Kelp, which grow in large marine 'forests', is rich in metabolism-boosting iodine. [Photo: Bigstock]

Q&A: Super seaweeds

19 April, 2016

Q — I have read that seaweed is a healthy addition to the diet. Can you tell me more about it?


A — Seaweeds are a type of algae found throughout the world’s oceans and seas.

Seaweed has long been used as a food and medicine, especially for island nations like the UK. But really any country with a coastline will have some tradition of using seaweed to nourish and heal.

This tradition has never really faded and in Asia and some parts of Europe seaweeds are still cultivated as food. Indeed, there are no known poisonous varieties of seaweeds and many are actually nice to eat and even considered a delicacy in some countries.

Each type of seaweed has its own unique taste and texture, but all possess broadly the same nutritional benefits.

Boosting metabolism All seaweeds are a rich protein and a source of iodine, necessary for metabolism. The high iodine content of seaweeds help supports healthy thyroid function and this in turn helps regulate the metabolism of every cell in the body and has a role in weight management. Brown seaweeds like kelp and wakame contain the antioxidant carotenoid fucoxanthin, which improves insulin resistance and helps the body metabolise fat more efficiently.

Aiding detox Seaweeds are a good source of and fibre and chlorophyll, which can help remove toxins from the body. Many also contain a mucilaginous (gum like) fibre that helps maintain bowel regularity and binds to and removes toxins and fats from the body. One species of seaweed (the cyanobacterium Leptolyngbya crossbyana) has been found to generate natural products known as honaucins, which have potent anti-inflammation and bacteria-controlling properties.

Anti-cancer effects Plant hormones called lignans in seaweeds help slow the growth and spread of cancer cells. They have also been shown to balance estrogen levels – an effect that may contribute to lowering the risk of estrogen dependent cancers for example of the breast and ovary. A species of green algae, known as sea lettuce has recently been show to have anti-cancer properties.

Healthy heart Most seaweeds contain magnesium and potassium which help lower blood pressure, protect blood vessels and fight the effects of stress. They are also a source of folic acid which helps to break down homocysteine – a risk factor for heart disease and stroke. Folic acid also helps prevent certain birth defects, including spina bifida.

Calming stress Magnesium, pantothenic acid and riboflavin (B2), support the health of adrenal glands, which play a critical role in our response to stress. Without this nutritional support constant stress can exhaust the adrenal glands resulting in lowered immunity, chronic fatigue and mood changes.

Seaweeds are also a natural and vegetarian source of the essential fatty acid DHA (docosahexaenoic acid), is a type of omega-3 fatty acid commonly found in sea animal products, such as salmon, mackerel, tuna and sardines. DHA is important for promoting proper development of the nervous system and supports brain and vision health.

Most are also high in essential amino acids, which makes them valuable sources of vegetable protein in a vegetarian vegan diets.

Whether fresh or dried make sure your seaweed has come from pollution free waters because as living plants they can absorb pollutants in their environment. Beyond that, follow your taste buds to find the type that you enjoy the most and start incorporating that into your diet.

Here’s four popular types to try:


The term kelp is used to describe a number of brownish-green seaweed species. It is found in shallow ocean waters and forms thick colonies that could almost be described as an “underwater forest”. Fucus is a particularly common genus of brown algae (seaweed) that lives in the intertidal zones of rocky shores. Fucus vesiculosis (bladderwrack) is a natural source of supplemental iodine, which can provide adequate levels to stimulate a sluggish thyroid and encourage a healthy metabolism.

Kelp is an important part of the diet in Japan, Norway, and Scotland. For vegans (vegetarians who eat no animal products at all), it supplies vitamin B12, otherwise found almost exclusively in animal products, and is a concentrated source of minerals, including iodine, potassium, magnesium, calcium, and iron.


Nori, a red algae of the genus Pyropia, has a number of nutritional benefits. It is particularly high in protein, which makes up 50% of its dry weight, and has as much fibre as a serving of spinach. It is also rich in zinc, copper, magnesium and selenium as well as taurine, a compound aids the circulation of bile acid, thus preventing gallstone through controlling blood-cholesterol levels. It also contains useful levels of the omega 3 fatty acid eicosapentanoic acid (EPA), choline, inositol and other B-group vitamins are regarded as beneficial to health.


Dulse, also known as Palmaria palmata, is a red seaweed that grows attached to rocks. This salty sea vegetable is eaten fresh and dried in foods including soups, chowders and fish dishes. Dried dulse is uses as a seasoning. Dulse is high in protein and contains all the essential trace minerals as well as antioxidant beta carotene, and vitamins C and E and B-complex.

Dulse is also packed with valuable minerals, including potassium and iron. In fact a 3.4 oz (100g) serving of fresh dulse provides approximately 33 mg of iron and 1720 mg of potassium, which is more than 100% of the recommended daily intake for an adult.


Wakame, or Undaria pinnatifada, is particularly high in magnesium which improves heart function and acts as a diuretic. It is a fast growing seaweed that can grow up to an inch per day. In many places it is considered an invasive species that can quickly edge out any local marine life and choking up beaches. However, it is also a useful cooking ingredient. Its delicious leaves can be eaten raw or cooked and can be added to soups such as miso and salads, for example, to give them that extra “umami” or savoury taste.

Its nutritional benefits includes manganese, sodium, magnesium and calcium, and 5% of the recommended intake of folate in a 2 tablespoon serving. Wakame contains a compound, fucoxanthin, which seems to reduce the accumulation of body fat – at least in animal tests – and to stimulate the liver to produce more DHA, a type of omega-3 fatty acid that helps reduce the bad cholesterol associated with heart disease and obesity.

How to use seaweed

Seaweeds don’t keep well and unless you live by the sea can be difficult to obtain fresh. Drying is a traditional method of preservation and does not damage the nutritional content of the seaweed.

Ground seaweed can be used as a flavour enhancer in place of salt. Alternatively try adding mixed seaweed flakes to the salt in your grinder. Because of their mucilaginous fibre content seaweeds can be used to thicken stocks, and added to soups, broths or miso to give extra protein and vitamins. If using fresh seaweed make sure to rinse well.

Seaweeds are also a traditional ingredients in bread. Seaweed bread balances blood sugar and slows the rate at which food is digested, reducing hunger for longer. Substitute ground or powdered seaweed for up to half the flour.  In addition, when using seaweed, use water where milk is called for, omit salt and add an extra tbl of oil or butter.

It should also be noted that the anti-oxidant and anti-inflammatory properties of seaweeds make them a useful cosmetic ingredient as well especially for hair and skin preparations!