The 5:2 diet gave me motor neurone disease, scientist claims
A molecular biologist has warned of the dangers of the 5:2 fasting diet after developing motor neurone disease.
Dr Vivienne Cox, who worked at two leading pharmaceutical companies and co-founded two biotech firms, believes that restricting food intake stopped her cells from functioning properly, triggering disease.
Dr Cox, 65, discovered she was carrying a gene mutation that causes toxic proteins to be made which interfere with energy metabolism in cells. When her diet involved plenty of sugar and carbohydrates, the energy deficits could be restored.
But she believes that when she began the fasting diet to get in shape for her 60th birthday, it triggered the onset of amyotrophic lateral sclerosis (ALS), a fatal version of MND.
"I led a carefree and indulgent life up to my late 50s and enjoyed good food, booze and sweet treats," she said. "I was pretty fit, from an outdoorsy life with gardening and country walks my main pastimes.
"I had never had to worry about weight, much to the envy of my teenage contemporaries and the annoyance of my sister and my husband, who were both prone to bulges in the wrong places, despite following similar lifestyles.
"Then Michael Mosley's intermittent fasting idea became the fad diet of the period. I had gained a little weight, so signed up to the 5:2 diet with great enthusiasm. I lost a stone immediately and felt pretty good. I cut out refined sugar and limited carbohydrates."
The 5:2 diet which was pioneered by the late Michael Mosley is an intermittent fasting regime which sees adherents eat normally for five days a week and then for two non-consecutive days eat just 25 per cent of the normal calorie total.
It has been hailed for not only helping people to lose weight but for potentially also bringing extra health benefits, such as helping diabetics control blood sugar. Studies in animals have even shown it may boost the regenerative abilities of stem cells, fight cancer and even improve lifespan.
However, less than two years after starting the diet Dr Cox began to notice a change in her health.
"I developed a lop-sided walk. I started to stumble occasionally, and didn't really enjoy walks as much as I used to. By age 62 I was starting to fall and hurt myself, and broke a few bones, always tripping over my right foot," she said.
"Fast forward to now, aged 64, and I am in a wheelchair with a diagnosis of motor neurone disease.
"As a scientist, I have delved deep to see what might have been the trigger for the onset of disease, when I have been carrying this mutation since birth. I strongly suspect intermittent fasting to be the culprit."
The cell's batteries are known as mitochondria and they are thought to play a pivotal role in neurodegenerative diseases like MND and Parkinson's disease.
Recent scientific research into the cause of MND suggests that sufferers are 'hypermetabolisers' – getting through more energy than other people because of an inherited problem with the mitochondria.
"While I was feeding my body with sweet treats and carbs, I was probably keeping the disease at bay," added Dr Cox, "as soon as I starved myself, I allowed it to take hold."
Dr Ikjae Lee, an assistant professor at Columbia University, has also been researching the link between diet and motor neurone disease.
"As an ALS physician, I heard similar stories from many of my patients that they tried to lose weight with various methods prior to the onset of weakness," he said.
"Initially, losing weight was delightful. Then weight loss gets quite pronounced leading to the onset of ALS. These anecdotal cases made me intrigued and led me to study metabolism and its association with the disease."
In a recent study, published in Annals of Neurology, Dr Lee found that a diet with high glycemic index – raising blood glucose quicker and higher – seems to slow down the disease progression in patients with ALS.
"This finding needs to be confirmed by a randomised interventional trial, providing one group with a high glycemic diet while keeping the other group with a regular diet and observing whether progression differs between these groups."
ALS is a fatal disease which brings progressive muscle weakness, swallowing and respiratory problems. The average survival is just three years and half of people are dead within 18 months of diagnosis.
Prof Stephen Hawking proved a notable exception, living for 50 years after his diagnosis aged 21.
Dr Cox's gene mutation – C9orf72 – is the most common associated with ALS and is found in about 40 per cent of patients with a family history, and seven per cent of sporadic cases.
Researchers have previously warned about the potential harms of intermittent fasting.
A study of 20,000 adults presented at an American Heart Association meeting in March, found that people who followed an eight hour time-restricted eating schedule had a 91 per cent higher risk of cardiovascular death.
Dr Francisco Lopez-Jimenez, a cardiologist from the Mayo Clinic in Rochester, Minnesota, warned that an intermittent fasting diet is not for everyone.
"It actually became popular because studies on fruit flies show that when you restrict the calories, the flies will actually live longer. But we are not flies," said Dr Lopez-Jimenez.
"This recent study actually showed that those people practising intermittent fasting are twice as likely to die from heart disease or dying in general than those who don't practise this."
Dr Cox worked at Wellcome Biotech and SmithKline Beecham as well as co-founding Adprotech and Epsilogen, companies developing biological therapies. She said that since her diagnosis, she had stopped the diet and gone back to a more indulgent diet.
