Study Shows Many with Treatment-Resistant Schizophrenia Have a Poor Diet

A recent study showed individuals with treatment-resistant schizophrenia have a low diet quality and do not follow nutritional recommendations.¹

Treatment-resistant schizophrenia is associated with more than a high level of psychotic symptoms, cognitive deficit, and poor functioning—they are also at an increased risk of mortality for cardiometabolic diseases. Previous studies have shown diet may increase the risk of obesity and metabolic complications in these patients.

A study published in 2021 reported that people with schizophrenia are at a 2 – 5-fold increased risk for diabetes, metabolic syndrome, obesity, and cardiovascular diseases compared to the general population.² Up to 50% of people on antipsychotics gain weight, which can be explained by neurotransmitter mechanisms affecting the brain’s satiety center and insulin and gastrointestinal hormones, making people prefer food with high levels of sugar and fat.

Lifestyle issues, such as diet, can also contribute to weight gain. People with schizophrenia are more likely to have a diet rich in saturated fats and calories but poor in fiber and fruit.

Investigators, led by Claudia Vetrani, PhD, from the department of wellbeing, nutrition, and sport, at Pegaso Telematic University in Naples, Italy, conducted a cross-sectional study to evaluate diet quality and eating habits in individuals with treatment-resistant schizophrenia.¹ They recruited 17 participants (13 male; aged 37.8±13 years) to examine the dietary composition and food group consumption by a 7-day food record. The team also collected demographic and clinical data.

Most participants were overweight or obese (82%) and only 35% were physically active. Based on the nutritional recommendations, participants had an insufficient intake of fiber (15.9 ± 3.2 g/day), vitamins (thiamine, riboflavin, vitamins A, D, and E), minerals (calcium, magnesium, selenium, and iron), and polyunsaturated fatty acids (2.11 ± 0.8%).

For reference, this is the recommended intake for fiber, according to the Dietary Guidelines for Americans, 2020 – 2024: ³

Linked here are the nutritional recommendations, broken into age groups, for thiamine, riboflavin, vitamin A, vitamin D, vitamin E, calcium, magnesium, selenium, iron, and polyunsaturated fatty acids.

Investigators explained the participants’ lack of nutrients was likely due to their low consumption of fish and plant-based foods, such as legumes, fruit, vegetables, and nuts.

Moreover, participants exceeded the intake of saturated fatty acids (11.6±3.4%) and cholesterol (242±124 mg/day), likely due to the high consumption of red and processed meat. Participants also had a high intake of simple sugars (15.2±3.9%), caused by sweet foods.

“These results support the importance of including nutritional assessment in the management of individuals with [treatment-resistant depression],” investigators wrote.

References

1. ^{Vetrani C, DE Simone G, Saia V, Barrea L, Muscogiuri G, Graziadio C, DE Bartolomeis A, Macchia PE, Colao A. Diet quality in patients with treatment-resistant schizophrenia: time for improving nutritional recommendations. Minerva Endocrinol (Torino). 2024 Nov 20. doi: 10.23736/S2724-6507.24.04158-7. Epub ahead of print. PMID: 39565366.}
2. ^{Sankaranarayanan A, Johnson K, Mammen SJ, Wilding HE, Vasani D, Murali V, Mitchison D, Castle DJ, Hay P. Disordered Eating among People with Schizophrenia Spectrum Disorders: A Systematic Review. Nutrients. 2021 Oct 27;13(11):3820. doi: 10.3390/nu13113820. PMID: 34836076; PMCID: PMC8618287.}
3. ^{How Much Fiber You Need and Why it Matters. Cleveland Clinic. March 14, 2023. https://health.clevelandclinic.org/fiber. Accessed November 26, 2024.}