23rd October

Seaweed: a rich source of vitamins and bioactive compounds

Simon Faulkner, Ocean Harvest Technology
Awareness of  the potential health benefits of seaweed – not just for human consumption–  is gathering apace, whereby selected seaweed species are now being added to aquaculture and agriculture feed with resulting benefits. One reason for this is that seaweed is a significant source of vitamins and other interesting compounds that have a number of biological functions.

Biological functions of vitamins
Vitamins can be divided into those that are either water or fat-soluble. Water-soluble vitamins include both B-complex vitamins and vitamin C.  The B-complex vitamins are the largest group and have roles associated with metabolism, muscle tone, cell growth and the nervous system.

For example, Nori (Porphyra sp.) and sea lettuce (Ulva sp.) are good sources of vitamin B12 which has an important role in DNA synthesis. Vitamin C is a water-soluble vitamin that is important for gum health, iron absorption and resistance to infection.

Fat-soluble vitamins include vitamin A, D, E and K. Vitamin A (retinol) plays an important role in bone growth, tooth development, reproduction and cell division. Vitamin D, another fat-soluble vitamin, is important for bone growth and maintenance. Vitamins E and K also have a number of biological functions including antioxidant activity and blood clotting.

In addition to their biochemical functions and antioxidant activity, seaweed-derived vitamins have been demonstrated to have other health benefits such as reducing hypertension, preventing cardiovascular disease and reducing the risk of cancer.

Factors affecting vitamin content
Although seaweed contains both water and fat-soluble vitamins, the vitamin composition of seaweed is variable and depends on a number of factors.
For example, evidence exits of seasonal variation in the vitamin content of the seaweed Eisenia arborea,wherefat-soluble vitamins follow a different pattern to those that are water-soluble.

Another factor affecting seaweed vitamin content is light exposure, as plants growing in bright light can contain higher levels of some vitamins.
Seaweed species is another critical factor which can affect vitamin composition. For example, the level of niacin (vitamin B3) in some brown seaweeds (e.g. Laminaria sp.) is approximately one tenth the level found in the red seaweed, Porphyra tenera.
Other factors that can influence vitamin content include geographical location, salinity and sea temperature. Vitamin content can also be affected by processing as both heat and dehydration can have a significant effect on the vitamin levels.

Seaweed-derived compounds
In addition to vitamins, seaweed also contains bioactive compounds which have been proven to have antibiotic; antiviral; antimicrobial; mitogenic anti-inflammatory; anti-adhesion; ACE-inhibitory; antioxidant; anti-cancer and antithrombotic effects.
These bioactive compounds include polysaccharides; proteins; amino acids; pigments phenolic compounds and sterols. The levels of these bioactive compounds also depend on factors such as species, geographical location and season.

Incorporating seaweed into feed
Ocean Harvest Technology’s fully sustainable feed product ‘OceanFeed™’ is a specially selected, unique blend that harnesses the bioactive compounds and vitamins present in seaweed. 
OceanFeed™ therefore offers a natural, fully sustainable feed ingredient formula for the aquaculture and animal feed sectors that can replace costly synthetic ingredients.

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