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Jan 4, 2021 | Nutrition

Iron, Magnesium and Vitamin B12 in Seaweed

Edible seaweeds are natural and colourful sea plants packed with a variety of vitamins, minerals and antioxidants. The sea vegetables are loaded with vitamin C, B12, A, iodine, magnesium, iron, and so on. Beyond all the carried nutrition goodies, some people might be less familiar with iron, magnesium and vitamin B12. These 3 amazing nutrients are absolutely necessary for human health, playing different roles in every nook and cranny in our body!


Iron is an essential component of hemoglobin and is responsible for carrying oxygen in human body. People with insufficient iron intake may suffer from iron-deficiency anemia, and experience poor concentration, weakness, fatigue, as well as mood changes. Women need more iron than men. Deficiency occurs more often in women due to the iron loss during menstruation, and the extra amount required for mothers during pregnancy to allow baby’s hemoglobin production and brain development.

Iron could be either plant-based or animal-based, the nutrient could be better absorbed when eaten with vitamin C. In terms of seaweed, kelp, sea lettuce, and dulse are relatively high in iron. Here are the iron contents in some iron rich foods:

 Iron content/ servingMen RDI (%)Women RDI (%)
Rainbow Seaweed Flakes 2.5g2mg25%11%
Beef 3.5oz (100g)1.9 mg24%10.6%
Organ meats (chicken liver) 100g9.8 mg122%54%
Baby Spinach 100g1.75 mg21.8%10%
Cooked Lentils 200g6.6 mg82.5%37%
Dried pumpkin seeds 1oz (28g)2.8 mg35%15.6%
Cooked broccoli 150g (1 cup)0.87 mg11%5%
Oysters 3oz (85g)4mg50%28%
Recommended daily iron intake – Men adults 8mg, Women adults 18mg; Data from Nutrient Reference Values for Australia and New Zealand; Data from Australian Food Composition Database


Did you know? Magnesium is a real busy bee working in more than 300 enzyme systems in human bodies. The nutrient supports energy production, and muscle and nervous functioning. It also helps provide strong bones and a healthy immune system. Seaweed is a great natural food source that provides magnesium efficiently, especially sea lettuce, kelp, and Irish moss. Magnesium also distributes in nuts, seeds, and vegetables, these are some foods which magnesium could be found:

 Magnesium content/ servingMen RDI (%)Women RDI (%)
Rainbow Seaweed Flakes 2.5g52mg12.4%16%
Dried pumpkin seeds 1oz (28g)166mg39%52%
Roasted almonds 10g26.6mg6%8%
Roasted cashews 10g25 mg6%8%
Soymilk 1 cup (240ml)52.8mg12.6%16.5%
Avocado 50g13mg3%4%
Recommended daily magnesium intake – Men 420mg, Women 320mg; Data from Nutrient Reference Values for Australia and New Zealand; Data from Australian Food Composition Database; Data from U.S. Department of Agriculture.

Vitamin B12

Last but not least, vitamin B12 is also an essential micronutrient contained in seaweed. Vitamin B12 is capable of fatty acid and DNA synthesis. Besides, it also plays a role in normal blood functioning, as well as neuro system functioning.

The main food sources for the vitamin are animal foods, dairy products, and breakfast cereals. People with strict vegan diets, elderlies, and people with gastrointestinal disorders are high-risk groups for B12 deficiency. Insufficient intake may cause B12 anemia, and signs and symptoms that may take months to years to show up, here are some listed:

1. Jaundiced or pale skin

2. Fatigue, weakness, lack of energy

3. Nerve damage, sensation of pins and needles on the skin

4. Glossitis, mouth ulcers, and other oral symptoms

5. Dizziness

6. Blurred vision

7. Mood changes, such as depression

The symptoms of deficiency could be serious, making it crucial to ensure sufficient B12 intake. Regarding sea vegetables, sea lettuce, dulse, and nori could serve as natural vegan choices that provide a relatively high level of B12 within a small amount.

 B12 content/ servingMen RDI (%)Women RDI (%)
Rainbow Seaweed Flakes 2.5g0.6 μg25%25%
Boiled egg 1 large (50g)0.7μg (mostly in yolk)29%29%
Whole milk 1 cup (240ml)0.6μg25%25%
Cereal 1 cup (30g)1.5μg or more62.5%62.5%
2 Shitake mushrooms (36g)2μg83%83%
Chicken 1 cup (140g)1μg41%41%
Beef 3 oz (85g)2.5μg104%104%
Recommended daily vitamin B12 intake – Men 2.4ug, Women 2.4ug; Data from Nutrient Reference Values for Australia and New Zealand; Data from Australian Food Composition Database.

Do you eat enough of these trace elements? Simply incorporate some crunchy Rainbow Seaweed Flakes that is blended with sea lettuce, Atlantic nori, dulse, winged kelp and wakame in your food to complete your healthy diet. Make a small delicious change today for a totally big difference!


Australian Government, Department of Health and Aging, 2006. Nutrient Reference Values For Australia And New Zealand. Canberra: Commonwealth of Australia, pp.1 – 317.

MacArtain, P., Gill, C. I., Brooks, M., Campbell, R., & Rowland, I. R. (2007). Nutritional value of edible seaweeds. Nutrition reviews65(12), 535-543.

Nutrient Data Laboratory (U.S.), & Consumer and Food Economics Institute (U.S.). (1999). USDA nutrient database for standard reference. Riverdale, Md: USDA, Nutrient Data Laboratory, Agricultural Research Service.

Potter, J. D., Robertson, S. P., & Johnson, J. D. (1981, December). Magnesium and the regulation of muscle contraction. In Federation proceedings (Vol. 40, No. 12, pp. 2653-2656).

Written by: Sarah Leung