Seaweed has only recently received its trendy ‘superfood’ status, but unsurprisingly, it has been consumed world over for thousands of years and has, and continues to feature prominently in Asian diets – those of Japan, Korea and China, in particular. But Seaweed also has a long history in ancient medicine, farming and food growing in Europe, predominantly in Ireland.

Immensely diverse in both flavour and nutritional properties, there are thought to be over 10,000 species of seaweed. In terms of food, the most popular species is ‘Nori’, which is often dried in sheets and widely used in the preparation of sushi. The other commonly eaten species of seaweed include dulse, wakame, kelp, spirulina and arame.


So what exactly is Seaweed?

Seaweed is not actually a “weed” but a kind of sea vegetable that grows in nutrient rich ocean waters along rocky shorelines all over the planet.  Seaweed also known as algae belongs to a group of plant-like organisms that grow in the sea. The seaweed that we consume as food has numerous cells, unlike some algae, which are single-celled organisms, known as ‘microalgae’. These microalgae are more like bacteria that also generate energy through photosynthesis.


Seaweed has been categorised according to its cell structure, pigments and other traits. The groups of seaweed that are commonly consumed are:

  • Green algae that includes ulva or sea lettuce, sea grapes
  • Brown algae that includes arame, kelp, kombu and wakame (for miso soup)
  • Red algae that includes laver, dulse, and nori (for sushi)
  • Blue-green algae that includes chlorella and spirulina


Nutritional benefits of Seaweed

Packed with nutrients, seaweed comes in a multitude of colours, textures, shapes and sizes. All species of seaweed are particularly rich in minerals such as calcium, copper, iodine and iron. Seaweed is also rich in fibre, protein, and vitamins. It contains especially high levels of vitamin K and folic acid, while boasting little in the way of calories and fat. Seaweeds have also been found to contain a molecule called ‘fucoidans’, which benefits our health by helping our bodies to fight infection and disease, further adding to seaweed’s already impressive nutritional profile.


Here are some of the other health benefits to be gained by including Seaweed in your diet:

  • Seaweed contains up to 10 times more calcium than milk and 8 times as much as beef.
  • Seaweed helps to alkalise our blood, thus helping to neutralise the effects of our modern highly acidic diets.
  • Seaweed acts as an excellent regulator and purifier of blood due to its chemical composition, which closely resembles human blood plasma.
  • Seaweed contains ‘lignans’ – a naturally occurring chemical compound with antioxidant properties – which can protect against oxidative stress and prevent chronic diseases like cancer and digestive problems.
  • Seaweed is rich in chlorophyll – the green pigment in plants – that acts as a naturally powerful detoxifier, helping to draw out waste products.
  • Seaweed plays in important role in boosting weight loss and preventing the build up of cellulite.
  • Seaweed has a high content of ‘glutamate’ – one of its key components – an amino acid that is vital for normal brain function.
  • Seaweed is a nutrient-dense source of the micronutrients calcium, magnesium, folate, zinc, iron and selenium.
  • Seaweed contains more preformed DHA and EPA omega-3 fatty acids than in land-based plants, which makes seaweed or algae oil a reliable source of omega-3 for vegetarians.
  • Seaweed is also naturally high in iodine, which helps to stimulate the thyroid gland, which is responsible for maintaining a healthy metabolism. And the minerals present in seaweed act like electrolytes, helping to break the chemical bonds that seal the fat cells, thus allowing trapped waste to escape.
  • A 2011 review of 100 studies that was published in the America Journal of Agricultural and Food Chemistry reported that seaweed might be beneficial in lowering blood pressure and promoting heart health.


B U T . . .

There’s always a ‘but’ when it comes to something that has a myriad of amazingly positive benefits, isn’t there! So what can be the issue with a superfood that boasts great health benefits?

As great as seaweed is for an array of health reasons, it also contains a variety of carbohydrates that our digestive systems can’t digest and are passed down to our gut bacteria. These indigestible carbohydrates, carrageenan and agar, are widely used in the food industry to stabilise and texturise food. Carrageenan, in particular, is extremely problematic as it causes inflammation both in the gut, and throughout the rest of the body. However, there is no current evidence that links carrageenan in whole foods with the same health problems that have been linked to it in its isolated form. So it would be prudent to avoid carrageenan as a food additive, as well as seaweeds with a higher carrageenan content such as Irish Moss.


Further health concerns that can arise from eating seaweed include the overconsumption of Vitamin K, which can interfere with blood thinning medications, and the ingestion of high levels of potassium, which can cause serious issues for those with kidney issues. The overconsumption of iodine is another potential issue, especially from eating too much of species such as kelp or bladderwrack. This can lead to serious health implications for those suffering from thyroid imbalances. If you suffer from any of the mentioned health issues or think you might, please consult your GP before adding seaweed to your diet.


Another big concern with seaweed is that it can also contain toxic metals; however this varies depending on the species of seaweed, where it’s harvested from, and the toxicity levels in the water in which it has been grown. The levels of heavy metal in seaweed can vary vastly from one batch to another. The only way to know for certain is to purchase your seaweed from brands that regularly test their products for heavy metal levels in third-party labs. One company that employs third-party lab testing is ‘Maine Coast’, and they even publish their findings on their website.


It is also important to remember that exposure to heavy metals can also occur as a result of contact with other aspects of the environment and through eating other sea foods including fish. So, if you’re concerned about exposure to heavy metals, then you might want to consider avoiding the consumption of seaweed and seafood entirely.


If you do decide to give seaweed a try, you can easily find it in Asian supermarkets. It usually comes ready to eat, but sometimes needs to be soaked first. You can also find a variety of dried seaweeds in the major supermarkets and online shopping sites like Amazon.

Seaweeds are very versatile and you can enjoy them by adding them to salads, soups, sprinkled on other foods or even as a snack out of a bag.


TIP: When buying seaweed, make sure to choose certified organic brands where possible. And because seaweeds absorb the properties of the water in which they are grown, you may want to ensure that they have been grown and harvested in unpolluted waters that are pure and free from toxic chemicals and metals.

It is best to avoid seaweeds that are cultivated off the coast of Japan because of the higher potential that they might contain radioactive contaminants from the 2011 Fukushima disaster. Generally, seaweed harvested from the Korean coast is quite safe. The higher quality seaweeds that are available today most often come from the colder, nutrient-rich waters in the Northern Hemisphere.


Some of the recommended suppliers of seaweed are Maine Coast Sea Vegetables, Seaweed Iceland, Mountain Rose Herbs, Rising Tide Sea Vegetables and Earth Circle Organics.



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