The authors, two from Canada and one from Denmark, took a look at the properties of numerous red and green marine macroalgae species, including as Hypnea charoides, Mastocarpus stellatus, Palmaria palmata, Laminaria japonica, and Ulva pertusa. These algae as a class contain a number of constituents of interest in ameliorating the effects of cardiovascular disease and underlying metabolic syndrome including dietary fiber, fatty acids and various antioxidant compounds.
Fiber, nutrient profile benefits
On the fiber front, marine macroalgae exhibit a high overall content of dietary fiber and a high ratio of soluble to insoluble fiber. For example, the authors noted the brown alga Fucus vesiculosus has a fiber content of about 59% of dry weight, with a soluble-to-insoluble fiber ratio of about 1:5. Wheat bran, by comparison, consists of about 43% fiber by dry weight, and most of its fiber is in the insoluble form. Soluble fiber is the form most associated with heart health and metabolic health.
“The high total DF content of some seaweeds is well established, and so are the extensive health benefits of these fibres [sic] in relation to obesity, diabetes, and CVD associated with the consumption of a high-fibre diet,” the authors noted.
The alginate-bearing seaweeds could be potential sources of prebiotic activity, the authors noted. Research conducted in 2012 “reported that increased levels of specific short-chain fatty acids were produced from low-molecular-weight seaweed extracts” from a number of species. “These preliminary results indicated that gut microbiota are able to effectively ferment the low-molecular-weight seaweed polysaccharides investigated in this study, with the red alga G. sesquipidale exhibiting the most significant increase in short-chain fatty acids,” the authors wrote.
The authors noted that many macroalgae species provide a wealth of nutrition, including fiber, protein and a host of vitamins, notably vitamin B12, and minerals including sodium, potassium, calcium, iron and magnesium. What they don’t provide in adequate amounts is calories, so they would always form a supplement addition to the diet. Extrapolations from populations such as the Japanese that traditionally have consumed seaweeds led the authors to postulate a dosage level of about 5g to 10g daily.
Seaweeds are also a signifacnt source of omega-3 fatty acids, which have a long history of research in heart health preparations. While lipid content varies widely by species, the authors noted that “both the red and the brown seaweeds had substantial amounts of the fatty acids EPA and ARA, whereas the green macroalgae contained docosahexaenoic acid. The nutritional quality of the lipids most often found in seaweeds suggested that the incorporation of a variety of macroalgae into the human diet on a frequent basis would be advantageous for health and nutrition.”
But perhaps the most important aspect of seaweeds in terms of their potential effects on heart heath centers on their antioxidant capacity. The research around this is still developing, the authors noted, but they did say that by their very nature seaweeds are built to survive in a challenging environment, which boosts their antioxidant potential.
“The diversity and ancient lineage of macroalgae has endowed them with enormous abilities to cope with stress, which is directly linked to their antioxidant capacities. Collectively, edible seaweeds possess a multifunctional and extensive antioxidant profile (Jiménez-Escrig et al. 2012) and could, in theory, mitigate the presence of excessive ROS to restore homeostatic balance. The major groups of antioxidant compounds found in the macroalgae are included under the general categories of carotenoids, phenolic compounds, phycobilin pigments, polyphenols, sulphated [sic] polysaccharides, and vitamins,” the authors wrote.
Among the antioxidant constitutes of macroalgae that has already been extensively studied (and marketed as a dietary supplement ingredient) is fucoidan. Fucoidan is one of the many sulfated polysaccharides found in a number of seaweeds, and the authors said in vitro research has shown promise. “Extensive oxidative stress was moderated by an up-regulation of antioxidant enzyme activities, such as increased superoxide dismutase, catalase, and glutathione peroxidase, and by limiting lipid peroxidation. Although there is extensive published research to show that seaweeds are rich in antioxidants and antioxidant compounds, more recent studies now focus on the impact of specific antioxidants and their effect on targeted metabolic systems,” they noted. But fucoidan might represent only the tip of that particular iceberg, the authors said, noting that in a 2010 study all 11 species collected and studied showed in vitro antioxidant activity from their sulphated polysaccharides.
Whole food challenge
Taste is a major hurdle in adapting edible seaweeds as a functional food ingredient for Western palates. Extracting specific compounds, as been done in the case of fucoidan, is one way around this, of course, but such an approach leaves some of the seaweeds’ other potential benefits by the wayside. The authors put a brave face on this by highlighting the potential of edible seaweeds to boost the umami flavor profile of foods. For the moment, it can be expected that whole seaweed ingredients would find a home most easily on the supplement side in green superfood powders which often have aggressive flavors that are tolerated by a dedicated core of consumers, and on the food side in prepared foods that already trend toward the savory side of the flavor spectrum.
“Capitalizing on the diversity of algae around the world could potentially lead to custom blending to achieve desired sensory effects and nutritional benefits. As a rich source of umami, described as the essence of deliciousness (Mouritsen 2012a), some seaweeds enhance sensory perception of a meal and limit our craving for salt, fat, and sugar,” the authors noted.
Finding ways to add small amounts of seaweed to existing foods could go a long way toward helping to combat the rising tide of lifestyle diseases such as cardiovascular disease in the Western (and Westernized) world, the authors postulated. Research shows that many consumers have a hard time differentiating between ‘health’ and ‘unhealthy’ food.
“If all these foods could be made even moderately healthier, perhaps even functional, by the addition of specific seaweeds, then an effective and long-term intervention strategy for pathologies related to CVD could be initiated,” they wrote.
"A role for dietary macroalgae in the amelioration of certain risk factors associated with cardiovascular disease"
Phycologia: 2015, Vol. 54, No. 6, pp. 649-666
Authors: M. Lynn Cornish, Alan T. Critchley, and Ole G. Mouritsen