What each product is
- Spirulina — a cyanobacterium (blue-green algae) grown in alkaline water ponds. Dried and powdered. Very high protein (55–70%), dense in iron, phycocyanin, and carotenoids.
- Wheatgrass — the young grass shoots of the wheat plant (Triticum aestivum), harvested before jointing. Very high in chlorophyll, vitamins C and E, some iron and calcium. Low in protein per gram. Gluten-free (the gluten is in the seed, not the young grass).
- Barley grass — similar to wheatgrass, from young barley plants (Hordeum vulgare). Rich in chlorophyll, superoxide dismutase (SOD), lutonarin and saponarin (antioxidant flavonoids). Slightly different profile from wheatgrass; often studied together.
- Matcha — powdered Japanese green tea (Camellia sinensis). Very different category from the grasses and spirulina. Rich in L-theanine and caffeine (a cognitive performance combination), catechins (particularly EGCG), and some chlorophyll. A beverage ingredient as much as a supplement.
Protein content comparison
This is where spirulina stands apart:
- Spirulina: ~60% protein by dry weight
- Wheatgrass: ~17–25% protein by dry weight
- Barley grass: ~20–25% protein by dry weight
- Matcha: ~6% protein by dry weight (irrelevant as a protein source)
At a 5 g serving, spirulina provides approximately 3 g protein. Wheatgrass and barley grass at 5 g provide approximately 1–1.5 g — meaningful but much lower. For protein supplementation, spirulina is the clear choice.
Chlorophyll content
This is where the grasses dominate. Wheatgrass and barley grass contain very high chlorophyll — typically 3–5× the chlorophyll of spirulina per gram. Chlorophyll is the basis of most of the marketed “detox” and “blood cleansing” claims for these products.
The evidence for dietary chlorophyll having significant detoxification effects in humans is limited. It has chelation properties in vitro, and one study showed reduced aflatoxin absorption. The broader detox claims are largely unsubstantiated.
Chlorella (see the spirulina vs chlorella comparison) contains even more chlorophyll than wheatgrass and is often a better choice if chlorophyll is specifically the goal.
Iron content
- Spirulina: ~2–3 mg iron/g — one of the richest plant iron sources
- Wheatgrass: ~0.5–1 mg iron/g
- Barley grass: ~0.5–1 mg iron/g
- Matcha: ~1–1.5 mg iron/g — present but tannins inhibit absorption
For iron, spirulina is the clear winner. Matcha’s iron is largely blocked by its own tannins — taking matcha alongside iron supplementation actually reduces absorption.
Antioxidant activity
All four products have significant antioxidant activity, but through different compounds:
- Spirulina: phycocyanin (potent, unique), beta-carotene, zeaxanthin
- Wheatgrass/barley grass:chlorophyll, SOD, vitamins C and E. Barley grass’s lutonarin and saponarin are notably potent antioxidants.
- Matcha: EGCG and other catechins — among the best-studied antioxidants in the human diet, with significant RCT evidence for metabolic and cardiovascular benefit
Evidence base comparison
This is perhaps the most important comparison for evidence-focused buyers:
- Spirulina: Largest and most robust evidence base. Dozens of human RCTs for cholesterol, blood pressure, inflammation, iron deficiency, hay fever, blood glucose. Clinical evidence base built over 40+ years.
- Matcha/green tea: Extensive evidence base for catechins in general, and matcha specifically for cognitive performance (L-theanine + caffeine), cardiovascular health, and metabolic markers. Among the best-evidenced plant supplements overall.
- Barley grass: A growing evidence base. Several human studies on blood glucose and cholesterol, particularly from Japanese research groups. Less robust than spirulina but more than wheatgrass.
- Wheatgrass: Weakest clinical evidence base. A few small trials in anaemia and ulcerative colitis; mostly anecdotal benefits and in vitro studies. Not well-supported for most claims.
Taste comparison
- Spirulina: Strong, fishy/seaweed, intensely algae — challenging for many
- Wheatgrass: Grassy, earthy, intense — many find it easier than spirulina
- Barley grass: Milder and greener than wheatgrass — generally the most palatable of the grasses
- Matcha: Umami, slightly sweet, pleasant — the most versatile as a flavour ingredient
Who should choose which
- For protein: spirulina — no competition
- For iron: spirulina — no competition
- For cognitive performance and a morning ritual: matcha — the L-theanine/caffeine combination is unique
- For highest chlorophyll intake: barley grass or chlorella (not spirulina)
- For evidence-backed metabolic benefits: spirulina first, then matcha for cardiovascular/metabolic
- For taste ease in plain water: barley grass — mildest
Can you combine them?
Yes. Many users take spirulina as their primary daily supplement and matcha in the morning as a coffee alternative. “Greens” blended products often combine several of these — check the actual doses per ingredient, as some blend products contain token amounts of each rather than effective doses of any.
There are no known negative interactions between any of these products. If combining, apply the same quality verification process to each.