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The impact of food processing and diet quality on nutrition management for adults living with kidney disease
- Author / Creator
- Picard, Kelly
Background: Food processing changes the health value and nutrient content of foods. In the general population, consumption of minimally processed foods is encouraged to reduce the intake of free sugar, fat and sodium and increase fibre, protein and potassium intake. Many nutritious foods are high in potassium and phosphorus. For adults living with chronic kidney disease (CKD) low potassium and phosphorus diets are recommended to prevent hyperkalemia and hyperphosphatemia, respectively. There is inherent friction between healthy diets and diets for CKD, though how food processing may either contribute to or alleviate this friction has not been well elucidated. The overarching objective of this research was to explore the impact of food processing on medical nutrition therapy and health outcomes for adults living with CKD.
Methods and Results: In Study 1, The United States Department of Agriculture’s Branded Foods Product Database (USDA-BFPD) (n=239,089) was used to explore potassium and phosphate additive use in processed foods. Ingredient lists were searched for potassium and phosphorus additives. For products with potassium or phosphorus content available the relationship between additive use and mineral content was explored. In the USDA-BFPD potassium and phosphorus additives were found in 14.7% and 31.2% of foods, respectively. Potassium and phosphorus content were available for 5.5% and 1.5% of food items, respectively. Subset analysis showed that a greater proportion of foods with potassium additives were considered high or very high in potassium than in foods without potassium additives. Surprisingly, median phosphorus content was lowest in products with only added lecithin than in products without any phosphorus additives (86 (54-200) vs 145 (77-351) mg per 100g, p<0.01), which was not different from products with phosphate salts (176 (101-276) mg per 100g, p=0.22) or products with both phosphate salts and lecithin (161 (99-285) mg per 100g, p=1.00). For all products, phosphorus and potassium content were correlated, but the relationship was stronger for products which contained potassium phosphate additive when compared to products without potassium phosphates (rho = 0.81 vs 0.53, p < 0.05). Study 2 was a longitudinal study of adults living with diabetes and CKD (n=50). Six years of diet records were reviewed. Diet quality scores were calculated and processed food intake was quantified to investigate the relationship between diet quality and processed food intake with cardiovascular health, health related quality of life and nutritional adequacy. Over 61% of energy intake came from processed foods. Diet quality was not associated with blood lipids or glycemic control. High vs low diet quality was associated with improvements in mental and general health quality of life scores (84.4 ± 14.3 vs 80.3 ± 17.1, p < 0.05 and 62.6 ± 21.0 vs 56.3 ± 19.8, p < 0.01, respectively) and nutritional adequacy. Study 3 was a cross-sectional study of adults living with advanced CKD (n=216). Diet histories were used to investigate the relationship between protein sources (plant/animal) and electrolyte disturbances, nutrition and health status. Data did not demonstrate a correlation between plant protein intake and hyperkalemia or hyperphosphatemia events. Those who consumed more plant proteins had higher diet quality and consumed more fibre.
Conclusions: The mineral content of processed foods is not well documented. However, when potassium and phosphorus additives are used these foods may be higher in potassium and/or phosphorus, respectively. Adults living with CKD consume significant amounts of processed foods. This consumption pattern was associated with a reduced nutrient adequacy and lower health related quality of life but not cardio-metabolic risk factors. There was not a relationship between increased plant protein intake and higher rates of hyperkalemia or hyperphosphatemia. Taken together, this suggests that restriction of minimally processed foods would benefit from re-evaluation, though ultimately a safety study is needed to understand more about the impact of healthy foods on serum potassium and phosphorus levels.
- Graduation date
- Spring 2023
- Type of Item
- Doctor of Philosophy
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