Spirulina For High Blood Pressure

Spirulina is a form of blue-green algae that flourishes in warm, alkaline lakes, and is increasingly recognised as a natural remedy for high blood pressure. Spirulina provides over 100 easily absorbed nutrients including amino acids, antioxidant carotenoids, vitamins, minerals, enzymes and other bioactive substances that can lower blood pressure.

Spirulina lowers blood pressure

A recent study assessed the blood pressure lowering effects of Spirulina in 40 people whose high blood pressure that was controlled by diet and lifestyle, or with a single antihypertensive medication. Their average age was 53 years, and they were slightly overweight but with a stable body weight. Those receiving blood pressure medication had been on the same treatment for at least six months.

The volunteers were divided into two groups, one of which took 2g Spirulina per day, while the other took placebo for three months. They were instructed not to make any other changes to their usual diet and exercise for the duration of the study.

At the end of the trial, those taking Spirulina supplements showed a significant reduction in blood pressure of 6/5 mmHg (from 149/84 mmHg down to 143/79 mmHg) while in those taking placebo, blood pressure increased slightly by 1/1 mmHg (from 150/85 mmHg up to 151/86 mmHg).

Strikingly, those taking Spirulina lost 5kg in weight (75.5kg down to 70.5 kg) over the 12 weeks, despite not trying to lose weight, while those taking placebo gained 2.1kg in weight (from 70.4 kg up to 72.5 kg).

How Spirulina lowers blood pressure

The significant reduction in blood pressure may partly have resulted from the weight loss, but measurement of their arterial stiffness also showed that the elasticity of their arteries (endothelial function) had improved. This was thought to result from the antioxidant effects of Spirulina, and to the promotion of nitric oxide synthesis within artery walls, which dilates arteries.

Spirulina is also a source of potassium, calcium, magnesium and vitamin C which have blood pressure lowering effects.

Spirulina dose

Spirulina supplements are available as powder, to add to food, drinks and smoothies, or as tablets and capsules to take with meals.

The recommended dose of Spirulina varies but in the study above, was 2g per day. Higher doses of 6g a day or more can be consumed as food without apparent harm.

Select a recognized, mainstream brand of Spirulina, and preferably one that is certified organic, meaning it has grown in unpolluted waters.

Spirulina side effects

Few side effects have been reported, and are mostly mild such as headache, flushing and sweating.

Blue green algae contain the amino acid, phenylalanine, which can cause adverse effects in people with the inherited condition of phenylketonuria.


If your blood pressure is raised, self-monitoring is important to maintain good control.

Image credits: nouchkac/pixabay;  perdita/wikimedia;


About DrSarahBrewer

Dr Sarah Brewer MSc (Nutr Med), MA (Cantab), MB, BChir, RNutr, MBANT, CNHC qualified from Cambridge University with degrees in Natural Sciences, Medicine and Surgery. After working in general practice, she gained a master's degree in nutritional medicine from the University of Surrey. Sarah is a registered Medical Doctor, a registered Nutritionist and a registered Nutritional Therapist. She is an award winning author of over 60 popular self-help books and a columnist for Prima magazine.

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