Wednesday, March 21, 2012

Red Meat Consumption Linked To Earlier Death

The red meat study in the news:
Red Meat Consumption and Mortality, Results From 2 Prospective Cohort Studies, Archives of Internal Medicine, March 12, 2012

The participant pool was large: 37,698 men from the Health Professionals Follow-up Study, plus 83,644 women from the Nurses' Health Study. The follow-up was long: over 20 years.

It found the more red meat one consumed, the greater their risk of premature death from cancer, heart disease, and other causes. How much greater? After controlling for possible confounders,1 the risk of death was 13% greater for each serving of unprocessed red meat eaten in a day; 20% greater for processed meat.

Replacing meat with other sources of protein lowered risk:
"We estimated that substitutions of 1 serving per day of other foods (including fish, poultry, nuts, legumes, low-fat dairy, and whole grains) for 1 serving per day of red meat were associated with a 7% to 19% lower mortality risk.

We also estimated that 9.3% of deaths in men and 7.6% in women in these cohorts could be prevented at the end of follow-up if all the individuals consumed fewer than 0.5 servings per day (approximately 42 g/d) of red meat."
42 grams is about 1.5 ounces, or a couple big bites.

Here's a chart from the study. Kind of small but you can see that swapping any of these foods (nuts, legumes, low-fat dairy, whole grains, poultry, fish) for meat lowered risk. Look at that protection from replacing processed meat with nuts! (The further the black dot is to the left, the more protective that food was when eaten in place of meat.)

These were epidemiological studies, not more telling clinical trials. It would be a challenge to design and conduct a randomized controlled trial to test this hypothesis. How could you realistically get tens of thousands of people to eat the exact foods except for varying quantities of red meat? For 2 decades! So, these observational studies are useful, but not without their weaknesses.

The increases in risk, I thought, were small. Still, the trend was apparent, and dose dependent. There could always be an unaccounted confounder, though. Maybe those who ate more red meat slept less, had less restful sleep, had poor mental health (depression, anxiety, unmanaged stress, and curiously narcissism all impact health). Even poor dental hygiene has been linked to heart disease.

But it's fun to speculate. What could be making red meat so risky? Dr. Gregor offered a list of possible causes:
"I think the most interesting finding in the new Harvard studies is that even after factoring out known contributors of disease, such as saturated fat and cholesterol, they still found increased mortality risk, raising the question: what exactly is in the meat that is so significantly increasing cancer death rates, heart disease, and shortening people’s lives? A few possibilities include heme iron, nitrosamines, biogenic amines, advanced glycation end products, arachidonic acid, steroids, toxic metals, drug residues, viruses, heterocyclic amines, PCBs, dioxins, and other industrial pollutants."
1The results were adjusted for age; body mass index; alcohol consumption; physical activity level; smoking status; race; menopausal status and hormone use in women; family history of diabetes mellitus, myocardial infarction, or cancer; history of diabetes mellitus, hypertension, or hypercholesterolemia; and intakes of total energy, whole grains, fruits, and vegetables. ... So, for instance, it wasn't that those who ate more red meat also happened to consume fewer fruits and vegetables.


RB said...

The study is good news for me. I have greatly reduced my meat consumption. I switched to nuts (unsalted) and beans instead of a sandwich for lunch years ago. Before that, I switch from cold cuts to peanut butter for my sandwich.

Did the study mention fruits and veggies? I have a lot of those in my diet too. Blueberries at breakfast and an orange at lunch.

pronutritionist said...

"what exactly is in the meat that is so significantly increasing cancer death rates, heart disease, and shortening people’s lives?"

Even more intrestingly: What is it in processed meat that seems to do more harm than fresh red meat? After all, processed meat seems to be more unhealthy even with 50 % "doses" (45 g vs 85 g).

Anyway, it's not only saturated fat, for sure.

Bix said...

I agree with you, pronutritionist.

Laurie Endicott Thomas said...

It's not just saturated fat and the toxins dissolved in it. It's also absence of fiber and presence of too much "high-quality" protein. The overload of protein tends to cause the liver to secrete insulin-like growth factor 1, which is a powerful growth promotant for cancer cells. Also the cancer cells need protein to grow, just like regular tissue.

Even small amounts of animal-source food are bad for you.

Ben P. DaSalt said...

Assuming paleo/ancestral health crowd would even allow epidemiological evidence (many don’t since it’s correlation) they would say that the problem is industrial meat and if there were a study on pastured/free-range meat, things would be different.

Of course there is epidemiological data from other areas of the world that don’t have our system of meat production, and meat still garners an associated risk factor with certain diseases and decreased longevity.

As mentioned, cured meats seem to have very sharp risk increase and it's not clear that it has to do with industrial production per se, might even be the traditional curing methods. Whenever I read about paleo/ancestral health eating pattern, they seem to eat a lot of bacon and sausage (at events, in meal journals, etc.) which seems odd if meat is supposed to be consumed in a more natural state.

I can appreciate the idea that maybe straight cuts of clean meat don’t carry a high enough risk factor worth worrying about so long a other healthful lifestyle patterns are undertaken, but cured meat consistently scores a high enough risk factor association that can’t really be discounted as a data blip.

In other news, according to an Australian study:

Red Meat Makes Women Happy

The Telegraph

Daily Mail

My bet is that the same people that claim epidemiology is worthless, will be touting this study in the usual places. Correlation is not causation, unless it correlates with preconceived notions of course.

Bix said...

I did see that study about meat and depression in the Telegraph. Sure, it's small, 1000 women. But maybe there's something to it.

But I noted that:

"We found that regularly eating more than the recommended amount of red meat was also related to increased depression and anxiety."

And their recommended amount (so weird to have a recommended amount of red meat) was "65-100g of lean, red meat three to four times a week." That's about a 3-ounce serving 3-4 times a week. Which is just about identical to the half a serving/day that this Harvard study says not to go above too.

They both warn about eating too much meat, more than a couple bites a day. But, you know, just correlation.

Bix said...

This meat and depression study mentioned the higher amounts of omega-3 in grass fed beef. I hear this a lot. But this chart I did a few years ago shows beef in general is not a good source of omega-3, pastured or not:

The data was from NutritionData who got it from the USDA's data base. Maybe things have changed.

Bennedict said...

I'm vegan because...

It’s unnatural to be anything else! I think the idea that we drink another baby’s nursing milk is legitimately strange, let alone the fact that we do even stranger things to it and make more products out of it. I don’t think I’ve ever heard of human milk cheese. I certainly hope I never do!

Meat makes me sad. I mean, you’re eating something’s insides. Isn’t that kinda… I dunno. Disturbing? Unless cannibalism becomes a popular thing, I don’t think people will realize just what the eff they’re doing.

But probably my biggest reason for being vegan is that I refuse to support companies that endorse and practice animal cruelty with MY money. Oh no, I am NOT paying for that shit. It amazes me that people don’t realize they’re funding these awful people by buying their cheese and bacon. I hope they wise up and make the change.