Seaweed for human health

Seaweed has a fascinating nutritional profile and this makes it a popular ingredient for nutraceutical products. First and foremost, there are many different varieties of seaweed that can be utilised for their unique nutrients. While there are several claims that can be made about the species supplied by Horizon Seaweed, we feel it is important to be realistic with what seaweed can do. Soon after commencing production in Caithness, we embarked on a research project with a local university to investigate the nutritional content of our seaweed. This covered a wide range of nutrients and included 141 batches from eight different species to ensure we captured natural variability. The research was published in 2022.

Carbohydrate, fat and protein

The largest component of dried seaweed is carbohydrate (usually 40-70%). This is mostly complex polysaccharide groups, including alginate and cellulose, that are not readily digested. The thickening and emulsifying properties of these compounds are exploited by the food industry to improve the texture and stability of processed foods. Seaweed therefore has a high fibre content (usually 35-55%), enough to boost fibre levels when added as an ingredient.

Seaweed does not contain much fat, but what is there has an interesting profile. Our Species Spotlight on channelled wrack takes a look at fatty acid composition in seaweed. Our research project with a local university found there were traces of monounsaturated fatty acids like oleic acid (found in olive oil) and polyunsaturated omega-3 fatty acids like EPA. However, it is worth noting that relatively large portions need to be consumed to achieve health benefits associated with omega-3s.

Protein content is quite variable, but red seaweeds tend to have the highest levels. There are nine amino acids that cannot be synthesised in the human body; a study detected all of these essential amino acids were detected in each of the edible seaweeds tested in a 2007 study. Some seaweeds also contain interesting bioactive proteins (e.g. lectins, phycobiliproteins), peptides (e.g. glutathione, carnosine) and amino acids (e.g. taurine, laminine). 

Vitamins

Edible seaweeds are reported to contain traces of many vitamins, such as A, B, C, D and E, although relatively large portions need to be consumed to achieve significant intakes. One vitamin of particular interest is vitamin B12. This is usually found in animal products and so seaweed may be particularly helpful for vegans who are at greater risk of deficiency. We have engaged in a series of research projects to investigate this further. Initial results were surprising, because levels in the wracks we harvest were higher than expected and some species contained very little – watch this space! 

Minerals 

Traces of dozens of minerals can be found in edible seaweed. However, a large portion may need to be consumed to achieve an intake where that seaweed could be considered a source of a mineral. Iron is a good example: the average iron levels found in our dulse is approximately ten times the level in beef steak, but the steak is a better source of iron because a portion is significantly larger.

Seaweed has a salty flavour of course, but this comes from a wider range of minerals than just sodium. Average content of calcium in dried seaweed can be as high as 7% (in bladder wrack) and potassium up to 7% (in sea spaghetti). Magnesium is also present, but at lower levels (e.g. 0.7% in Atlantic wakame). Moderate portions (five to ten dry grams) of some seaweed species consumed weekly can provide you with a boost of these essential minerals. They each have their own wide range of health claims, some of which are well-known like maintenance of bones and teeth (calcium and magnesium), but also lesser known benefits like electrolyte balance (magnesium), normal blood pressure (potassium), normal neurotransmissions and muscle contractions of the heart muscle (magnesium), and functioning of your digestive enzymes (calcium). 

The unique feature of seaweed is naturally high iodine content, which is essential for thyroid health. You only need to consume a small amount (under one dry gram) every day to provide all the iodine you would need to maintain a healthy body. This means it is easy to add seaweed to a naturally fortify a product with iodine and achieve the remarkable of associated approved health claims:

• Normal production of hormones that are essential for the healthy functioning of your thyroid. 
• Healthy metabolism
• Healthy skin
• Normal cognition and neurological functions. 

However, it is possible to have too much of a good thing and high iodine intake can have a negative impact on thyroid function. We make a distinction in portion sizes and frequency to help our customers avoid consuming too much iodine for a sustained amount of time. Whilst a daily dose of under a dry gram of seaweed is great for iodine, this is not enough seaweed to make a meaningful contribution of other minerals to your health. Spacing out larger portions of seaweed over a longer time may help you reach nutritional claims for minerals like calcium and potassium, while allowing your body to naturally utilise the iodine intake. Crucially, anyone with an underlying thyroid condition should be careful when incorporating seaweed into their diet. If iodine is of further interest, please take the time to read through our article on iodine as it provides much more detail.

Our recommendation

Seaweed is a great addition to a varied and balanced diet and we want to encourage wider consumption. Unfortunately, the term 'seaweed' encompasses a wide diversity of species: we are literally comparing apples with oranges! We also supply a natural non-GMO product that will vary in its exact content. While we could be more specific here on recommendations regarding portions and species, our best advice is to get in touch with us so we can take a deeper dive into your exact requirements.