Are Barbecues Bad For Your Health?

As we settle into the barbecue season, it's time to consider whether the meat on your grill is harming your health. Conflicting messages in the media certainly don't help. On one hand are advertisements with Sam Neill claiming red meat is the reason that humans are smarter than orangutans. On the other, the prestigious World Cancer Research Fund reports that red meat may cause colorectal cancer. Whom to believe?

Image courtesy of Shutterstock

The good bits, and bad

Some red meat does contain fats our brains need. Omega-3 fats form part of the structure of brains and eyes, and may also help reduce blood pressure and modify inflammation. But meat isn't the only food containing omega-3 fats. In fact, the richest sources are oily fish.

And if you buy grain-fed steak, you may be getting hardly any omega-3 fats at all. Grass-fed meat (and wild meats, such as kangaroo) is not only better for the environment, but better nutritionally, containing healthier fats and a lower fat content overall.

Red meat also contains decent amounts of zinc and protein, as well as iron, which is one of its big nutritional selling points. Indeed, the iron in red meat is in a form that our bodies absorb easily — "haem" iron.

Meat producers are fond of producing colourful ads that equate the iron content of a bucket-load of spinach with that of a small juicy-looking nugget of lean beef. And iron deficiency is an important issue — but that same haem iron may be harmful in fatty processed meat as you will see.

As well as beneficial nutrients, meat also contains saturated fat, the kind that promotes increased cholesterol levels in the blood and blocks blood vessels that the heart relies on to keep working.

The fat content of meat varies markedly with species and cut. If you buy untrimmed brisket, chuck or shoulder, or luxury marbled meat, such as wagyu or kobe beef, your meat will be around 10% to 20% fat. Ribs, neck, pork belly, and the cheapest minced meat can be up to 50% fat. You can get down to 3% to 5% fat if you trim your meat well of all visible fat and choose leaner cuts, such as loin and round steak, flank and shanks.

Meat and cancer

The cancer risk associated with high consumption of red meat, particularly processed red meat, is definitely cause for concern. In 2007, the World Cancer Research Fund (WCRF) produced an expert report that assessed the evidence for causal links between food, lifestyle and cancer, based on data from all studies that met quality standards.

In the report, the WCRF concluded that there was "convincing" evidence (that is, evidence of both the mechanism and the effect) for a link between colorectal cancer and high intakes of red meat. The link was strongest for processed red meat — bacon, salami, sausages and hot dogs, which contain curing agents such as nitrates and nitrites.

The studies' data indicated that cancer risk continued to rise with higher meat intakes. This rise appears to start once red meat consumption exceeds 300 grams in a week. The WCRF's recommendation is that people who eat red meat should consume less than 500 grams a week, including very little if any processed meat products. There was no data to indicate that any level of processed meat intake was free of risk.

Eating fish may help reduce colorectal cancer risk, and some studies indicate that a high fibre intake, and eating lots of fruits and vegetables, are associated with reduced cancer risk.

How it works

How red meat causes the increase in cancer risk is still a question in search of a complete answer. Many different components of meat have been suggested as a mechanism, including the curing agents nitrate and nitrite that are present in processed meat; the fat or the haem iron in meat; the excess protein load that big meat eaters might often consume; and the carcinogens, such as heterocyclic amines (HCAs)and polycyclic aromatic hydrocarbons (PAHs), that can be formed during the cooking of meat.

Protein doesn't appear to be the culprit, despite the fact that the end products of excess protein intake are quite toxic (these are excreted if the kidneys are working normally). Unlike high-protein diets, high-fat diets have been shown in animal studies to increase cancer risk, apparently promoting gut cancers through their damaging effects in the gut as well as contributing to obesity, which itself is a cancer risk factor.

But studies of low-fat diets haven't shown a reduction in risk, so other factors may also be involved. The problem with processed meat seems mainly to stem from its salt content (associated with risk of stomach cancer) and its content of nitrates and nitrites, which are added as part of the curing process and can be converted to carcinogens.

And unlike the iron in plant foods, the haem iron in meat seems to help produce mutagens and carcinogens in the meat and in the gut by reacting with the fat in the meat, and by helping to convert nitrates and nitrites to their carcinogenic form.

There are a lot of studies showing that the carcinogenic substances HCAs and PAHs are produced when you cook your meat at a high temperature or on an open flame, and that colorectal cancer risk increases when you consume a lot of these. Some people have a genetic sensitivity to HCAs and they're at even higher risk.

Mysteriously, although barbecuing chicken and seafood produces large amounts of HCAs, these don't seem to be associated with increased cancer risk, perhaps because they are different types from the ones that red meats produce. And perhaps their lower iron content has something to do with it.

Cooking for shorter times, or at lower temperatures, produces smaller amounts of HCAs and PAHs. Raw meat, surprisingly, is no less digestible than meat cooked briefly either at high or low temperatures. What really makes a difference in digestibility is overcooking until meat is tough. This reduces digestibility significantly but that increases again in long, slow cooking.

The magic of marinades

Interestingly, marinating meat may be a good idea for health as much as for flavour. A Portuguese study found that several hours' marinating in beer or red wine significantly reduced the production of HCAs in beef, perhaps by reducing movement of precursor substances to the surface of the meat, or by adding antioxidants that inhibit the reaction.

Other studies have successfully used garlic, rosemary, thyme and sage, and olive oil with garlic and lemon. Cooking with extra-virgin olive oil had a similar effect. But adding sugar or fruit to marinades appears to increase the risk of burning and forming more carcinogens.

So, as you wheel out your barbecue this summer, consider serving sustainable seafood or organic chicken some of the time instead of red meat; stick to smaller serves of grass-fed lean meat, marinated without sugar or salt and cooked to a juicy medium-rare, away from a bare flame; and have plenty of salad with your meal. Food for thought?

Suzie Ferrie is a clinical affiliate at the University of Sydney. She does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.

The Conversation This article was originally published at The Conversation. Read the original article.


Comments

    In this space the majority of research is to fractured, and with to much funding from different sides of the food supply chain (bias).

    For the majority of our existence as humans, we have had far more veg to meat as a ratio, even cooked, so if you take a stab in the dark and say 10:1 veg to meat, then some charcoal on your meat is totally offset by the phyto goodness in plants.

    meat causes colon cancer only holds up in a modern diet model ignoring the above ratio of huge plant to meat ratio.

    there should be research on multiple food models but can you really wait for such a long study that has not probably even begun.

    Came here expecting interesting information about cooking on charcoal, smoke etc...you know, barbecues? Instead found an article about meat in general. Yawn.

      Yeeeaah... Kind of agree. What's wrong with vegies on the BBQ? Nope, no mention. Oh well.

    grilling might be bad for you - burning the meat produces those pesky HCA's - but that isn't barbecue... Barbecue is cooking meat with an offset smoker - usually for 6 hours or more on slow temperature. Often with rubs, marinades, and flavored woods... The only bad thing about BBQ is I get drunk as it takes 6 hours to cook and I like to BBQ with a beer in my hand :)

    "Sustainable seafood" - the stuff that according to another article on The Conversation, should also be limited because of mercury content (http://theconversation.edu.au/is-your-health-at-risk-from-fish-and-frying-pans-5000)?

    As for chickens: http://theconversation.edu.au/vaccines-for-chickens-have-created-virulent-new-viruses-8234

    On the bright side, vegetarians aren't off the hook either: http://theconversation.edu.au/ordering-the-vegetarian-meal-theres-more-animal-blood-on-your-hands-4659

    So the answer seems to be, as always, moderation.

    > But meat isn’t the only food containing omega-3 fats. In fact, the richest sources are oily fish.
    Because fish isn't meat? 8\

      Yeah, that is a pretty stupid line. Either someone didn't pay enough attention when they wrote that line, or they don't class fish as meat (even though it is, considering it's flesh from a living creature), or they just didn't do their research. A quick Google search shows that non-meat alternatives that contain Omega-3 fats includes; edamame (yum), wild rice, walnuts, canola oil, flax, and beans.

    Point 1: too much of something is bad.
    Point 2: moderation and varied diet is good.
    Point 3: exercise is often overlooked.
    Point 4: barbecue with a gas burner makes cleaning less of a pain.
    Yay. Funfactsforkids

    Are people that stupid that they can no longer buy their own food and prepare it themselves without somebody having to reassure them that it's OK, or to scare them into thinking it's going to give them cancer?

    Personally I like to live a life outside cotton wool.

    Is it just me or does anyone else see the face of ET in the meat on the left?

    I love a good BBQ, and I've known for years that organic grass fed meat is the best way to go. I have my meat with a great deal of salad, with tonights meal being a red wine and garlic marinated rump steak with minimal fat, potato salad, lettuce, beetroot, carrot sticks and pineapple. I had a dessert of apple pieces and few biscuits. Not the healthiest meal, by any means, but very tasty and well flavoured.

    Did you look into the research done in Japan that shows consuming pickled veg with BBQ meat help stop the body absorption of HCAs and PAHs.

    also extra virgin olive oil has a low smoking point you should use the "light" version for cooking as the extra processing raises the smoking point to above 170 c

    hahahaha ET phone home. I just saw the cute little fella.

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