Assessment of Plasma Phospholipid Very-Long-Chain Saturated Fatty Acid Levels and Healthy Aging.

Importance: Identifying novel factors that protect against age-related diseases and promote healthy aging is critical to public health. Higher levels of circulating very-long-chain saturated fatty acids (VLSFAs) are integrated biomarkers of diet and metabolism shown to have beneficial associations in cardiovascular disease and total mortality, but whether they are associated with overall healthy aging is unknown. Objective: To examine the association of circulating levels of 3 VLSFAs with unhealthy aging events, including incident chronic disease (cardiovascular disease, cancer, lung disease or severe kidney disease), physical dysfunction, and cognitive decline. Design, Setting, and Participants: This cohort study used 1992 to 2014 data from the Cardiovascular Health Study (CHS). The CHS is a multicenter, population-based study of cardiovascular disease among older adults. Among the 4559 CHS participants with available fatty acid data, 1879 participants who had an age-related event before their first measurement were excluded. Data analysis was performed in 2020. Main Outcomes and Measures: Plasma phospholipid VLSFA levels were measured by thin-layer chromatography followed by gas chromatography. The main outcome was the hazard ratio (HR) of an incident unhealthy aging event associated with serial measures of plasma arachidic acid, behenic acid, and lignoceric acid. Results: Among the 2680 study participants (976 men [36.4%]), the mean (SD) age was 74.7 (4.8) years old at entry. During a median (interquartile range) of 6.4 (2.9-12.9) years of follow-up, 2484 participants experienced an unhealthy event. Compared with the lowest quintile, levels of behenic acid in the highest quintile of the fatty acid distribution were associated with 15% lower risk of an unhealthy event (HR, 0.85; 95% CI, 0.74-0.97; P for trend = .01) after adjustment for demographic characteristics, lifestyle factors, and clinical conditions. In analogous comparisons, levels of lignoceric acid were similarly associated with 16% lower risk of an unhealthy event (HR, 0.84; 95% CI, 0.73-0.95; P for trend = .001). Conclusions and Relevance: These findings suggest that higher levels of circulating behenic acid and lignoceric acid are associated with lower risk of unhealthy aging events. These results highlight the need to explore determinants of circulating VLSFAs for potential novel efforts to promote healthy aging.

Buccal cell DNA yield, quality, and collection costs: comparison of methods for large-scale studies.

There is considerable interest in noninvasive and cost-effective methods for obtaining DNA in large-scale studies. In this randomized crossover study of 22 participants, we compared the DNA yield, quality, and associated costs of buccal cell DNA collected using cytobrushes (three brushes per collection) and swish (i.e., mouthwash) in self-administered procedures. There was a nonstatistically significant higher yield from the mouthwash compared with cytobrush collections (15.8 microg versus 12.0 microg, respectively; P = 0.53). PCR reactions that required short (0.3 kb) or intermediate (1.1 kb) DNA fragments were 100% successful for DNA from brush and mouthwash, whereas PCRs for reactions that required long fragments (7.8 kb) failed for all of the participants from cytobrush DNA and were 81% successful for DNA from the mouthwash source. The brush collections provided sufficient DNA for an estimated 150-225 PCR reactions requiring short and intermediate DNA fragments. The estimated per person costs for buccal brush DNA collections in large studies were less then half (8.50 dollars) those for the mouthwash method (18 dollars). In addition, we tested whether cytobrush instructions to rub cheeks before collection or collect cells only in the morning increased DNA yield and whether repeat brushings of the same cheek reduced DNA yield. These variations resulted in no significant differences in DNA yields. We conclude that the collection of DNA with cytobrushes using simple instructions is cost effective in large-scale studies, and yields sufficient quantity and quality of DNA for genotyping.