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Starving cancer

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We’ve all heard about the Fast Diet – characterized by the 5:2 rule, where we eat normally for five days and then a very restricted diet for two days – but one of the inspirations behind the concept thinks it not only helps us lose weight, but could also be the key to beating cancer.

Simply put, we starve cancer by not eating. Valter Longo, professor of gerontology (the study of aging) and biological sciences at the University of Southern California, estimates that cancers lose their primary food source if we fast for four days. In itself, that’s not enough: people who don’t eat for four days won’t beat cancer because cancer cells will then seek out new energy supplies in the form of enzymes called ‘protein kinases.’

In what he calls a ‘one–two knock-out punch,’ Longo says that, after fasting, the cancer patient then takes kinase inhibitors, drugs that have already been approved as a cancer treatment by the US Food and Drug Administration (FDA). These will block the final food source for cancer cells.

Right now, this is all at the experimental stage, and Longo has so far tested the theory only on colon-cancer cell lines in his laboratory. But it’s a theory that’s also being studied by scientists in Europe who want to try it out on cancer patients. Longo is quietly confident that he’s discovered a major new way to treat cancer – one that doesn’t cause the catastrophic damage to the immune system of chemotherapy.1

Longo hasn’t made this discovery all by himself. Aside from the scientists in his native city of Genoa, Italy, who have been working with him, Longo has also been heavily dependent on the insights of German biochemist Otto Warburg, who died in 1970. Warburg was awarded the Nobel Prize in Physiology or Medicine in 1931 for his research into the respiratory systems of cells, or how they ‘breathe.’

More significantly, he also discovered that cancer cells don’t need oxygen (they are anaerobic), but instead depend on an energy source from fermenting sugar, or glucose, which they get from carbohydrates in our diet.

The Warburg effect

The cancer cell is in constant overdrive, metabolizing at a rate that is eight times greater than a healthy cell and so is constantly craving glucose in a process that’s been called the ‘Warburg effect.’ In fact, cancer begins when healthy cells are deprived of oxygen, said Warburg. This can happen when the body’s alkaline/acid balance goes out of kilter and becomes too acidic, which means the body’s normal pH (potential hydrogen) level falls below the healthy 7.365 level. Cancer cells thrive in a lower pH environment, often as low as 6.

So the idea of fasting – quite literally starving cancer cells – isn’t such a jump from Warburg’s research. And it doesn’t just starve cancer cells of glucose, but could also make kinase-inhibiting drugs more effective, Longo says. But although they’re not as toxic as chemotherapy, the drugs are still no walk in the pharmaceutical park, and patients can react badly. Longo believes that patients who fast will not have to take the drugs for as long and yet will still achieve the same results as a non-fasting patient.

Longo’s theory about kinase inhibitors has some support from an earlier study he carried out, demonstrating that fasting can lessen the worst effects of chemotherapy agents.

In an experiment using laboratory mice, Longo and his team found that the animals not fed for two days thrived after receiving a high dose of chemotherapy, while half the mice that were eating normally died. The remainder of the non-fasting group suffered permanent weight loss after the chemo.2

Hibernating cells

Longo’s team were confident they would see similar results in humans, and studies of human cell lines in the lab seem to back up their claim. Healthy and cancerous brain cells given low levels of glucose – designed to replicate the effects of fasting – were resistant to chemotherapy. In this laboratory study, the researchers speculated that starving healthy cells go into hibernation, while the cancer cells that continue to feed on glucose remain susceptible to chemotherapy, which targets fast-growing cells.

Conventional medicine agrees with Warburg: cancer cells do feed off glucose, and student doctors are taught all about the Warburg effect in medical school. Yet, despite this ready acceptance, it has never changed the way cancer is treated because the conventional view is that the Warburg effect is a symptom of cancer, not its cause. The prevailing theory maintains that cancer is a genetic disorder. Even Warburg’s biographer, Hans Krebs, accused him of oversimplifying the problem. Other critics said that Warburg’s theory failed to explain some of cancer’s other processes, such as mutations and spreading.

Longo and other biologists, such as Thomas Seyfried at Boston College, are part of a vanguard that is putting Warburg and the theory of cancer as a metabolic disease back on the map. Seyfried argues that cancer is a metabolic disease, not a genetic one, as Warburg claimed, and that this conclusion changes the way the disease should be treated.

Essentially, Longo argues, cancer has to be deprived of glucose, and this is most easily achieved through dietary changes like fasting or adopting a ketogenic diet, the high-fat, low-carb regime that has been used successfully to control epileptic seizures.3

Cancer also ceases to be a mysterious disease, one that has its genesis in genetic patterns. Instead, it’s a disease triggered by the inability of our cells to ‘breathe,’ a process brought about by radiation, chemicals, viruses – and the food we eat.

Careful with that fast

There are many virtues to introducing fasting into your health regime. Studies abound of it kick-starting the immune system and even reversing arthritis, improving the health of the heart and cardiovascular system, and as a way to prevent diabetes.

Even going on a ‘mini-fast’ – where just one meal a day is occasionally skipped – could help us live longer.1 And just never eating after the evening meal can reduce a woman’s risk of breast cancer; those who indulge in a ‘midnight feast’ are more likely to develop the disease.2

But despite its health benefits, fasting should be done with caution and ideally with the guidance of a nutritionist or health practitioner.

For a start, reverting to your normal diet immediately after a fast can cause blood sugar levels to spike, undoing all the good achieved by the fast. Others have started to dramatically overeat once the fast was over. And it could be dangerous for diabetics to even begin to fast.

Fasting can have many shades too. Some brave souls manage a water-only fast, while Longo usually has in mind restricting food intakes to just 200 calories a day for no more than four days, supplemented with plenty of water. The Fast Diet talks about reducing calories to 600 a day for men and 500 for women on the two fasting days each week.

But simply restricting calories – and avoiding refined carbohydrates and processed foods – can give us many of the benefits of more rigorous fasting.

Sensible fasting

Start slow and end slow. Cut down on food gradually by eating a light protein, cooked vegetables and rice. When you break the fast, do the same in reverse.

Consider a juice fast (but not orange juice), as juice provides calories and important nutrients. Choose either raw fresh fruit or vegetable juices.

Ensure you drink enough water – in fact, drink more than usual so your urine isn’t dark.

Try one meal a day (say, fish or chicken with steamed vegetables or rice) in the midafternoon instead of a fast. The rest of the day, consume water, juice, teas, and fresh fruit and vegetables.

Move on to a fast from one meal a day, then to fasting for five days and, finally, for a week or two.

A light dinner followed by a 12- to 14-hour break from food can constitute calorie restriction and a daily mini-fast.

Fast masters

Fasting has been recognized as a way to better health for centuries. Even Hippocrates, the Ancient Greek considered the Father of Medicine, said: “Instead of using medicine, rather fast a day.”

1921 – Nearly a hundred years ago, endocrinologist Dr Henry Rawle Geyelin was advocating the use of fasting to control epileptic seizures, something that Hippocrates and other Ancient Greeks were also doing. The problem was that it wasn’t a long-term remedy, and the seizures returned when the patient started eating again.

Longo’s own mentor was Dr Roy Walford, a maverick professor at the University of California at Los Angeles (UCLA) who became convinced that we could extend our lifespan by a further 50 or even a hundred years by fasting or, more correctly, dramatically reducing calorie intake. Even so, Walford’s catchphrase was “undernutrition, not malnutrition,” suggesting we still had to be careful.

1992- Longo joined UCLA in 1992 as an undergraduate to work with Walford, having given up a career as a pop musician. But when he arrived, Walford was locked away in a biosphere with a bunch of volunteers. It was a two-year experiment, and food supplies were so restricted that Walford convinced his seven ‘co-pilots’ to adopt a calorie-reduced diet – which lasted for nearly a year until they all gave up and plundered the emergency food supplies.

2004 – Walford’s early research gave him encouragement that eating less meant living longer. Laboratory experiments with mice seemed to support the theory, with those fed a restricted diet living twice as long as the normal eaters.

But it didn’t work for Walford, who died at the age of 79 in 2004 from ALS (amyotrophic lateral sclerosis; also known as motor neurone disease). Scientists drily observed that fasting doesn’t prevent ALS or help us live longer.

Undaunted, Longo was getting similar results as those obtained by Walford from his own early experiments. Playing around with the diets of lab mice as part of his doctoral thesis in 1997, Longo wasn’t always able to demonstrate that fasting helped to increase longevity, but there was in nearly every case a positive impact on chronic diseases, either as a way of preventing them or reversing the conditions if they were already there.



Oncotarget, 2015; published online ahead of print: March 30, 2015


Proc Natl Acad Sci U S A, 2008; 105: 8215–20


Nutr Metab [Lond], 2010; 7: 7

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Article Topics: Cancer, chemotherapy, oncology
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