Sunday, June 21, 2015

What the Public Reads

If you read only a stream of news from vegans, you probably think every animal product is a deadly poison. But even if that is the truth, all that really matters is what the public believes. Here is an example of what they are reading these days:

Can’t resist red meat? It may not be the healthiest menu option but some equally tasty side orders could limit the damage

A succulent steak with creamy peppercorn sauce or a chunky burger laden with cheese. Could there be a better route to heaven (via a heart attack)?

Meat often gets a bad rap when it comes to health. When consumed in abundance, red meat probably does raise the risk of colorectal cancer and cardiovascular disease.

So what do you do if steak and blue cheese just happen to be your favourite flavour combination? Well, you might be on to a winner – it's just possible that adding dairy to your meat consumption might limit the damage.

First, it might help mop up some of the fat. France has one of the highest levels of cheese consumption in the world, yet one of the lowest levels of coronary heart disease. Some put this down to the fact that the French also consume a lot of vegetables, but several studies suggest that consuming cheese or milk causes a drop in the levels of "bad" LDL cholesterol in people's blood. "When you look at people who eat a lot of cheese compared to those who don't eat any, there's no difference in cardiovascular risk or diabetes – and if anything it tends to be beneficial," says Arne Astrup at the University of Copenhagen in Denmark.

One possible explanation is that the calcium present in abundance in cheese is binding to fatty acids and cholesterol in the gut, causing some of them to be excreted. However, giving people calcium supplements doesn't seem to have the same beneficial effect. It's also possible that certain bacteria or fermentation products in the cheese influence the balance of nutrients that are absorbed by the body.

Super spuds

Calcium consumption could also be a way to reduce the damage caused by another constituent of red meat: heme. This iron-rich substance plays a key role in transporting oxygen around the body, but free heme can react with DNA in the cells lining the gut and boost the risk of developing colorectal cancer.

Calcium seems to mop up heme and render it harmless; rats fed a heme-rich diet seem to be protected against its carcinogenic effects if calcium is added to their food. Sadly for steak-lovers, high levels of calcium react with protein, rendering meat hard and dry. Adding milk, cheese or yogurt to the meal might have the same effect, but it's unclear how much you would need to eat to negate heme completely. And high cheese consumption is bad for your waistline and so can bring health problems of its own.

What about vegetables? The EPIC trial, one of the largest investigations into the health effects of red meat, found that the early death risk was lower in meat eaters who reported consuming lots of fibre (abundant in many plant-based foods) than in people who ate very little meat. Similarly, people benefit from eating cold potatoes with their meat. It appears that what is called butyrylated resistant starch, produced when potatoes are cooked and then left to cool, protects against DNA damage to gut cells and so may blunt red meat's association with colorectal cancer.

Then there's processed meat, widely considered more harmful than fresh on account of the nitrite preservatives used in its production. These can react with fats in the diet and produce other cancer-promoting substances. Here, too, fruit and vegetables may provide a solution as some of them contain chemicals called flavonoids. Concentrated flavonoids are currently being investigated as an alternative to nitrites for preserving meats. "They stop microbes from growing and the meat has a shelf life which is acceptable to meat producers," says Gunter Kuhnle at the University of Reading, UK. "The idea is to help the food industry to produce meat where the links with colon cancer are at least reduced, or maybe not there at all."

From issue 3023 of New Scientist magazine, page 32-33.

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