How much iron is in a pack of seaweed?

December 3, 2025 •

4 min read

Did you know that some seaweed varieties, like sea lettuce, can contain more iron per gram than spinach? A typical snack pack, however, provides a much smaller amount, and the answer to how much iron is in a pack of seaweed depends heavily on the specific brand and product size.

Quick Summary

The iron content in seaweed snack packs ranges from roughly 0.3mg to over 1mg, with significant variations among brands and product types. Factors like seaweed species and processing methods influence both the total iron and its bioavailability. Nori and sea lettuce generally contain high amounts of bioavailable iron.

Key Points

Iron Varies by Pack: The iron content in a seaweed snack pack depends heavily on the brand and size, typically ranging from 0.3mg in a small pack to over 1mg in larger ones.
Best Seaweed Types: Nori and sea lettuce provide some of the most bioavailable iron among common edible seaweeds, offering a better absorption rate than some land plants like spinach.
Non-Heme Iron Source: Seaweed provides non-heme iron, which is absorbed less efficiently by the body compared to heme iron found in animal products.
Boost Absorption with Vitamin C: Pairing seaweed with vitamin C-rich foods, such as citrus or bell peppers, can significantly increase the bioavailability and absorption of its iron.
Nutrient Booster, Not Cure: While nutrient-dense, seaweed snack packs offer a small amount of iron and should be seen as a dietary booster, not a treatment for iron-deficiency anemia.
Consider Sourcing: Some seaweed varieties can contain high levels of heavy metals like arsenic, so it is important to be mindful of your intake and source.

The Iron Content of Common Seaweed Snacks

The iron in a pre-packaged seaweed snack is highly variable, largely depending on the serving size and the type of seaweed used. A typical small, roasted seaweed pack, often weighing around 5 grams, contains a modest amount of iron. For instance, brands like gimme Seaweed and Sea Crunchy offer small packs with approximately 0.3mg of iron, representing a small percentage of the daily value. In contrast, a larger 1-ounce (28g) bag of Nora Snacks, another common snack brand, can contain around 1.2mg of iron. This highlights the need to check the nutrition label, as there is no standardized iron level per 'pack.'

Iron Levels by Seaweed Type

Different species of seaweed naturally contain different concentrations of iron. These variations can be substantial, with some types being excellent sources and others providing very little. Green seaweeds, for example, often have higher levels of iron than red or brown seaweeds.

Nori (Red Seaweed): Commonly used for sushi and snack packs, nori provides a decent amount of bioavailable iron. Studies show that 100 grams of dried nori can contain between 15 and 20 mg of iron. Notably, the iron in nori and sea lettuce has been shown to be more bioavailable than in some other seaweeds or spinach.
Sea Lettuce (Green Seaweed): Considered one of the best sources of bioavailable iron among seaweeds. Research indicates sea lettuce has a high iron concentration and is a good source of dietary iron.
Dulse (Red Seaweed): This red seaweed is also known to be rich in iron, sometimes containing more per gram than sea lettuce. A small 5g portion can contain nearly 1mg of iron.
Wakame (Brown Seaweed): While still a source of iron, wakame has a lower concentration compared to varieties like nori and sea lettuce.

Factors Affecting Iron Content

Beyond the type of seaweed, several other factors influence the final iron concentration in a product. These include the harvest location and time of year, which can cause natural fluctuations in mineral content. Additionally, processing methods such as washing, drying, and toasting can slightly alter the iron content and bioavailability. It's also important to remember that the iron in seaweed is non-heme iron, which is absorbed less efficiently by the body compared to heme iron found in meat and seafood.

Seaweed as an Iron Source: Boosting Absorption

Since the iron in seaweed is non-heme, there are ways to maximize its absorption. Combining seaweed with foods high in vitamin C is a proven method to significantly enhance iron uptake. Unlike some plant-based iron sources, seaweed has a low content of phytates, which are compounds that can inhibit iron absorption.

Best practices for boosting iron from seaweed:

Pair with citrus: Add roasted nori to a salad with a lemon or lime-based dressing.
Mix with vegetables: Combine seaweed flakes into stir-fries or soups that include bell peppers or tomatoes.
Enjoy with sushi: The vitamin C from the fresh vegetables and fish in sushi complements the nori wrap.

Seaweed vs. Other Common Iron Sources


Food (per 100g dry weight)	Iron Content (mg)	Source of Iron	Bioavailability Considerations
Sea Lettuce	~83.0	Non-heme	High for seaweed; enhanced by Vitamin C.
Nori	~15-20	Non-heme	Good for seaweed; enhanced by Vitamin C.
Dulse	~19.6	Non-heme	High for seaweed.
Spinach	~1.75 (raw)	Non-heme	Lower bioavailability compared to nori/sea lettuce; contains inhibitors.
Beef	~1.9 (cooked)	Heme	Highly bioavailable and easily absorbed.
Lentils	~6.6 (cooked)	Non-heme	Bioavailability can be affected by phytates; needs enhancers.

Important Considerations for Seaweed Consumption

While seaweed is a nutrient-dense food, it's not a silver bullet for iron deficiency. Due to small serving sizes in snack packs, they are best viewed as a supplement to a balanced diet rather than a primary source of iron. Furthermore, some varieties of seaweed may contain high levels of heavy metals, like arsenic, which could limit their regular consumption. Research from the University of Hawaii found that certain seaweeds had high arsenic levels, necessitating caution. Always consider the sourcing and processing of the seaweed products you consume.

Conclusion

So, how much iron is in a pack of seaweed? The simple answer is: not a lot, but every bit counts. While the quantity may seem small, seaweed, particularly varieties like nori and sea lettuce, can be a valuable, bioavailable source of supplemental iron for those seeking plant-based options. For individuals with iron-deficiency anemia, however, it is essential to consult a healthcare provider, as snack packs are not an effective treatment. By understanding the different types and boosting absorption with vitamin C, you can make the most of this nutritious ocean vegetable. For more in-depth nutritional information on seaweed varieties, one can explore sources like this study detailing mineral content and iron bioavailability.

This article is for informational purposes only and is not medical advice. Consult a healthcare professional for personalized dietary guidance.

Frequently Asked Questions

Among the most common edible varieties, sea lettuce and dulse contain notably high levels of iron, often more per gram than other species. Green seaweeds generally contain higher iron content overall.

The iron in seaweed is non-heme iron, which is less efficiently absorbed by the body than heme iron found in meat. However, unlike some plant-based sources, seaweed generally has low levels of phytates, which inhibit absorption, and absorption can be improved by consuming it with vitamin C.

To maximize iron absorption from seaweed, pair it with foods rich in vitamin C. Try adding crushed roasted nori sheets to a salad with a citrus-based dressing or mixing seaweed flakes into a soup with tomatoes or bell peppers.

No, the iron content varies widely based on the specific type of seaweed and the brand's processing. It's important to check the nutrition facts on the label and be aware that some varieties, like Red Ogo, have very poor iron bioavailability despite high iron content.

Yes, seaweed can be a valuable plant-based source of iron for vegetarians and vegans, especially varieties like nori and sea lettuce. When combined with other plant-based iron sources and consumed with vitamin C, it can help bolster overall iron intake.

The primary risk is the potential for high levels of heavy metals, such as arsenic, in some species, which could pose a health risk if consumed in large quantities regularly. As with any food, moderation and knowing your source is key.

No, seaweed is not a treatment for anemia. While it can contribute to your iron intake, it is not a sufficient replacement for supplements or a diet designed to combat a serious deficiency. You should always consult a doctor for diagnosis and treatment of anemia.