inshore ireland April/May 2014 19
aquaculture news
Macroalgae as a source of healthy lipophilic compounds Simon Faulkner
S
eaweed contains a number of healthy components including carbohydrates, proteins, minerals and pigments. In addition to these compounds, macroalgae also contains significant amounts of lipids. Lipids are generally defined as organic molecules that are insoluble in water and include fats, waxes, sterols, fat-soluble vitamins mono, di and triacylglycerols, diglycerides and phospholipids. As a source of energy, lipids also have an important role in the human diet as they include components such as essential fatty acids and vitamins vital for human health. Seaweed lipids Lipids represent up to 5.0% of the seaweed dry weight which is, in general, lower than the levels found in other marine organisms. The lipid content of seaweed depends on a number of factors including both season and seaweed species. For instance, literature suggests that the lipid content of the brown seaweeds Laminaria and Saccharina is in the range of 0.3%-2.1%, whereas the brown seaweed Ascophyllum has a lipid content of in the region of 1.24.0%. In contrast, the lipid content
Seaweed lipid extractin at OHT
of the green seaweed, Ulva, is reported to be in the range of 0.3-1.6%. Red seaweeds such as Chondrus and Palmaria have a lipid content in the range of 0.23.8% of the dry weight. The majority of the seaweed lipid fraction is formed by a wide range of fatty acids including significant amounts of Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) which are important for consumer health. Health benefits Omega 3 fatty acids Eicosapentaenoic acid and Docosahexaenoic acid are two long-chain polyunsaturated fatty acids that beneficial for human health in various ways. The most established role of these Omega-3 fatty acids is the prevention of cardiovascular diseases (CVDs). A protective role of EPA and DHA was first hypothesised over 30 years ago when two population studies in Greenland and Japan found a strong correlation between high fatty fish consumptions and a low incidence of cardiovascular events. In the three decades that followed, more prospective observational studies and large randomised controlled trials were carried out to establish the potential effects of fish or EPA/DHA consumption on CVD outcomes than for any other nutrient. Various meta-analyses and reviews now show that consumption of fish and/or fish oil reduces Coronary Heath Disease (CHD) incidence and mortality and thereby reduces overall mortality. There is further evidence to suggest that intake of these fatty acids protects against cerebrovascular events such as stroke.
These findings can be explained by the numerous physiological effects of EPA and DHA intake, which includes a decrease in various inflammation markers, inhibited platelet aggregation, lower plasma triglyceride levels, improvement of endothelial function and reduction of cardiac arrhythmia. There is also evidence suggesting an inverse relationship between n-3 PUFA levels in the body and mental disorders such as schizophrenia, attention-deficit hyperactivity disorder, dyslexia, personality disorder, depression, Alzheimer’s disease and bipolar disorder. More research needs to be done however before these cause and effect relationships can be established. Health benefits – Carotenoids Carotenoids are yellow, orange, or red coloured pigments found in both land plants and marine algae. Examples of carotenoids that occur in marine algae include astaxanthin, β-carotene and fucoxanthin, the latter of which has received considerable attention by scientists due to its potential health-promoting effects.
Fucoxanthin, a lipophilic compound that has been isolated from brown seaweed, has been reported to have antioxidant, anti-inflammatory, anti-obesity, anti-cancer, anti-diabetic and hepatoprotective activity in numerous studies. For instance, one study has reported that fucoxanthin reduces white adipose tissue, blood glucose and plasma insulin in mice resulting in a 5-10% weight loss. It is proposed that
Chrondrus crispus
Seaweed found on Ireland’s west coast
Green seaweed
this activity is derived from the ability of fucoxanthin to alter lipid-regulating enzymes and uncoupling proteins in the lipid tissue. The health-promoting lipophilic components present in seaweed, together with additional plethora of seaweed-derived bioactive compounds, make macroalgae an excellent choice for use in the agri and aquaculture industries and as a functional food ingredient.