Abstract
Objectives
Vitamin deficiencies are prevalent in the elderly. Common diseases of aging are characterized by alterations of one-carbon (1C) metabolites, namely homocysteine. Despite the importance of diet-derived nutrients and interconversion to active coenzymes for regulation of 1C metabolism, little is known about age-related alterations in 1C metabolism in response to meals. This study aimed to identify whether postprandial 1C metabolite regulation is impaired in older adults, and determine the influence of meal type. We hypothesized that older adults would have altered 1C metabolite responses, and that these would differ between energy dense and nutrient dense meals.
Methods
In a double-blinded randomized crossover design, healthy younger (n = 15) and older (n = 15) adults consumed mixed-meal breakfasts on separate occasions: an energy-dense (ED) meal (sausage and egg sandwich) and a nutrient-dense (ND) meal (oats, toast, cottage cheese and fruit). Plasma collected at fasting and hourly for 5 h was analysed for 12 1C metabolites using high-performance liquid chromatography with tandem mass spectrometry.
Results
Postprandial concentrations of five 1C metabolites differed between older and younger subjects, dependent on meal type. Unlike younger subjects, older subjects had similar meal responses for betaine, choline, taurine, and glycine concentrations (meal × age interactions P < 0.05 each, respectively; older ED vs. ND meal P > 0.05 each, respectively). Younger subjects had higher homocysteine concentrations than older after the ED meal (meal × age interaction P < 0.05; older vs. younger P < 0.05), but lower choline, glycine, and taurine concentrations than after the ND meal (P < 0.05 each, respectively).
Conclusions
Postprandial 1C metabolite responses are unaffected by meal type in older subjects, responding more similarly to divergent meals than in younger subjects. Although the implications to biological pathways and health outcomes relying on 1C metabolites are not clear, modification of these responses through acute dietary change may be less effective in the elderly.
Funding Sources
This research was funded by the Liggins Institute Trust, AgResearch Science Strategic Investment Fund Nutritional Strategies for an Aging Population, the Maurice and Phyllis Paykel Trust and a Faculty Research and Development Fund from the University of Auckland.