More evidence needed to support use of high-calorie diet for ALS

Such diets don't appear to slow progression, a review of clinical trials shows

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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While eating a high-calorie diet is safe and well tolerated, it does not appear to slow disease progression or reduce the risk of death in people with amyotrophic lateral sclerosis (ALS), a review of published clinical trials found.

Combining data from multiple trials helps to create a single, more precise estimate of the effect of high-calorie diets in people with ALS. Yet, the review study included only four trials, all of which had few patients and short observations times. Consequently, the available evidence may not be strong enough to establish clear conclusions regarding the use of a high-calorie diet.

“A larger randomized controlled trial with longer observation might be needed to truly establish its efficacy,” which should offer more accurate information to make informed decisions about dietary choices, the researchers wrote.

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The study, “Efficacy, safety and tolerability of high caloric diet in amyotrophic lateral sclerosis patients: A systematic review and meta-analysis,” was published in Revue Neurologique.

ALS affects the motor nerve cells responsible for movement, causing muscles to weaken and waste away over time, making it difficult to walk, speak, eat, and drink.

Poor nutrient intake (malnutrition) and weight loss are common in people with the disease and have been linked with worse survival outcomes. This occurs mainly due to difficulty swallowing, so establishing a proper diet plan can help maintain good nutrition and offer other food options when swallowing becomes harder.

While there is no one-size-fits-all diet, many randomized clinical trials have tested if adding extra calories through sugars (carbohydrates) or fats (lipids) is safe and well tolerated and helps people with ALS live longer.

“However, most of these trials have been small and the results are conflicting,” the researchers wrote.

To draw broader conclusions, a trio of researchers in the Philippines and Canada used a method called meta-analysis to pool data from multiple published studies that had tested high-calorie diets in people with ALS.

Four studies used in the analysis

After reviewing the literature, a total of four studies, published between 2013 and 2022, were included in the analysis.

The studies included 311 patients. Of them, 176 followed high-calorie diets with carbohydrate or lipid supplementation, whereas 135 individuals used as controls ate fat-free or moderate-calorie diets.

The four studies lasted between 1-15 months. In all, it was concluded that high-carbohydrate and high-lipid diets “were generally safe and tolerable,” the researchers wrote.

The chances of high-calorie diets causing side effects or leading to dropping out were about the same as they were for controls. However, the results varied widely across studies.

Following high-calorie diets also did not significantly reduce the chances of dying or slow the decline in the revised ALS Functional Rating Scale (ALSFRS-R) score, a measure of how quickly a patient’s functional ability becomes impaired over time.

They also didn’t lead to significant increases in weight versus controls, “even when there was no or there was minimal heterogeneity [variation in results across studies],” the researchers wrote.

Pooled data was not statistically significant

While some studies showed beneficial effects of high-calorie diets on certain outcomes, the analysis of pooled data did not reveal statistically significant differences versus controls.

“Current evidence suggests that high calorie supplementation is generally safe and tolerable for patients with ALS. However, it has not been shown to be efficacious in improving weight and functional disability,” the researchers concluded.

However, “the low sample size, high drop-out rate and short observation time in most studies may have affected the result,” they noted, calling for a “larger-scale study, with a longer observation period.”