What is chlorella?

Chlorella is a single-cell, blue-green freshwater algae with a rich colour due to its high concentration of chlorophyll. There are 30 different species of chlorella, with the most researched being chlorella vulgaris. Typically consumed as either a powder or in tablet form, you can find chlorella in health food stores.


Discover our full range of health benefit guides and find out the top 5 benefits of cinnamon, moringa and baobab.

Nutritional benefits

One teaspoon (3g) of chlorella in powder form provides:

  • 11Kcal / 44KJ
  • 1.8g Protein
  • 0.1g Fat
  • 0.5g Carbohydrate
  • 3.4mcg Iodine
  • 6.6mcg Vitamin B12

Top 5 health benefits of chlorella

1. May support immune function

In a small study, men were seen to produce more immune antibodies when they were supplementing with chlorella for a four-week period. Similarly, another small study showed an increase in immune cells called 'natural killer' cells, which are important in our fight against cancer and microbial infection.

2. May aid cholesterol balance

Several studies indicate a potential role for chlorella in helping balance cholesterol levels. This may be due to the nutrients found in chlorella, such as vitamin B3, carotenoids, fibre and protective antioxidants.

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3. May support a weight management programme

There has also been some limited evidence from animal studies 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, which reported that chlorella resulted in noticeable reductions in body fat percentage, serum total cholesterol and fasting blood glucose levels over a 16-week trial.

4. May aid blood pressure management

Chlorella has great nutritional credentials: it’s a source of heart-friendly fat as well as fibre and supplies the blood pressure-lowering nutrients potassium and arginine. So, perhaps it’s no wonder that one human study found daily supplementation helped reduce high blood pressure. Another small study reported less stiffness in the arteries, a factor that contributes to high blood pressure.

5. Binds to heavy metals

Often marketed for its detox benefits, animal studies suggest chlorella is effective at binding with heavy metals and other harmful compounds. However, it is rare for humans to experience such high levels of heavy metal toxicity, and in the vast majority of cases, our innate detox systems work sufficiently to manage most environmental insults and overindulgences.

As already stated, the research that has been conducted to date has either been conducted on animals or in small human trials, so more research is needed to know the true efficacy of this algae for the population at large.

Is chlorella safe for everyone?

Chlorella is generally recognised 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.

If you are pregnant, breastfeeding, have iodine sensitivity, an allergy to moulds, a weakened immune system or an autoimmune condition, you may be advised not to take chlorella in case of a reaction. It is also advised that you do not take chlorella if you are taking any medication that decreases the immune system, as well as blood thinners such as warfarin.

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This article was last reviewed on 8 August 2022 by Kerry Torrens.

Kerry Torrens is a qualified nutritionist (MBANT) with a postgraduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the past 15 years she has been a contributing author to a number of nutritional and cookery publications including BBC Good Food.

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 urbanwellness.co.uk.


All health content on bbcgoodfood.com 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 health care professional. If you have any concerns about your general health, you should contact your local health care provider. See our website terms and conditions for more information.

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