Is There Folic Acid in Seaweed? Folate Content & Benefits Explained

January 5, 2026 •

4 min read

According to a study published in Food & Function, specific types of dried seaweed, particularly purple laver (nori), contain remarkably high levels of folate compounds, the natural form of vitamin B9. While often used interchangeably, folate and folic acid differ chemically, with seaweed offering the natural, bioavailable version. This makes seaweed a surprisingly potent source of this essential nutrient, vital for DNA synthesis and cell growth.

Quick Summary

Yes, seaweed is a source of naturally occurring folate, with certain species like nori containing particularly high amounts. The content varies significantly by species and preparation method. It offers key benefits for cell production and cardiovascular health, but it's important to consume it in moderation to avoid excessive iodine intake.

Key Points

Source of Folate: Seaweed contains naturally occurring folate (vitamin B9), with specific types like nori containing exceptionally high levels compared to many land vegetables.
Folate vs. Folic Acid: Seaweed provides natural folate, which is distinct from synthetic folic acid. Natural folate is often more bioavailable to the body.
Varies by Species: The amount of folate differs significantly between seaweed types; nori, wakame, and kelp are good sources, while others like hijiki have lower concentrations.
Supports Key Body Functions: Folate from seaweed is vital for cell production, DNA synthesis, cardiovascular health (by regulating homocysteine levels), and cognitive function.
Important for Pregnancy: Adequate folate intake is crucial for preventing neural tube defects in early pregnancy, and seaweed can be a part of a diet contributing to this.
Moderate Consumption Advised: Due to high iodine content, excessive seaweed intake can lead to thyroid issues. Sourcing from clean waters and consuming in moderation is important.
Versatile Culinary Ingredient: Seaweed is easily incorporated into various dishes, such as sushi, soups, and salads, providing a nutrient boost and unique flavor.

Seaweed: A Rich Source of Natural Folate

Seaweed, often hailed as a 'superfood,' is gaining recognition for its dense nutrient profile, which includes a significant amount of folate. While the terms folate and folic acid are often used interchangeably, it is important to distinguish between them. Folate is the naturally occurring form of vitamin B9 found in foods, while folic acid is its synthetic counterpart, typically added to fortified products and supplements. The folate compounds found in seaweed are in their natural, bioactive forms, such as 5-methyltetrahydrofolate (5-MTHF), which is more readily utilized by the body.

Dried purple laver, commonly known as nori, is an especially notable source of folate. Studies have shown that nori can contain significantly higher folate levels than many common land vegetables, making it a valuable dietary component, especially for vegetarians and vegans seeking alternative nutrient sources. Other varieties, such as kelp and wakame, also contribute meaningful amounts of folate to a balanced diet.

Folate Content Varies by Seaweed Species

Not all seaweeds are created equal when it comes to nutrient concentration. The folate content can differ based on the species, growing conditions, and processing methods. For example, research indicates a stark contrast between the folate content of dried purple laver (nori) and other edible seaweeds like kombu and hijiki. This means that selecting the right type of seaweed is crucial if you are primarily seeking to boost your folate intake. The bioactive compounds in seaweed, including folate, contribute to several health benefits, but variety in your diet is key to ensuring a broad spectrum of nutrients.

Health Benefits of Seaweed-Derived Folate

Consuming folate-rich seaweed offers numerous health advantages beyond just addressing a deficiency. Folate is critical for DNA synthesis, cell division, and healthy red blood cell formation. The natural folate in seaweed can contribute to:

Cardiovascular Health: Folate helps the body break down homocysteine, an amino acid that, in high levels, can damage blood vessel walls and increase the risk of heart disease and stroke. By aiding this process, seaweed may support better heart health.
Cognitive Function: Adequate folate intake is linked to reduced risk of cognitive decline. It supports the production of neurotransmitters and is vital for brain health throughout the lifespan.
Support During Pregnancy: For women of childbearing age, consistent folate intake is crucial for preventing neural tube defects in infants. The CDC recommends 400 mcg of folic acid daily for all women of childbearing age, and while many rely on supplements, including folate-rich foods like seaweed can contribute to this goal.
Cancer Risk Reduction: Studies have indicated that diets rich in folate-containing foods are associated with a reduced risk of certain cancers, such as colon cancer.

Important Considerations and Risks of Consumption

Despite the health benefits, seaweed consumption requires a cautious approach, especially due to its high iodine content. Excessive intake of iodine can lead to thyroid problems, including hyperthyroidism. Different species contain varying levels, with brown seaweeds like kelp being particularly high in iodine. This is why eating seaweed in moderation is essential. It is also important to source seaweed from reputable suppliers, as it can absorb heavy metals from the water in which it grows.

Comparison Table: Folate in Different Seaweeds


Seaweed Type	Folate Content (per 100g dry weight)	Key Characteristics & Uses
Nori (Purple Laver)	Very high (approx. 880–1300 µg)	Popular for sushi and as a crispy snack. Also a notable source of Vitamin B12 for vegans.
Wakame	High (approx. 157 µg)	Commonly used in miso soup and salads. Provides significant calcium and iodine.
Kelp	High (approx. 144 µg)	Often used in supplements, as well as a flavour enhancer in soups and broths. Very high in iodine, requires cautious consumption.
Hijiki	Lower (less than 230 µg)	Small, black strands used in cooked dishes. Known to absorb higher levels of inorganic arsenic, requiring careful preparation.

How to Incorporate Folate-Rich Seaweed into Your Diet

There are many simple and delicious ways to add seaweed to your meals to benefit from its natural folate. For example, nori sheets can be used to make vegetable rolls or torn into flakes to sprinkle over rice or salads. Wakame can be rehydrated and added to soups, smoothies, and salads for a boost of nutrients. Flaked or powdered seaweed can also be used as a seasoning substitute for salt, adding a savory, umami flavor to a variety of dishes. Incorporating different types of seaweed throughout your meals can provide a varied nutrient intake and keep your iodine consumption in check.

Conclusion

So, is there folic acid in seaweed? Yes, but it is more accurately described as folate, the natural form of the B9 vitamin. Seaweed, particularly nori, is an excellent source of this vital nutrient, providing numerous health benefits for cellular function, heart health, and more. While seaweed can be a highly nutritious addition to your diet, moderation is essential due to its high iodine content and potential for heavy metal absorption. By understanding the differences between species and consuming mindfully, you can safely and effectively incorporate this marine superfood into your diet for better health. For more on the health benefits of seaweed and its nutritional properties, consult reputable sources like the National Institutes of Health.

Frequently Asked Questions

No, folate is the natural form of vitamin B9 found in foods like seaweed, while folic acid is the synthetic, man-made version used in supplements and fortified foods.

Dried purple laver, known as nori, contains significantly higher levels of folate compounds (approximately 880–1300 µg per 100g dry weight) than other common edible seaweeds like kombu and wakame.

While seaweed is an excellent source, it is not recommended to rely solely on it for your folate needs due to the risk of excessive iodine intake. A balanced diet with various folate sources is the best approach.

Seaweed can contribute to a pregnant woman's folate intake, but they are advised to consult a healthcare provider, as the CDC recommends a specific dose of folic acid, which is proven to prevent neural tube defects.

Folate is a water-soluble vitamin that can be lost during prolonged cooking or boiling. To preserve the folate content, it is best to cook seaweed for shorter periods or consume it raw in salads.

The main risks are consuming too much iodine, which can affect thyroid function, and potential heavy metal contamination, depending on the sourcing location. It's important to consume seaweed in moderation and from reputable sources.

Dried nori can have a much higher folate concentration per 100g than spinach, but since typical serving sizes of seaweed are much smaller, a diet balanced with both provides a comprehensive nutrient profile.