A high-carbohydrate, high-calorie diet could delay the progression of
Amyotrophic Lateral Sclerosis (ALS), also known as motor neuron disease
or Lou Gehrig's disease, according to a phase 2 study published in The Lancet. ALS is a rapidly progressive, fatal neurodegenerative disorder affecting
the nerve cells that control muscle movement (motor neurons). Patients
gradually lose the ability to control the body's muscles, including the
muscles which control breathing. This leads to respiratory failure and
death on average about 3 years after patients are diagnosed. Loss of weight, both muscle and fat, is common as ALS progresses, and
patients experience more difficulties eating, swallowing, and
maintaining their bodyweight. Recent work suggests that these problems
might also contribute to the course of the disease: patients who are
mildly obese are more likely to live longer, and mice carrying a gene
which causes ALS lived longer when they were fed a calorie-rich diet
high in fat.
The new study, funded by the Muscular Dystrophy Association, was
performed at 12 ALS centres and led by Dr Anne-Marie Wills at the
Massachusetts General Hospital, in Boston, USA. To participate in the
study, patients with advanced ALS had to already have a feeding tube
(known as PEG tubes, or percutaneous endoscopic gastrostomy tubes),
which allows food to be delivered directly into the stomach. Twenty
patients were split into three groups, each with a different diet plan
-- a control group (to maintain weight) and two high-calorie
(hypercaloric) groups: one high in carbohydrates, the other high in fat.
The diets lasted for 4 months, and data on safety and survival were
collected from the beginning of the study for a total of 5 months.
This
study was primarily intended to assess safety and tolerability of the
diets for ALS patients: patients given the
high-carbohydrate/high-calorie diet experienced fewer adverse events (23
vs 42), and significantly fewer serious adverse events (0 vs 9) including deaths from respiratory failure than the control group.
Patients
given the high-carbohydrate/high-calorie diet also gained slightly more
weight than the other groups (an average of 0·39kg [about 0·86lbs]
gained per month, compared to an average gain of 0·11kg [0·24lbs] per
month in the control group, and an average weight loss of 0·46kg
[1·01lbs] in the high-fat high-calorie diet group).
According to
Dr Wills, "There is good epidemiological evidence that, in ALS, survival
is determined by nutritional status. This pilot study demonstrates the
safety of a novel, simple, low-cost treatment for a devastating disease
where currently, very few treatment options are available. The adverse
outcomes that we feared might result from weight gain, such as diabetes
or heart disease, were not observed in our study period of five months."
Nonetheless,
the authors point out that the findings should be interpreted "with
caution," and call for larger trials, with similar nutritional
interventions tested at an earlier stage in the disease for ALS
patients.
"Although the sample size was small, we are optimistic
about these results, because they are consistent with previous studies
in ALS mouse models that showed that hypercaloric diets improve
survival," says Dr Wills. "Not only could this type of nutritional
intervention be a novel way to treat and slow down the progression of
ALS, it might also be useful in other neurological diseases."
Writing
in a linked Comment, Dr Ammar Al-Chalabi, of King's College London, UK,
states that, "I will not be changing my advice to patients on the basis
of this study, but I am eager to see the results of a large Phase 3
trial. Wills and colleagues have taken the first steps needed to provide
evidence for a robust, non-pharmacological treatment that is well
tolerated and easy to administer. We must finish the work they have
started."
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