Abstract
Ageing is associated with postprandial muscle vascular and metabolic dysfunction, suggesting vascular modifying interventions may be of benefit. Reflecting this, we investigated the impact of acute cocoa flavanol (450–500 mg) intake (versus placebo control) on vascular (via ultrasound) and glucose/insulin metabolic responses (via arterialised/venous blood samples and ELISA) to an oral nutritional supplement (ONS) in twelve healthy older adults (50% male, 72 ± 4 years), in a crossover design study. The cocoa condition displayed significant increases in m. vastus lateralis microvascular blood volume (MBV) in response to feeding at 180 and 240-min after ONS consumption (baseline: 1.00 vs. 180 min: 1.09 ± 0.03, p = 0.05; 240 min: 1.13 ± 0.04, p = 0.002), with MBV at these timepoints significantly higher than in the control condition (p < 0.05). In addition, there was a trend (p = 0.058) for MBV in m. tibialis anterior to increase in response to ONS in the cocoa condition only. Leg blood flow and vascular conductance increased, and vascular resistance decreased in response to ONS (p < 0.05), but these responses were not different between conditions (p > 0.05). Similarly, glucose uptake and insulin increased in response to ONS (p < 0.05) comparably between conditions (p > 0.05). Thus, acute cocoa flavanol supplementation can potentiate oral feeding-induced increases in MBV in older adults, but this improvement does not relay to muscle glucose uptake.
Highlights
In the m. tibialis anterior, microvascular blood volume (MBV), microvascular flow velocity (MFV) and microvascular blood flow (MBF) did not change over time within the cocoa or control condition and there were no significant differences between the conditions (Figure 3D–F)
Our primary finding was that acute cocoa flavanol supplementation may overcome ageOur primary finding was that acute cocoa flavanol supplementation may overcom related vascular dysfunction in the postprandial state, age-related vascular in thegoes postprandial context of the m. vastu suggesting that the impact dysfunction of cocoa flavanols beyond thestate effect(in of the the feeding-related lateralis), suggesting that the impact of cocoa flavanols goes beyond theenhanced effect of the feed insulin response, which alone is known to enhance microvascular flow [34]
We found that neither oral nutritional supplement (ONS) or ONS plus cocoa flavanols had any impact on MFV, and despite changes in MBV, MBF did not change in either m. vastus lateralis or m. tibialis anterior
Summary
Of the conditions associated with skeletal muscle deterioration, agerelated sarcopenia represents a global health problem, demonstrating robust associations with risk of frailty [2], morbidity [3], and in extreme cases, mortality [4]. Reduced muscle microvascular blood flow is observed in response to anabolic stimuli (e.g., feeding) [9,11], with nutrient-induced increases in whole-limb perfusion being attenuated with age [8]. Such blunted micro- and macrovascular blood flow responses are hypothesised to contribute to age-related “anabolic resistance” to feeding, via the limited delivery and/or utility of insulin and amino acids by muscle [12]
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