The Underrated Vegetable That Has More Calcium Than A Glass Of Milk

Have you tried fresh or dried seaweed as a snackable treat or sushi roll ingredient? Though seaweed was once an unconventional food in places like the United States and Europe, it's become a far more common household kitchen staple. And that could be a very good thing if you're trying to rev up the variety of your diet as well as increase your consumption of calcium.

Just how popular has seaweed become around the world? Let's look at two polls: According to a survey of young Australians published in 2022 (via Foods), 49.4% of participants said they ate seaweed in a restaurant once a month. Just under 40% said they consumed seaweed at a sushi bar during the same time frame. A 2020 survey conducted by the Maine Aquaculture Innovation Center (MAIC) revealed that 36% of United States-based survey respondents have bought or eaten a form of seaweed.

Whether or not you've hopped onto the seaweed bandwagon, you may want to dive in and add seaweed to your diet. Why? The calcium in dried seaweed is enough to rival the calcium in a glass of milk. Data from the U.S. Department of Agriculture shows that a two tablespoon serving of dried hijiki seaweed contains 89 milligrams. And while, per the Dietary Guidelines for the Americas, a one-cup glass of low fat or 1% milk has 305 milligrams, you'd only need about 3.5 tablespoons of dried seaweed to get as much calcium as you would from a cup of milk.

A 2020 analysis of marine-based calcium in Scientific Reports suggests that seaweed-derived calcium needs to be investigated further as an inexpensive, consistently available calcium source. That's especially important if you're at all worried about the future state of your bones. A 2021 study published in Solids concluded that seaweed could help ward off osteoporosis due to its high concentration of calcium.

What if you're already taking a daily vitamin or supplement to give your body more calcium? You might still want to ask your healthcare provider about augmenting your calcium intake with seaweed. A 2021 comparative study of plant-based calcium versus synthetically created calcium in The International Journal of Pharmaceutical Chemistry and Analysis concluded that plant-based calcium was better absorbed than synthetic calcium.

Calcium isn't the only reason to pick up a package of seaweed, though. Yes, it's high in calcium, but that's not its only advantage. Healthline reveals that most seaweed is chock-full of folate, iron, and magnesium, too. And that's not all. 

WedMD notes that seaweed also seems to have antioxidant properties. According to a 2021 review from the Journal of Food Quality, the antioxidants found in seaweed could benefit people therapeutically. Specifically, the review suggested that seaweed could be useful in an antiviral capacity, or as an anti-inflammatory solution.

If the idea of incorporating more calcium into your meals by way of eating seaweed makes you excited but you're not sure where to start, try bringing it into foods you already love. Seaweed, particularly dried seaweed or seaweed in flake form, can be added in small amounts to stews, noodles, dressings, stir-fries, soups, and more. You can also chow down on plain or flavored seaweed as a nutrient-dense snack food.

One caveat, though: Be aware that, because of its aquatic nature, seaweed may contain trace amounts of heavy metals found in other sea-based foods. For example, a 2022 article from PLoS One notes that seaweed harvested from the Salish Sea exceeded the recommended international amounts for lead and cadmium. 

Similarly, a Chemosphere-published 2021 study on seaweed available throughout Italy concluded that arsenic and iodine were present in some regional seaweed samples. However, the researchers acknowledged that seaweed can be valuable dietarily and advised that proper source labeling might be a way to reduce consumers risk of exposing themselves to potential toxins or allergens.

So, should you think twice about getting calcium through seaweed? Not necessarily. Just look for reputable seaweed brands you trust and that have upfront nutritional labels. As a result, you'll be able to experiment with seaweed to give your body a healthy, plant-based calcium boost beyond having a glass of milk.