Seaweed carotenoids: diverse nutrients from the ocean

Carotenoids are organic pigments that are present at significant levels in brown seaweed and other photosynthetic organisms. These pigments are powerful antioxidants that can help to prevent cancer, heart disease and also act to enhance immune response to infections. Carotenoids are present in all algae, higher plants and photosynthetic bacteria and are produced from fats and other basic organic metabolic building blocks by these organisms. Although humans are incapable of synthesising carotenoids, recent research suggests that a diet rich in carotenoids can result in improved health, reduced mortality rates and a lower instance of chronic disease.

In the marine environment carotenoids are widely present in seaweed, the most notable being astaxanthin, β-carotene and fucoxanthin, which have all been reported to be effective antioxidants. Algal carotenoids are powerful antioxidants which have been associated with the prevention of cardiovascular and neurodegenerative diseases as well as certain types of cancer. As antioxidants, carotenoids can protect the body from oxidative stress, a physiological state that is putatively involved in the development of cancer, Parkinson’s disease and Alzheimer’s disease to name but a few.

Fucoxanthin

In recent years fucoxanthin has received considerable attention due to its wide array of beneficial effects on human health. This compound has an unusual allenic bond, which is responsible for its high antioxidant activity. It is also one of the most abundant carotenoids in nature, and contributes more than 10% of the estimated total carotenoid production. As a result, fucoxanthin has been isolated from several brown seaweeds in many recent studies with the aim of investigating its bioactive potential. Many edible brown seaweeds are abundant on Irish shores and contain significant amounts of fucoxanthin. These seaweeds include Fucus serratus (serrated wrack), Ascophyllum nodosum (bladder wrack), Laminara digitata (kelp) and Saccharina latissima (sugar kelp).

Fucoxanthin and Health

The obesity epidemic is now at a global scale and is linked with insulin resistance and an increased risk of some chronic diseases. Indeed, there is a strong association between obesity, diabetes, impaired glucose tolerance and cardiovascular disease. Lifestyle changes, including improved diet and increased physical inactivity can help to prevent obesity, however, much attention has also recently been given to the anti-obesity potential of fucoxanthin. For example, one study in mice has reported that fucoxanthin induces the expression of a specific protein called uncoupling protein 1 (UCP1) in abdominal white adipose tissue (WAT) which in turn leads to oxidation of fatty acids and increased heat production. The authors of this study also reported that fucoxanthin has the potential to reduce white adipose tissue, blood glucose and plasma insulin resulting in a 5-10% weight loss. Research also suggests that the anti-diabetic activity of fucoxanthin could be due to the fact that fucoxanthin seems to promote the levels of a fatty acid called Docosahexaenoic acid (DHA). Adequate human consumption of DHA has been shown to reduce the risk of cardiovascular disease and protect against Alzheimer’s disease, depression and rheumatoid arthritis.

The chemo-preventive and anti-cancer activity of fucoxanthin has also been investigated with promising results for leukaemia, prostate, bladder and colon cancer. Additional studies have reported that this carotenoid can significantly decrease damage caused by exposure to UV radiation from sunlight, indicating that fucoxanthin can protect the skin from photodamage induced by UV rays.

In summary, growing evidence from numerous scientific studies suggests that fucoxanthin is a multi-functional, bioactive nutrient with numerous health-promoting properties. Fucoxanthin can protect against a number of diseases and, notably, help fight obesity. This is of great importance, as over thirty per-cent of the current population is considered obese and five per-cent have type II diabetes. Therefore, there is no doubt that the integration of seaweed into the Irish diet will contribute to improved overall health and well-being while using 100% natural and sustainable ingredients.

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