Can Seaweeds Reduce Blood Pressure?
Seaweeds are a part of traditional Japanese food. Animal studies have found that intake of seaweeds or an extract of seaweeds lowers blood pressure. Its relevance in adults has however not been established due to inconsistent results from various conducted studies.
Researchers in Japan conducted a study to assess the benefits of a diet of seaweeds on blood pressure in children between the ages of 3 and 6 years. This age group was selected keeping in mind that early control of blood pressure through diet could reduce the incidence of hypertension in adulthood.
Baseline blood pressure was recorded before the study. Height and weight were either recorded or the details were obtained from parents, and body mass index was calculated. Information regarding the child's lifestyle and health status was obtained from the parents. Physical activity was recorded based on an outdoor playtime checklist.
Food intake of the children was recorded by the parents for 3 days covering 2 consecutive weekdays and 1 weekend day.
Blood pressure was measured once in the midmorning.
Depending on the quantity of sea weed consumed, the children were divided into three groups - low, middle or high intake.
The study, which was completed in 417 children, found that boys with middle and high intake of seaweed had lower diastolic blood pressures as compared to those with low seaweed intake. Systolic blood pressure and pulse was not associated with seaweed intake in boys.
In the case of girls, those with high seaweed intake had significantly lower systolic blood pressures than those with low seaweed intake. The diastolic blood pressure of girls with low seaweed intake was also higher than those of middle and high intake of seaweed.
Intake of salt, other diet or lifestyle factors like sleep and physical activity, did not affect the apparent effect of seaweed on blood pressure.
The study thus indicates that seaweeds could influence blood pressure in children. However, it does have some shortcomings. The dietary record was maintained for a very small duration. Blood pressure was measured only once following the baseline measurement. Studies carried out for longer durations could provide a clearer picture regarding the benefit of seaweeds on blood pressure.
It appears to be very early to decide, based on this study alone, whether seaweed intake in children could affect blood pressure in later adulthood. Further studies are required to establish this beneficial effect of seaweeds.
1. Wada K, Nakamura K, Tamai Y, Tsuji M, Sahashi Y, Watanabe K, Ohtsuchi S, Yamamoto K, Ando K, Nagata C. Seaweed intake and blood pressure levels in healthy pre-school Japanese children. Nutr J. 2011 Aug 10;10:83.