Effect of Dietary Nori (Dried Laver) on Blood Pressure in Young Japanese Children: An Intervention Study

Abstract

Background: Few studies have examined the association between seaweed intake and blood pressure in children. We conducted an intervention study to investigate whether seaweed intake affects blood pressure. Methods: Subjects were children aged 4 to 5 years attending a preschool in Aichi Prefecture, Japan, in 2010. Among 99 students, 89 (89.9%) were enrolled in our study. Nori (dried laver), an edible seaweed widely consumed in Japan, was used as a dietary intervention. Children in the intervention group were asked to consume 1.76 grams per day of roasted nori in addition to standard meals for 10 weeks. Children in the control group consumed their usual diet. Before the intervention and at the 10th week of the intervention, children's blood pressure was measured three times successively using an automated sphygmomanometer with subjects in a sitting position. Changes in systolic (SBP) and diastolic blood pressure (DBP) were compared between 55 children in the intervention group and 26 in the control group after adjustment for SBP and DBP before the intervention. Results: Changes in SBP were −8.29 mm Hg in the intervention group and +0.50 mm Hg in the control group (P for difference in change = 0.051). Changes in DBP were −6.77 mm Hg in the intervention group and −0.05 mm Hg in the control group (P = 0.031). In girls, no difference in blood pressure changes was found between the intervention and control groups. Conclusion: Nori intake lowered DBP level in boys. Seaweed intake might have preventive effects on elevated blood pressure in childhood.

Impact of seaweed intake on health

“…As for the association between seaweed intake and blood pressure levels, a crosssectional study of Japanese preschool boys and girls reported that the tertiles of seaweed intake calculated from a 3-day dietary record for the lowest tertile (median 0.06 g/day for boys and 0.07 g/day for girls) versus the highest tertile (median 1.11 g/day and 1.30 g/day, respectively) were inversely associated with systolic blood pressure (SBP) among girls (102.4 versus 96.9 mmHg, p for trend = 0.030) and diastolic blood pressure (DBP) among boys (62.8 versus 59.6 mmHg, p for trend = 0.038) 38 . In a cluster-randomized trial study of Japanese preschool children (39 boys and 42 girls) aged 4 to 5 years, school lunch with 6 sheets of roasted Nori per day for 10 weeks lowered DBP and SBP compared to that without Nori among boys (-6.77 mmHg versus -0.05 mmHg, p = 0.031 for DBP and -8.29 mmHg versus 0.50 mmHg, p = 0.051 for SBP), but not among girls 39 . In a randomized double-blind placebo-control trial, supplementation of 4-6 g/day seaweed capsules lowered SBP more (-10.5 mmHg versus -6.4 mmHg for 2 months) than did 0-4 g/day seaweed capsules among Ecuador participants with at least 1 symptom of metabolic syndrome 40 .…”

Association of Seaweed Consumption with Metabolic Syndrome and Its Components: Findings from the Korean Genome and Epidemiology Study

“…Seaweed polysaccharides have antihypertensive effects in rats [ 43 ]. In a study on young children in Japan, the consumption of laver showed a diastolic-blood-pressure-lowering effect in boys [ 44 ]. Although several studies have reported significant relationship between blood pressure and seaweed consumption, no relationship was found between hypertension and seaweed consumption in the present study.…”

Rice-Based Diet and Cardiovascular Disease Mortality in Japan: From the Takayama Study

“…Because an additional adjustment for these food intakes weakened its association with coronary heart disease and stroke, the reduced risk of mortality in these two diseases related to rice intake may be due in part to the association with these food intakes. The intake of soy products and seaweed is associated with decreased risk of cardiovascular disease and related risk factors, especially in Asian countries [ 22 , 23 , 24 , 25 ]. In contrast, the consumption of red and processed meat is associated with increased risk of cardiovascular disease [ 26 , 27 ], although there is no conclusive evidence for the role of egg intake in cardiovascular disease risk [ 28 ].…”