Nutrition Meets Food Science

Seaweed-A Marine Wonder

Nature is bountiful in so many ways. Every resource available in nature is to help all the organisms thriving in world.  The seas and oceans are no different, besides their beauty they also provide food not only for the marine organisms but also for humans.

It is now very common to come across dishes namely crispy seaweed, seaweed salad at any restaurants specialising in Asian cuisine.

So, what exactly is this seaweed?

Seaweed is the name given to the many species of marine algae and plants that grow in water bodies such as rivers, seas and oceans. They generally live attached to rock or other hard substrata in coastal areas. They range in colours from red, green, brown and black and also vary in size, from microscopic to large underwater forests.

There are many varieties of edible seaweed in the world. Here are a few of the most common:

  • Nori: This is a red algae commonly sold in dried sheets and used to roll sushi.
  • Sea lettuce: This is a type of green nori that looks like lettuce leaves. It is commonly eaten raw in salads or cooked in soups.
  • Kelp: These brown algae is usually dried into sheets and added to dishes during cooking. It can also be used as a gluten-free alternative to noodles.
  • Kombu: This is a type of kelp with a strong flavour. It’s often pickled or used to make soup stock.
  • Arame: This is a different type of kelp with a mild, sweet flavour and firm texture. It can be incorporated into a variety of dishes, including baked goods.
  • Wakame: These brown algae are commonly used to make fresh seaweed salad. It can also be cooked in stews and soups.
  • Dulse: This is a red algae with a softer, chewier texture. It is used to add flavour to a variety of dishes and may also be eaten as a dried snack.
  • Chlorella: This green, edible freshwater alga is often sold as a supplement in powdered form.

Agar and carrageenan are jelly-like substances obtained from algae and are used as plant-based binding and thickening agents in a variety of commercially sold food products.

There is another well-known marine product – spirulina, which is a biomass of cyanobacteria (blue-green algae) that can be consumed by humans and animals. However, spirulina has a different structure than other algae and is therefore technically considered a type of cyanobacteria (blue-green algae).

Generally, 1 cup (15 grams) of seaweed provides following nutrients:

  • Calories: 45
  • Protein: 5 grams
  • Fat: 1 gram
  • Carbs: 8 grams
  • Fibre: 1 gram
  • Folate: 13% of the daily value (DV)
  • Riboflavin: 22% of the DV
  • Thiamine: 15% of the DV
  • Copper: 56% of the DV
  • Iron: 21% of the DV
  • Magnesium: 17% of the DV

Seaweed Contains:

  • A wide range of vitamins & minerals, including iodine, iron and calcium. Some types can even contain high amounts of vitamin B12. Moreover, it’s a good source of omega-3 fats.
  • A concentrated source of iodine and amino acid called tyrosine. Thyroid gland requires both to function properly.
  • A wide range of antioxidants, such as vitamin A, C and E, carotenoids and flavonoids. These organs protect the body from cell damage.

Fibre and sugars, both of which can be used as food sources for the bacteria in human gut. This fibre can also increase the growth of ‘good’ bacteria and nourish your gut.

Seaweed may also help:

  • lose weight because it contains few calories, filling fibre, and fucoxanthin (a substance that helps burn fat)
  • Reduce risk of Type 2 Diabetes by improving blood sugar management-
  • Protect against skin and bones damage
  • Reduce inflammatory diseases and improve the immunity of the body
  • Studies are on to prove that seaweed may help reduce cholesterol, blood pressure, risk of blood clots and also to check for anti-cancer properties.

So, it’s always a good practice to try out different seaweed varieties and incorporate them in the diet.

Though seaweed consumption is generally safe there may be rare cases where seaweeds may have heavy metal content. Patients with kidney disease and those who are on blood thinners should consult their doctor before consuming seaweeds, also kelp, dulse, and kombu are types of seaweed with the tendency to contain very high levels of iodine, it could hamper thyroid function if had regularly.


Seaweeds grow abundantly along the Tamil Nadu and Gujarat coasts and around Lakshadweep and Andaman and Nicobar Islands. There are also rich seaweed beds around Mumbai, Ratnagiri, Goa, Karwar, Varkala, Vizhinjam and Pulicat in Tamil Nadu and Chilka in Orissa.

The cultivation of seaweeds can be done by Open water farming, Pond farming or Integrated Multi-Trophic Aquaculture (IMTA) by controlling parameters such as water current, transparency, turbidity, light intensity, temperature, pH, DO, salinity, phosphate, silicate, nitrite, nitrate, sedimentation.


In the presence of sunlight, on the surface water, they can grow 5 times more of their original weight within a culture period of 45 days. Harvesting can be done by handpicking or using scissors/knives. The harvested seaweeds should be thoroughly washed in clean seawater to remove the sand and other foreign materials. Seaweeds can be sold wet or dry. The clean seaweed sundried for 2-3 days and with moisture content of 35-39% fetches more price. The harvested seaweed must be kept in a cool dry and well-ventilated place.

According to Outlook India, our country has plans to raise seaweed production from the current level of about 20,000 tonnes, valued at around $500 million (Rs 50 crores) to 11.2 lakh tonnes by 2025.

Advantages of seaweed farming in India

Carbon sequestration is the most impactful advantage of seaweed farming. It doesn’t need extensive maintenance in the form of freshwater supply, fertilizers, etc. It can help to reverse ocean acidification and improve the marine environment. Seaweeds have both health and environmental benefits along with providing a means of income for several families.


Ms Nithyakalyani V.

Food Technologist, PFNDAI

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