Last week saw the emergence of some news reports (example here) regarding research which linked the eating of processed meat. The study looked at the relationship between dietary habits and risk of death from a variety of causes in a group of people pooled from 10 European countries [1]. Analysis occurred over an average of about 13 years.
After adjustments making adjustments for factors which can bias results (including so-called ‘confounding factors’ such as body weight, exercise and smoking), red meat was not found to be associated with an increased risk of death, but processed meat was. Here’s a summary of their findings:
These findings show that for each 50 g portion of processed meat eaten each day, overall risk of death was 18 per cent higher. The researchers went from here to make their prediction regarding restricted processed meat consumption and the lives this would save.
This study, however, has the same fundamental weakness that all studies of this type (epidemiological studies) have: that they can only tell us about associations between things. Even if two things are associated with each other, that does not mean that one is causing the other. It doesn’t matter how many statistical adjustments one makes, this inherent weakness in such studies does not go away.
As it happens, I am suspicious of processed meats myself. It’s not so much the meat that bothers me, but the usual presence in them of preservative chemicals (specifically nitrites) that appear to have the capacity to harm (they’ve been implicated cancer, for instance). My instinct and first principles tell me that it’s probably not a good idea to be ramming myself full of bacon, sausage and salami.
However, I do eat these foods. But I eat them in the context of a diet in which the vast majority of what I eat is ‘natural’ and unprocessed. Meat (including red meat), fish, seafood, vegetables, nuts and seeds make up the bulk of my diet. The presence of occasional processed meat in it is not, in my view, likely to jeopardise my health too much, particularly if I am also looking after other key lifestyle factors such as activity and sleep.
As it happens, since this study was published, another study emerged which suggests that the presence of processed meat in a diet may indeed not ring the ring knell for us.
This study concentrated on a large group of men and women in the US [2]. The data was extracted from what is known as the NHANES III (National Health and Nutrition Examination Survey III). After adjusting for confounding factors, here’s what the researchers found:
In other words, eating more red and processed meat was not associated with an elevated risk of death. Incidentally, this newest study was performed by the same group of researchers in Switzerland that produced the earlier one which got the lion’s share of the press.
We have other evidence that supports the idea that some processed meat in the diet is not deadly in the form of studies which show that meat-eaters are at no heightened risk of death compared to vegetarians. It’s a fair assumption, I think, that the vast majority of meat-eaters consume some processed meat in addition to fresh meat.
This evidence, along with the most recent study from the US, suggest that the eating of red meat (including processed meat) is not associated with a greater risk of death. If that’s the case, then how bad can it be?
References:
1. Rohrmann S, et al. Meat consumption and mortality – results from the European Prospective Investigation into Cancer and Nutrition. BMC Medicine 2013, 11:63 (7 March 2013)
2. Kappeler R, et al. Meat consumption and diet quality and mortality in NHANES III. Eur J Clin Nutr. 2013 Mar 13. [Epub ahead of print]
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The developments and advances within the human origins program that study human evolution suggest we owe our distinctive morphology and supposed superior intelligence (as compared with other primates) to the consistent trend seen in our evolution of moving up the food chain. The idea, a false one, that saturated fat and cholesterol cause heart disease has been one great influence via which people have jumped upon the ‘vegetarianism is healthiest bandwagon’. But socio-economic factors have had a bearing upon this too. The agricultural inputs needed to produce food ‘higher up the food chain’ are greater when compared to those that produce food ‘lower down the food chain’ and this reflects in the price to the consumer at the point of sale. Given the gains in efficiency and energetics that associate with provisioning human food that have been made over the long run of time food ought to be both plentiful and affordable. But there are demographics of people, at home and abroad, for whom food of satisfactory quality is decreasingly affordable. Some of the multiples that serve the needs of these people entice them in with lots of promos of and deals around products in which wheat is the main constituent. (Muffins, doughnuts, crumpets, cookies, and the like).
The least well off in society, even in the developed world, are being driven back down the food chain. There is something of an ‘effect’ to be witnessed for which there is a ’cause’. The ’cause’ is identifiable, man-made, doesn’t get discussed so much as it ought, and results from the bipolar nature and distribution of a familiar entity.
Vegetarianism is an emotive matter involving complex moral issues, but if the ‘science’ is becoming more objective in its association with debate and policy that has to represent progress.
Mostly, for humanity’s prospects of security and well-being, we have to embrace natures expediencies and capitalise upon them as fully as we are able, when in actuality the people who have command over humanity’s adopted methodologies judge ‘security’ in alternate terms and so denigrate the human relationship with natural expediencies, in agriculture, process, and medicine. I wonder would you agree Dr Briffa?
I’ve always had concerns about the addition of Sodium Nitrate to processed meat products, used primarily I think to keep a pink colour (supposedly more appetising to the eye) to a product that would otherwise be a mucky beige colour. It is fairly easy to overdose on this kind of stuff … bacon for breakfast, ham butty for dinner, sausage for tea etc. I think it is a real worry.
It was interesting that the person being interviewed on TV about the harmful effects of processed meats, said she believed they were harmful because of the fat and salt levels in such foods. no mention of the preservative.
Just on the nitrate thing, Chris Kresser has done a bit of work on seeing science appears to show on that one: You might be surprised!
http://chriskresser.com/the-nitrate-and-nitrite-myth-another-reason-not-to-fear-bacon
Like so many “health myths” much of the original literature associating nitrates with cancer risk have been discredited by rigorous scientific peer review.
For every scare story and reseach paper, there are others showing no link between nitrates or nitrites and cancer.
Much like cholesterol (another demonised compound) nitrites are produced by the body. And in far greater amounts than you would get from your diet (whether you eat bacon or not) – salivary nitrite for example.
Also, what about veggies? Nobody picks on them yet many contain much,much larger amounts of nitrites than bacon. Celery, lettuce, beetoot etc.
The nitrates in betroot juice are even consumed as an ergogenic aid and work by reducing the metabolic cost of exersice (I consume beetroot juice for this reason). Hell, nitrites might even support immune and cardiovascular function.
So I’m not worried about nitrites / nitrates in bacon. I get more from veggies and my own spit!!
Plus my body is pretty darn clever – any excess that may occur is harmlessly excreted down my toilet bowl.
SmartEaters – thanks for the link. Interesting reading from Chris and helps give me more confidence I’m not killing myself with my occasional ‘full English’ breakfast.
Vitally, the study did NOT adjust for sugar, starch or any carbohydrate. Indeed, do a ctrl+f on the full study for any of those terms, or any related terms. Nothing!
Since processed meats are HIGHLY associated with processed carbs, this omission alone invalidates the study completely, even under its own terms.
SmartEaters – Thanks for the link to Chris Kresser’s article about nitrites/nitrates. Very informative.
This from Zoe Harcombe, who was actually part of the study…at least a bit
http://www.srl.cam.ac.uk/epic/images/ffq.pdf This is the questionnaire which the study used.
further pertinent comments: http://www.zoeharcombe.com/2013/03/meat-consumption-and-mortality/
The only concern with nitrates and nitrites in processed meat is their combination with certain amino acids to form nitrosamines. This process happens particularly under highly acidic conditions such as in the stomach. It can also happen lower down in the intestine where certain types of bacteria can create it. Other types of bacteria break it down into harmless by products.
However, we have eaten healthy greens full of nitrates with protein sources for millenia, Are nitrosamines really as bad for us as we are led to believe. The evidence is at best epidemiological and as Zoe Harcombe pointed out regarding the latest report, only those eating more than 160g per day of processed meat had any significant increase in risk.
It could well be that some of this risk relates to other substances such as benzpyrenes that are present in many smoked foods.
Either way the risk looks to me pretty small unless you are eating the stuff every day. I wrote a bit about the dangers of smoked and cured products a few month ago on my website at: http://www.drdobbin.co.uk/health-dangers-smoked-and-cured-products
Chris, What on earth does your last paragraph mean ? Simple English to communicate your point would be much better. No offence meant.
Life would not be worth living without bacon!
Dr Briffa:
Thanks for the info on statins. I’m trying to get my friends off of them, but it’s a hard sell.
Regarding nitrates and nitrites:
I’m also not concerned with nitrates or nitrites. Vegetables have many times the amounts as cured meats and as was stated in the article linked above: Your saliva has more than any food you might eat.
Not a problem.
Next issue…
One of my favorite breakfasts is scrambled eggs with bacon. I pour olive oil over the eggs. No, I don’t eat this everyday. Some days I eat only one meal late in the day. Of course this is breaking another rule of the “food police”–we should always eat breakfast.
People that consume a lot of carbohydrates need to eat breakfast because they have depleted their glycogen stores by morning. Because I consume a low carb, moderate protein, relatively high fat diet, I don’t experience much hunger even when I skip meals.
I agree with Dr. B–I’m not concerned abuut nitrates and nitrites in processed meats:
1.There are many hundreds of times higher concentrations of these compounds in plant foods (ounce for ounce, spinach contains 30-80 times more than hot dogs do). In fact many manufacturers who profess not to use nitrates/nitrites in their products use celery compounds instead and then print on their labels something like: “no nitrates or nitrites except those naturally occurring in celery powder.”
2. It is not the nitrates/nitrites that are potential carcinogens, it is, as others have pointed out above, the nitrosamines that they can form when they come into contact with proteins in our bodies and in our foods. http://diagnosisdiet.com/food/meats/
3. Fresh, unprocessed meats are always best, but for those of us who eat a low-carb Paleo diet, myself included, splurging on the occasional bit of processed meat still seems safer to me than splurging on refined carbs–of course I have no way of knowing for sure which indulgence is safer, but at least after eating bacon, I don’t have to wrestle with carb cravings for 48 hours afterwards:)
I read the tabloid reporting of this study. It indicated the number of early deaths (about 35,000 in the UK, but didn’t state how ‘early’ these deaths were). I did a ‘back of a fag packet’ calculation, and assumed that the deaths were about one year ‘early’.
In terms of average life expectancy, it worked out that if their statistics were correct, it would result in a shocking life shortening expectancy of about 10.5 days.
One could knit tofu, or suck mung been sprouts for years, sure in the knowledge that avoiding the odd bacon sandwich would result in a week and a half of extra life.
Clearly, the ‘early death statistics’ were well within statistical error margins and essentially meaningless, but it won’t stop the Daily Mail from publishing scare stories about ‘processed meat’.
To be really honest, I’m not really sure what ‘processed meat’ actually is. Anything that isn’t directly off a carcass is ‘processed’. And, as someone who makes his own bacon and salt beef from scratch occasionally, I feel a very strong obligation to use Prague Powder in order to avoid poisoning my entire family from botulism.
Surely botulism is a far higher threat for almost immediate death than the probability of a 11 day shorter lifespan?
Methinks that some scientists (aka statisticians) should get a proper job….
Thanks Salbobs from the Zoe Harcombe post.
Ah Hilda, you are so right, that last paragraph is cryptic.
Nature and evolution is responsible for making the rules that determines what works for us and what works for the grand ecology that supports us. We’re better suited and adapted to some things than we are to others. I am no Luddite, and I do not baulk at progress, but I increasingly appreciate that not all theoretical or practical advances are actually that progressive. Indeed some seem blatantly regressive. To fully explain this I’d have to discuss mineral cycles (Earthly and Universal), introduce ‘backward dependency’ and ‘economic democracy’ as unfamiliar terms and premises that bolster the argument. Here is not the place and now is not the time.
But risks are introduced when theory and practice takes insufficient account of natures ways, and when we think we can better nature. The importance of evolution and adaptation in determining how we fit in nature and within the natural order of things largely dictates that innovative ways will have intrinsic prospects of being maladaptive. The difference between adaptive and maladaptive being the root of many a risk.
The prevalence of financial-ism holds a certain appeal that is readily satisfied and greatly promotes the willingness to innovate, to sell a lie and to sell some product or service of the back of the lie. The vendor has one way to judge the appeal while the principle stakeholders (consumers) bear risks that may only manifest themselves further along the road of time. The vendors have retired upon the proceeds and have a villa in Florida. The appeal of innovation is greater than it ought to be, and it is judged upon the wrong terms.
Money is a great selection pressure that influences outcome. It’s not money per se so much as it is the features of the particular kind of money we happily use in everyday transactions. And I don’t advocate we do away with it. But if its faults were more commonly known and understood, and if companion currencies could be promoted and utilised more greatly than is the case now then my reasoning assures me this could be an influence for the better.
My wording was intentionally cryptic, I wouldn’t want to be branded as a revolutionary, when actually I believe it is possible to evolve our way away from many a man-made problem by decreasing the influence of that which drives us to them.
I cannot be concise and simple. Money in its present incarnation has a bearing over what people eat and a bearing over the health conditions they suffer. Many a mind will not accept that proposition without it being party to the rather long and involved string of reasoning that backs it up. Many a mind would struggle to follow the several steps in that string.
I was intentionally cryptic, if more cryptic than I could have been.
World War II arrived at a time when companion currencies could have alleviated great systemic duress.
Ask me no questions and I will tell you no lies.
Ask a person to limit an answer to the simple and concise and it greatly impedes prospects of describing something important and truthful. Our preference for simple and concise greatly raises prospects that the message will not be properly understood. “All flesh is grass” (Isaiah 40:6) being a case in point.
Four words point to the importance of backward dependency in the grand scheme of things. ‘Creatures’ had no future before the basic and lower level of the food-chain became established. The most basic of biology, really, Yet the faithful miss the meaning and implications.
Non taken and non intended.