There is a need to identify alternative sources of protein that can be introduced into diets to effectively meet the protein requirements of the population. Seaweed presents a potential source of sustainable, alternative protein. In order to determine their utility in future foods, in this study we will undertake an acute postprandial trial to explore whether a macroalgae (porphyra) and a microalgae (chlorella) protein isolates are more beneficial for acute metabolic health as compared to their respective whole biomasses. In particular, we will compare the effects of whole biomasses and their protein isolates on acute glucose homeostasis, amino acid availability as well as on satiety and gut hormones.

Seaweed presents a potential source of sustainable, alternative protein. Broadly categorised into macroalgae and microalgae, macroalgae including those of the genus Porphyra are traditionally known as nori or laver and is a common ingredient in several Asian dishes such as soups and sushi. Porphyra is rich in protein, micronutrients and dietary fibre and the equivalent variety in New Zealand is a red macroalgae known as Karengo. A prominent genus of microalgae is Chlorella, which is a green microalgae also rich in protein and currently used mainly in dietary supplements. The interest in seaweed as an ingredient incorporated into meals, food products and dietary supplements has been growing due to their macronutrient composition and bioactive substances with studied health benefits including improvements in glucose homeostasis, appetite and anti-hypertensive and hypocholesterolemic properties.

However, controlled human studies comparing specific macroalgae and microalgae, particularly for their potential to be used as a source of alternative protein, has been limited. Therefore, the present study aims to compare macroalgae (Porphyra) biomass and its protein isolates versus microalgae (Chlorella) biomass and its protein isolates on postprandial satiety and nutrient metabolism in healthy adult Chinese males by adding these as ingredients to a noodle soup dish. We specifically aim to explore whether the protein isolates are superior to the respective whole biomasses in terms of glucose homeostasis, amino acid availability as well as in terms of satiety and gut hormones. Results from this study will be used towards future food applications to enhance the potential of the use of seaweed as a sustainable and nutritious source of alternative proteins.

Inclusion Criteria:

• Male
• Chinese ethnicity
• Aged 21 to 50 years
• Able to give informed consent
• Body Mass Index (BMI) of 18.5 to 25.0 kg/m2

Exclusion Criteria:

• Diabetic (HbA1C ≥ 6.5%)
• Smoking
• Having a dislike towards seaweed- or soy-based products
• Having allergies or intolerances to any common food ingredients including seaweed, soy, eggs, seafood, fish, milk, peanuts, tree nuts, wheat, gluten, cereal, fruits, dairy products, meat, vegetables, sugar, sweeteners, natural food colourings or flavourings, etc.
• Following special diets or having intentional dietary restrictions (e.g, vegetarians/vegans)
• Not willing to adhere to diet modification as in the study protocol
• Taking part in strenuous physical activities
• Not willing to stop any strenuous activity during or within 24 hours of study days (for those actively participating in sports at the competitive and/or endurance levels)
• Having glucose-6-phosphate dehydrogenase deficiency (G6PD deficiency)
• Having alcohol consumption on > 4 days per week with ≥ 6 alcoholic drinks per week
• Having sustained elevation of blood pressure (≥140/90 mm Hg)
• Having previously undergone any gastrointestinal surgery or having history of gastrointestinal disorders
• Having a history of heart, liver, kidney, blood disorders (e.g., thalassemia) or thyroid dysfunctions
• Having history of tuberculosis, HIV, Hepatitis B or Hepatitis C infections
• Having any prescription medication or any other alternative medicines or supplements which may interfere with study measurements in the opinion of the study investigators
• Having donated blood within 4 weeks of study participation
• Having poor veins or having history of severe vasovagal syncope (blackouts or fainting) from blood draws