Nutrition care for CF patients needs to junk the legacy diet

Cystic fibrosis

By Mardi Chapman

26 Mar 2024

It’s time for a pivot to a healthier diet for patients with cystic fibrosis: away from the legacy high fat/high energy CF diet which may have adverse health consequences as people with CF age and in the era of effective CFTR modulator therapies.

Ms Tamarah Katz, a paediatric respiratory dietician at the Sydney Children’s Hospital, told the TSANZSRS 2024 meeting that in the past the importance of nutrition for patients with CF trumped the importance of a healthy diet.

However the evidence from a 2018 study [link here] was that children with CF were receiving 44% of their energy intake from junk food, mirroring an increase in overweight and obesity in the CF population.

Ms Katz said there was a need to consider not just the impact of nutrition on the underlying CF but on the patient’s future risk of cardiovascular disease and cancer, particularly colorectal cancer (CRC) which was already increased in people with CF.

She said the Dietary Approaches to Stop Hypertension (DASH) diet had been shown to reduce the risk of CVD in an otherwise healthy population by about 20%.

DASH dietary patterns focus on fruit, vegetables, whole grains, nuts, seeds, legumes and lean meat such as fish and chicken. Dairy foods, either low or full fat, were also included but butter should be limited. Monounsaturated fatty acids from sources such as walnuts, avocado, and olive oil, and polyunsaturated fatty acids from canola oil were included.

DASH also recommended reducing salt intake which Ms Katz said was probably twice as high as required in an average Australian diet.

Ms Katz said the DASH diet was also one of a few dietary patterns shown to be inversely associated with CRC risk [link here]

She said there was convincing evidence that alcohol, processed meat and body fatness were associated with increased risk of CRC and probable evidence of an association with red meat.

Her conclusion was that the new CF diet should probably be the DASH diet.

Overcoming outdated thinking

She told the limbic that there was still a significant patient and health professional education piece required to negate the lingering perception that people with CF required unlimited calories.

“I think it’s really important for them to understand that they no longer require all these extra calories … and that education needs to be targeted from weaning really. It has to start from the very beginning because dietary habits do become very entrenched and they’re very hard to change later on in life.”

She said it was not enough to encourage children, adolescents or young adults with CF to eat like the rest of their family given many Australians were eating a poor quality diet.

“We should be focusing on adopting healthy habits in a gradual way, chipping away on what they can do to be healthier. And that might be different from one person to another – in one person it might be eating less takeaway food, in another person it might be having more vegetables.”

Ms Katz said the use of highly effective modulator therapies and observations of associated weight gain added another dimension to the issue of personalised nutrition for people with CF.

For example, the 2024 ESPEN-ESPGHAN-ECFS guideline on nutrition care for cystic fibrosis [link here] said the effect of CFTR modulators on body weight and BMI varies according to the particular genetic mutation and the type of CFTR modulator.

“Appropriate dietary counselling should be provided prior to starting CFTR modulators, this should include discussions about possible weight gain and exploration of any potential concerns regarding body image,” the guideline said.

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