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How to Improve Gastrointestinal Health by Eating Algae?

HK BioTek Intern

Having bad conditions in gastrointestinal health is troublesome, people who develop gastrointestinal symptoms (GIS) such as diarrhea, abdominal pain, bloating, or gassing suffer a lot in their daily lives. Are you facing GIS which makes your days bad? People’s awareness of nutraceuticals is also rising. Nutraceuticals are functional food ingredients that can be added to diets. It provides calories and nutrients but also health benefits with their bioactive compounds, so to improve the health status1. Algae are one of the nutraceuticals. In 2020, Mr. Fields and his colleagues from the University of California San Diego in the USA conducted the first experiment on the effect of algae on gastrointestinal health through mice and humans. Results support if you are suffering from acute colitis or GIS, consuming the algae Chlamydomonas reinhardtii (C. reinhardtii) is beneficial to relieve the sickness2. Nutritional Values of Algae

Algae are a group of single-celled photosynthetic microorganisms and seaweeds. Organisms that are photosynthetic do not get energy by consuming food, while they make their food by using sun lights and carbon dioxide. In daily lives, we often eat kelps, grilled seaweeds, and lavers, they belong to the groups of algae. Algae give us macronutrients (carbohydrates, proteins, fats, and fiber), micronutrients (vitamins and minerals), and antioxidants4, they are all essential food substances for maintaining healthy and functional bodies. Besides, having microalgae in diets can reduce the risks of cancer, aging effects, and obesity, etc4, thus increasing life expectancy. Algae Heal Acute Colitis There are different kinds of algae. The algae C. reinhardtii was used to investigate if the algae helped in reducing weight loss. There were two groups of male mice, and they caused both groups to have acute colitis. It is an inflammation of the internal wall of the colon with symptoms like abdominal pains or diarrhea and weight loss. After the symptoms were developed, Group A was treated with the algal biomass. For Group B, no algal biomass was given2. They recorded the weight loss of mice every day for 2 weeks. Results showed that Group B lost more than 20% of the original weight, and the targeted Group A lost only 12% of their weight after nine days of studies. It showed that the algae reduced weight loss. Also, at the end of the experiment, Group B only recovered around 90% of the starting weight. On the contrary, Group A treated with the algae gained more weight at 2%. Obviously, they proved that the algae can relieve colonic damage and enhance the recovery rate of mice2. The Guardian Angel for People Suffering From Gastrointestinal Illnesses Has Come!

After the success in the mouse trial, they put another experiment on 51 humans for a 30-day dietary investigation to study whether dried algal powder could improve gut functions and gut microbiome (bacterial community in intestines). Participants with normal and poor gut functions were invited. They were categorized into four groups based on their GIS, either in high or low frequency in GIS, and the assigned dose of either consuming 1g or 3g of dried algae per day2.

When participants were asked about how frequently they had diarrhea or bowel discomfort, the answers were appealing. For LowGIS groups, the majority responded ‘rarely’ before algal consumption, and they shifted to ‘never’ after consumption. For HighGIS groups, they had much diarrhea or bowel discomfort before the experiment, their rankings were ‘often’ or ‘sometimes’. Nevertheless, most of the HighGIS reported ‘rarely’ after consumption. From the results, they suggested that there is a functional ingredient in the algae C. reinhardtii, which mitigates the seriousness of diarrhea or bowel discomfort3. It is just like diarrhea can be cured or relieved by taking medicines. However, scientists have found a food ingredient that acts like pills to improve gut sickness2.

The second focus on the human test was how frequently the participants had gas or bloating. Bloating occurs when the belly is swollen after eating, it can be caused by too much gas production6. For LowGIS groups, they reported ‘rarely’ before or during consumption, there were not many observable differences between before and during consumption. In comparison, 100% of HighGIS had experienced ‘sometimes’ or ‘always’ in producing gas or bloating, but most of them again showed improvement from ‘sometimes’ or ‘always’ to ‘rarely’ after they started to consume the algae. As a result, having the algal biomass had an ideal effect on relieving some gastrointestinal symptoms2.

In addition, this study also focused on the classification and frequency of bowel movements. HighGIS groups reported that they had more regular bowel movements after consumption. For stool types, both LowGIS and HighGIS groups had softer stools during consumption. Therefore, we can tell having the algae biomass can also improve stool quality2. Nowadays, scientists have found another natural ingredient, algae to relieve GIS, just like consuming fruits and vegetables, they all contribute to regular bowel movements.

Future Uses of Microalgae

In conclusion, having the microalgae C. reinhardtii could reduce weight loss and symptoms caused by acute colitis, and improve gastrointestinal health by causing less diarrhea or bowel discomfort, less gas or bloating, more regularities on bowel movements, and better stool qualities2. All results supported that the algae caused an improvement in gut health, let us consume more algae in our daily lives! After the research done by Mr. Fields and his team, the microalgae would be used in the medical field in the near future.


  1. Mollet B, Rowland I. Functional foods: at the frontier between food and pharma. Current Opinion in Biotechnology. 2002 Oct 01 [accessed 2020 Feb 19]; 13(5):483-485. https://www-sciencedirect-com.eproxy.lib.hku.hk/science/article/pii/S0958166902003750. DOI: 10.1016/S0958-1669(02)00375-0

  2. Fields FJ, Lejzerowicz F, Schroeder D, Ngoi SM, Tran M, Mcdonald D, Jiang L, Change JT, Knight R, Mayfield S. Effects of the microalgae Chlamydomonas on gastrointestinal health. Journal of Functional Foods. 2020 Feb. [accessed 2020 Feb 19]; 65: 103738. https://www.sciencedirect.com/science/article/pii/S1756464619306620. DOI: 10.1016/j.jff.2019.103738

  3. Batista AP, Gouveia L, Bandarra NM, Franco JM, Raymundo A. Comparison of microalgal biomass profiles as novel functional ingredient for food products. Algal Research. 2013 Mar. [accessed 2020 Mar 18]; 2(2): 164–173. https://www.sciencedirect.com/science/article/pii/S2211926413000210?via%3Dihub. DOI:10.1016/j.algal.2013.01. 004.

  4. Caporgno MP, Mathys A. Trends in microalgae incorporation into innovative food products with potential health benefits. Frontiers in Nutrition. 2018 Jul 31. [accessed 2020 Mar 18]; 5. https://www.frontiersin.org/articles/10.3389/fnut.2018.00058/full. DOI: 10.3389/fnut.2018.0005

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