What eating too much meat is really doing to your health

The World Health Organisation (WHO) said this week that bacon and other processed meats can cause cancer and that red meat such as beef or pork rank as a group one carcinogen (alongside cigarettes and alcohol). Though the risks are small for most people, the warning has led many of us to think twice about how much meat we consume and even to ask ourselves if it is time to give up eating meat completely.

According to a new book, Proteinaholic, the answer to that question should be a resounding yes — or at least a promise to cut back on meat drastically. People whose diets are high in animal protein have significantly higher health risks, not just of cancer but of heart disease, hypertension, diabetes and many other chronic diseases, the book claims. Heavy meat consumption may be linked to depression, loss of mental concentration and dementia. Meat is also one of the biggest factors behind the obesity epidemic, closely correlated with weight gain.

Surprisingly, this scenario is laid out by a bariatric (weight loss) surgeon who once recommended that we eat hearty quantities of meat every day. Dr Garth Davis, now a vegan, was a “hamburger-guzzling fiend” and even pushed protein powder and liquidised chicken on his patients recovering from gastric bypass surgery.

In 2008, as the head of a thriving weight-loss practice in Houston, Texas, he published The Expert’s Guide to Weight Loss Surgery in which he recommended people go on the Zone diet, with its ratio of 30 per cent protein, 30 per cent fat and 40 per cent carbohydrates. “I was promoting what everyone in the weight loss community believed,” Davis recalls.

His lightbulb moment came in his mid-30s when he was diagnosed with high blood pressure, high cholesterol and fatty deposits on his liver. He also had irritable bowel syndrome. “I was overweight. I wasn’t feeling well and I felt like a hypocrite because I was well on my way to the same chronic diseases that my patients were suffering from,” he says. “I wondered how we had all become resigned to accepting these bleak prognoses like diabetes and heart disease.”

As he thought about where he and his patients were going wrong, he found some answers in Dan Buettner’s bestselling book The Blue Zones. People living in the five regions in Latin America, Europe, Asia and the US identified as having the highest concentrations of centenarians in the world (the so-called Blue Zones identified by population researchers Michel Poulain, Anne Herm and Gianni Pes in 2004) live on a predominantly plant-based diet. The Sardinians, for example, eat meat once or twice a week, and the people of Okinawa, Japan, get only 7 per cent of their calories from protein — the majority comes from sweet potatoes.

In the following years, as he changed his lifestyle, Davis estimates that he looked at more than 800 scientific studies on nutrition and health. He lays a lot of this evidence out in Proteinaholic and has come to a conclusion he knows not everyone will agree with. He believes our obsession with meat is making us fat and sick and is leading to early death.

“The link between diet and longevity is a complex one and there’s a lot that we still don’t know, but we shouldn’t let that complexity hide the main point; it is absolutely clear that an animal protein-rich diet is associated with a shortened life,” he says.

Davis acknowledges the confusion surrounding protein. Some of us eat protein to lose weight while others eat it to gain weight. “Some people believe that eating protein will make them healthier and everybody seems to think protein will give us energy and make us feel full,” he says. In fact, the 45-year-old doctor points out in the book, energy comes from carbs or fat, not protein.

Part of the problem, he says, is that we have been encouraged by nutritionists, doctors and the food industry to break down food into macronutrients — fats, carbs and proteins. “We no longer talk about food as food,” Davis explains, “leading us to develop this unhealthy obsession with protein as the prime nutrient. It’s leading us down a dangerous road.”

Because protein is seen as a nutritional rock star, drinks and snacks are loaded with it, he says. Even people who avoid red meat eat masses of chicken because they believe it is healthy, he says. “Chicken hasn’t been listed by WHO yet but it will be one day because the things WHO found in meat that cause cancer are also found in chicken.”

There is a wealth of research that shows a correlation between animal protein and cancer, according to Davis. Heterocyclic amines (HCAs), the chemicals formed in meat that is grilled or barbecued, are implicated in many cancers including breast cancer and prostate cancer. Animal foods are also

a source of heme iron, which is linked to colorectal cancer. Neu5Gc is an antigen found in animals, which when we consume it as part of meat is recognised by the body as a foreign invader, causing an inflammatory immune response that may contribute to carcinomas.

Meat consumption is a chief cause of diabetes, carbohydrates are not, he claims in the book. Davis quotes the EPIC (European Prospective Investigation into Cancer and Nutrition) study that followed 512,000 people in ten countries for 12 years and which concluded in September 2011 that meat, especially processed meat, is significantly associated with the development of type 2 diabetes while fruit and vegetable consumption is associated with a decrease in diabetes development. He quotes another study published in 2014 that says people who replace just 5 per cent of the animal fats in their diets with fructose, or fruit sugar, cut the risk of developing diabetes by 30 per cent.” Study after study has shown that people eating fruits and vegetables and especially grains exhibit remarkably low levels of inflammation… and have considerably lower levels of diabetes than the general population,” he writes.

He quotes research called the Western Electric Study that followed 1,714 male employees for eight years and found that the more animal protein and saturated fats people ate, the more at risk they were of developing hypertension. “Doctors have known for some time that people who avoid most animal proteins have lower blood pressure,” he says.

Meat-eaters suffer more heart disease, Davis claims, quoting a study by the University of Copenhagen that implicated saturated fat and animal protein as “having a causative role” in heart disease. “The less animal protein you eat, the happier your heart will be,” he concludes.

Research suggests that memory loss and poor brain function may also come from a meat-heavy diet, he adds. “Several studies point to a link between high amino acids and high fat in the diet affecting a worsening mood, worsening concentration on mental tasks and a higher rate of dementia,” Davis says. “And high amino acids and saturated fats come from animal sources.”

Nor is protein the key to weight loss, the book claims. One of the reasons for writing Proteinaholic, says the doctor, is not only to get the message across that our obsession with protein is sapping our vitality, undermining our health and shortening our lives but it is making us fat.

As a weight loss surgeon, he says, he regularly sees some of the heaviest people in the US and most of them believe that their weight gain is due to not eating enough protein. “So-called experts stress these high-protein diets and yet all the science shows that is the completely wrong way to be healthy. You might lose weight in the short term but you will put it back on. The Atkins diet (a low-carbohydrate, low-sugar, high-protein plan) is just a complete crime and goes against the recommendations of every major medical organisation,” Davis says, pointing out that its creator, Dr Robert Atkins, had a history of heart problems and weighed 258lb when he died, aged 72, following a fall.

As for the Paleo Diet (another high-protein plan based in theory on the type of foods early humans would have eaten): “There are things I like about the Paleo Diet and things I can’t stand. The premise that cavemen were healthier than us and living long lives is a complete fallacy and the idea that they ate meat every day is a complete fallacy. The thing that I do like about the Paleo Diet is the idea of not eating processed food, of cutting out dairy and going for natural food sources. The problem is that the message has come as out ‘eat more protein,’ as if the Paleo people were eating tons of protein, and that just isn’t true.”

The longest-lived, healthiest people eat very little protein, he repeats. “Meat disrupts your intestinal bacteria, which leads to weight gain. Most meat contains antibiotics, which leads to weight gain. Meat creates increased acidity in the blood and inflammation, which leads to weight gain,” he insists. If you are going to eat meat, the least harmful variety is grass-fed (the most, red meat and anything processed), he says, but fish (wild, not farmed) would be preferable and plant-based protein the ideal.

So how much protein should we eat? “Protein is so abundant in all foods that, if we are eating adequate calories, we need never worry about being protein-deficient,” Davis says. “We eat about 100g of protein a day when the recommended daily allowance for a woman is about 46g and for men it’s about 56g, so we overeat what’s recommended and our bodies don’t even need that much. On the Atkins or the Paleo or any of the diets I used to recommend, the figures can double or even triple.”

Plant-based protein not only exists but it is better for you than animal protein, Davis says. “It doesn’t increase inflammation, doesn’t contribute carcinogenic materials, isn’t bound to saturated fat and doesn’t increase the hormones that can affect cancer,” he says. He believes it’s important to have a good source of omega-3 and that fish can provide this — but points out that much of the fish we eat now is farmed, which has lower levels of omega-3 (because the fish are fed grains rather than eating algae), and can also be subject to diseases. Nuts and seeds are a good alternative source of omega-3 — walnuts have the highest content.

His anti-animal protein rules for himself seem extreme. He doesn’t eat eggs but says that so long as you have a healthy diet otherwise, it’s fine to eat several per week. Eggs are high in methionine, an amino acid that cancer cells thrive on, he says, and also contain carnitine, a known contributor to heart disease.

A low-protein, low-fat diet (with plenty of fibre) is the best way to lose weight and stay healthy and carbohydrates in their natural state, far from being the enemy, are the source of human health, vitality and vigour, he states. He believes that for optimal health and longevity, most of the calories you consume should come from fresh fruits and vegetables, nuts and seeds, beans of all types and whole, unrefined grains. Plant foods contain all the protein people need, as well as antioxidants, anti-inflammatories, vitamins, minerals and other micronutrients.

Many parents might be concerned about cutting animal protein from their children’s diet because they are growing but Davis’s daughters, aged eight and six, are vegetarians and perfectly healthy, their father says. “I hear this all the time; isn’t it bad to feed children a vegetarian diet — and it’s inconceivable to me because I look at kids eating hot dogs and hamburgers and I think how can that possibly be better than my kids eating salads and fruits and vegetables?” he says. “The only nutrient that they would possibly be deficient on is B12 so my kids take a little supplement of that and they’re about as healthy as they can possibly be.”

After overhauling his own health, Davis went from being a sluggish, overweight man who was out of breath after climbing stairs to becoming an Ironman competitor. He says people think vegans or vegetarians are frail weaklings but many Ironman champions, boxers, runners and cyclists eschew meat.

Leaving meat did not come easily, he admits, because food tastes and preferences are established over time and are hard to get rid of. “I‘m a Texan and I was brought up as a carnivore, so it was certainly not easy but I’m glad I did it,” he says.

Proteinaholic by Garth Davis is published by HarperCollins at £16.99. To buy the book for £14.99, call 0845 2712134 or visit thetimes.co.uk/bookshop

Meat: the facts

The average Briton eats 70g of meat a day (equivalent to two small sausages)

One in three people consumes more than 100g of meat every day

This week the World Health Organisation placed processed meat (such as bacon and sausages) in the same carcinogenic category as cigarettes and alcohol

Red meat was placed in the category below this, as a “probable carcinogen”

The report said that eating just 50g processed meat per day increases the risk of bowel cancer by 18 per cent

Processed meat can contain up to 400 per cent more salt than fresh meat

Preparation can make a difference: barbecuing meat, cooking it for a very long time or cooking it at very high temperatures so that it chars will all produce chemicals linked to breast cancer and prostate cancer

An earlier conclusion from a WHO study found links between meat (in particular processed meat) and type 2 diabetes

People who live in the areas across the globe with the highest concentrations of centenarians (“blue zones”) have predominantly plant-based diets