Heavy Metal Concerns
One of the reasons sea vegetables are such a great source of nutrients is due to their absorptive abilities (kelp stem was once used to widen the cervix in medical procedures.) This capability makes seaweeds vulnerable to polluted waters. Sea vegetables can sponge up arsenic, cadmium and lead. They’ve even been used to measure the content of such pollutants in bodies of water by marine ecologists.
In particular, hijiki may contain high levels of arsenic if you don’t buy organic varieties.There is still a lack of consensus among scientists about whether or not the inorganic forms of arsenic found in seaweeds are as harmful as the organic forms but sea vegetables are still included in The World’s Healthiest Foods because of their health benefits and because dangers can be avoided by buying organic varieties.
Whole Foods Market offers some advice for ways to add sea vegetables to your diet other than eating sushi: sprinkle on top of salads, add to soups, use as a substitute for salt as a flavor enhancer, mix re-hydrated sea vegetables with shredded carrots and ginger and add salad dressing.