A spoon of green chlorella powder next to a green juice

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.

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 teaspoon (5g) containing approximately 3g.

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 teaspoon (5g) contains almost 75% of the recommended daily allowance (RDA) for iron in adult men and women over 50 years, and around 45% 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 human study found that daily chlorella supplementation may help reduce high blood pressure 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.

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This article was reviewed on 22 March 2018 by Kerry Torrens.

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.

A qualified nutritionist (MBANT), Kerry Torrens is a contributing author to a number of nutritional and cookery publications including BBC Good Food magazine. Kerry is a member of the The Royal Society of Medicine, Complementary and Natural Healthcare Council (CNHC), British Association for Applied Nutrition and Nutritional Therapy (BANT).


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