Is a high-protein diet for weight loss bad for the kidneys?
For some time now I have been following a high-protein diet to lose weight and achieve good results with it. I recently read that high-protein diets are bad for the kidneys. I therefore doubt whether I should continue with my diet. What is sensible?
In May 2012, researchers at Indiana University published their findings on the effect of a high-protein diet on the kidneys1. Their conclusion: “In healthy obese individuals, a low-carbohydrate high-protein weight-loss diet over 2 years was not associated with noticeably harmful effects on GFR, albuminuria, or fluid and electrolyte balance compared with a low-fat diet. Further follow-up is needed to determine even longer-term effects on kidney function. ” Thus, no significant effect of a protein-rich diet was detected on the kidneys. This study was the largest and long-term study in which the effects of a protein-rich diet were compared with those of a standard diet.
However, there is a “but”… Protein-rich food may have a different effect on the elderly than the young2. A 2008 study from the Mayo Clinic School of Medicine found that the glomerular filtration rate (GFR) decreased when the elderly followed a high-protein diet. The GFR is an indicator of how well the kidneys filter substances from the blood and excrete them in the urine. No reduction in GFR was seen in adolescents on a high-protein diet. People with reduced kidney function, to which people over 65 can often be attributed, are therefore wise according to this study to be moderate with proteins.
One step this risk group can take is to exchange part of their animal proteins for vegetable protein sources. Researchers from the Canadian Unversity of Manitoba in 2011 investigated the effect of different protein sources on rats with impaired renal function3. The balance was drawn up eight weeks after the start of the trial: Kidneys from diseased rats given diets which contained soy or hemp protein compared with casein-based diets were less enlarged, had lower fluid content, smaller cyst volumes, less fibrosis, lower chemokine receptor 2 (CCR2) levels and normalized serum creatinine levels. Soy and hemp protein diets also normalized heart size, which was enlarged in diseased compared with normal rats consuming casein. ” So, compared to casein protein, soy and hemp protein had a positive effect on kidney function and resulted in less heavy heart muscle. Perhaps the vegetable proteins increased blood pressure less. With high blood pressure, the heart has to work harder, which can lead to unwanted enlargement.
In conclusion, it can be said that healthy, young individuals can safely follow a protein-rich diet. For the elderly and people with kidney problems it may be wise to limit the consumption of proteins. This group also advises exchanging part of their animal protein for protein from soy or hemp.
Also have a look at the article ¨To lose weight? This is how you prepare a smart diet! ¨