Spirulina is a blue-green algae that is usually consumed either in powder form or as a supplement.
What is the nutritional profile of spirulina?
Spirulina is known as a nutrient-dense food as it is packed full of vitamins, including vitamins A, C, E and B vitamins, as well as a whole host of minerals such as calcium, magnesium, zinc and selenium.
In particular, vitamin C and selenium are both antioxidants and help protect our cells and tissues from damage.
This algae is also an excellent vegan source of iron, providing 2mg per tablespoon (7g) which is about 23% of the Nutrient Reference Value (NRV) for men over 18 years and women over 50 years, and 13% of the NRV for women aged 19-49 years old.
Spirulina is also high in protein, with just 1 tbsp (7g) providing almost 4g of protein per serving.
How well researched are the benefits and risks of spirulina?
Most of the studies that have been conducted to date have been either on animals or in small human trials, so more research is needed before any health claims relating to spirulina can be confirmed.
There has been some research into the benefits of spirulina and its positive effects on blood glucose levels. In 2017 a paper was published which demonstrated that spirulina decreased blood glucose levels in diabetic mice and the researchers suggested that this may be beneficial in the future to those with type 1 diabetes. This is further supported by another study in the Journal of Medicinal Food that found spirulina supplementation of 2g a day for 2 months on 25 individuals with type 2 diabetes helped control blood sugar levels and improved their lipid profile. However, more research is needed before we can say for sure that spirulina is helpful in managing conditions such as diabetes.
A 2010 study on rabbits found that spirulina had anti-atherogenic effects (reducing the build-up of plaque within arterial walls) even when fed a high cholesterol diet.
There is also some evidence that spirulina may help reduce anaemia, although more research is required. One study on 40 older people with a history of anaemia found that supplementing with spirulina helped improve the haemoglobin levels in red blood cells.
There have also been a few trials into spirulina supplementation in sport, and early evidence that it may help improve both muscle strength and exercise performance.
Spirulina contains a phytonutrient known as c-phycocyanin, which also gives it a deep green/blue colour. Research has suggested that this phytonutrient has potential benefits, including anti-inflammatory properties, oxidative stress protection and neuroprotective qualities.
However, as already stated, the research that has been conducted to date has either been on animals or in small human trials so more research is needed to know the true efficacy of this algae in the population at large.
Are there any side effects of spirulina?
Spirulina also contains salt. One 7g tablespoon contains 73mg of sodium which counts towards 3% of the Nutrient Reference Value for adults. If you know salt is an issue for you, or you have high blood pressure then always check with your GP before supplementing. Others who should check with their GP before taking spirulina include those taking prescription medication, pregnant or breastfeeding women and anyone younger than 18.
Those with the condition called phenylketonuria (PKU) should avoid spirulina completely as it contains an amino acid called phenylalanine which they cannot metabolise, as should anyone with an autoimmune condition such as rheumatoid arthritis, lupus or multiple sclerosis.
Always make sure you buy spirulina from reputable brands or sources, as there has been concern in the past that it can be contaminated with toxins from bacteria known as cynobacteria.
