Hemodialysis (HD) patients are characterized by malnutrition, which adversely affects their survival. The development of malnutrition is influenced, among other factors, by improper diet and the advanced age of patients. The study aimed to assess the nutritional status and adherence to dietary recommendations among older patients. The multicenter study included 179 stable HD patients. The nutritional status was assessed by a 7-point Subjective Global Assessment (SGA). Anthropometry and body composition was analyzed. The diet was assessed based on the 3-day food diary and the Food Frequency Questionnaire with 6 answers (FFQ-6). Blood laboratory tests were performed. Based on the 7-point SGA, malnutrition was diagnosed in 38.5% of HD patients. The decreased content of the muscle tissue (LTI < 14 kg/m²) was observed in 70.4% of the examined patients and the decreased concentration of s-albumin was observed in 44.1% of patients. Older patients had significantly lower LTI. 26% of patients consumed less than 25 kcal/kg body weight and less than 0.8 g protein/kg body weight. Older patients’ diets contained significantly fewer calories. There were significant differences between nutrient intake on a weekday with dialysis, a weekday without dialysis, and a weekend day without dialysis. The lowest intake of nutrients was observed on the day of dialysis. Nutritional education and the determination of whether food is permitted during hemodialysis are necessary to improve patients’ nutrition.

The concentration of water-soluble vitamins (except folic acid and vitamin B₁₂) is not routinely measured, which may lead to undiagnosed deficiencies among hemodialysis (HD) patients. The aim of the study was to assess the blood concentration of water-soluble vitamins in HD patients in comparison with healthy subjects and to assess the impact of diabetes mellitus (DM) coexistence on the concentration of these vitamins. The two-center study included 142 HD patients and a control group of 31 healthy subjects. Vitamins concentration was determined using high-performance liquid chromatography (HPLC). Vitamin B₁, B₆, and B₁₂ levels were significantly lower in the HD group than in the control group (p < 0.001). Vitamin B₁ and B₂ were negatively correlated with blood urea nitrogen (BUN) levels before HD (R = −0.39, R = −0.38; p < 0.05). Vitamin B₃, B₁₂, and C were positively correlated with the albumin concentration (R = 0.26, R = 0.27, R = 0.28; p < 0.05). Among diabetic patients, only the concentration of vitamin B₁ was lower than among non-diabetic patients. The concentration of water-soluble vitamins may be related to the adequacy of dialysis, the time of laboratory determination since the last dialysis, diet, coexistence of other diseases, use of drugs, and dietary supplements in individual patients.