Dietary Acid Load, Kidney Function and Disability in Elderly (BICARB)

The purpose of this research study is to determine the effect of a bicarbonate supplement on kidney function and physical function.

Physical decline and frailty result from age- and disease-related impairments in organs and tissues. Frailty research has focused on the musculoskeletal, neurological and circulatory systems; yet interventions targeting these systems had limited success in preventing and treating functional decline. Given the aging of the US population, additional avenues for intervention development are urgently needed. Fragility and disability in people ≥65 strongly correlate with declining kidney function and are evident even in early stages of chronic kidney disease (CKD). Moreover, CKD is highly prevalent in the elderly and associates with sarcopenia, osteopenia, and increased incidence of fractures/falls with hospitalization. Low serum bicarbonate and impaired acid-base homeostasis, also common in CKD, are increasingly appreciated as contributors to functional decline with advancing age. With aging, the adaptive response of the kidney to low serum bicarbonate and high metabolic acid load becomes maladaptive, facilitating CKD progression. Conversely, in adult patients with CKD, maintenance of serum bicarbonate at 24 meq/L with oral bicarbonate supplementation or increased consumption of base-forming foods slows CKD progression. The study investigators propose the current study and protocol based on the evidence summarized above and our preliminary studies, which suggest that: In the Health Aging and Body Composition cohort (age 70-79) lower dietary acid load associates with stable kidney function over a 7-year follow-up, independent of age, race, gender, BMI, diabetes, hypertension or smoking status; metabolomics analysis in participants of the African American Diabetes Heart Study suggested that it is feasible to segregate a urine metabolomics profile in the early stages of CKD (stages 2 and 3), and that lower consumption of base-forming fruits and vegetables and higher rates of acid excretion may be associated with CKD and its progression. The investigators therefore hypothesized that decreasing metabolic acid production by titrating dietary acid load may ameliorate the generally expected, age-related decline in kidney function, decrease loss of lean body mass, preserve physical function, and ameliorate disability. This is not a treatment study as the investigators are exploring the effects of bicarbonate on these age-related issues.

measurement taken from a blood sample; measures how much carbon dioxide is in your blood; a normal result is between 23 and 29 millimoles per liter (mmol/L) for adults

measurement taken from a blood sample; measures how much carbon dioxide is in your blood; a normal result is between 23 and 29 millimoles per liter (mmol/L) for adults

The number of participants randomized divided by the number of participants screened. Count of participants reflects the number of participants randomized.

Blood test that measures the total dissolved Carbon dioxide in blood; expressed in milliequivalents per liter (mEq/L)

Blood test that measures the total dissolved Carbon dioxide in blood; expressed in milliequivalents per liter (mEq/L)

a measurement from a blood sample; shows how well kidneys are working According to the National Institutes of Health (NIH), normal results range from 60 to 120 mL/min/1.73 m2. Older people will have lower than normal eGFR levels, because eGFR decreases with age

a measurement from a blood sample; shows how well kidneys are working According to the National Institutes of Health (NIH), normal results range from 60 to 120 mL/min/1.73 m2. Older people will have lower than normal eGFR levels, because eGFR decreases with age

a measurement from a blood sample; shows how well kidneys are working According to the National Institutes of Health (NIH), normal results range from 60 to 120 mL/min/1.73 m2. Older people will have lower than normal eGFR levels, because eGFR decreases with age

a measurement from a blood sample; shows how well kidneys are working According to the National Institutes of Health (NIH), normal results range from 60 to 120 mL/min/1.73 m2. Older people will have lower than normal eGFR levels, because eGFR decreases with age

Estimated Glomerular Filtration Rate (eGFR) - Measurement of Kidney Function After 6 Months Post Baseline

a measurement from a blood sample; shows how well kidneys are working According to the National Institutes of Health (NIH), normal results range from 60 to 120 mL/min/1.73 m2. Older people will have lower than normal eGFR levels, because eGFR decreases with age

Bone Mineral Density tests can identify osteoporosis, determine the risk for fractures (broken bones), and measure the response to osteoporosis treatment.

Bone Mineral Density tests can identify osteoporosis, determine the risk for fractures (broken bones), and measure the response to osteoporosis treatment.

Bone Mineral Density tests can identify osteoporosis, determine the risk for fractures (broken bones), and measure the response to osteoporosis treatment.

Bone Mineral Density tests can identify osteoporosis, determine the risk for fractures (broken bones), and measure the response to osteoporosis treatment.

The albumin-to-creatinine ratio (ACR) is the first method of preference to detect elevated protein, measuring urinary ACR in a spot urine sample. ACR is calculated by dividing albumin concentration in milligrams by creatinine concentration in grams.

The albumin-to-creatinine ratio (ACR) is the first method of preference to detect elevated protein, measuring urinary ACR in a spot urine sample. ACR is calculated by dividing albumin concentration in milligrams by creatinine concentration in grams.

The albumin-to-creatinine ratio (ACR) is the first method of preference to detect elevated protein, measuring urinary ACR in a spot urine sample. ACR is calculated by dividing albumin concentration in milligrams by creatinine concentration in grams.

Inclusion Criteria: Age 65 +years of age Short physical performance battery (SPPB) score>3 Estimated glomerular filtration rate (eGFR) 30-89 Net endogenous acid production (NEAP) >=40 mEq/d Willing to provide informed consent and agrees to randomization Not involved in another intervention study Exclusion Criteria: Uncontrolled (>160 mg/dl fasting blood glucose), insulin-dependent diabetes and/or uncontrolled hypertension (Systolic Blood Pressure >160, Diastolic BP>100) a current diagnosis of psychotic disorder take more than 14 alcoholic drinks per week plan to relocate out of the study area within the next year self-reported inability to walk across a room those who reside in nursing homes have difficulty communicating with study personnel due to speech or language or hearing problems had cancer requiring treatment in the past 1 year lung disease requiring regular use of corticosteroids or of supplemental oxygen cardiovascular disease (Class III or IV congestive heart failure) significant valvular disease, uncontrolled angina myocardial infarction, major heart surgery (i.e., valve replacement or bypass surgery) in past 6 months stroke, deep vein thrombosis, or pulmonary embolus in the past 6 months, Parkinson's disease or other progressive neurological disorder other medical or behavioral factors that in the judgment of the principal investigator may interfere with study participation or the ability to follow the intervention clinical judgment concerning safety or noncompliance Individuals with BMI <18.5; or weight loss >4% in last 6 months Montreal Cognitive Assessment (MoCA) score under 24 End Stage Renal Disease (ESRD) on dialysis or primary kidney disease Other illness of such severity that life expectancy is less than 12 months Smoking; defined as not smoking for more than a year prior to the study Serum Bicarbonate (HCO3)>30 milliequivalents per liter (mEq/L); serum potassium out of normal range