October 31, 2025 · 5 min read

Chlorella in a Cyclist's Diet — Iron, Chlorophyll and Aerobic Capacity

Chlorella (Chlorella vulgaris) is a single-celled freshwater alga, taken as a supplement mainly for its high levels of iron, vitamin B12, chlorophyll and protein. For cyclists with a heavy weekly training load, especially vegetarians and vegans, chlorella can make up for shortfalls in micronutrients that are critical for oxygen transport and oxidative recovery. The clinical evidence is moderate — it is worth looking at it before you add green tablets to your supplement stack.

What in chlorella matters for a cyclist's performance

• Iron: 40–130 mg/100 g of dry matter — much more than spinach. The iron in chlorella is non-haem iron (Fe³⁺), so its bioavailability is lower than from red meat, but higher than from most plants thanks to the accompanying vitamins C and B12
• Vitamin B12: 100 g of chlorella contains 250–1000% of the daily requirement. Note: part of it is in the form of pseudo-vitamin B12 (a non-functional analogue) — choose CGF (Chlorella Growth Factor) products with a confirmed profile of active methylcobalamin
• Chlorophyll: 1–3 g/100 g — a strong antioxidant, with potential chelating properties for heavy metals (especially lead, cadmium and mercury)
• Protein: 50–60% of dry matter, all the essential amino acids — a supplement after strength sessions or as support for vegans
• CGF (Chlorella Growth Factor): a mixture of nucleotides, polysaccharides and peptides — credited with regenerative and immune-stimulating properties (in vitro research; less clinical evidence)

Does chlorella improve cyclists' results?

There are few direct studies in cycling. A study by Nakano et al. (2010) showed that supplementing chlorella for 4 weeks in students who trained increased VO2max by ~10% as well as aerobic capacity — but the sample was small (n=10) and the methodology has limitations. Studies on endurance athletes in general (Kim et al., 2017) suggest a reduction in markers of oxidative stress (MDA, 8-OHdG) after long-term supplementation. Chlorella is not a first-line ergogenic aid — its value is more nutritional (micronutrients, antioxidants) than directly ergogenic.

Does chlorella help against smog when you ride?

Chlorophyll and chlorella have chelating properties towards heavy metals — they bind them in the digestive tract and support their excretion. Cyclists who ride regularly in urban environments with high concentrations of PM2.5 and heavy metals (lead, cadmium) absorb some of these substances through the lungs and the digestive system. Chlorella can be a helpful part of a detox-oriented diet, but it will not replace an FFP2/FFP3 filter mask when you ride in smog.

A chlorella supplementation protocol for cyclists

What dose of chlorella works?

Doses used in clinical studies: 3–10 g/day (6–20 tablets of 500 mg). For preventive supplementation and topping up micronutrients, 3–5 g/day is enough. Higher doses (up to 10 g/day) were used in heavy-metal detox protocols. Start with 2–3 g/day and increase over 1–2 weeks — higher doses at the start can cause stomach complaints in people who do not tolerate a high fibre intake.

When to take chlorella?

Chlorella can be taken at any time of day. A practical routine for a cyclist:

• In the morning with your first meal — iron is absorbed more easily with a meal that contains vitamin C (e.g. orange juice)
• Avoid combining it with coffee or tea — tannins inhibit iron absorption (keep a 1–2 h gap)
• Don't take it right before training — swallowing tablets with water just beforehand can cause discomfort during exercise

How to choose chlorella — what to look for?

• Broken cell wall — mandatory. An unbroken cell wall is indigestible for humans, and the chlorella provides no nutrients
• A purity certificate: no heavy metals or pesticides (a paradox — chlorella chelates metals, but it can also absorb them from a contaminated culture)
• Tablets or powder: powder is more versatile (for smoothies, food), but the taste is intense. Tablets are easier to dose

Chlorella is a dietary supplement, not a substitute for a balanced diet. Cyclists with iron deficiency confirmed by a blood test (ferritin below 30 ng/ml in women, 50 ng/ml in men who train hard) should first discuss haem iron or iron chelate supplementation with a doctor — the effect is faster and more reliable than with chlorella.

← All blog posts