Spirulina-enriched yogurt fails to lower blood pressure or improve vascular function in overweight adults

Hypertension remains a major global health challenge, often managed with pharmaceuticals like ACE inhibitors. While food-derived peptides, particularly those with angiotensin-I converting enzyme (ACE) inhibitory activity, offer a promising natural alternative with fewer side effects, their efficacy can be compromised by food-matrix interactions. This study aimed to investigate if spirulina's known ACE-inhibitory peptides could maintain their bioactivity when incorporated into a yogurt-like dessert and subsequently impact blood pressure in a clinical setting, addressing a critical gap in functional food development.

Researchers conducted both in-vitro and clinical evaluations. For in-vitro, spirulina biomass (SB), spirulina-enriched yogurt-like dessert (YSB), and control yogurt (YC) underwent simulated gastrointestinal digestion, with <3 kDa peptide fractions assessed for ACE-inhibition. The clinical trial was a randomized, placebo-controlled, parallel design involving n=64 overweight/obese adults with elevated cardiometabolic risk. Participants consumed either YSB (4g/day spirulina) or isoenergetic YC daily for 8 weeks, followed by a 4-week observation period. Primary endpoints included peripheral BP, central BP, pulse wave velocity (PWV), and augmentation index (AIx) measured at baseline, week 8, and week 12.

In-vitro results showed that SB and YC exhibited ACE-inhibitory activity, consistent with spirulina's known peptide profile and potential fermentation effects. However, the crucial finding was that YSB — the spirulina incorporated into the yogurt matrix — did not demonstrate any ACE-inhibitory activity in these simulated digestion conditions, suggesting a loss of bioactivity due to food-matrix interactions. Clinically, this lack of in-vitro activity translated to no significant physiological effects. No significant grouptime interactions were observed for any measured parameters, including peripheral BP, central BP, PWV, or AIx. These negative findings remained consistent even after sensitivity analyses, which excluded participants on antihypertensive medication and in subgroups with elevated baseline BP. This robustly indicates that the specific spirulina-yogurt formulation was ineffective in improving vascular health markers. > Daily YSB consumption (4g spirulina/day) for 8 weeks showed no significant grouptime interactions for peripheral BP, central BP, pulse wave velocity, or augmentation index.