In a recent study in the USA, researchers investigated the role of diet in the regulation of systemic inflammation and its association with chronic kidney disease causes.
Chronic kidney disease is a progressive irreversible decline in the function of the kidney which ultimately results in kidney failure. Chronic kidney disease may occur from some form of injury or inflammatory process to the kidneys, and this involves a variety of factors such as repeated or chronic urinary tract infection, homogenous blood infections, untreated severe dehydration, structural defects, diabetes, hypertension, and sometimes behavioural factors.
In a study published in the British Journal of Nutrition, researchers hypothesized that chronic kidney disease causes may include the diet. Specifically, they speculated that individuals with chronic kidney disease have pro-inflammatory diets compared to those who do not have kidney disease.
Pro-inflammatory diets were characterized as diets with saturated fatty acids, trans fatty acids, red meat, high sodium, process food, and sweet food. Anti-inflammatory diets were diets from fruits, vegetables whole grains and fish with nutrients such as polyunsaturated fatty acids, monounsaturated fatty acids, phytochemicals, fibers, and protective nutrients which are antioxidant vitamins including vitamin E, vitamin C, vitamin A, and minerals like potassium, phosphate, magnesium, and calcium.
The researchers used data from the Nutrition and Health Examination Surveys (NHANES) which included a special questionnaire to obtain information on the diets, demographics, socioeconomic status, and health behaviours of 21,649 adult participants along with a clinical examination, and dietary assessment using mobile examination centers. This study was analysed in cycles from 2005 to 2012, and a diet inflammatory index score was obtained.
During the study, blood and urine samples were used to determine the participants’ blood sugar levels, creatinine, and albumin in order to estimate the glomerular filtration rate (eGFR).
The study found that those who kept an anti-inflammatory diet had a lower or negative dietary inflammatory index (DII) score while those that had a pro-inflammatory diet had a higher or positive dietary inflammatory index (DII) score.
This study discovered that those with a pro-inflammatory diet and higher DII also experienced an increase in BMI, blood sugar levels, and blood pressure with worsening diabetes, and hypertension resulting in marked deterioration in kidney function unlike those who fed on the anti-inflammatory diet. It was therefore revealed that the pro-inflammatory diet is associated with reduced kidney function which invariably results in chronic kidney disease.
There have been several previous studies linking poor diet and systemic metabolic dysfunction. This study further emphasized the role of pro-inflammatory diets in propagating tissue injuries and markers of inflammation, which reduce the kidney function and therefore increase the risk and prevalence of chronic kidney disease while the anti-inflammatory diet can assist in improving kidney function and subsequently prevent chronic kidney disease. Therefore, the study found a strong association between diet, inflammation, and the development of chronic kidney disease.
The strength of this research lies in the large cross-sectional study of random participants from the general population which could be applied to the adults in the general population of the USA.
The researchers believe that if this study is confirmed in a clinical trial, the knowledge of employing the anti-inflammatory diet and avoiding pro-inflammatory diets could be a ground-breaking approach to preventing chronic kidney disease.
Written by Ijeoma C. Izundu, MBBS
Reference: Mazidi M, Shivappa N, Wirth M, Hebert J, Kengne A. Greater Dietary Inflammatory Index score is associated with higher likelihood of chronic kidney disease. British Journal of Nutrition. 2018;120(02):204-209.