While high-protein foods are in vogue, too much of the nutrient can harm the kidneys. This is highlighted by three scientists who have collaborated on an editorial calling for wider awareness. Although the kidney risks of a high-protein diet are widely known within the medical world, consumers continue to turn toward trendy keto-style diets as they seek weight loss and other health benefits. However, many of these people may unknowingly be at risk of kidney disease, with their protein intake exacerbating this condition.

“A diet high in protein and low in carbohydrates is effective in making you lose weight. However, if you start eating carbs again, you gain weight very quickly. These high-protein diets don’t work in the long-term – they are only good for starting to lose weight,” Professor Denis Fouque, Past-Chair of the European Renal Nutrition Working Group, tells NutritionInsight.

Fouque, along with Kamyar Kalantar-Zadeh and Holly Kramer, is also calling attention to two new studies showcasing the association protein intake and kidney health. An analysis of a Dutch cohort showed a strictly linear association between daily protein intake and decline in kidney function – the higher the intake, the faster the decline. However, this was specifically among patients who had experienced a heart attack in the past.

Meanwhile, an epidemiological study conducted in South Korea had similar findings. People with the highest intake protein intake had 1.3 times higher risk of faster glomerular filtration rate loss. The researchers concluded that the findings suggest that a high-protein diet has a deleterious effect on renal function in the general population.

Fouque explains that while a high-protein diet may not be dangerous to everyone, it can be difficult to know exactly who is at risk. He notes that around 5 percent of people have a single kidney and are unaware of it, which means eating a high-protein diet could put them at particularly high risk. Additionally, other risk factors include taking drugs, such as anti-pain or anti-inflammatory pills, having diabetes or high blood pressure, or being older. “When you get older – for example older than 65 – your kidneys are failing progressively, but you don’t know it. This can create a vicious circle.”

Lurking dangers

Nephrologists already recommend that patients with a known early-stage chronic kidney disease consume low-protein diets. As long as it is unclear whether it makes any difference if the proteins are animal- or plant-based, the recommendation is to abstain in general from a high protein intake.

However, the editorial authors highlight that some people have a mild chronic kidney disease that they are totally unaware of. If this group follows the trend of eating a protein-rich diet because they believe it is healthy, they are “taking the fast lane to irreversible kidney failure.”

In view of the rising number of people affected by Type 2 diabetes, and the fact that at least 30 percent of patients with diabetes suffer from underlying chronic kidney disease, the experts believe it is high time that the diabetes population and the general public are warned.

Fouque acknowledges that a high-protein, low-carb diet is an effective weight-loss method as ketones help satiate the appetite, so people do not feel the need to overeat. Despite the serious health outcomes linked to obesity, a high-protein diet should still be used with caution in this population as obesity is also a predisposing factor for kidney disease. “This should be for only a short period – no more than two months,” he recommends.

“To put it in a nutshell: To recommend a high-protein diet to an overweight diabetes patient may indeed result in loss of weight, but also in a severe loss of kidney function. We want one, but we also get the other,” Fouque concludes.

Last week, a Safefood report noted that there was “no need for protein bars.” The public body found that despite more than one in three people believing protein bars to be “healthy,” 77 percent of offerings are high in saturated fat, while 38 percent contain chocolate as a main ingredient. It also highlighted that adults’ protein needs can be met by consuming a varied diet containing a range of protein sources, without the inclusion of commercial high-protein food products.

However, a ketogenic diet has been associated with other health benefits. Last week, a Yale University study found that the diet helps to enhance production from airway cells that can effectively trap the influenza virus. Earlier this year, a high-fat, low-carbohydrate diet – similar to a keto or Atkins diet – was found to potentially improve brain function and memory in older adults. Separate research also found that a keto diet is the optimal way to combat obesity in the military and promote soldiers’ fitness levels.