The progressive age-related loss of muscle mass is termed sarcopenia. Consequences of sarcopenia are, but not limited to, decreased muscle strength, frailty, and an increased risk for the development of chronic metabolic diseases. Impaired postprandial protein digestion and amino acid absorption with advancing age has been suggested to be a key mechanism underlying sarcopenia. To overcome age-related skeletal muscle atrophy, sufficient dietary protein intake is required. However, the production of animal-based protein sources, such as milk, is associated with a number of economic, environmental, and ethical issues. Accordingly, there is a need to develop sustainable dietary protein sources to support our nutrition. Mycoprotein, spirulina, chlorella, pea, and lupin are novel, sustainable, non-animal derived protein sources that may represent potential alternative protein sources. However, the efficacy of these sources to stimulate muscle mass growth in both young and older adults is unknown.

Therefore, the present study will investigate the postprandial bioavailability of mycoprotein, spirulina, chlorella, pea, and lupin protein when compared to the animal-derived milk protein. Moreover, postprandial protein handling of these novel protein sources across different ages will be assessed. Briefly, 12 healthy young, and older adults will visit the University for 6 separate test days, with each day lasting 6 hours. Participants will consume the one of the 6 protein drinks on each test day. Repeated blood sampling will be used to assess protein digestion and subsequent systemic amino acid appearance.

Inclusion Criteria:

• Males and females aged 18-35 or 55 - 80 years old.
• Body mass index between 18.5 - 30.

Exclusion Criteria:

• Any diagnosed metabolic impairment (e.g. type 1 or 2 Diabetes).
• Any diagnosed cardiovascular disease or hypertension.
• Elevated blood pressure (>150/90 mmHg) at the time of screening.
• Known pre-existing liver disease/condition.
• Any medication known to affect protein and/or amino acid metabolism.
• Allergy to mycoprotein/Quorn/edible fungi, edible algae, lupin/legumes, or milk.
• Smoking.