Men who drink small amounts of alcohol or frequently exercise may be at increased risk of renal function decline, regardless of body weight, according to a Japanese study.
As part of the Saitama Cardiometabolic Disease and Organ Impairment Study, Eiichiro Kanda, MD, of Tokyo Kyosai Hospital, Meguro, Tokyo, and colleagues examined data from 7,473 healthy men and women (average age 38.8 years) living or working in Saitama, Japan, from 1999 to 2008. They gathered information on participants’ alcohol consumption, exercise frequency, and sleep duration, along with clinical histories and demographic information. The investigators grouped participants according to gender and body mass index (BMI). Subjects had an average estimated glomerular filtration rate (eGFR) of 78.1 mL/min/1.73m2.
Men who consumed a small amount of alcohol each week (20 to 140 grams, roughly equivalent to 1 to 7 glasses of sake) were more likely to experience a greater than 25% decrease in eGFR or to develop CKD within 3 years compared with men who drank more than 140 grams per week, researchers reported online in PLOS One. Their odds were elevated whether they were normal weight (37%) or overweight/obese (63%).
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Similarly, men who exercised 2 or more times a week (more than 30-minute sessions with sweating) also had greater odds of kidney function decline, compared with men who exercised rarely. Men of normal weight and overweight/obesity had greater odds by 41% and 84%, respectively.
The investigators found no correlation between alcohol consumption and exercise frequency and loss of kidney function in the female groups.
For each analysis, the researchers adjusted for age, gender, BMI, smoking, eGFR, urinary protein excretion, and histories of diabetes, hypertension, dyslipidemia, and cardiovascular diseases.
The results on male alcohol consumption are in line with previous studies, the investigators noted. Possible mechanisms include the effects of alcohol on preventing hyalinization of renal arterioles, increasing high-density lipoprotein level, and/or reducing inflammation and oxidation. “These mechanisms may more strongly affect kidney function in males than in females by the prevention of atherosclerosis,” the investigators explained. Alcohol might also modify the effect of sex hormones on kidney function.
The relationship between alcohol amount and kidney decline is still unclear and may vary by age. While alcohol metabolism tends to decrease in the elderly, men in this study were relatively young.
The researchers noted that exercise may decrease renal cortical blood flow. Exercise may also lead to weight loss with uncertain effects on the kidney. “Therefore, a recommendation of exercise should be accompanied by instructions of the appropriate type and an amount of exercise provided by healthcare professionals to prevent the loss of kidney function.”
Future studies should examine types of alcohol and exercises and investigate whether lifestyle adjustments prevent kidney function loss. The researchers found no correlation for sleep duration, but noted that further exploration of sleep quality and sleep disorders is warranted.
