There is growing evidence that links increased coffee drinking with better kidney function, although the evidence is still unclear. In the present study, researchers investigated whether a person's regular use of coffee was associated with changes in their eGFR and urinary ACR over time. The team used information from the Rotterdam Study (RS), a population-based study design.
Although the data is still inconclusive, there is rising evidence linking higher coffee consumption to improved renal function. Observational studies, such as one Mendelian Randomization (MR) study, have found that increased coffee consumption is either associated with a lower risk of chronic kidney disease (CKD), albuminuria, or renal failure, or there is no association with CKD. It is yet to be determined if consuming coffee increases estimated glomerular filtration rate (eGFR) in other high-risk categories for chronic renal disease.
It is critical to assess these connections in these subgroups because, due to their high levels of inflammation, these individuals may benefit more from coffee consumption. Furthermore, there is a paucity of research linking coffee consumption to a high urine albumin-to-creatinine ratio.
Renal Function And Coffee
The current study looked at whether a person’s regular coffee consumption was linked to changes in their eGFR and urine ACR over time.
The Rotterdam Study (RS), a population-based study design now being undertaken in the Ommoord district of Rotterdam, Netherlands, was employed by the team. The first sub-cohort was formed between 1989 and 1993, with 7,983 volunteers over the age of 55 signing up to participate. In 2000-2001, an additional 3,011 people were added to the second sub-group. These people were either newcomers to the study district or participants who had reached the age of 55 since the start of the study.
The third sub-cohort, RS-III, was developed in 2006-2008, with 3,932 people aged 45 and up recruited. At the start of the study, a total of 14,926 participants were recruited. Follow-up examinations were performed on each sub-cohort at four to six year intervals.
The current study’s baseline data came from the third follow-up assessment of the first cohort (RS-I-3) and the initial evaluations of the second and third groups (RS-II-1 and III-1). Follow-up data were obtained on future visits. A total of 8718 people completed food intake questionnaires. 7914 people in this cohort had at least one eGFR evaluation for longitudinal eGFR investigations. The team identified participants having baseline and at least one follow-up eGFR test to explore inadvertently impaired renal function.
Urine ACR measurements were repeated for RS-III patients and were performed in the same research cohort as eGFR analyses. To gather baseline data on habitual total coffee intake, in-home interviews and standardised 170-item and 390-item food frequency questionnaires (FFQs) were employed. Subjects were asked if they drank coffee during the in-home interviews, and the number of cups consumed daily was recorded. Individuals were asked about the frequency and quantity of meals and beverages they consumed on a regular basis, including coffee consumption, in all FFQs. Serum creatinine was measured at baseline and subsequent visits using an enzymatic assay method.
The participants’ mean age at the start was 66 years, with 57% of them being female. Over half of the participants had hypertension, and 10% had CVD or type 2 diabetes mellitus (T2D). The average BMI was 27 kg/m2, and 21% of the research participants were obese. The average daily coffee intake was three cups, with 4% of people not drinking coffee at all. Men were more likely to be heavy coffee consumers than non-coffee consumers. Additionally, heavy coffee drinkers were more likely to smoke, drink more alcohol, and consume the most calories.
The average eGFR fell by 4.92 ml/min per 1.73 m2 during a median of 5.4 years of follow-up. In all, 13,798 eGFR assessments were repeated. During the follow-up period, coffee was not associated with longitudinally assessed eGFR. Coffee and eGFR associations were constant across genders but not across age groups. Consuming one extra cup of coffee per day was associated with a 0.84 ml/min per 1.73m2 higher eGFR at the time of follow-up in subjects over the age of 70.
CVD, hypercholesterolemia, or hypertension had no effect on the coffee-eGFR relationship. The team observed a trend for higher eGFR with coffee intake among T2D individuals, while the interaction term was not significant. During the 6.1-year follow-up period, 619 more instances of reduced kidney function were discovered. Each additional cup of daily coffee was associated with a lower risk of impaired renal function, though this link was not statistically significant. In model 3, estimates for coffee intake classes ranged from 0.92 for non-coffee drinkers to 0.84 for those consuming more than four cups per day versus zero to two cups per day.
Overall, the study findings revealed that, while coffee intake was not connected with ACR and eGFR in the general population, it was associated with higher longitudinal eGFR in patients at a higher risk of CKD, specifically those aged 70 and older and obese adults. More prospective cohort studies, according to the researchers, should validate the findings.
Researchers investigated the relationship between frequent coffee drinking and renal function in a recent study published in Clinical Nutrition. Although the data is still inconclusive, there is rising evidence linking higher coffee consumption to improved renal function.
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