Does protein cause cancer?

michael300891

I am absolutely fed up with the number of posts on here, re-quoting the media headlines about animal protein increasing cancer risk as much as smoking. (Original study: http://www.cell.com/cell-metabolism/abstract/S1550-4131(14)00062-X)

I would like to demonstrate why the conclusions of the study are void, the media headlines are ridiculous, and hopefully nip this story in the bud for good! (I have used the quotation feature for emphasis only)

The Study:

- The study found that high animal protein intake between the age of 50-65 correlated to increased risk of mortality (including cancer mortality)

- Interestingly, at age 66+ this effect was entirely reversed, with protein providing a protective effect against cancer and mortality

- The effect was only significant for animal protein and dissipated when animal protein was factored out.

- The authors ' validated ' their study by cause and effect animal work



The reality:

Why we can not conclude protein causes cancer in humans:
- The study found no effect of protein on mortality in those over age 50 when considered as a whole. Thus the media headline should have been "Protein does not cause cancer". But of course thats too boring.

- This was a correlational study. No cause and effect can be established. You can not conclude from this study that protein causes cancer. It is as simple as that.

- The study used a 24 hour recall, once, before and after 18 years of follow-up. Tell me, if someone asked you what you had to eat yesterday, would it really be representative of the next 18 years of your life? Not to mention the well-documented issues of undereporting food intake with this method (1) (These people apparently survived for 18 years of an average of 1800 kcal). In other words, the classification of individuals by protein group, is invalid.

- The study did not to any extent account for confounding factors that may affect cancer risk such as exercise, lifestyle, smoking habits, alcohol etc). So we cannot be sure protein was actually causing the ‘effect’ (2,3,4).




Why the animal work does not apply to human research:
- First up, rodents are not humans. While that may seem obvious, you can induce diabetes in a healthy rat in 48 hours. Knowing that, can a 39 day study where they gave an enormously high dose of protein to a rodent (who typically live off almost entirely a very high carbohydrate diet) really be applied to findings from an 18 year longitudinal study in humans? No is the simple answer. All you can really conclude is that a high protein diet is inappropriate for rodents.

- Next up, in the rodent work they implanted cancer cells, they did not measure incidence of cancer. In other words, they gave rodents both protein and cancer, and measured the growth of the cancer. Even accepting the animal conclusions, you can only conclude that a high protein diet increases the GROWTH of cancer and not CAUSES cancer, as media headlines would suggest. Interestingly, the occurrence of cancer is modulated by many things including immune health, which is supported by a high protein intake (5).



Why we should still consume a moderate-high protein diet:

Whilst this single paper suggests protein may increase cancer risk in 50-65 year olds, this fails to consider the wider importance of protein within the diet. A high protein diet is important for muscle mass particularly in the elderly (6) and muscle mass correlates to reduced cancer mortality across all age groups (7). In other words, consuming protein causes cancer but not consuming protein causes cancer! In addition, what will fill the energy gap of a lower protein intake – the author’s suggest carbohydrate but this is already known to be driving the obesity epidemic (8) and thus associated health outcomes such as cardiovascular disease (9).



Concerns over the intentions of the author:

- Delving a little deeper into the paper, it is apparent that the author’s have tried very hard to find something wrong with protein.

- They first look at diabetes and protein, but find no effect.

- Then they look at protein intake across the entire over 50 population and find no effect.

- At this point, they have their data infront of them, and arbitrarily choose the 50-65 sample to run against the 66+ sample. Why did they choose 50-65 and not 50-70? Undoubtedly because there was no significant effect in the later group. Im still yet to determine how protein gives you cancer at age 65 but suddenly prevents it at age 66?

- Also, the authors how now run 3 statistical models. As a function of the mathematics, one in twenty statistical models provide a false positive finding. How many did they really conduct before finding a sub-set population in which ‘protein did something bad’.

- As for the animal vs plant stuff, this is because animal protein was the larger proportion of protein intake. If you mathematically factor this out, the effects will of course dissipate making animal protein look like the enemy.

So why would someone go to so much effort to make animal protein look bad?

Well the head author is the founder of L-Nutra, a company who sell low-protein plant supplements (10). What a coincidence!

Take Home Message:

When it comes to nutrition, media outlets love a good controversial story. They’ve hated on fats for 30+ years, the big enemy now is carbohydrates, and this was their shot to take down protein. Considering that just about every media outlet in the world featured a title comparing protein intake to smoking, yet smoking wasn’t even examined in the study, just demonstrates that the journalists didn’t even bother to ready the study!

Educate yourself from more reliable sources than fox news or the guardian. Consume a balanced and varied diet.

As for protein intake: Whilst this single flawed study suggests protein could be harmful in 50-65 year olds, there is a wealth of much stronger and established evidence of protein’s importance within the diet to health across all age groups.



Let me know your thoughts on this article.



References:
(1) Klesges RC, Eck LH, Ray JW. Who underreports dietary intake in a dietary recall? Evidence from the Second National Health and Nutrition Examination Survey. J Consult Clin Psychol 1995;63(3):438.
(2) Saxton J. Exercise and Cancer Mortality. Exercise and Cancer Survivorship: Springer; 2010. p. 189-210.
(3) McLaughlin JK, Hrubsec Z, Blot WJ, Fraumeni JF. Smoking and cancer mortality among US veterans: A 26‐year follow‐up. International journal of cancer 1995;60(2):190-193.
(4) Tsugane S, Fahey MT, Sasaki S, Baba S. Alcohol consumption and all-cause and cancer mortality among middle-aged Japanese men: seven-year follow-up of the JPHC study Cohort I. Japan Public Health Center. Am J Epidemiol 1999 Dec 1;150(11):1201-1207.
(5) Daly JM, REYNOLDS J, SIGAL RK, SHOU J, LIBERMAN MD. Effect of dietary protein and amino acids on immune function. Crit Care Med 1990;18(2):S94.
(6) Paddon-Jones D, Short KR, Campbell WW, Volpi E, Wolfe RR. Role of dietary protein in the sarcopenia of aging. Am J Clin Nutr 2008 May;87(5):1562S-1566S.
(7) Ruiz JR, Sui X, Lobelo F, Morrow JR,Jr, Jackson AW, Sjostrom M, et al. Association between muscular strength and mortality in men: prospective cohort study. BMJ 2008 Jul 1;337:a439.
(8) Srikanthan P, Karlamangla AS. Relative muscle mass is inversely associated with insulin resistance and prediabetes. Findings from the third National Health and Nutrition Examination Survey. The Journal of Clinical Endocrinology & Metabolism 2011;96(9):2898-2903.
(9) Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. Saturated fat, carbohydrate, and cardiovascular disease. Am J Clin Nutr 2010 Mar;91(3):502-509.
(10) L-Nutra. L-Nutra. Available at: http://www.l-nutra.com/

---

Doctoral Researcher in Exercise Metabolism and Adaptation

Feel free to add me or ask any questions if you wish

kimmieb2u

Loved your post! I'm "sick to death" (lol) of stupid NEW and AMAZING "studies".

Habiteer

You explained it pretty well to me. I mostly feel that the main problem is sensationalism of the media. There just isn't strong enough evidence which would need to come from well-designed studies.

Bagelsan

Cells are made out of protein, cancer come from cells, therefore protein causes cancer. ...Is about the only refutation I can offer. ;p

In other words, you nailed it!

AwesomeGuy37

Have you seen the stuff about water causing cancer? Man I can't believe any of these things people say on the interwebs.

Bagelsan

Other things that cause cancer: exercise, toast, breathing, "chemicals", food groups, small dogs... if you live long enough you're gonna get cancer, and usually your immune system will kill it before you ever find out.

HollisGrant

My late husband dealt with prostate cancer for 13 years. I remember a lecture we attended at Georgetown Hospital's Lombardi Cancer Center in Washington, D.C. My husband's oncologist, Dr. Edward Gellman, was one of the speakers.

About animal protein and cancer:

Dr. Gellman said that diet appears to play a large part in prostate cancer. Men who eat a diet heavy in red meat and dairy get the disease at far higher rates than men who eat a diet with fish, vegetable protein like beans, and no dairy. Men in countries with the fish/veg/no dairy diet get prostate cancer at the same rate as men in the west when they move to countries like the United States and adopt a western style diet. Yes, studies were mentioned at the lecture, but I attended it years ago and don't have that information.

ComradeTovarich

At the rate they find new information about stuff that causes cancer, you think I'd be a walking tumor by now. Can't wait for the headline that states "Living causes cancer." Good post dude.

SquidVonBob

Holy crab you cited your sources. Don't you know citing sources on the internet is illegal. How am I supposed to take you seriously if you're just stealing other peoples data and not making your own? Cheater.

arcana7609

I am absolutely fed up with the number of posts on here, re-quoting the media headlines about animal protein increasing cancer risk as much as smoking. (Original study: http://www.cell.com/cell-metabolism/abstract/S1550-4131(14)00062-X)

Great explanation. If I were a scientist I would be fed up with these sort of sensationalist studies grabbing headlines, because it makes scientists look like idiots. Most people don't trust this sort of side show medicine show, which is what these studies are.

michael300891

Great comments on here guys,

Sorry for using references I realise that’s against the internet rules :P

My late husband dealt with prostate cancer for 13 years. I remember a lecture we attended at Georgetown Hospital's Lombardi Cancer Center in Washington, D.C. My husband's oncologist, Dr. Edward Gellman, was one of the speakers.

About animal protein and cancer:

Dr. Gellman said that diet appears to play a large part in prostate cancer. Men who eat a diet heavy in red meat and dairy get the disease at far higher rates than men who eat a diet with fish, vegetable protein like beans, and no dairy. Men in countries with the fish/veg/no dairy diet get prostate cancer at the same rate as men in the west when they move to countries like the United States and adopt a western style diet. Yes, studies were mentioned at the lecture, but I attended it years ago and don't have that information.

Really sorry to hear about your husband. The theories about protein are certainly not new so I don’t doubt this lecture at all and the evidence does show in a role of protein in some animal models. However, there’s been a lot of research into it and nothing translates into humans. Whilst it’s not impossible, the study published which is making media headlines is rubbish and doesn’t show anything. If you want to avoid meat out of personal preference, or even because of (unfounded in humans) cancer concerns that’s fine, but just don’t do it off the back of this publication is all im saying ☺

At the rate they find new information about stuff that causes cancer, you think I'd be a walking tumor by now. Can't wait for the headline that states "Living causes cancer." Good post dude.

Yes that would be a great headline. I haven’t found one that good for you but this one is brilliant:


For anyone who is still unsure if protein causes cancer, here’s a great fox news spin on the story:









Whenever I see some truly awful Fox headline I just think of family guy.

amflautist

Let me know your thoughts on this article.

What - UCLA? I expect better. Isn't this a refereed journal?

Charlottesometimes23

I am absolutely fed up with the number of posts on here, re-quoting the media headlines about animal protein increasing cancer risk as much as smoking. (Original study: http://www.cell.com/cell-metabolism/abstract/S1550-4131(14)00062-X)

I would like to demonstrate why the conclusions of the study are void, the media headlines are ridiculous, and hopefully nip this story in the bud for good! (I have used the quotation feature for emphasis only)

The Study:

- The study found that high animal protein intake between the age of 50-65 correlated to increased risk of mortality (including cancer mortality)

- Interestingly, at age 66+ this effect was entirely reversed, with protein providing a protective effect against cancer and mortality

- The effect was only significant for animal protein and dissipated when animal protein was factored out.

- The authors ' validated ' their study by cause and effect animal work



The reality:

Why we can not conclude protein causes cancer in humans:
- The study found no effect of protein on mortality in those over age 50 when considered as a whole. Thus the media headline should have been "Protein does not cause cancer". But of course thats too boring.

It's a rather big call saying that the conclusions of the study are void. I would agree that it's been sensationalised in the media (which is common in science reporting) but I certainly won't be writing it off for a number of reasons:

It was published in a very high impact factor journal, which in my mind, generally means it's gone through a pretty rigourous process of peer review.

While I agree that correlation studies can find all sorts of erroneous links, this one used a pretty reasonable regression type analysis method that adjusted for a large range of possible confounders, including smoking. While they found no effect of protein on mortality in those over age 50 when considered as a whole, when they stratified their sample according to age range, there was a significantly increased risk of cancer for those 50-65, in fact 4x the risk in the high protein group.

- The study used a 24 hour recall, once, before and after 18 years of follow-up. Tell me, if someone asked you what you had to eat yesterday, would it really be representative of the next 18 years of your life? Not to mention the well-documented issues of undereporting food intake with this method (1) (These people apparently survived for 18 years of an average of 1800 kcal). In other words, the classification of individuals by protein group, is invalid.

- The study did not to any extent account for confounding factors that may affect cancer risk such as exercise, lifestyle, smoking habits, alcohol etc). So we cannot be sure protein was actually causing the ‘effect’ (2,3,4).

While the study used a 24 hour recall, many of those were ‘usual intake’. Underreporting is an issue, I agree, however in reality, the participants may have been consuming even greater amounts of protein.

The study absolutely did take counfounders into effect and adjusted accordingly. See the description of their model in table 1. “Adjusted for age, sex, race/ethnicity, education, waist circumference, smoking, chronic conditions (diabetes, cancer, myocardial infarction), trying to lose weight in the last year, diet changed in the last year, reported intake representative of typical diet, and total calories. Model 2: Adjusted for covariates and % kcals from total fat. Model 3: Adjusted for covariates and % kcals from total carbohydrates. Model 4: Adjusted for covariates and % kcals from animal protein”

Why the animal work does not apply to human research:
- First up, rodents are not humans. While that may seem obvious, you can induce diabetes in a healthy rat in 48 hours. Knowing that, can a 39 day study where they gave an enormously high dose of protein to a rodent (who typically live off almost entirely a very high carbohydrate diet) really be applied to findings from an 18 year longitudinal study in humans? No is the simple answer. All you can really conclude is that a high protein diet is inappropriate for rodents.

- Next up, in the rodent work they implanted cancer cells, they did not measure incidence of cancer. In other words, they gave rodents both protein and cancer, and measured the growth of the cancer. Even accepting the animal conclusions, you can only conclude that a high protein diet increases the GROWTH of cancer and not CAUSES cancer, as media headlines would suggest. Interestingly, the occurrence of cancer is modulated by many things including immune health, which is supported by a high protein intake (5).

The point of the animal study was not to replicate the human condition, but to examine the possible mechanistic aspects of how dietary protein can stimulate tumourogenesis and tumour progression……which it did when they implanted melanoma and breast cancer cells. IGF1 has been associated with cancer in a number of studies and therefore it’s a reasonable step to look at protein intake, IGF1 and IGFBP-1 and influence on tumour cells in a mouse model as a predictor of what could be happening at a molecular level.

Concerns over the intentions of the author:

- Delving a little deeper into the paper, it is apparent that the author’s have tried very hard to find something wrong with protein.

- They first look at diabetes and protein, but find no effect.

- Then they look at protein intake across the entire over 50 population and find no effect.

- At this point, they have their data infront of them, and arbitrarily choose the 50-65 sample to run against the 66+ sample. Why did they choose 50-65 and not 50-70? Undoubtedly because there was no significant effect in the later group. Im still yet to determine how protein gives you cancer at age 65 but suddenly prevents it at age 66?

- Also, the authors how now run 3 statistical models. As a function of the mathematics, one in twenty statistical models provide a false positive finding. How many did they really conduct before finding a sub-set population in which ‘protein did something bad’.

Perhaps, but this is an issue with most statistical analysis in research and we aren’t aware whether there was correction for multiple analyses, if they ran just 3 models, or if correction was built into the model.

I’m also yet to determine why this particular age group is more at risk, however there was never any claim that “protein gives you cancer” at any age…..you have overstated this (like the media).

As for protein intake: Whilst this single flawed study suggests protein could be harmful in 50-65 year olds, there is a wealth of much stronger and established evidence of protein’s importance within the diet to health across all age groups.

I absolutely disagree that this is a ‘flawed’ study. Certainly it has limitations, but the authors acknowledge most of them. Let’s be real here, ALL research has limitations. It’s the nature of the research process, whether it be statistical models, recruitment, participant adherence, issues with reagents etc etc …..the list goes on

In my opinion, the study has a lot of strengths and I will be very interested to see follow-up related studies. I consume relatively high protein and I’m in the risk group, so I’ll be watching similar work with great interest. I won’t be changing my diet to any great degree at this stage (although I may sub in some more vege protein).

If I get a chance, I’ll post a few studies I’ve been looking at re cancer and diet (particularly high animal protein). I look at it for more of a molecular/genetic aspect so I’ll try no to bore anyone to tears. :laugh:

Rocbola

My late husband dealt with prostate cancer for 13 years. I remember a lecture we attended at Georgetown Hospital's Lombardi Cancer Center in Washington, D.C. My husband's oncologist, Dr. Edward Gellman, was one of the speakers.

About animal protein and cancer:

Dr. Gellman said that diet appears to play a large part in prostate cancer. Men who eat a diet heavy in red meat and dairy get the disease at far higher rates than men who eat a diet with fish, vegetable protein like beans, and no dairy. Men in countries with the fish/veg/no dairy diet get prostate cancer at the same rate as men in the west when they move to countries like the United States and adopt a western style diet. Yes, studies were mentioned at the lecture, but I attended it years ago and don't have that information.

Doctors know the truth. They see it all the time. The food industry, especially meat and dairy, loves to defend their products, and one inexpensive method they use is to come onto sites like this one and try to convince you that there is no problem with eating their food. (Move along, nothing to see here...)

Booksandbeaches

Thanks for posting..subscribing so I can read it in the morning.

tennisdude2004

Yeh thanks for posting this:mad:

How am I supposed to sell my L-Nutra shakes now.

Thanks for nothing.

Blokeypoo

I'm enjoying this from a research nurse perspective, good read

It's a shame that, what often was "just" someone's PhD work (I'm not referring to this case) now gets swept across the web/press and quoted as the latest advice. It dilutes those studies which might be in a different league although as already mentioned, no study is flawless.

Dewymorning

I'm enjoying this from a research nurse perspective, good read

It's a shame that, what often was "just" someone's PhD work (I'm not referring to this case) now gets swept across the web/press and quoted as the latest advice. It dilutes those studies which might be in a different league although as already mentioned, no study is flawless.

I wrote a report in which I said "x is 1/3 larger than y" and it got quoted by a media report that "x is 3 times larger than y"

1/3 =/= 3

spg71

People are living longer, body`s get older, Cancer`s becomes more prevalent along with a multitude of other things, liver, kidneys etc

Everything we do gives us CANCER if you would belive everything they tell you. One thing is certain. YOU WILL DIE, dont be sad about it, embrace it, prevent it if you want, but it will catch up with youl.

Anyway a chart.

http://www.theguardian.com/news/datablog/2011/oct/28/mortality-statistics-causes-death-england-wales-2010#zoomed-picture

snowflake954

My late husband dealt with prostate cancer for 13 years. I remember a lecture we attended at Georgetown Hospital's Lombardi Cancer Center in Washington, D.C. My husband's oncologist, Dr. Edward Gellman, was one of the speakers.

About animal protein and cancer:

Dr. Gellman said that diet appears to play a large part in prostate cancer. Men who eat a diet heavy in red meat and dairy get the disease at far higher rates than men who eat a diet with fish, vegetable protein like beans, and no dairy. Men in countries with the fish/veg/no dairy diet get prostate cancer at the same rate as men in the west when they move to countries like the United States and adopt a western style diet. Yes, studies were mentioned at the lecture, but I attended it years ago and don't have that information.

I found it very interesting here in Italy that the head oncologist, also a Minister of Health for a few years, and the owner of several large oncology clinics quietly announced that he doesn't eat meat (this after he retired from the ministery). He was pressed by the journalists on this issue for quite a while. While he had the government position, nothing was said--the meat lobby is very powerful. By the way, I do eat meat, although I limit it, prefering other protien sources. My husband, on the other hand, has never eaten meat--spit it out as a kid. He has always been slim and the picture of health.

Greytfish

My late husband dealt with prostate cancer for 13 years. I remember a lecture we attended at Georgetown Hospital's Lombardi Cancer Center in Washington, D.C. My husband's oncologist, Dr. Edward Gellman, was one of the speakers.

About animal protein and cancer:

Dr. Gellman said that diet appears to play a large part in prostate cancer. Men who eat a diet heavy in red meat and dairy get the disease at far higher rates than men who eat a diet with fish, vegetable protein like beans, and no dairy. Men in countries with the fish/veg/no dairy diet get prostate cancer at the same rate as men in the west when they move to countries like the United States and adopt a western style diet. Yes, studies were mentioned at the lecture, but I attended it years ago and don't have that information.

I'm so sorry for your loss.

Even that generalization about diet (which I've seen before and don't recall any of the studies controlling well for the other factors that tend to go along with men who eat diets high in red meat and dairy) supports the OP's position. Fish is quite obviously an animal protein. Cultures with fish heavy diets tend to have much, much higher levels of Omega 3s and to the extent they eat red meat, don't consume red meat raised on feed lot GMO corn. A grass raised ungulate will have muscle mass that carries a balance level of omega 3/6. If you add to that fish high in omega 3s you get a diet high in antioxidants and general improvement of the immune system.

lizzyclatworthy

Doctors know the truth. They see it all the time. The food industry, especially meat and dairy, loves to defend their products, and one inexpensive method they use is to come onto sites like this one and try to convince you that there is no problem with eating their food. (Move along, nothing to see here...)

OP just got called a big meat shill. This is a good day. Welcome to the shilling family. (I have been accused of being a shill for 'big pharma' maybe you are a shill for 'big farmer') :laugh: