and in vegetarians (0·88, 0·82, 0·95). When the vegetarians were subdivided into lacto-ovo-vegetarians and vegans, risks for all cancers combined relative to meat eaters were statistically significant (0·89, 0·83, 0·96 for lacto-ovo-vegetarians and 0·81, 0·66, 0·98 for vegans). Further adjustment for BMI made little difference to the relative risks, and the associations remained statistically significant.

Analyses of the incidence of cancer in relation to diet group have also been reported for AHS-2( 43 , 44 ). Colorectal cancer incidence was compared across five diet groups; the lowest risk was found among fish eaters (described as pesco-vegetarians in the study), with an adjusted relative risk for all colorectal cancers of 0·57 (95 % CI 0·40, 0·82) compared with non-vegetarians( 44 ). Risks were non-significantly lower than in non-vegetarians for semi-vegetarians (who ate meat at least once per month but not more than once per week), lacto-ovo-vegetarians and vegans (relative risks and 95 % CI 0·92, 0·62, 1·37; 0·82, 0·65, 1·02; and 0·84, 0·59, 1·19, respectively). When the vegetarian groups, including the fish eaters, were combined, the relative risk compared with the non-vegetarians was 0·78 (95 % CI 0·64, 0·95)( 44 ). For all cancers combined, the incidence in comparison with non-vegetarians was 0·98 (95 % CI 0·82, 1·17) for semi-vegetarians, 0·88 (95 % CI 0·77, 1·01) for fish eaters, 0·93 (95 % CI 0·85, 1·02) for lacto-vegetarians and 0·84 (95 % CI 0·72, 0·99) for vegans, with a significantly lower risk for all vegetarian groups combined (relative risk and 95 % CI 0·92, 0·85, 0·99)( 43 ).

Breast cancer incidence was also compared across four diet groups in the UK Women's Cohort study: red meat eaters, poultry eaters (who did not eat red meat), fish eaters (who did not eat meat) and vegetarians( 45 ). In pre-menopausal women there were no differences in risk between the diet groups. In postmenopausal women fish eaters but not vegetarians had lower risks compared with meat eaters (relative risks and 95 % CI 0·60, 0·38, 0·96; and 0·85, 0·58, 1·25, respectively).

In summary, there is some evidence that the risk for cancer at all sites combined is slightly lower in vegetarians than in non-vegetarians, and that people who eat fish but not meat may have a lower risk of colorectal cancer, but the findings for other individual cancer sites are inconclusive."


"All-cause mortality and life expectancy


In the pooled analysis of mortality in five prospective studies in 1999, the death rate ratio in vegetarians compared with non-vegetarians, based on a total of 8330 deaths, was 0·95 (95 % CI 0·82, 1·11)( 20 ). However, the death rate ratios for vegetarians compared with non-vegetarians varied between studies from 0·80 to 1·17, and the test for heterogeneity between studies was highly significant (P < 0·0001). When the diet groups were subdivided, all-cause mortality was significantly lower in occasional meat eaters (death rate ratio and 95 % CI 0·84, 0·77, 0·90), fish eaters (0·82, 0·77, 0·96), and lacto-ovo-vegetarians (0·84, 0·74, 0·96), but not in vegans (1·00, 0·70, 1·44) compared with regular meat eaters (defined as those eating meat at least once per week)( 20 ). Subsequent analyses of mortality data from the EPIC-Oxford and AHS-2 studies, based on 1513 and 2570 deaths, respectively, produced contrasting results. In EPIC-Oxford, there was no significant difference in all-cause mortality between vegetarians and non-vegetarians (death rate ratio and 95 % CI 1·05, 0·93, 1·19)( 40 ). When the non-vegetarians in this study were subdivided as meat eaters and fish eaters (who ate fish but not meat) the death rate ratios compared with meat eaters were 0·89 (95 % CI 0·75, 1·05) in fish eaters and 1·03 (95 % CI 0·90, 1·16) in vegetarians. Analyses in both AHS and AHS-2 have shown lower mortality in vegetarians and semi-vegetarians combined than in non-vegetarians( 57 , 41 ); in AHS-2, death rate ratios in semi-vegetarians, fish eaters, lacto-ovo-vegetarians and vegans compared with non-vegetarians were 0·92 (95 % CI 0·75, 1·13), 0·81 (0·69, 0·94), 0·91 (0·82, 1·00), and 0·85 (0·73, 1·01), respectively( 41 ).

In the analysis of mortality data from the EPIC-Oxford study, standardised mortality ratios relative to the UK population for all causes of death were 52 % for both vegetarians and non-vegetarians( 40 ). Low mortality relative to the general population is a common finding in prospective cohort studies owing to the ‘healthy volunteer effect’, partly as a consequence of healthy lifestyle choices such as the avoidance of tobacco( 17 , 13 ), but the strikingly low mortality of both vegetarians and non-vegetarians in EPIC-Oxford does suggest that the general health of both groups is good."


The long-term health of vegetarians and vegans.

Appleby PN, Key TJ.

Proc Nutr Soc. 2016 Aug;75(3):287-93. doi: 10.1017/S0029665115004334.

PMID: 26707634



Vegetarians, who do not eat any meat, poultry or fish, constitute a significant minority of the world's population. Lacto-ovo-vegetarians consume dairy products and/or eggs, whereas vegans do not eat any foods derived wholly or partly from animals. Concerns over the health, environmental and economic consequences of a diet rich in meat and other animal products have focussed attention on those who exclude some or all of these foods from their diet. There has been extensive research into the nutritional adequacy of vegetarian diets, but less is known about the long-term health of vegetarians and vegans. We summarise the main findings from large cross-sectional and prospective cohort studies in western countries with a high proportion of vegetarian participants. Vegetarians have a lower prevalence of overweight and obesity and a lower risk of IHD compared with non-vegetarians from a similar background, whereas the data are equivocal for stroke. For cancer, there is some evidence that the risk for all cancer sites combined is slightly lower in vegetarians than in non-vegetarians, but findings for individual cancer sites are inconclusive. Vegetarians have also been found to have lower risks for diabetes, diverticular disease and eye cataract. Overall mortality is similar for vegetarians and comparable non-vegetarians, but vegetarian groups compare favourably with the general population. The long-term health of vegetarians appears to be generally good, and for some diseases and medical conditions it may be better than that of comparable omnivores. Much more research is needed, particularly on the long-term health of vegans.


AHS-2 Adventist Health Study-2; EPIC-Oxford; European Prospective Investigation into Cancer and Nutrition-Oxford; Morbidity; Mortality; Vegan; Vegetarian

Link to comment
Share on other sites


This topic is now archived and is closed to further replies.

  • Create New...