Potassium Food Additives and Dietary Management of Serum Potassium: Proposed Best-Practice Recommendations.

The contribution of potassium food additives to total dietary potassium intake is unknown. This poses challenges for individuals living with kidney disease who may need to monitor their potassium intake. Additionally, different countries have varying regulations regarding the reporting of dietary potassium content in foods. This article examines the potential of published food databases in assisting clinicians to help individuals with kidney disease manage their serum potassium levels. It uses the United States Department of Agriculture's Branded Food Products Database as an example. Evidence for potassium additive content in database entries, along with their bioavailability, is discussed, and best-practice recommendations are made based on current evidence. Clinical practice and future research priorities are suggested.

Potassium-Based Sodium Substitutes Impact the Sodium and Potassium Content of Foods.

OBJECTIVE: Potassium-based sodium substitutes (PBSS) can be used to replace sodium during food processing. How potassium and sodium content is associated with PBSS is not known. The objectives of the study were to describe the prevalence of PBSS by sodium content claim category and describe how PBSS are associated with sodium and potassium concentrations by sodium level. DESIGN AND METHODS: This cross-sectional analysis used the July 2018 version of the United States Department of Agriculture's Branded Food Products Database. Products were divided into sodium content claim category and were analyzed for the presence of PBSS. Products with nonmissing values for sodium and potassium were grouped by sodium level and analyzed for the prevalence of PBSS to explore potassium and sodium concentration. Column proportion z-test with the Bonferroni correction was used to explore the occurrence of PBSS by sodium content claim category. Mann-Whitney U-test was used to assess differences in potassium and sodium concentrations across sodium levels and within levels by the presence/absence of PBSS. RESULTS: The prevalence of PBSS in the categories "without a sodium content claim" (2.4%), "lightly salted" (0.5%), and "unsalted" claims (0.6%) were statistically significantly lower than prevalence of PBSS in the "sodium free" (9.5%), "low sodium" (10.3%), and "reduced sodium" claim categories (23.3%; all P < .01). Among the group of products with serving sizes more than 30 g containing PBSS, there was a 357 mg per serving higher median sodium concentration and a 160 mg per serving higher median potassium concentration compared to the group without PBSS (both P < .01). CONCLUSION: In the "reduced sodium" claim category, a higher prevalence of PBSS was found compared to other sodium claim categories. The presence of PBSS was associated with higher potassium and sodium concentrations in foods.

Phosphorus Additives and Their Impact on Phosphorus Content in Foods-An Analysis of the USDAs Branded Foods Product Database.

OBJECTIVES: The frequency of phosphate additives reported in the United States Department of Agriculture Branded Foods Product Database and how these additives impact phosphate content is unknown. METHODS: All products included in the Branded Foods Product Database reporting phosphorus content were reviewed for presence of phosphate salts and/or lecithin additives. RESULTS: Phosphorus content information was available for 3,466 (1.45%) food items, of these 1791 (51.6%) contained additives. Median phosphorus content was lowest in products with lecithin only compared to products without phosphorus additives (86 [54-200] vs. 145 [77-351] mg per 100 g, P < .01), which was not different from products with phosphate salts (176 [101-276] mg per 100 g, P = .22) or products with both phosphate salts and lecithin (161 [99-285] mg per 100 g, P = 1.00). The impact of a phosphorus salt on phosphorus content (mg per 100) was explored among ultra-processed products grouped by similar phosphorus contents. The phosphorus content of in in nondairy alternatives, dairy, plant proteins, and grains were significantly higher when the product contained a phosphate salt compared to products without a phosphate salt. For all products phosphorus and potassium content were correlated, but the relationship was stronger for when a potassium phosphate additive was present compared to absent (rho = 0.81 vs. 0.53, P < .05). Similar patterns were seen for sodium, calcium, and iron with stronger correlations with phosphate content for products with additives than those without (calcium phosphate: rho = 0.47 vs. 0.32; iron phosphate: rho = 0.47 vs. 0.33; sodium phosphate: rho = 0.45 vs. 0.07. All P < .05). The relationship between phosphate and sodium for products without phosphate additives was weak. CONCLUSIONS: Lecithin may not be associated with increased phosphorus content. Calcium, potassium, sodium, and iron phosphorus salts appear to be associated with increases in the composite mineral and phosphorus content, with the strongest correlation between potassium and phosphorus content.

The impact of protein source on serum potassium and phosphate levels in adults living with advanced kidney disease.

BACKGROUND AND AIMS: Plant proteins may be restricted on low potassium/phosphorus diets. The primary objective was to investigate the impact of protein source on serum potassium and phosphate levels in adults with stage 4-5 chronic kidney disease (CKD), including hemodialysis (HD). METHODS AND RESULTS: Using a cross-sectional design, 24-h recalls or food frequency questionnaires were used to assess dietary intake. Serum values were obtained from medical records. Quartiles (Q1-4) of plant:animal protein serving ratios was considered to investigate outcomes, with Q1 having high animal and low plant serving intake and those in Q4 having high plant and low animal servings. 216 participants were enrolled, 135 on HD and 81 stage 4/5 CKD. For both HD and CKD, there was no difference in either serum potassium or phosphate levels between those in Q4 consuming high plant:animal vs Q1 low plant:animal (for HD: potassium 4.6 mmol/L vs 4.6 mmol/L; phosphate 1.8 mmol/L vs 1.6 mmol/L, respectively; for CKD: potassium 4.7 mmol/L vs 4.6 mmol/L; phosphate 1.4 mmol/L vs 1.4 mmol/L; all p > 0.05). Those in Q4 consuming high plant:animal consumed 7.5 g (62%) more fibre than those in Q1 (low plant:animal). For diet quality, Q4 (high plant:animal) had a 12.8 point (24%) higher healthy eating index score than Q1 (low plant:animal). There was no relationship between plant:animal and serum albumin or hospital admissions (all p > 0.05). CONCLUSIONS: Consumption of higher proportions of plant protein was not associated with higher serum potassium or phosphate levels but was associated with higher fibre and diet quality.

Soaking to Reduce Potassium and Phosphorus Content of Foods.

OBJECTIVES: To achieve and maintain normal serum potassium and phosphorus levels reducing potassium and phosphorus intake is frequently recommended for adults living with chronic kidney disease. Exploring food preparation methods to reduce potassium and phosphorus content appears warranted. The study aim is to determine the impact of soaking foods in hot water on potassium and phosphorus content in a variety of plant- and animal-based foods. METHODS: Twenty foods were selected that are common staples in Brazilian diet patterns. Food was soaked for 5-10 minutes in deionized water that had been brought to a boil and then removed from heat using a 5-part water to 1-part sample ratio. The potassium content was determined by flame photometry. The phosphorus content was determined by visible ultraviolet spectrophotometry. RESULTS: Soaking foods resulted in a reduction in potassium and phosphorus. Potassium reduction in beef, green leafy vegetables, and grains was 40-49%; in chicken, fish, and nonleafy vegetables 30-39%; and tubers 10-20%. Phosphorus reduction in grains and beans was 30-39%; in nonleafy vegetables 20-29%; and beef, chicken, and fish 10-20%. CONCLUSIONS: Soaking foods in hot water for 5-10 minutes reduces potassium and phosphorus content. Using this technique to prepare foods may be a more acceptable alternative to longer demineralization periods making it easier for adults living with chronic kidney disease to follow diet recommendations.

Currently Available Handouts for Low Phosphorus Diets in Chronic Kidney Disease Continue to Restrict Plant Proteins and Minimally Processed Dairy Products.

OBJECTIVES: The 2020 Kidney Disease Outcome Quality Initiative guidelines recommend adjusting phosphorus intake to achieve and maintain normal serum phosphorus levels for adults living with chronic kidney disease. These guidelines also recommend considering the dietary source of phosphorus as different sources have different bioavailability; however, phosphorus food lists are not provided. Therefore, the aim of this study is to investigate the current teaching materials in Canada regarding low phosphorus diet. DESIGN AND METHODS: Using a geographical approach, websites from each province and territories' government, health, and renal programs (where applicable) were reviewed for resources on dietary phosphorus restriction in chronic kidney disease. All publicly available handouts/booklets/printable webpages were obtained and reviewed for recommendations on how to implement a low phosphorus diet. RESULTS: Sixty-one resources in total met inclusion criteria (52 handouts from health agencies in 6 provinces and 9 handouts from the Kidney Foundation of Canada). Items with minimal nutrition value, such as cola, beer and cocoa, chocolate, and baking powder, were the most commonly restricted with 84% (51/61) resources making this recommendation. Plant proteins and minimally processed dairy were restricted in 80% (49/61) of resources. Processed animal meat was recommended to be restricted in 70% (43/61) of resources and whole grains in 65% (40/61). Sixty-three percent of the handouts (39/61) discuss avoiding phosphorus additives. CONCLUSIONS: Many resources restrict items with minimal nutrition value to lower phosphorus intake; however, plant foods, including plant proteins and whole grains, continue to be restricted in the majority of resources, despite having lower bioavailability. The 2020 Kidney Disease Outcome Quality Initiative guidelines recommend considering bioavailability of phosphorus source when implementing low phosphorus diets; current handouts in Canada would likely benefit from review.

Sarcopenia and sarcopenic obesity in chronic kidney disease: update on prevalence, outcomes, risk factors and nutrition treatment.

PURPOSE OF REVIEW: This review summarizes literature from the last 18 months reporting on sarcopenia (or its components) in chronic kidney disease (CKD). RECENT FINDINGS: The prevalence of sarcopenia in CKD is reported to be 5-62.5%, with higher rates observed later in the disease. Sarcopenic obesity rates are reported to be 2-23%. Sarcopenia in CKD is associated with increased risk of mortality, cardiovascular disease and vascular calcification. Risk factors include kidney disease itself and the impacts of CKD on lifestyle (reduced physical activity, diet changes). In earlier stages of CKD, if the risks from sarcopenia outweigh the risk of reaching end-stage renal disease, ensuring adequate energy intake combined with modest protein liberalization and physical activity may be indicated. Protein intakes above 1.3 g/kg of body weight per day should be avoided. For dialysis patients, interventions that provide a combination of carbohydrate, protein and fat appear more effective than those that provide protein alone, though it may take as long as 48 weeks for detectable changes in muscle mass. SUMMARY: Sarcopenia is prevalent in CKD as kidney disease significantly impacts muscle mass and function. Nutrition interventions can improve components of sarcopenia, with an emphasis on adequate energy and protein.

Comparison of diet quality tools to assess nutritional adequacy for adults living with kidney disease.

There is no specific diet quality tool recommended for adults living with chronic kidney disease (CKD). Identifying how diet quality tools assess nutritional adequacy and correlate with potassium and phosphorus (nutrients of interest in CKD) is warranted. Our aim was to compare Mediterranean Diet Scores (MDS), Healthy Eating Index (HEI), and Healthy Food Diversity (HFD) to determine their correlation with nutrient intake in adults living with diabetes and CKD. Using data from a longitudinal study of 50 participants with diabetes and CKD, diet quality was assessed at baseline and 1 or more times at annual visits up to 5 years (complete diet records n = 178). Diet quality was investigated for correlation with nutrient intake. Compared with HEI and HFD, MDS was poorly correlated with nutrient intake (all r values <0.40). HFD and HEI were moderately correlated with potassium (r = 0.66, P < 0.01 and r = 0.57, P < 0.01, respectively). HEI was weakly correlated with phosphorus (r = 0.365, P < 0.01). MDS recommends moderation of dairy and meat, this may have specific benefits for CKD as these are both sources of phosphorus, as such high MDS were associated with lower phosphorus intake. This study suggests that development of a renal specific diet quality assessment tool may be useful; however, further studies are needed.

Potassium content of the American food supply and implications for the management of hyperkalemia in dialysis: An analysis of the Branded Product Database.

Ultraprocessed foods can be a source of potassium additives. Excess potassium consumption can lead to hyperkalemia. How frequently potassium additives are found in the food supply and how they impact potassium content is not well documented. Using the Branded Product Database, ingredient lists were searched for "potassium" to identify products containing additives. For products listing potassium content, accuracy of potassium content reporting and how potassium content differed with additive use was also assessed. A total of 239,089 products were included, 35,102 (14.7%) contained potassium additives, and 13,685 (5.7%) provided potassium content. Potassium additives were most commonly found in dairy products, supplements, and mixed foods (at 37%, 34%, and 28%, respectively). Potassium additives in mixed foods and vegetables and fruits were associated with 71% and 28% more potassium per serving, respectively (p < 0.01). Potassium content increased by 1874 mg (66%) when a 1-day sample menu compared foods with and without additives. Potassium content of foods with and without additives is not well documented. Potassium additives are prevalent and can be associated with increased potassium content. However, more information is needed to better understand how different additives used in different foods change potassium content.

The Impact of Protein Type on Phosphorus Intake, Serum Phosphate Concentrations, and Nutrition Status in Adults with Chronic Kidney Disease: A Critical Review.

Lower phosphorus intake to prevent hyperphosphatemia for those with chronic kidney disease (CKD) is often recommended. Plant proteins are frequently restricted for their high phosphorus content despite having lower bioavailability. To summarize the evidence on protein type and dietary phosphorus intake, serum phosphate concentrations, and nutritional adequacy in adults with CKD, a search in MEDLINE via Ovid was conducted. Citation lists were reviewed to identify any additional articles. Sixteen articles were included-7 intervention (n = 290) and 9 observational (n = 4933). All intervention trials reported high-plant-protein diets provided adequate protein and adhered to low phosphorus diet guidelines. All intervention trials reported higher plant-protein intake was associated with lower serum phosphate; however, only 2 achieved statistical significance. For observational studies, 2 reported that higher proportions of plant to animal protein resulted in lower phosphorus intake but equivalent serum phosphate concentrations. Two reported that plant protein and animal protein had equivalent correlation values to phosphorus intake and no correlation to serum phosphate concentrations. One trial reported lower total phosphorus and protein intake among those who consumed more plant proteins but did not examine serum concentrations. Four reported lower serum phosphate concentrations among those who consumed more plant proteins but did not report dietary phosphorus intake. Of the observational studies that reported on protein intake, all reported lower protein intake among those with higher versus lower plant-protein intake. BMI tended to be lower among those consuming more plant protein. There was not a consistent relation between protein type and albumin concentrations. Routine restriction of plant-protein foods to prevent hyperphosphatemia in CKD would likely benefit from re-evaluation, as evidence does not suggest that higher plant-protein intake leads to higher serum phosphate concentrations or worse nutritional status, although longer-duration intervention trials with larger sample sizes appear to be warranted.

Low Mediterranean Diet scores are associated with reduced kidney function and health related quality of life but not other markers of cardiovascular risk in adults with diabetes and chronic kidney disease.

BACKGROUND AND AIMS: How Mediterranean-style diets impact cardiovascular and health outcomes in patients with diabetes and chronic kidney disease (CKD) is not well known. Our aim was to investigate the association between diet quality, using Mediterranean Diet Scores (MDS) and health outcomes. METHODS AND RESULTS: This is a post-hoc analysis of an RCT and longitudinal study investigating patients with diabetes and CKD. MDS was calculated annually. Scores were analyzed for correlation with lipids, HbA1c, serum potassium, health-related quality of life (HRQOL) and depression. 178 diet records from 50 patients who attended two or more visits were included. Mean MDS was moderate (4.1 ± 1.6) and stable over time. Stage 1-2 vs 3-5 CKD had lower raw MDS (3.8 ± 1.5 vs 4.6 ± 1.5, p < 0.001). Having hyperkalemia was associated with a lower raw MDS scores (3.6 ± 1.6 vs 4.2 ± 1.5, p = 0.03) but not energy adjusted MDS. MDS was not associated with HbA1c or lipids. High vs low MDS was associated with improved HRQOL (mental health 84.4 ± 14.3 vs 80.3 ± 17.1, p < 0.05; general health 62.6 ± 21.0 vs 56.3 ± 19.8, p < 0.001) and fewer depressive symptoms (9.1 ± 7.4 vs 11.7 ± 10.6, p = 0.01). CONCLUSIONS: Low MDS was associated with reduced kidney function and health related quality of life, but not other markers of cardiovascular risk. Further studies are needed to understand the nature and direction of the association between diet quality and disease outcomes in this population.

Handouts for Low-Potassium Diets Disproportionately Restrict Fruits and Vegetables.

OBJECTIVE: Several recent publications, including an expert summary on hyperkalemia management, have encouraged plant-based foods for patients with chronic kidney disease (CKD) and highlighted the impact of potassium additives on total potassium intake. The aim of this research brief was to investigate if and/or how current recommendations for low-potassium diet may incorporate these new recommendations. DESIGN AND METHODS: Using a geographical approach, each province's and territory's government health and renal program (where applicable) website was reviewed for resources on dietary potassium restriction. All handouts/booklets/printable webpages were obtained and reviewed. RESULTS: Eighteen resources from 6 provincial health agencies in Canada were included. Six additional resources from national agencies were also included, 4 from Canada and 2 from the United States. The 5 most commonly restricted foods were bananas, potatoes, oranges, cantaloupe, and avocados. All resources recommended restriction of fruits and vegetables, 67% recommended restriction of dairy products, 57% recommended restriction of whole grain products, 62% recommended restrictions of plant-based proteins, and 67% mentioned restriction of other foods (such as coffee, tea, and chocolate), 28% mentioned restriction of potassium additives in ultraprocessed foods. CONCLUSION: Low-potassium diets primarily restrict fruits and vegetables while the least common restriction is ultraprocessed food. Several recent publics have recommended a greater focus on ultraprocessed versus unprocessed food for hyperkalemia management. These new recommendations differ from current teaching materials that predominately restrict plant-based foods to manage hyperkalemia in CKD. Updates will likely be needed to current resources to reflect new recommendations.

Dietary Potassium Intake and Risk of Chronic Kidney Disease Progression in Predialysis Patients with Chronic Kidney Disease: A Systematic Review.

The prevalence of chronic kidney disease (CKD) is increasing and dietary interventions may be a strategy to reduce this burden. In the general population, higher potassium intake is considered protective for cardiovascular health. Due to the risk of hyperkalemia in CKD, limiting potassium intake is often recommended. However, given that poor cardiovascular function can cause kidney damage, following a low-potassium diet may be deleterious for patients with CKD. The aim of this systematic review was to summarize the evidence on dietary potassium intake and CKD progression. Multiple databases were searched on 7 June 2019 and data were managed with Covidence. No intervention trials met the inclusion criteria. Eleven observational studies met the inclusion criteria (10 post hoc analyses, 1 retrospective cohort), representing 49,573 stage 1-5 predialysis patients with CKD from 41 different countries. Of the 11 studies, 6 studies reported exclusively on early CKD (stage 1-2), 4 studies separately reported analyses on both early and late (stage 3-5) CKD, and 2 studies reported exclusively on late CKD. A total of 9 studies reported risk of disease progression in early CKD; in 4 studies high potassium intake was associated with lower risk, while in 2 studies the low intake showed a higher progression of risk, and 3 studies reported no relation. In late CKD, results are mixed: 2 studies suggested benefit of higher potassium intake and 1 suggested benefit of lower potassium intake, whereas 3 studies were neutral. These results should be interpreted with caution, as considerations preventing firm conclusions include 1) the overall low range of dietary potassium intake, with all studies reporting an average intake below the 2004 Kidney Disease Outcomes Quality Initiatives guidelines, and 2) the method used to assess potassium intake in most studies (i.e., urine) in late stages of CKD. Ideally, well-controlled intervention studies are needed to understand how dietary potassium intake is linked to CKD progression.

How Food Processing Impacts Hyperkalemia and Hyperphosphatemia Management in Chronic Kidney Disease.

Food processing has a unique impact on patients living with chronic kidney disease who may need to restrict dietary sodium, potassium, and phosphorus intake. Canada is the second largest consumer of processed food in the world. Highly processed foods tend to be more nutrient dense, contain less fibre, and are higher in sodium than unprocessed foods. To reduce the amount of sodium in processed food, Health Canada has encouraged food producers to reduce the sodium in their food. Potassium additives have been identified as an attractive alternative to sodium and their use in food processing is expected to increase. Phosphorus additives have been reported to be present in about 44% of processed foods. Given the changes in the nutrient profiles of processed foods, dietary advice on ways to reduce sodium, potassium, and phosphorus intake may be best achieved by recommending minimally processed food and encouraging unprocessed foods more often.

Potassium Additives and Bioavailability: Are We Missing Something in Hyperkalemia Management?

Hyperkalemia and hyperphosphatemia are common metabolic disturbances in chronic kidney disease. Management may include instructions on a low-potassium or low-phosphorus diet, respectively. Low-phosphorus diet teaching includes information on phosphorus additives in addition to naturally occurring phosphorus food sources. Phosphorus additives are known to be more bioavailable compared with naturally occurring phosphorus. The concentration of phosphorus can also be much higher in processed foods compared with whole foods. Similar considerations may also be needed for dietary potassium teaching. The use of potassium additives in processed foods is growing, and when additives are used, the potassium concentration far exceeds naturally occurring potassium. Evidence also suggests, much like phosphate, potassium additives are more bioavailable than potassium found in whole foods. Clinicians and patients need to be aware of these changes in the food source to ensure potassium diet teaching is effective and safe.