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Results of a prospective study indicate that moderate consumption of alcoholic beverages several days per week can decrease the risk of kidney disease whereas excessive intake will have the opposite effect.
A recent Japanese study reports that consuming up to 23 g of ethanol on 4 to 7 days per week almost halved the risk of consecutive proteinuria. Proteinuria describes a condition in which urine contains an abnormal amount of protein. Although it is normal to leak tiny amounts of albumin (a protein of small molecular size and that is water-soluble) into the urine, an abnormal amount of protein in the urine, i.e. proteinuria, is a good indicator of kidney damage.
Healthy kidneys contain roughly one million nephrons, which filter out the waste products in the blood along with water. The end product of this process is urine, which normally contains mainly excess fluid and waste products since most proteins are too big to pass through the kidneys’ filters. If the filters are damaged, increased amounts of albumin and other larger proteins from the blood can pass through and escape into the urine.
Proteinuria is thus a sign that the kidney function is progressively deteriorating. Even small degrees of albuminuria/proteinuria are associated with an increased risk of developing heart and blood vessel disease. The distinct causes of proteinuria are difficult to define: inflammation of the kidney filters (glomerular nephritis) can be involved, but also other processes such as diabetes, high blood pressure (hypertension), and some other forms of kidney disease can also damage the kidney filters and cause proteinuria.
Moderate consumption of alcoholic beverages has been reported to be associated with a decreased risk of cardio-metabolic diseases. But whether drinking alcohol is associated with the risk of proteinuria, has been unknown so far. Recently, Japanese researchers studied 9154 non-diabetic Japanese men, aged 40-55 years, with an estimated glomerular filtration rate ≥ 60 mL/min/1.73 m2, who had no proteinuria, and did not use antihypertensive medications at study entry. Their alcohol intake was documented via questionnaire. “Consecutive proteinuria” was defined as detecting proteinuria at least twice consecutively at the annual examinations during the follow up period.
In total, 385 subjects developed consecutive proteinuria during the follow-up period. For subjects who reported drinking up to 23 g ethanol/day (*) on 4 to 7 days per week, their risk for consecutive proteinuria was reduced by 46 % compared to non-drinkers. However, drinking alcoholic beverages of more than 69.1 g ethanol/day was associated with a significantly increased risk of consecutive proteinuria.
The scientists concluded that middle-aged men with frequent and moderate intake of alcoholic beverages of up to 23 g ethanol/day had the lowest risk of consecutive proteinuria, while those with frequent heavy alcohol consumption (≥ 69.1 g ethanol/day) had an increased risk. The mechanism still needs to be examined.
(*) One Japanese standard drink contains 23 g of alcohol.
Uehara S, Hayashi T, Kogawa Sato K, et al. Relationship Between Alcohol Drinking Pattern and Risk of Proteinuria: The Kansai Healthcare Study. J Epidemiol. 2016;26(9):464-70.