Is meat good or bad for us?
It's the best natural source of iron and protein - but it has also been linked to cancer. Maxine Frith investigates the pros and cons
Tuesday 21 November 2006
The benefits of red meat...
Children and teenagers, particularly girls, have been found to be deficient in zinc - half of all girls in their teens do not have healthy levels of the mineral.
Some research has shown that having red meat less than twice a week can result in zinc deficiencies. Zinc is particularly important for healthy skin and a healthy immune system. During the winter months in particular a good supply may help prevent colds and other infections.
While other foods such as oysters, milk and lentils contain zinc, red meat is the most efficient way of getting it into your body.
Red meat is an essential source of iron - lean beef has 2.7mg of iron per 100g - and is vital to good health, as well as preventing conditions such as anaemia. Up to a quarter of menstruating women are thought to be deficient in iron. Meat contains more iron than most foods, and it is more easily utilised by the body than from vegetable sources.
Elderly people, pregnant women, children and those recovering from surgery could all benefit from increased iron intake. Iron helps to generate red blood cells, which carries oxygen from the lungs to the tissues and carbon dioxide back to the lungs. Red meat is also a good source of other vitamins and minerals such as phosphorus, potassium, magnesium and selenium.
Red meat is a major source of protein, which is needed for muscle and organ health. The protein found in meat is "complete", meaning that it contains all the amino acids that the body cannot make on its own. It is essential for the body's repair and renewal as well as general health.
Australian scientists have found that people who ate a diet high in protein, based on lean red meat, as well as fruit and vegetables, lost 25 per cent more weight over a fixed period of time than those who ate a low protein, carbohydrate-rich diet that contained the same amount of calories and fat.
The scientists concluded that some people might be more successful in losing weight on a high-protein diet because they felt less hungry and could go without food for longer. Those on the high-protein diet also saw levels of their "bad" cholesterol drop.
Red meat is one of the best sources for these vitamins, which are found only in animal foods, and which help to maintain nerve cells and normal blood formation.
This is a controversial argument, but some experts have said that humans are in fact natural meat-eaters - and that to totally eliminate such a big food-group from our diets could be unhealthy. There is a theory that our guts contain bacteria that help us to digest meat, and that not to eat meat could mean that the bacteria are lying idle, so making it easier for diseases to flourish.
Pork, lamb and beef: what's in your meat
Cancer-causing, artery-clogging and brain-damaging? Or a rich source of essential vitamins and minerals that we can't do without? The debate over red meat and its impact on health continues to rage, and it hit the headlines again last week when a study suggested that a high intake could double a woman's chances of developing breast cancer.
So what is the truth about red meat? In essence, it all comes down to the type of red meat you are talking about - and how you are eating it.
* The three official red meats are pork, lamb and beef. Pork is the leanest, lamb the fattiest and beef the most nutritious.
* Beef has 2.7mg of iron per 100g, and 4.1mg of zinc. A large proportion of the population, particularly teenage girls and women, are deficient in both minerals.
* Pork and lamb also contain zinc and iron, but not in the same quantities.
* Red meat is high in saturated fats and "bad" cholesterol, which can lead to clogged arteries and heart disease.
* But lean beef is actually fairly healthy; it will provide you with essential vitamins and minerals, but it will not have a high fat content.
* The British Dietetic Association says that up to 90g of lean red meat a day (equivalent to a portion of bolognese) is acceptable.
* But the Food Standards Agency (FSA) points out that different cuts of meat will have very different nutritional contents.
A lean pork leg joint will contain around 5.5g of fat per 100g, of which 1.9g will be saturated fat; compare that with a grilled joint of pork belly, which has 23.4g of fat, of which 8.2g will be saturated.
* A lean rump steak, grilled, has 5.9g of fat per 100g, of which 2.5g is saturated.
But the same cut of beef, not trimmed of its fat, and fried instead of grilled has 12.7g of fat, of which 4.9g is saturated.
The fat content of mince will vary widely, so the advice is always to look at the label and go for the leanest versions.
The FSA recommends that you also look at the meat itself; the more white you can see, the more fat it will contain.
* Some of the concerns that exist about red meat in America do not apply here; for instance, the US still allows animals to be fed growth hormones (a potential risk factor in cancer), but the practice has been outlawed by the European Union for some years now. The things to avoid are processed meats - these will contain far more additives and fat than a simple cut of beef, pork or lamb.
* And, while red meat can have real health benefits, it is important that the food is treated simply as one part of an overall balanced diet. For example, it is a poor source of fibre, which aids digestion; other foods are required to provide that.
...and the risks
A pan-European study of nutrition and cancer found that people who ate more than two 80g portions of red meat a week were 30 per cent more likely to develop bowel cancer than those who ate less than one portion.
Scientists are still unsure why there is an increased risk, but there is a theory that the compounds haemoglobin and myoglobin, found in red meat, trigger a process called nitrosation in the gut which in turn leads to the formation of cancer-causing compounds.
Processed meats such as sausages may also be risky because the cooking process can create carcinogenic compounds called heterocyclic amines.
Research has shown that a Mediterranean diet - low in red meat but rich in plant foods and fish - can reduce the chances of developing Alzheimer's by up to two-thirds.
Again, there is no firm theory on this. Researchers University of California Los Angeles (UCLA) suggested last month that red meat could be linked to a build-up of iron in the brain, causing the opposite effect of antioxidants; in effect, the brain rusts. The researchers suggest it may also explain why more men develop Alzheimer's, as men eat more red meat than women.
Too much red meat can have an adverse effect on bone health. The digestive process of protein leaves acid residues in the body that need to be neutralised with alkalising minerals - and these may be taken from the bones, leading to a higher risk of osteoporosis and other conditions. While green, leafy vegetables are high in calcium, red meat has a low level and can cause excess acid to form, creating bone problems for the future.
Eating red meat every day could double your risk of developing rheumatoid arthritis. Scientists believe that collagen, found in red meat, may trigger an immune system response, which may also affect the joints.
Additives contained in processed meats may also play a part in the increased rate of the disease.
Red meat is one of the first foods that doctors advise patients to stop eating if they are at risk of heart disease, because it contains high levels of dietary cholesterol.
A build-up of cholesterol in the arteries can eventually stop blood flow and trigger heart attacks.
However, it depends on the type of meat you are eating; lean red meat is relatively healthy - it is the fatty chops and burgers that are more risky.
Red meat is also high in saturated fat, which has been linked to a range of cardiovascular problems, including high blood pressure.
The Food Standards Agency has launched an investigation into the safety of red meat after research suggested that beef, lamb and pork are the cause of one in six outbreaks of food poisoning. Experts are to test samples to find out the amount of bacteria in them, although the problems are more likely to be linked to poor hygiene in the home than to standards at abattoirs.
A study from the Harvard Medical School last week suggested that eating more than 100g of red meat a day could double the risk of a woman developing breast cancer. The risk was associated with young women who had not yet gone through the menopause. Experts said the increased risk may be down to the cancer-causing compounds created by cooking meat, or by excess iron levels.
However, the study was among women in the US, where animals are given growth hormones that are banned in the EU; British experts say that women here may not be at such risk.
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