Renal Insufficiency: Acidifying Foods in question
The Western diet, acidifying, could increase the risk of chronic kidney disease and influence its progression. Conversely, an alkalizing diet, rich in potassium, would be protective.
Why it’s important
The acid-base balance of our body is essential to health. To function properly, our body must be in a zone of slightly alkaline pH: the blood pH is about 7.40, ranging between 7.35 and 7.45. Diet influences this acid-base balance. There are indeed acidifying foods – usually high in animal protein such as meat, cheese, but also salty foods – and basifying foods (fruits and vegetables). When the acidic food load induced by acidifying foods is not adequately compensated by the basifying foods – low-grade metabolic acidosis may develop which may lead to health problems; the definition of this metabolic acidosis is a “normal” blood pH but slightly and permanently lowered, as well as “normal” but slightly lowered plasma bicarbonate levels.
An acidifying diet could impact kidney health because it has to adapt to greater acid excretion to maintain the acid-base balance. Recent studies have shown that a Western-type diet may be a risk factor for kidney failure and chronic kidney disease, while an alkalizing diet may slow the deterioration of kidney function in patients with kidney failure chronic with metabolic acidosis.
What the researchers found
In one study, researchers collected data on 12,293 participants in the National Health and Nutrition Examination Survey (NHANES) 1999-2004, aged over 20 years. In particular, they evaluated the acidity resulting from the diet by estimating net acid excretion (Net acid excretion NAEes), calculated from the PRAL index and expressed in mEq / day. Urine samples were collected to determine the different stages of chronic renal insufficiency: Albuminuria (urine albumin) was measured to assess possible kidney damage as it shows a defect in filtration kidney. The glomerular filtration rate (GFR), which is the volume filtered by the kidneys per unit time, has been used to evaluate renal function.
The results show that acid loading in the diet is associated with albuminuria: people with higher net acid excretion (NAE) also have higher albuminuria. Similarly, the 20% of participants with the highest net acid excretion had 40% risk in addition to having kidney dysfunction (estimated by the GFR) than the 20% of participants with excretion. net of the lowest acid.
In another cross-sectional study of elderly Koreans, a diet with a higher net acid load was associated with CKD, while a high intake of potassium appeared to protect against renal failure. This is not the first time that potassium has been associated with protection of renal function: this was the case in the NHANES and PREVEND studies. Not only is potassium a major contributor to acid-base balance, but a good potassium status prevents hypertension, which is a risk factor for kidney disease.
These are observational studies describing an association but not allowing a conclusion of cause and effect. However, a low salinity and plant-based diet, so alkalizing, may be advisable because it does not present health risks and could instead prevent many chronic diseases . Such a diet does not necessarily exclude animal protein: it can continue to be consumed, ensuring that plants remain the majority. In Singapore’s prospective health study, red meat consumption was associated with a higher risk of end-stage renal disease, while soybeans and legumes, which provide vegetable protein, appeared to protect. This suggests that with respect to meat, proteins from plant sources can have different effects on kidney function. The Potential Renal Acid Load ( Pral ) – a potential acidic renal load – allows you to evaluate the acidity of the urine (and thus the body) according to the food you eat. It is measured in milliequivalent (mEq) from the amount of acidic minerals and basic minerals brought by our diet. When the Pral is greater than zero, the feed is acidifying. If the Pral is negative, the power is basifying.
Banerjee T. Dietary acid load and chronic kidney disease among adults in the United States. BMC Nephrol. 2014 Aug 24;15(1):137. doi: 10.1186/1471-2369-15-137.
Ko BJ, Chang Y, Ryu S, Kim EM, Lee MY, Hyun YY, Lee KB. Dietary acid load and chronic kidney disease in elderly adults: Protein and potassium intake. PLoS One. 2017 Sep 27;12(9):e0185069.