According to a new study from the University of Oxford, obesity is a cause of kidney disease. It suggests that if someone has fat all over the body, they are prone to developing kidney disease. Hence, controlling weight could be a new way to manage it.
Past studies have suggested the same, but it was unclear whether obesity directly caused kidney disease or whether other factors were involved, such as more salt in people’s diet.
In this study, scientists studied almost 300,000 DNA samples from the UK Biobank. They looked at more than 1,000 genetic variations known to predispose people to a higher overall body mass index (BMI) or more abdominal fat deposition (fat around the center). People with these gene variations are bound to become overweight or obese because they acquire these genes.
The team found kidney disease risk didn’t change based on fat location – is increased by the same amount regardless of whether fat was deposited centrally (around the organs) or across the body generally (such as around the legs and arms).
Professor Will Herrington, from the Medical Research Council Population Health Research Unit at the University of Oxford, who co-led the research, explains: “In this study, we found these genetic variants were consistently linked to kidney disease – each 5 kg/m2 increase in BMI caused roughly a 50% increased risk in chronic kidney disease. Using a genetic approach meant we could be more rigorous than with a conventional approach and rule out other factors.”
“In some diseases linked to obesity, such as heart disease, fat deposited around the abdominal organs (tummy fat) is worse than fat that accumulates around the buttocks. But our results clearly show that regardless of where it is deposited in the body, fat increases the risk of kidney disease.”
To understand why this happens, scientists tested whether the genetic variations that predispose certain people to corpulence were also connected with diabetes or high blood pressure, leading to kidney disease.
Scientists demonstrated that in most cases of obesity-associated kidney disease, diabetes and blood pressure were the driving causes. When fat was stored around the central organs, kidney disease was caused only by diabetes. On the other hand, when petroleum was stored for the most part over the body, both diabetes and hypertension lead to kidney disease.
Professor Herrington explains: “This is good news because we already know a lot about diabetes and high blood pressure, and we have treatments for them. If we can prevent diabetes and control blood pressure in those who are over, we may be able t patients prevent many cases of kidney disease from developing in the first place. Ultimately, these results give us all more incentive to manage our weight.”
He continues: “A new class of drugs called gliflozins reduce the kidney’s ability to retain sugar and salt, meaning the body is more able to get rid of excess sugar and salt. This helps people with diabetes control their weight and blood pressure, and recent trials are revealing they are particularly effective at treating diabetic kidney disease and other kidney diseases. We’re running a large clinical trial to find out if this is true in a wider range of people with kidney problems.”
Dr. Aisling McMahon, executive director of research, innovation, and policy at Kidney Research UK, said: “Around three million people live with chronic disease in the UK. One of the charity’s priorities is to transform treatments for kidney did new ways to treatments review. By identifying obesity as a new risk factor for kidney disease, this important research has revealed new avenues for doctors, patients, and healthcare teams to support a renewed focus on weight management and encourage patients to look at ways they can improve their health.”
She continues: “This research backs up why we’re supporting Kidney Beam – an online exercise and wellbeing platform for kidney patients. We’re also watching the gliflozin trials with interest. If clinical trials reveal they benefit an even wider group of patients, we would like to see these research findings brought into clinical practice quickly so they can benefit patients across the country.”
The study was funded by Kidney Research UK and the Medical Research Council.
- Pengfei Zhu et al. Conventional and Genetic Evidence on the Association between Adiposity and CKD. DOI: 10.1681/ASN.2020050679