The health benefits of chlorella

What is chlorella, which nutrients does it contain, and is it safe for everyone? We look at the potential benefits and side effects of this food supplement.

A spoon of green chlorella powder next to a green juice

What is chlorella and how is it usually consumed?

Chlorella is a blue-green algae, just like spirulina. Its rich green colour is due to a high concentration of chlorophyll. Chlorella is consumed either as powder or in tablet supplement form.

What is the nutritional profile of chlorella?

Chlorella is a really good source of protein with one 5g teaspoon containing 2.6g.

Chlorella is nutrient-dense, containing a whole host of vitamins and minerals including calcium, magnesium, zinc, vitamin A, vitamin E and B vitamins.

It is also an excellent vegan source of iron. One 5g teaspoon contains almost 90% of the recommended daily allowance (RDA) for iron in adult men and women over 50 years, and over 50% RDA for women aged 19-49 years.

How well researched are the benefits and risks of chlorella?

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 chlorella can be confirmed.

There has also been some limited evidence that chlorella may help with weight loss by improving fat metabolism and blood sugar regulation. This is further supported by The Journal of Medicinal Food who reported over a 16-week trial that chlorella resulted in noticeable reductions in body fat percentage, serum total cholesterol and fasting blood glucose levels. Another small human study found that daily chlorella supplementation may help reduce high blood pressure, lower cholesterol and be of benefit to those suffering with conditions such as fibromyalgia and ulcerative colitis.

There has been some evidence to suggest that chlorella could be of benefit for smokers. A 2013 investigation by Clinical Laboratory gave 38 smokers 3,600mg of chlorella a day for six weeks and they found that their antioxidant status significantly improved. The researchers suggested that chlorella may be useful to reduce the mortality rate associated with smoking, although these results are far from conclusive due to the limited sample size and time frame of this study.

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 chlorella?

Chlorella is usually regarded as safe if used in the short-term, but it can cause some side effects such as diarrhoea, nausea and stomach cramps. There have also been some reported cases of allergic reaction and an increase in sun sensitivity, so you should always check with your GP before supplementing with chlorella.

If you are pregnant, breast-feeding, have iodine sensitivity, an allergy to moulds, a weakened immune system or autoimmune condition, then it is advised not to take chlorella in case of a reaction.

It is advised that you do not take chlorella if you are taking any immunosuppressants, medication that decreases the immune system, or blood thinners such as warfarin.

Enjoyed this? Now read...

The health benefits of spirulina
What is maca powder and is it good for you?
Is baobab powder really healthy?
More health benefits guides

This article was published on 19th February 2018.

Nicola Shubrook is a nutritional therapist and works with both private clients and the corporate sector. She is an accredited member of the British Association for Applied Nutrition and Nutritional Therapy (BANT) and the Complementary & Natural Healthcare Council (CNHC). Find out more at

All health content on is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other healthcare professional. If you have any concerns about your general health, you should contact your local healthcare provider. See our website terms and conditions for more information.

Comments, questions and tips

Sign in or create your My Good Food account to join the discussion.
Be the first to comment...We'd love to hear how you got on with this recipe. Did you like it? Would you recommend others give it a try?
Be the first to ask a question about this recipe...Unsure about the cooking time or want to swap an ingredient? Ask us your questions and we’ll try and help you as soon as possible. Or if you want to offer a solution to another user’s question, feel free to get involved...
Be the first to suggest a tip for this recipe...Got your own twist on this recipe? Or do you have suggestions for possible swaps and additions? We’d love to hear your ideas.