BBC: We don't need nearly as much protein as we consume

Many of us consciously eat a high-protein diet, with protein-rich products readily available, but how much protein do we really need? And does it actually help us lose weight?

• By Jessica Brown

23 May 2018

This story is featured in BBC Future’s “Best of 2018” collection. Discover more of our picks. 

In the early 20th Century, Arctic explorer Vilhjalmur Stefansson spent a collective five years eating just meat. This meant that his diet consisted of around 80% fat and 20% protein. Twenty years later, he did the same as part of a year-long experiment at the New York City’s Bellevue Hospital in 1928.

Stefansson wanted to disprove those who argued that humans cannot survive if they only eat meat. But unfortunately for him, in both settings he very quickly became ill when he was eating lean meats without any fat. He developed "protein poisoning”, nicknamed “rabbit starvation”. His symptoms disappeared after he lowered his protein intake and he raised his fat intake. In fact, after returning to New York City and to a typical US diet with more normal levels of protein, he reportedly found his health deteriorating and returned to a low-carb, high fat, and high protein diet until his death aged 83.

His early experiments are some of the few recorded cases of high protein intake having extreme adverse effects – but despite soaring sales of protein supplements, many of us are still unsure how much protein we need, how best to consume it, and if too much, or too little, is dangerous.

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Despite obesity rates doubling over the past two decades, we’re becoming increasingly conscious of what we’re eating. In recent years many of us have swapped white bread for brown and wholemeal bread and full-fat milk for skimmed. Taking centre stage in our health kick is protein, with protein balls, bars and enhanced protein versions of staple products, from cereals to soup, dominating supermarket shelves. And with the global protein supplements market valued at $12.4bn (£9.2bn) in 2016, it’s clear we’re buying into the idea that we need as much protein as possible.

But some experts now argue that foods with inflated protein (and prices) are a waste of money.

Supplement brands advise drinking protein shakes after a workout to help the growth and repair of muscle tissue (Credit: Getty Images)

Protein is essential for the body to grow and repair. Protein-rich food such as dairy, meat, eggs, fish and beans are broken down into amino acids in the stomach and absorbed in the small intestine, then the liver sorts out which amino acids the body needs. The rest is flushed out in our urine.

Adults who aren’t especially active are advised to eat roughly 0.75g of protein per day for each kilogram they weigh. On average, this is 55g for men and 45g for women – or two palm-sized portions of meat, fish, tofu, nuts or pulses.

Not getting enough protein can lead to hair loss, skin breakouts and weight loss as muscle mass decreases. But these side effects are very rare, and largely only occur in those with eating disorders.

Despite that, most of us have long associated protein with building muscle. This is accurate. Strength-based exercise causes a breakdown of protein in the muscle. For muscles to grow stronger, the proteins need to rebuild. A type of amino acid called leucine plays a particularly big part in triggering protein synthesis.

Some experts even argue that not consuming protein post-workout could cause the breakdown of muscle to be higher than the synthesis – meaning there’s no net gain in muscle mass. Supplement brands advise drinking protein shakes after a workout to help the growth and repair of muscle tissue, usually in the form of leucine-rich whey protein, a by-product of making cheese.

Many people consume sport nutrition products such as protein bars and shakes (Credit: Getty Images)

Many consumers agree. Research company Mintel’s 2017 Report found that 27% of Brits use sport nutrition products such as protein bars and shakes. This figure rises to 39% for those who exercise more than once a week. But more than half of the individuals who use the products (63%) find it difficult to tell whether they’re having any effect.

Protein bars are really just candy bars with a bit of extra protein

Indeed, research on the muscle-building power of protein supplements is varied. A 2014 analysis of 36 papers found that protein supplements have no impact on lean mass and muscle strength during the first few weeks of resistance training in untrained individuals.

Over time and if the training becomes harder, supplements can promote muscle growth. However, the paper also concludes that these changes have not been proven over the long term. A 2012 review paper further says that protein “increases physical performance, training recovery and lean body mass”… but for the benefit to be optimal, it should be in combination with a fast-acting carbohydrate.

But even if athletes and gym goers may benefit from a post-workout protein boost, that doesn’t mean they should reach for the supplements and smoothies. Most people get more than their daily recommended allowance from food, says Kevin Tipton, a sport professor of the University of Stirling. “There’s no need for anyone to have supplements. They’re a convenient way to get protein, but there’s nothing in supplements you can’t get in food. Protein bars are really just candy bars with a bit of extra protein.”

The global protein supplements market was valued at $12.4bn (£9.2bn) in 2016 (Credit: Getty Images)

Tipton adds that even among bodybuilders, products like whey protein aren’t as critical as they are hyped up to be. “There’s too much focus on which supplements to take, as opposed to getting in the gym and working harder. There are so many other variables, such as sleep, stress and diet,” he says.

We need to maintain our muscle mass as we age, because we become less active and frail

Most experts agree with Tipton that protein is best consumed in food instead of supplements. But there are some exceptions, such as athletes who find it difficult to hit their daily protein targets, points out Graeme Close, professor of human physiology at Liverpool John Moores University. “I believe most need more than the recommended daily allowance, and there’s good evidence to support this,” he says. In this case, he says, a shake can be useful.

Another demographic who can benefit from extra protein? The elderly. That’s because as we age, we need more protein to retain muscle mass. But we also tend to eat less protein as we get older because our taste-buds begin to prefer sweet over savoury.

Emma Stevenson, professor of sport and exercise science at Newcastle University, is working with food companies to get more protein into snacks that the elderly  are known to regularly buy, such as biscuits. “We need to maintain our muscle mass as we age, because we become less active and frail,” she says. 

Close says the elderly should increase protein intake to around 1.2g per kg body weight.

Most people get more than their daily recommended allowance of protein from their diet (Credit: Getty Images)

Fortunately, it’s difficult to have too much protein. While we do have an upper limit of protein intake, it’s “virtually impossible” to reach, says Tipton. “There are concerns among some dieticians that a high protein diet can hurt the kidneys and bones, but evidence in otherwise healthy people is minimal. It is possible there could be a problem if someone with an underlying kidney [issue] eats high amounts of protein, but the odds of any adverse effects are very low.”

If you’re trying to lose weight, it’s more important to have a high-protein breakfast

But while protein itself isn’t harmful, many protein supplements are high in carbohydrates called FODMAPs that trigger digestive symptoms like bloating, gas and stomach pain. Stevenson advises reading labels carefully on supplements, bars and balls. “Often, they’re very high in calories and contain huge amounts of carbs, often in form of sugar. You shouldn’t necessarily think that because it says it’s high protein that its healthy,” she says.

Weight loss

Protein has long been linked to weight loss, with low-carb, high-protein diets such as Paleo and Atkins promising to prolong the feeling of fullness. People fail to lose weight often because they feel hungry, and MRI studies have shown that a high-protein breakfast can help stop cravings later in the day.

There is sufficient evidence that protein is satiating, says Alex Johnstone of the University of Aberdeen. If you’re trying to lose weight, it’s therefore more important to have a high-protein breakfast, such as beans on toast or a dairy smoothie, rather than to have supplements.

But she doesn’t advocate “Atkins-type” diets and has found that cutting out carbohydrates has adverse affects on gut health (and we now know that maintaining a healthy gut is crucial to many aspects of our health and well-being).

Protein balls are often high in calories and can contain huge amounts of carbs (Credit: Getty Images)

Instead, Johnstone recommends that overweight people eat a high-protein and moderate-carb diet, consisting of 30% protein, 40% carbs and 30% fat – compared to the average diet of around 15% protein, 55% carbs and 30% fat.

But, of course, upping protein intake alone won’t help you lose weight. Choosing lean meat such as chicken or fish is key. Studies also show that eating large amounts of animal protein is linked to weight gain and red meat in particular is linked to an increased risk of cancer as well as heart disease.

Consuming more protein than need is wasteful in terms of money, and it’s paid down the toilet

There are, though, healthy proteins which are not meat, such as mycoprotein, which is derived from fungi. Quorn, for example, contains this type of protein, and is high in fibre too.

Researchers now are looking into how this unique composition (of both protein and fibre) can affect satiety and insulin levels, which are linked to type two diabetes. One team compared a mycoprotein diet to a chicken diet and found that the insulin levels in those who ate quorn achieved the same sugar control, but needed less insulin to be produced by the pancreas.

The risk of consuming too much protein is small, but the bigger risk might just be falling for overpriced products offering us more protein than we need. “Some products labelled as high protein aren’t, and they’re quite expensive. Anyway, consuming more protein than need is wasteful in terms of money, and it’s paid down the toilet,” says Johnstone.

http://www.bbc.com/future/story/20180522-we-dont-need-nearly-as-much-protein-as-we-consume

Could Carbs Help Us Live Longer?

Emerging evidence suggests a 10:1 ratio of carbohydrates to proteins may protect the body from the ravages of ageing

• By David Robson BBC

18 January 2019

The search for the “elixir of youth” has spanned centuries and continents – but recently, the hunt has centred on the Okinawa Islands, which stretch across the East China Sea. Not only do the older inhabitants enjoy the longest life expectancy of anyone on Earth, but the vast majority of those years are lived in remarkably good health too.

Of particular note is the number of people who reach 100 years of life. For every 100,000 inhabitants, Okinawa has 68 centenarians – more than three times the numbers found in US populations of the same size. Even by the standards of Japan, Okinawans are remarkable, with a 40% greater chance of living to 100 than other Japanese people.

Little wonder scientists have spent decades trying to uncover the secrets of the Okinawans’ longevity – in both their genes and their lifestyle. And one of the most exciting factors to have recently caught the scientists’ attention is the peculiarly high ratio of carbohydrates to protein in the Okinawan diet – with a particular abundance of sweet potato as the source of most of their calories.

“It is quite the opposite of current popular diets that advocate a high protein, low carb diet,” says Samantha Solon-Biet, who researches nutrition and ageing at the University of Sydney. Despite the popularity of the Atkins and Paleo diets, however, there is minimal evidence that high-protein diets really do bring about long-term benefits.

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So could the “Okinawan Ratio” – 10:1 carbohydrate to protein – instead be the secret to a long and healthy life? Although it would still be far too early to suggest any lifestyle changes based on these observations, the very latest evidence – from human longitudinal studies and animal trials – suggest the hypothesis is worth serious attention. 

According to these findings, a low protein, high carbohydrate diet sets off various physiological responses that protect us from various age-related illnesses – including cancer, cardiovascular disease and Alzheimer’s disease. And the Okinawan Ratio may achieve the optimal dietary balance to achieve those effects.

The people of Okinawa remain active and independent into their 90s, and are less 

likely to develop age-related illnesses (Credit: Getty Images)

Much of this research comes from the Okinawa Centenarian Study (OCS), which has been investigating the health of the ageing population since 1975. The OCS examines inhabitants from across the Okinawa prefecture, which includes more than 150 islands. By 2016, the OCS had examined 1,000 centenarians from the region.

Rather than suffering a prolonged demise, the Okinawan centenarians appeared to have delayed many of the usual effects of ageing, with almost two thirds living independently until the age of 97. This remarkable “healthspan” was evident across many age-related diseases. The typical Okinawan centenarian appeared to be free of the typical signs of cardiovascular disease, without the build-up of the hard “calcified” plaques around the arteries that can lead to heart failure. Okinawa’s oldest residents also have far lower rates of cancer, diabetes and dementia than other ageing populations.

Genetic jackpot

Given these results, there is little doubt that Okinawa has an exceptional population. But what can explain that extraordinary longevity?

Genetic good fortune could be one important factor. Thanks to the geography of the islands, Okinawa’s populations have spent large chunks of their history in relative isolation, which may has given them a unique genetic profile. Preliminary studies suggest this may include a reduced prevalence of a gene variant – APOE4 – that appears to increase the risk of heart disease and Alzheimer’s. They may also be more likely to carry a protective variant of the FOXO3 gene involved in regulating metabolism and cell growth. This results in a shorter stature but also appears to reduce the risk of various age-related diseases, including cancer.

Even so, it seems unlikely that good genes would fully explain the Okinawans’ longevity, and lifestyle factors will also be important. The OCS has found that Okinawans are less likely to smoke than most populations, and since they worked predominantly in agriculture and fishing, they were also physically active. Their tight-knit communities also help the residents to maintain an active social life into old age. Social connection has also been shown to improve health and longevity by reducing the body’s stress responses to challenging events. (Loneliness, in contrast, has been shown to be as harmful as smoking 15 cigarettes a day.)

A feeling of social connection can protect your health, while loneliness is thought to be 

as damaging as smoking 19 cigarettes a day (Credit: Getty Images)

It is the Okinawans’ diet, however, that may have the most potential to change our views on healthy ageing. Unlike the rest of Asia, the Okinawan staple is not rice, but the sweet potato, first introduced in the early 17th Century through trade with the Netherlands. Okinawans also eat an abundance of green and yellow vegetables – such as the bitter melon – and various soy products. Although they do eat pork, fish and other meats, these are typically a small component of their overall consumption, which is mostly plant-based foods.

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The traditional Okinawan diet is therefore dense in the essential vitamins and minerals - including anti-oxidants - but also low in calories. Particularly in the past, before fast food entered the islands, the average Okinawan ate around 11% fewer calories than the normal recommended consumption for a healthy adult.

For this reason, some scientists believe that Okinawans offer more evidence for the life-enhancing virtues of a “calorie restricted” diet. Since the 1930s, some doctors and scientists have argued that continuously limiting the amount of energy you consume could have many benefits above and beyond weight loss – including a deceleration of the ageing process.

In one of the most compelling experiments, a group of resus macaques eating 30% fewer calories than the average monkey showed a remarkable 63% reduction in deaths from age-related diseases over a 20-year period. They also looked younger – they had fewer wrinkles and their fur retained its youthful lustre rather than turning grey. Due to practical difficulties, long-term clinical trials in humans have yet to be completed to test the effects on longevity, but a recent two-year experiment, funded by the US National Institute on Aging, was highly suggestive: participants on a calorie restricted diet showed better cardiovascular health – including lower blood pressure and cholesterol.

It’s still not clear why a calorie restricted diet would be so beneficial, but there are many potential mechanisms. One possibility is that calorie restriction alters the cell’s energy signalling, so that the body devotes more resources to preservation and maintenance – such as DNA repair – rather than growth and reproduction, while limiting ‘oxidative stress’ caused by the toxic by-products of metabolism that can cause cellular damage.

Sweet potatoes are one of the principle ingredients in traditional Okinawan cuisine (Credit: Alamy)

The benefits of the Okinawan Diet may not end with its calorie restriction.

Solon-Biet has conducted a series of studies examining the influence of dietary composition (rather than sheer quantity) on ageing in animals, and her team has consistently found that a high-carb, low-protein diet extends the lifespan of various species, with her most recent study showing that it reduces some of the signs of ageing in the brain. Amazingly, they have found that the optimum ratio is 10 parts carb to one part protein – the same as the so-called Okinawan Ratio.

Although there aren’t yet any controlled clinical trials in humans, Solon-Biet cites epidemiological work across the world that all point to similar conclusions. “Other long-lived populations have also been shown to have dietary patterns that include relatively low amounts of protein,” she says. “These include the Kitavans, [who live on] a small island in Papua New Guinea, the South American Tsimane people and populations that consume the Mediterranean diet.”

Once again, the exact mechanisms are murky. Like calorie restriction, the low protein diets seem to promote the cell repair and maintenance. Karen Ryan, a nutritional biologist at the University of California, Davis, points out that the scarcity of amino acids can encourage cells to recycle old material (rather than synthesising new proteins).

“Together, these changes may prevent the ageing-associated accumulation of damaged proteins within cells,” she says. This build-up of damaged proteins may usually be responsible for many diseases, she says – but the regular clean up when we eat a low-protein diet could prevent it.

So should we all start adopting the Okinawan Diet? Not quite. Ryan points to some evidence that low protein intake may limit bodily damage up to the age of 65, but you may then benefit from increasing your protein intake after that point. “Optimal nutrition is expected to vary across the life history,” she says. And it’s also worth noting one study, which found that the relative merits of protein and carbohydrates may depend on the protein's source: a diet higher in plant-based protein appears to be better than a diet rich in meat or dairy, for instance. So the Okinawans may be living longer due to the fact that they are eating (mostly) fruit and vegetables, rather than its high carb, low protein content.

Ultimately, the Okinawans’ health is probably due to a lucky confluence of many factors, Ryan says. “And specific interactions among these factors will also be important.” And we may need many more years of research to understand the importance of each of those ingredients before we finally come up with a true recipe for the “elixir of youth”.

http://www.bbc.com/future/story/20190116-a-high-carb-diet-may-explain-why-okinawans-live-so-long

Does this viral photo of kidney stones really show the effect of too many energy drinks?

A graphic image of severe kidney stones has been circulating for years online, with a message about the dangers of consuming too many energy drinks. 

Claudia Tanner 8 months Thursday August 9th 2018


This image has been shared online hundreds of thousands of times – but experts warn it’s message is somewhat misleading (Photo: Facebook/Jason Hallman)

One version of the photo, which has been shared hundreds of thousands of times on Facebook, claims that it “belonged to someone who overindulged in energy drinks” and tells other users, “Show this to folks that’s [sic] addicted”. 

But experts say that while guzzling gallons of the stuff isn’t advisable, the viral post doesn’t paint an entirely accurate picture. i spoke to one urologist who warned that he’s seen a rise in young people suffering with the condition which he blames on increased consumption of protein drinks.

What are kidney stones? 

Kidney stones are hard deposits made of minerals and salts that form inside your kidneys. They are quite common with around three in 20 men and up to two in 20 women developing them at some stage of their lives, according to the NHS. Stones can develop in one or both kidneys and most often affect people aged 30 to 60. 

Small kidney stones may go undetected and be passed out painlessly in the urine. But it’s fairly common for a stone to block part of the urinary system which can cause severe pain in the abdomen or groin and sometimes causes a urinary tract infection (UTI). 

Larger stones may need to be broken up using ultrasound or laser energy. Occasionally, keyhole surgery may be needed to remove very large kidney stones directly. 

Is there a link between kidney stones and energy drinks? 

Kidney stones are usually formed following a build-up of certain chemicals in the body, such as calcium, oxalate, uric acid and cysteine, according to the NHS. Most are calcium stones, usually in the form of calcium oxalate. Energy drinks and other caffeinated beverages like coffee, tea and soda contain oxalate, hence the belief that they can cause the problem. 

Spire consultant urologist Subu Subramonian confirmed that the case pictured did appear to be kidney stones. However, he said such a severe case is unlikely to be caused entirely by excessive consumption of energy drinks.

“The appearance suggests that the patient may have a congenital condition such as renal tubular acidosis which predispose them to multiple calcification in the meat and tubes of the kidney due to a fault in the filtration mechanism for calcium in the micro tubes of the kidney. This condition leads to recurrent and multiple stones in the kidney and patient may end up with some kidney dysfunction as well.” 

He explained that kidney stones often have no definite, single cause, and that several factors increase risk. “Other contributing factors in play here could be inadequate water intake (as in most patients with kidney stones) and high consumption of animal protein and salt,” he said. 

“Although energy drinks could be responsible for a number of health hazards such diabetes due to excessive sugar content, there is no direct evidence to link it with kidney stone disease. It has been shown that people with diabetes have more incidence of kidney stones and therefore there might be indirect link.” 

Therefore, drinking a lot of energy drinks isn’t a good idea for their sugar content, but this alone is very unlikely to cause kidney stones. “Kidney stones tend to be calcium based, but it usually has no relationship with consuming calcium through diet and supplements,” added Mr Subramonian. 

The risks of protein drinks 



A diet rich in animal protein, because of its high purine content, which produces uric acid as it metabolises, may increase the risk of uric acid stone formation, experts say. 

Mr Subramonian said: “As a stone specialist, I am more worried more about the recent trend in increased consumption of protein drinks amongst youngsters as I see a lot of these young people coming to my stone clinic with new onset kidney stones. This is a trend I am seeing more recently over the last 10 years as protein drinks are promoted by sports shops, advertisements and even some gym trainers. 

“My advice to the public is to drink at least two litres of water a day and eat a healthy balanced diet to prevent kidney stones.” 

5 steps for preventing kidney stones 

The following advice appears from an expert on a Harvard Health Blog: 

Drink plenty of water: Drinking extra water dilutes the substances in urine that lead to stones. Strive to drink enough fluids to pass 2 liters of urine a day, which is roughly eight standard 8-ounce cups. It may help to include some citrus beverages, like lemonade and orange juice. The citrate in these beverages helps block stone formation. 

Get the calcium you need: Getting too little calcium in your diet can cause oxalate levels to rise and cause kidney stones. To prevent this, take in the  amount of calcium appropriate to your age. Ideally, obtain calcium from foods, since some studies have linked taking calcium supplements to kidney stones. Men 50 and older should get 1,000 milligrams (mg) of calcium per day, along with 800 to 1,000 international units (IU) of vitamin D to help the body absorb the calcium. 

Reduce sodium: A high-sodium diet can trigger kidney stones because it increases the amount of calcium in your urine. So a low-sodium diet is recommended for the stone prone. Current guidelines suggest limiting total daily sodium intake to 2,300 mg. If sodium has contributed to kidney stones in the past, try to reduce your daily intake to 1,500 mg. 

Limit animal protein: Eating too much animal protein, such as red meat, poultry, eggs, and seafood, boosts the level of uric acid and could lead to kidney stones. A high-protein diet also reduces levels of citrate, the chemical in urine that helps prevent stones from forming. If you’re prone to stones, limit your daily meat intake to a quantity that is no bigger than a pack of playing cards. 

Avoid stone-forming foods: Beets, chocolate, spinach, rhubarb, tea, and most nuts are rich in oxalate, and colas are rich in phosphate, both of which can contribute to kidney stones. If you suffer from stones, your doctor may advise you to avoid these foods or to consume them in smaller amounts.


https://inews.co.uk/news/health/does-this-viral-photo-of-kidney-stones-show-the-effect-of-drinking-too-many-energy-drinks/

'Give up dairy products to beat cancer’

A leading scientist, who has been fighting breast cancer since 1987, says the disease is overwhelmingly linked to animal products

By Cherrill Hicks

7:10AM BST 02 Jun 2014

Comment

In 1993, the breast cancer that had plagued Jane Plant since 1987 returned for the fifth time. It came in the shape of a secondary tumour – a lump in her neck the size of half a boiled egg. Doctors told her that she had only months to live.

Then a mother of two young children, Prof Plant recalls the shocked discussion she had with her husband, Peter. As scientists – she is a geochemist, he a geologist – they had both worked in China on environmental issues, and knew that Chinese women had historically very low rates of breast cancer: one epidemiological study from the Seventies showed the disease affected one in 100,000 Chinese women, compared with one in 12 in the West.

“I had checked this information with senior academics,” Prof Plant says. “Chinese doctors I knew told me they had hardly seen a case of breast cancer in years. Yet if Chinese women are on Western diets – if they go to live in the US or Australia, for example – within one generation they got the same rate. I said to Peter, 'Why is it that Chinese women living in China don’t get breast cancer?’ ”

Her husband recalled that on field expeditions his Chinese colleagues provided him with powdered milk because they did not drink it themselves. “He pointed out at that time they did not have a dairy industry. It was a revelation.”

Feeling she had nothing to lose, Prof Plant switched to a dairy-free, Asian-style diet virtually overnight, while also undergoing chemotherapy. Having already cut down on animal protein such as meat, fish and eggs, she now cut out all milk products, including the live organic yogurt she had religiously eaten for several years.

Within six weeks the lump in her neck had disappeared; within a year, she was in remission and remained cancer-free for the next 18 years. Convinced that her diet had helped, she devised the Plant programme – a dairy-free diet, relying largely on plant proteins such as soy – similar, she says, to the traditional diet in rural China.

It was originally intended to help other women with breast cancer and, later, men with prostate cancer. Her book about her experience, Your Life in Your Hands, caused a sensation when it was published in 2000, with many cancer patients claiming it helped them to recover.


'As a scientist, all I can do is tell the truth based on the evidence,' says Dr Jane Plant Photo: MARTIN POPE

But in 2011, Prof Plant’s breast cancer returned for the sixth time, with the discovery of a large lump beneath the collarbone and some small tumours in her lungs. Under stress writing an academic book, she had become lax about both her diet and lifestyle – regularly eating, among other forbidden items, calves’ liver cooked in butter at a restaurant, and falafel made from milk powder.

“I went straight back to my oncologist, who prescribed letrozole [an oestrogen suppressor]. But I also went back on my strict diet, as well as walking regularly and doing meditation.” After a few months, her cancer was again in remission.

All of which may sound too good to be true, but Plant, 69, is no crackpot. Professor of geochemistry at Imperial College London, where she specialises in environmental carcinogens, she is highly regarded in her field, having been awarded a CBE in 1997 for her services to earth science; and her approach to cancer is supported by some eminent scientists. Her latest book, co-written with Mustafa Djamgoz, professor of cancer biology at Imperial, has a foreword from Prof Sir Graeme Catto, president of the College of Medicine, who describes its findings as “illuminating… even, at times, shocking” but all backed up by scientific research.

Prof Plant, however, is not dismissive of conventional cancer treatment, having had, at various times, a mastectomy, chemotherapy, radiotherapy and irradiation of her ovaries to induce menopause.

She believes new and “wonderful” anti-cancer treatments are vital – but so, she argues, is a dairy-free diet, as well as other diet and lifestyle measures, such as stress reduction.

Much of the advice in the new book, Beat Cancer, chimes with current guidance on how to reduce cancer risk, such as eating more plant food and less red meat, salt, sugar and fat; taking regular exercise and reducing stress.

She also advises going organic, using complementary therapies where there is good evidence they help recovery, and avoiding potential pollutants such as pesticides.

But her far more radical message is that a diet that totally excludes dairy products – milk, cheese, butter and yoghurt – can be successfully used to help stop the disease “in its tracks”, by depriving cancer cells of the conditions they need to grow.

“We have all been brought up with the idea that milk is good for you,” says Prof Plant. “But there is evidence now that the growth factors and hormones it contains are not just risky for breast cancer, but also other hormone-related cancers, of the prostate, testicles and ovary.”

Going dairy-free, she says, may also help patients with colorectal cancer, lymphoma and throat (but not lung) cancer. “Cows’ milk is good for calves – but not for us,” she adds.

With the relatively new science of epigenetics, scientists now understand that cancer-causing genes may not become active unless particular conditions arise that switch them on – and if those conditions change, they may be switched off. “This means that what you eat can have an impact at the genetic level,” says Prof Plant.

_{For those with cancer or at high risk of the disease, Prof Plant advocates cutting out all dairy}

Cancer cells, scientists now believe, are hypersensitive to chemical messenger proteins called growth factors, as well as (in the case of hormone- dependent cancers) hormones such as oestrogen. Produced by our own bodies, growth factors perform vital tasks such as making cells grow. Other substances called binding proteins normally control them, including their potential impact on cancer cells. The risk of cancer arises when we have abnormally high levels of “unbound” growth factors (or hormones) circulating in our blood.

This can happen, say Profs Plant and Djamgoz, because the same growth factors and hormones as we produce are found in food that comes from animals, providing the very “fertiliser” that cancer cells need. Casein, the main protein in cows’ milk, is considered most dangerous. One eminent US nutritional scientist, Prof Colin Campbell at Cornell University, argues that it should be regarded just like oestrogen – as a leading carcinogen.

“Cow’s milk [organic or otherwise] has been shown to contain 35 different hormones and 11 growth factors,” says Prof Plant. High circulating levels of one such growth factor in milk, called IGF-1, is now strongly linked to the development of many cancers. Research has also found that “unbound” IGF levels are lower in vegans than in both meat-eaters and other vegetarians.

“This means that a vegan diet is lower in cancer-promoting molecules and higher in the binding proteins that reduce the action of these molecules,” she argues.

A second growth factor implicated in cancer spread is VEGF, found at high levels in cancer patients and a target for some newer anti-cancer drugs. Prof Plant points out that in the udders of cows with mastitis, VEGF is present to help fight infection. Mastitis is thought to affect nearly half of all cows in Britain. “There are increasing numbers of papers about high levels of VEGF in milk, particularly from high- yielding cattle breeds typical of modern industrialised dairy units.

“It seems likely that if a cancer patient is consuming dairy products, they are also consuming VEGF, especially if the milk originated from cows with mastitis. That is not helping to defeat their illness – and it may be making things worse.”

She is particularly worried about the fashion for high- protein diets, pointing out that there is evidence that too much protein generally – particularly from animals – is “at best unhelpful and at worst dangerous to those at risk of cancer”.

A second theory around diet concerns the levels of acid in our bodies. Prof Plant explains that if we consume too much acid-generating food, our bodies become acidic – an environment in which cancer cells can flourish. The foods highest in generating acid (not, as might be assumed, citrus fruit) include eggs, meat, fish and dairy – with cheese the most acid generating-food of all.

For those with cancer or at high risk of the disease, Prof Plant advocates, among other things, cutting out all dairy – from cows, sheep and goats, and whether organic or not. “If you have active cancer, there are no half-measures here.”

She also recommends limiting consumption of other animal protein, such as meat, fish and eggs, replacing this with vegetable protein such as soya – the main source of protein, she points out, in a traditional, rural Chinese diet.

But if the evidence that cutting out dairy can successfully “beat cancer” is that strong, why haven’t we been told?

Prof Plant puts it down to vested interests – the dairy industry represents about 12 per cent of Britain’s GDP – and medical conservatism: oncologists, she says, “might be excellent at conventional treatments but are not experts in nutritional biochemistry”. The big cancer charities, for their part, place too much emphasis on drug development. As a result, “if you rely solely on the cancer prevention advice from government, charities, health professionals or the media, you will be missing out on vital and potentially life- saving information.”

Cancer Research UK argues that so far studies investigating a link between cancer and dairy products have not given clear results.

“There’s no good evidence to support avoiding all dairy with the aim of reducing cancer risk,” said Martin Ledwick at Cancer Research UK. “It isn’t known if avoiding dairy plays a role in stopping cancer coming back. Patients should speak to their doctor or a qualified dietician before making any changes to their diet.”

Prof Plant acknowledges that advising cancer patients – and anyone keen on prevention – to change what they eat so radically is “a big ask”. Yet her own menu for that day – Weetabix and soya milk with molasses and linseeds for breakfast, wholegrain bread with hummus and salad for lunch and for that night, minestrone soup with cannellini beans, followed by pasta with homemade tomato sauce – is not so alien.

“People always worry about where they will get calcium if they give up dairy,” she says. “But you can get it from many plant sources.” Growth factors and hormones should be labelled on all dairy products, she argues, although eventually a wholesale shift away from dairy is needed.

Approaching her 70th birthday, Prof Plant has so far survived 27 years and six diagnoses of cancer and is a pretty convincing advert for the diet she advocates. Her story, though, has a sting in its tail: two weeks ago, a scan undertaken for a broken collarbone picked up two small secondaries, one in each lung. She is now taking tamoxifen and seems confident that a combination of medical treatment, diet and relaxation will knock this recurrence on the head.

“As a scientist, all I can do is tell the truth based on the evidence,” she says. “I started my first book because I didn’t want my daughter [Emma, now 39] to go through what I went through. All my books have come out of not wanting this to happen to others.”

'Beat Cancer: The 10-Step Plan to Help you Overcome and Prevent Cancer’ by Prof Mustafa Djamgoz and Prof Jane Plant is published by Vermilion (£14.99)

THE 'BEAT CANCER' DIET

Beat Cancer advises anyone with cancer or at high risk of the disease to cut out all dairy products, organic or not, from cows, sheep, goats and all other animals. Replace:

Dairy milk with almond, coconut, rice or soya milk

Hard cheese with tofu or bean curd for sauces, soft cheese with hummus

Dairy yoghurt with soya or coconut yoghurt

Crème fraiche, fromage frais and cream with coconut or soya cream

Butter and margarines containing dairy with soya spreads, hummus, peanut or other nut or seed butter

Dairy ice cream with soya, coconut ice cream or other dairy-free types; milk chocolate with dark chocolate

Other advice includes replacing refined and processed oils with

extra-virgin olive oil; refined and man-made sugars with raw cane sugar; refined white bread, pasta and rice with unrefined wholegrain products; and cutting out preservatives and artificial flavourings and colourings.

Consumption of meat, fish and eggs should also be limited. Instead, eat unrefined carbohydrates, beans, nuts, vegetables and fruit. Salt is best replaced by herbs, and coffee by homemade juices, tap water and herbal tea.

http://www.telegraph.co.uk/foodanddrink/healthyeating/10868428/Give-up-dairy-products-to-beat-cancer.html