On The Shelf
Mickie Cathers
Spirulina is a blue-green cyanobacterium that’s found and farmed in fresh and marine waters worldwide. Eco-friendly and widely consumed, spirulina is a popular dietary supplement purporting to offer a wide range of health benefits related to blood pressure, cholesterol, seasonal allergies, and more.
Background
Spirulina is the dried biomass of Arthrospira platensis, an oxygenic photosynthetic bacterium that is easy to digest due to its lack of cellulose cell walls. Used as a food source for centuries by the Aztecs and those living in the Lake Chad area in Africa, spirulina only flourishes in alkaline lakes with an extremely high pH. The phycocyanins and chlorophyll in spirulina give it that characteristic blue-green color.
This alga boasts a high content of protein comparable to the same levels seen in eggs and provides all essential amino acids. Spirulina is also a rich source of numerous essential nutrients such as B vitamins, vitamin E, chlorophyll, β-carotene, copper, and iron. Rich in phenolic acids, tocopherols, and γ-linolenic acid, spirulina provides anti-inflammatory, antioxidant, and immunomodulating properties.
In 1996, WHO pronounced spirulina as a food for the future based on its high content of proteins and vitamins. FDA approved the use of spirulina as a food coloring additive in 2013, determining that it is generally recommended as safe, and the Dietary Supplements Information Expert Committee of the United States Pharmacopeial Convention granted a Class A designation to spirulina as safe for human consumption when grown under controlled conditions. Spirulina was also endorsed by NASA after astronauts on a space missions used it as a dietary supplement.
Is there a benefit?
Researchers have studied spirulina’s effects on blood pressure, blood glucose, cancer, cholesterol levels, liver health, and obesity for decades. Multiple studies examining efficacy and clinical applications suggest spirulina may have anticancer, antiviral, and antiallergic effects as well.
Trotta and colleagues published a review in Nutrients in 2022 focusing on the neuroprotective role of spirulina. Through their analysis of studies on spirulina’s effect on the brain, the authors found beneficial anti-inflammatory and antioxidant effects acting on glial cell activation. They determined that spirulina demonstrated a neuroprotective role on development of the neural system, senility, and the prevention or progression of neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease, and multiple sclerosis.
The main active component of spirulina, phycocyanin, has strong antioxidant and anti-inflammatory properties that have also been shown to enhance endurance in athletes and improve muscle strength.
There are many studies examining metabolic syndrome and glycemic control in postmenopausal women that show beneficial effects from spirulina. A 2020 review in Open Heart by DiNicolantonio and colleagues showed spirulina aided in weight loss and reducing BMI as well as improving insulin resistance.
Spirulina has also been shown to have a positive effect on lowering total cholesterol and raising HDL cholesterol, with 1 g/day of spirulina lowering triglycerides by 16.3% and LDL by 10.1%. Studies have also shown that 4.5 g/day of spirulina may reduce blood pressure by increasing production of nitric oxide.
Dosage
Spirulina is widely available in stores and online as powders, tablets, and liquids and incorporated in foods and beverages such as chewing gum, candies, energy bars, and smoothies. While there is no official suggested dose, most studies employed a standard daily dose of 1-3 grams. Doses of up to 10 g/day have been used effectively in clinical trials.
What to tell your patients
Spirulina is generally safe as a supplement and food additive, but as with all supplements that are not regulated by FDA, care should be taken when using spirulina. Spirulina grows in lakes where heavy metals and bacteria may collect, and though the alga does not produce toxic compounds itself, there is a small risk of toxins such as microsystins contaminating some supplement products. Advise patients to opt for trusted brands certified by third-party authorities such as the U.S. Pharmacopeia.
Few adverse effects have been reported at recommended doses, but chronic exposure may induce diarrhea, bloating, upset stomach, flatulence, edema, headache, muscle pain, facial flushing, and sweating. Patients with autoimmune disorders should avoid using spirulina as it may interfere with blood clotting. Patients with phenylketonuria should also avoid using spirulina due to its high protein content. ■