The effects of a low-carbohydrate diet on oxygen saturation in heart failure patients: a randomized controlled clinical trial.

Introduction: Nutritional therapy in heart failure (HF) patients has been focused on fluid and sodium restriction with the aim of decreasing volume overload. However, these recommendations are not well established and sometimes controversial.

Objective: To evaluate the effect of the consumption of a low-carbohydrate diet on oxygen saturation, body composition and clinical variables during two months of follow-up in chronic, stable heart failure patients.

Methods: In a parallel group randomized controlled clinical trial, 88 ambulatory patients were randomly assigned to a low-carbohydrate diet group (40% carbohydrates, 20% protein and 40% fats [12% saturated, 18% monounsaturated and 10% polyunsaturated]) or a standard diet group (50% carbohydrates, 20% protein and 30% fats [10% saturated, 10% monounsaturated and 10% polyunsaturated]) for two months. Diets were normocaloric in both groups. At baseline and at two months of follow-up, the variables evaluated were: oxygen saturation, dietary intake, body composition and handgrip strength.

Results: After two months of follow-up, the low-carbohydrate diet group decreased the carbohydrate consumption and had improved oxygen saturation (93.0 ±4.4 to 94.6 ± 3.2, p = 0.02), while the standard diet group had decreased (94.90 ± 2.4 to 94.0 ± 2.9, p = 0.03). There were also differences between the groups at the end of the study (p = 0.04). No significant differences showed in handgrip strength in both groups, low-carbohydrate diet group (26.4 ± 8.3 to 27.2 ± 8.3 kg, p = 0.07) and standard diet group (25.4 ± 8.9 to 26.1 ± 9.5 kg, p = 0.14).

Conclusions: Low-carbohydrate diet may improve the oxygen saturation in patients with chronic stable heart failure.