Seaweed supplementation for metabolic and cardiovascular health: A double-blind RCT in women with metabolic syndrome

Abstract

Purpose: The purpose of this 8-week double blind RCT was to investigate the effects of a seaweed capsule (2g/day) on chronic metabolic and cardiovascular profiles compared to a control (placebo) capsule. The seaweed was a New Zealand grown green macroalgae (Ulva sp. B) which has only been investigated in rat trials. Methods: Criteria for participation was female adults over 18 y.o. with ≥2 indicators of metabolic syndrome (MS), including waist circumference greater >88 cm; fasting triglycerides ≥150 mg/dL, high density lipoprotein cholesterol <50 mg/dL; systolic blood pressure ≥130 mmHg and/or diastolic ≥85; and fasting glucose >110 mg/dL. Forty-four participants (55 y.o. ±11, BMI 35.3 ±9.2, number of MS indicators 3.5 ± 1.0) self selected through online advertisements (23 in experimental group). Body composition, waist/hip ratio, brachial blood pressure, pulse wave velocity (applanation tonometry), central augmentation and pulse pressure (both at aorta), blood glucose, Haemoglobin A1c, and blood lipids were collected in a laboratory pre and post supplementation. In SPSS, a repeated measures ANOVA, with Bonferroni correction, was conducted to assess pre-post differences for groups. Results/findings: A seaweed dosage variable (by body mass, n=19) was investigated through regression on the above health predictor variables after controlling for diet and exercise. Tests of between-subjects effects showed no significant group X time effect of the seaweed supplement, although there were beneficial trends. Seaweed dosage was predicted best by waist:hip ratio, HbA1c, systolic BP, LDL (p=.001, R² = .825). Conclusions: A 2g seaweed dosage per day did not illicit significant differences. Future studies should address the limitation of this study, such as increasing the seaweed dosage overall, increasing the dosage with increased body mass, increasing the duration of dosage and increasing the sample size. Significant differences did not appear in this dataset as was found with improved body composition and lipids in a rat trial. With correct dosage, green seaweed may significantly lower the risk factors for chronic health condition and benefit those with metabolic syndrome.