Natalie Ledesma, MS, RDN, CSO, CLT

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Seaweeds & their Health Benefits

Recently, I was in Hawaii to give a few presentations. I know, not a bad place to travel for work - I’m certainly not complaining. I ordered the seaweed salad pictured below and it made me realize that I should include an article about seaweeds in my newsletter. So, here we are.

Seaweeds, commonly considered sea vegetables, rank high in nutritional value containing protein, fibers, omega-3 and -6 unsaturated fatty acids, vitamins, and minerals. They function as true powerhouses of micronutrients, some varieties containing 13 vitamins and 60 trace minerals. There are over 600 edible seaweed species recognized worldwide – most common types are nori, wakame, dulse, and kombu.


Nutritional Components of Seaweeds
These nutritionally rich veggies contain polysaccharides, or fiber. These fibers are prebiotics, the fuel for the growth of our beneficial bacteria that you know of as probiotics. Prebiotic fibers are indigestible in the small intestine, but can be metabolized by bacteria in the large intestine to confer a beneficial physiological effect on the host, meaning you.

Seaweeds also contain protein and are complete protein sources as they contain all nine of the essential amino acids. Due to the greater amount of phenolic compounds, namely tannins, the digestibility of the protein in seaweeds is reduced, but remains similar to the digestibility of proteins in grains, legumes, and vegetables.

What about micronutrients? Seaweeds are rich in both water and fat-soluble vitamins, particularly A, Bs (B1, B2, B6, folate, and B12), C and E. Seaweeds are one of the very few vegetarian sources of vitamin B12. Minerals, however, are seaweeds collective claim to fame—iodine, calcium, iron, potassium, and magnesium. Seaweeds are the richest dietary source of iodine. The variation of the nutritional values is mainly dependent on the species cultivated, seasons, geography/location, seawater quality (nutrients available), and the influence of other environmental stress factors during growth (such as temperature, pH, conductivity, salinity, UV radiation, light, and herbivory).


Potential Health Benefits of Seaweeds
While more research is needed, seaweed and its bioactives show potential for use in prevention and, in some cases, treatment of human disease. Seaweeds have various protective properties:

  • Anti-cancer

  • Anti-inflammatory

  • Lower cholesterol

  • Thyroid support & metabolism

  • Blood pressure regulation

  • Hair, skin, & nail health

  • Eliminate toxins & reduce the absorption of heavy metals


Seaweeds exhibit antioxidant properties with their free radical scavenging ability, namely from the carotenoids. The antioxidant properties of seaweeds help to limit the development of cancers. Furthermore, fucoidans, polysaccharides found in seaweeds, have anti-cancer properties. Some fucoidans have been implicated in reducing drug resistance and improving chemotherapy response.

Additionally, brown seaweeds used in some nutraceuticals and functional foods, have been found to be helpful for treating metabolic syndrome comorbidities – including obesity, hypertension, dyslipidemia, hyperglycemia, and insulin resistance. These conditions increase the risk of developing type 2 diabetes and cardiovascular disease.

Because iodine is essential for thyroid function, seaweeds can be helpful to stimulate proper functioning of the thyroid gland, and hence, support your metabolism. Scientific evidence suggests an anti-obesity effect of several brown, red and green seaweeds. Similarly, an excessive intake of iodine may also influence thyroid hormones and lead to weight gain. You’re seeking that happy medium of adequate iodine status.

Seaweeds have a great ability to perform bioaccumulation of heavy metals, contaminants, and iodine – that can be a very good thing and also possibly a bad thing. They may be helpful in decreasing the absorption of heavy metals, but also if harvested from heavy shipping regions, may contain higher levels of these metals, namely lead, mercury, and arsenic. Generally speaking, colder waters and more northern waters are less polluted.


Summary
Ultimately, seaweeds can be an excellent addition to your diet, but do be sure to opt for cleanly sourced varieties. Incorporate seaweed with any meal of the day. Add to soups, use nori as a wrap, or make the base of your salad seaweed. Need a little salt, or umami – sprinkle seaweed flakes to salads and stir-fries or add kombu to flavor a broth.

Buddha Bowl – create as you wish!

Ingredients:
Cauliflower rice, brown rice, sweet potatoes
Steamed asparagus, sauteéd mushrooms, shredded purple cabbage, radishes, bean sprouts, shredded carrots
Greens, microgreens, sprouts
Scallions
Grilled tofu, salmon, poached eggs, edamame
Avocado
Seaweed strips
Pickled ginger
Miso dressing, tahini dressing, Ponzu sauce
Sesame seeds

Directions:

  1. Begin with a base of sweet potatoes, riced cauliflower, brown rice, or other whole grain.

  2. Top with greens and vegetables, flavored as you wish (ginger, garlic, tamari are a great base)

  3. Add protein of choice – salmon, tofu, edamame, poached eggs, organic chicken

  4. Top with sprouts.

  5. Sprinkle with seeds and/or nuts.

  6. Drizzle with a dressing or sauce (i.e., Sriacha, miso dressing, Ponzu sauce)

  7. Enjoy!

Jennifer Sato’s Winning Miso Soup Recipe from the Diversified Table Recipe Contest 

This nourishing recipe may help those with digestive issues given that miso is a fermented soybean paste high in probiotics and this recipe includes many soft vegetables. This nutrient dense recipe contains spinach, carrots, wakame, maitake mushroom, and tofu which are high in vitamins and minerals including iron, B vitamins, Magnesium, vitamin K, calcium, protein, fiber, and antioxidants. The subtle flavor of this soup may be soothing for those with a change in taste or appetite. 

Miso Soup is a traditional Japanese soup made with miso (fermented soybean paste) and dashi (soup stock) plus a variety of other ingredients such as wakame or seaweed, tofu, carrots, komatsuna (Japanese spinach), root vegetables including daikon (white radish), potatoes, and mushrooms. This recipe will use kombu (dried kelp) and bonito flakes (dried skipjack tuna) for its dashi. The soup is served warm, often consumed for breakfast with rice on the side, though it can be enjoyed any time of day. The subtle sweetness of white miso in this recipe combined with traditional Japanese vegetables make this dish a delicious, comforting way to consume lean protein, fiber, vitamins/minerals, and fluids without overpowering the palate. 

Servings: 3
Serving Size: 200ml per bowl
Total cooking time: 15-20 minutes 

Ingredients:
• 1 1⁄4 cup water
• 1⁄4 cup bonito flakes
• 1 (2-inch) piece kombu
• 1⁄4 cup dried maitake mushroom
• 1/8 cup komatsuna
• 1/8 cup carrots, chopped
• 1/8 cup daikon
• 1 stalk green onion
• ~4 ounces or 1/3 package of firm tofu, drained
• 2 tablespoons organic miso 
• 1 tablespoon wakame


Directions: 

1) Soak the dried maitake mushroom in hot water for at least 15 minutes in its own cup, put to the side

2) Make the dashi. Boil water with the kombu inside a small 1-quart saucepan. Remove the kombu when the water starts to boil. Add the bonito flakes to the boiling water. Turn the heat down to a simmer for at least 10 minutes. Drain the broth through a strainer, discarding the bonito. (Skip the bonito flakes for a vegetarian option) 

3)  Bring the broth back to a rapid simmer. 

4)  Prep the ingredients. Wash the produce. Peel the daikon radish and thinly slice into circles. Peel and chop the carrots. Trim the stems off the komatsuna spinach. Chop the green onion. Cut the tofu into small 1⁄4 inch cubes. 

5)  Add in ingredients that take longer to cook first: Add the daikon, carrots and spinach to the broth and cook until tender. 

6)  Mix the miso. Turn off the heat on the saucepan. Ladle a small amount of broth into a small measuring cup (1/4 cup works well) and carefully stir in the miso, 1 tablespoon at a time. Whisk with a fork until the miso is completely dissolved and no lumps remain. Pour the miso mixture into the saucepan. 

7)  Add the remaining ingredients. Add the tofu to the broth. The tofu contains a lot of water, the volume of the soup will increase. If the broth gets cooler after adding the tofu, reheat the soup until it is just hot, do not reboil. Add the dried wakame into the soup; it will expand into seaweed. Add the mushroom and green onion to the broth. 

8)  Gently stir all ingredients, serve immediately, and enjoy! 

Hope your summer is off to a great start!

To health & healing,
Natalie