Walk into any health food shop and spirulina and chlorella tablets are usually sitting on the same shelf, often lumped together under the same ‘superfood algae’ label. It’s an understandable pairing — both are sold as vivid green powders or tablets, both have a long history of being eaten in various cultures, and both tend to appear in almost identical marketing copy.

But spirulina and chlorella are, in fact, biologically quite different organisms. They have different cell structures, different nutrient profiles, and different practical considerations when you’re deciding what to add to a smoothie or a daily supplement routine. This guide looks at what each one actually is, how they compare, and how to choose between them — without the hype.

Quick answer

Spirulina is a blue-green algae (technically a cyanobacterium) that’s a good source of plant protein and has a comparatively mild flavour that blends easily. Chlorella is a true green algae with a tough cell wall that has to be mechanically ‘cracked’ during processing, and it’s chiefly valued for its concentrated chlorophyll content. If you’re new to algae supplements and want something easier to mix into food or drinks, most people find spirulina the simpler starting point; if you’re specifically drawn to chlorophyll, chlorella may be the better fit.

What is spirulina?

Spirulina (usually the species Arthrospira platensis) is a cyanobacterium — a type of photosynthesising bacterium — rather than a plant or a true algae in the strict biological sense. It’s still commonly referred to as a ‘blue-green algae’, a name that reflects both its colouring and where it grows: naturally alkaline lakes in regions including Central Africa and Central America, as well as being commercially cultivated worldwide, including organic spirulina grown in the UK and other approved organic sites, depending on the supplier.

The ‘blue-green’ colouring comes from a combination of chlorophyll (green) and phycocyanin, a blue pigment-protein that’s fairly unique to cyanobacteria and is often highlighted in spirulina benefits discussions as an antioxidant compound. In terms of typical nutrient profile, spirulina is commonly noted for its plant protein content, along with iron, some B vitamins, and a range of naturally occurring pigments and antioxidants. As with any wholefood supplement, exact composition varies by batch and growing conditions, which is why it’s always worth checking the nutrition panel on the specific product you buy rather than relying on generic figures.

What is chlorella?

Chlorella (typically Chlorella vulgaris or Chlorella pyrenoidosa) is a genuinely different organism from spirulina: a single-celled, freshwater green algae that is a true eukaryote, more closely related to plants than to bacteria. Its defining feature, from a supplement perspective, is its cell wall — a tough, cellulose-based structure that human digestion can’t easily break down on its own.

This is why you’ll often see chlorella products described as ‘cracked cell wall’ or ‘broken cell wall’. Manufacturers use a mechanical process to fracture the outer wall before drying and pressing it into tablets or milling it into powder, which is intended to make the contents more accessible when digested. Chlorella’s standout feature is its particularly high chlorophyll content, which gives it a deep, dense green colour — often noticeably darker than spirulina. If you like the idea of concentrated chlorophyll but would rather avoid tablets altogether, our KIKI Health Liquid Chlorophyll is a liquid alternative some customers prefer to add to water.

Tablets vs. powder: taste, convenience and mixing

Both spirulina and chlorella are available as tablets or loose powder, and the right format often comes down to taste tolerance and how you like to take supplements.

Tablets are the more convenient, mess-free option. There’s no flavour to mask, no measuring, and they travel well — useful if you’re taking them alongside other supplements as part of a routine. The trade-off is that a meaningful serving can mean swallowing several tablets, and you’ll always want to follow the number stated on the product label rather than any general figure you’ve read elsewhere.

Powder gives you more flexibility to blend into smoothies, juices or porridge, but both spirulina and chlorella have a distinctive, fairly strong ‘sea-like’ or grassy taste that can dominate milder-flavoured drinks. Most people find it easiest to start with a small amount, blended with naturally strong or sweet flavours — citrus, berries, banana, or other bold ingredients — rather than adding it to something delicate. If you’re already comfortable blending green powders into food, our post on how to use moringa powder in smoothies, porridge and savoury food covers techniques for masking flavour and working powders into everyday meals that apply just as well to spirulina and chlorella.

Can you take spirulina and chlorella together?

There’s nothing inherently contradictory about taking both — they’re different organisms with overlapping but distinct nutrient profiles, and people do combine them. Whether it makes practical sense for you is a different question.

Combining two supplements doesn’t automatically mean combined benefits, and there’s no strong evidence that stacking spirulina and chlorella together outperforms taking either on its own for general wellbeing. It also means managing two products, two labels, and potentially double the cost. A reasonable approach is to try one first, see how you get on with the taste and format, and only consider adding the second if you have a specific reason to want what it offers — for example, wanting more concentrated chlorophyll on top of spirulina’s protein content. If you’re taking any medication or managing a health condition, speak to a pharmacist before combining supplements of any kind.

What not to do: don’t rely on either as a substitute for other nutrients

It’s worth being clear about what spirulina and chlorella are not. Neither should be treated as a reliable substitute for iodine, vitamin B12, or other nutrients that are better sourced from foods or supplements specifically formulated and tested for that purpose.

Spirulina, for instance, can contain naturally occurring iodine, but the amount varies depending on growing conditions and isn’t standardised or controlled in the way a dedicated iodine supplement would be — so it isn’t something to rely on if you have a known or suspected iodine requirement. Algae are also sometimes marketed to vegans as a B12 source, but much of the B12-like compound present in algae is in a form the body can’t use effectively. The NHS advises that anyone following a vegan diet makes sure they get enough vitamin B12 from fortified foods or a supplement formulated to provide it in a usable form, rather than relying on algae alone.

The same principle applies to any ‘detox’ framing you might see around spirulina or chlorella. Your liver and kidneys carry out detoxification as an ongoing, built-in bodily process; no supplement, including spirulina or chlorella, treats, cures or accelerates that process, and we wouldn’t want to suggest otherwise.

Medicines, pregnancy and individual advice

A few groups of people should be particularly careful, and speak to a pharmacist or GP before starting either supplement:

• If you have an autoimmune condition. Spirulina has immune-stimulating properties in laboratory studies, and some practitioners advise caution for people with autoimmune conditions as a precaution.
• If you have a thyroid condition, particularly one where iodine intake needs to be controlled. Spirulina’s variable natural iodine content means it isn’t a predictable choice here.
• If you are pregnant, breastfeeding, or trying to conceive. As with most supplements, algae products aren’t something to start without checking with your GP or midwife first.
• If you take regular medication, particularly immunosuppressants or blood-thinning medicines. A pharmacist can check for anything specific to your situation.

This isn’t an exhaustive list, and it doesn’t replace individual advice. If in doubt, ask before you start — our in-store team and any community pharmacist are well placed to help you weigh this up against your own health history.

Buying spirulina and chlorella at BeWell

We stock organic tablet ranges for both, so you can try either without needing to source loose powder:

• KIKI Health Organic Spirulina Tablets, 200 Tablets — a straightforward way to try spirulina without measuring powder.
• KIKI Health Organic Chlorella Tablets, 200 Tablets — cracked-cell-wall chlorella in tablet form.

As always, follow the serving guidance printed on the label of the specific product you buy, since this can vary between suppliers and batches.

FAQs

The bottom line

Spirulina and chlorella are often marketed as interchangeable ‘superfood algae’, but they’re different organisms with different strengths: spirulina for its protein content and easier-to-blend taste, chlorella for its concentrated chlorophyll and distinctive cracked-cell-wall processing. Neither is a substitute for a varied diet or for nutrients like iodine and B12 that are better sourced elsewhere, and neither treats or prevents any medical condition. Choose based on taste, format and what you’re actually hoping to add to your routine, follow the label directions on whichever organic tablets you pick, and check with a pharmacist first if you’re pregnant, unwell, or taking medication.

Medical Disclaimer : This content is for general information only and is not a substitute for professional medical advice. Please consult your GP, pharmacist, or qualified healthcare professional before starting any new supplement, especially if you are pregnant, planning a pregnancy, breastfeeding, taking medication, managing a health condition, or considering supplements for children.