Some hail microalgal food sources as the new superfoods, and claim a variety of health benefits. But what are the realities of using edible phytoplankton as staple diet?
Micro-algae are also referred to as phytoplankton and are single celled plants which live in water. They reproduce by simple cell division and because phytoplankton don’t have to support non-productive parts such as stems and roots, they can grow and reproduce much faster than land based plants and may divide once or more per day.
There are a huge variety of different species of phytoplankton and although their numbers are usually kept down by the grazing of zooplankton and filter feeders in the water, they may occasionally form dense colonies known as blooms if plenty of nutrients are available. Some species of algae produce toxins and have reached the news headlines when they bloom due to the fish deaths and water pollution they cause. Other types of algae such as Spirulina & Chlorella spp. have been hailed as superfoods and are sold as health supplements due to their high nutritional content and possible health benefits. These species contain high levels of amino acids, vitamins and minerals. They provide the highest concentrations of protein and beta-carotene (pro-vitamin A, an antioxidant) of any foods and supply other micronutrients not found elsewhere.
Examples of possible benefits are:
- Increased antibody production and enhanced immune function (Bendich, A. 1989 J. Nutrition 119 p112-115)
- Enhanced brain function and learning (Laguna, M. Villar, R. Calleja, J. Cadavid, I. Planta Medica 1993; 59 p125-130.
- Allergy and asthma relief (Yang H, Lee E, Kim H. Life Sciences. 1997; 61(13) p1237-44)
- Antiviral, antibacterial and antifungal action(Woodruff H. Science. 1980; 208(449) p1225-9).
- Anti-inflammatory and antioxidant effects. Kelly F. Journal of The International Federation of Clinical Chemistry. 1998; 10(1) p21-3)
- Improved circulation and heart function. Cohen Z, Norman, H. Heimer Y. Plants in Human Nutrition. 1995; 77 p1-31)
- Detoxification. Sukenik A, Takahasi, H. and Modady, S. Annals of Nutrition and Metabolism. 1994; 38(2) p85-96)
- Cancer protection (Murakami A, Ohigashi, H. Koshimizu K. Biotechnology, and Biochemistry. 1996; 60(1) p1-8)
- Radiation protection (Weiss J, Landauer, M. Annals of the New York Academy of Science. 2000; 899 p44-60)
- Improved cell repair (Rothschild L, Cockell, C. Mutation Research. 1990; 430 p281).
Because such beneficial species can be grown quickly in large volumes in vats there is much current interest in using algae as both a food and biofuel source to ease the pressures on our planet due to increasing consumption. Algae are already used as a food source in many cultures including the ‘laver bread’ found in Wales which is made from a multi-cellular red seaweed Porphyra umbilicalis, known in China as jee choy and used in Japan as sushi wrapping where it is known as nori.
But are micro-algae destined to become a major part of our diet?
As they are single-celled they are very small and can actually cause health problems if eaten in large amounts because they don’t provide any bulk in the digestive system. This can lead to diarrhoea which in turn can lead to dehydration. So although they can be a valuable part of our diet it doesn’t look like they will be suitable to be our main food source. The health benefits of micro-algae are clear though and maybe in the future they will begin to make more of an appearance on or plates as side dishes or as ingredients in main dishes.
