Coffee’s Hidden Link to Longevity Protein Discovered

Study Reveals Key Connection Between Daily Brew and Klotho Levels

A groundbreaking study analyzing data from over 9,000 US adults aged 40-79 has unveiled a significant association between regular coffee consumption and levels of alpha-Klotho (SαKl), a protein linked to aging and overall health. The research, drawing from the National Health and Nutrition Examination Survey (NHANES), suggests that our daily cup of coffee might play a more profound role in our well-being than previously understood.

Unpacking the Research Methodology

Rigorous Data Collection and Participant Selection

The study meticulously examined data from five NHANES cycles spanning 2007 to 2016. These cycles, managed by the Centers for Disease Control and Prevention, utilize a comprehensive approach involving household interviews, physical examinations, and laboratory tests to ensure representative data on US civilians. All procedures adhered to the Declaration of Helsinki, with ethical approval and informed consent secured from participants.

The initial dataset comprised 19,344 eligible individuals aged 40-79 who consented to surplus serum use. After stringent exclusion criteria were applied—including missing Klotho data, incomplete coffee intake information, pregnancy, cancer diagnoses, and other missing covariates like demographic or health history factors—the final analytical sample narrowed to 9,811 participants.

Quantifying Coffee Intake and Measuring SαKl

Researchers quantified coffee consumption, differentiating between total, caffeinated, and decaffeinated varieties, by analyzing 24-hour dietary recall interviews. Data from the Food and Nutrient Database for Dietary Studies, developed by the US Department of Agriculture, was used to assess dietary caffeine content. The primary exposure variable focused on daily total coffee consumption in grams per day.

Levels of SαKl, a critical protein associated with aging, were measured using serum samples processed between 2019 and 2020. The analysis employed an enzyme-linked immunosorbent assay kit from IBL International, with each sample tested twice for accuracy. The average SαKl levels observed in the study were 698.0 pg/mL.

Examining Confounding Factors

A Multifaceted Approach to Data Analysis

To ensure the robustness of their findings, the research team accounted for numerous potential confounding variables. These included race/ethnicity, body mass index (BMI), family income to poverty ratio (PIR), education level, and smoking status. Alcohol consumption, total energy intake, physical activity levels, hypertension, cardiovascular disease (CVD), and chronic obstructive pulmonary disease (COPD) were also factored into the analysis.

For instance, hypertension was defined by specific blood pressure thresholds or the habitual use of related medication, following established clinical guidelines. The study meticulously adjusted for these factors to isolate the relationship between coffee intake and SαKl levels.

Statistical Insights into Coffee and SαKl

Uncovering Non-linear Relationships

Statistical analyses were performed using R software (version 4.3.2), with a significance threshold set at P < 0.05. The researchers utilized NHANES survey weights to manage sampling design and nonresponse, presenting baseline characteristics through weighted linear regression and chi-square tests.

Multivariate linear regression models were employed to explore the associations between various coffee consumption metrics and SαKl levels. The analysis was structured to progressively adjust for demographic factors, and then for a comprehensive set of lifestyle and health variables. To investigate potential non-linear connections, generalized additive models (GAM) and restricted cubic splines (RCS) were utilized. This approach allowed for the identification of a “turning point” in the relationship, which was then further analyzed using piecewise linear regression models.

Subgroup analyses were also conducted to examine potential differences in the coffee-SαKl association across various demographic groups, including by age (≥ 60 years) and sex, providing a nuanced understanding of the findings.

The study’s findings align with a broader understanding of how lifestyle factors impact health. For example, research published in 2023 in Scientific Reports also noted a connection between cigarette smoking and serum alpha-Klotho levels in US adults over 40, highlighting the complex interplay of habits and this crucial protein.