Could diet be associated with slower progression in MND?

Could diet be associated with slower progression in MND?

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Weight loss is a problem for many people living with MND, with approximately 20% of people already having lost 10% of their weight at diagnosis. Some of this weight loss may be due to a person experiencing difficulties with chewing and swallowing due to increasing muscle weakness, a lack of appetite due to tiredness, anxiety or low mood or because their body is simply using more energy than they are consuming, even without exercise, which is known as hypermetabolism.

At the 34th International Symposium on ALS/MND in Basel, Switzerland one of the sessions looked at nutritional assessment and management, with talks covering feeding tube management and the decision-making process, how diet might help slow progression, alternative ways to measure nutritional state and how appetite is controlled in the brain. In this series of blogs, we are going to look a little closer at each of these studies and their potential for helping people living with MND. This is part three in the series.

Higher glycaemic index and glycaemic load diet is associated with slower disease progression in ALS

Dr Ikjae Lee from the Eleanor & Lou Gehrig ALS Center in the USA talked about how a higher glycaemic index and glycaemic load diet could be associated with slower disease progression.

Previous interventional trials have demonstrated that very high calorie, high carbohydrate and/or high fat diets delivered via a feeding tube might help with weight stabilisation and prolong survival in people with MND.

However, several questions remain:

  • Is there an effective nutritional intervention for a broad MND population?
  • What would be the key macronutrient in that nutritional intervention? Macronutrients provide the body with energy and the components it needs to maintain its structure and functions. Carbohydrates, protein and fat are the three main macronutrients.
  • What about macronutrients that have not been comprehensively evaluated such as protein and fibre?
  • What about carbohydrates with different glycaemic properties, high vs low glycaemic index (GI) and high vs low glycaemic load (GL)?

Good to know

Glycaemic index (GI)Glycaemic load (GL)
This assigns a numeric score to a food based on how much it makes blood sugar rise. Foods are ranked on a scale from 0-100, compared to pure glucose (sugar) which has a value of 100. The lower a food’s GI, the slower the blood sugar rises after consumption. The more processed a food is, the higher its GI is likely to be. Foods higher in fat or fibre have a lower GI.Glycaemic load measures how quickly glucose enters the bloodstream AND how much glucose per serving it can deliver. This gives a more accurate indication of a food’s real -life impact on blood sugar levels. For example, watermelon has a high GI (80) but a serving of watermelon has very little carboydrate, so its GL is only 5.

What did the study look at?

The study – called COSMOS ALS – investigated if specific macronutrient intake is associated with functional decline and survival in MND. Sixteen sites across the USA collected baseline (data collected at the beginning of the study) and follow-up dietary habits of 304 participants with sporadic MND, who were less than 18 months since symptom onset, via a Food Frequency Questionnaire (usual eating habits in the last 6 months). It examined whether dietary macronutrient intake (calories, fat, carbohydrate, protein, fibre, GI and GL) is associated with disease progression, using the ALSFRS-R, and length of tracheostomy-free survival as outcome measures. Baseline data showed that participants were slightly fast-progressing (1.1 points per month on the ALSFRS-R, with an average score of 36), and with an average BMI of 26.5.

The researchers studied the connection between the baseline nutrients and how they related to a decline in function. They examined total calories, caloric deficits (when more calories are used than are consumed), protein, fat, carbohydrate, GI, GL and fibre one at a time, to see if there is a relationship between these nutrients and the change in function in people with MND over a 3-month period. The findings were adjusted to account for things like age and gender, and other factors that can affect prognosis such as disease duration, site of onset, riluzole use, and BMI and ALSFRS-R score at the beginning of the study. They also considered the nutrient density, which means the percentage of calories that come from fat, protein and carbohydrates to see if that had any impact. The researchers also looked for changes in ALSFRS-R over a 6-month period.

What did they find?

When data from the whole group was analysed, ALSFRS-R and forced vital capacity (FVC) scores declined consistently to start with and then evened out. This is the effect of fast-progressing participants who died before the end of the study.

When the data is analysed for only those participants who completed the study, when adjusted for age and gender, it shows that an increased calorie intake of 100 calories per day results in less functional decline. Increasing fat intake by 10g and GI and GL by one unit also results in less functional decline. These results were statistically significant, meaning that the results are likely to be caused by the increase in nutrient intake rather than just by chance. By contrast, total protein and total fibre did not show a significant association with functional decline.

When the data was adjusted for other variable factors such as site of onset, disease duration and baseline ALSFRS-R and FVC scores, total calories, fat and carbohydrate intake no longer makes a significant difference to decline. However, higher GI and GL still resulted in less functional decline.

Survival analysis indicated that a one unit increase of GI was associated with a longer time to tracheostomy, suggesting that dietary glycaemic index is associated with functional decline and survival in MND.

Overall, while there may be some benefit to a high calorie-high fat diet for some people with MND, when taking into account variable factors the association with functional decline was not statistically significant.

What might the potential mechanisms be for this association with a high glycaemic diet with a slow down in progression? Although this is speculation on the part of Dr Lee, he mentioned that other studies have shown that the uptake of glucose is increased in muscle and lower motor neurons of people with MND and an excess of glucose helped to reduce protein misfolding, a hallmark of the disease.

What next?

Moving forward, Dr Lee suggests looking into overall dietary patterns, directly measuring food intake, continuously monitoring blood glucose levels, and conducting nutritional trials to see if specific diets or supplements can truly make a difference in the progression of the disease.

The International Alliance of ALS/MND Associations held a webinar in February 2024 that discussed nutrition in ALS/MND – its importance, nutritional changes after diagnosis, considerations for bulbar onset ALS/MND and the myths and benefits of feeding tubes. You can watch the webinar in the video below.

Part four in this series of nutritional assessment and management blogs looks at how using different body measurements might improve the ways in which weight loss is monitored in people with MND.

None of this research would be possible without the people with MND who take part, and those who support them. We thank them for their trust and time.