What Is Chlorella?
Chlorella (Chlorella vulgaris and Chlorella pyrenoidosa) is a single-celled green alga that is one of the most nutrient-dense foods found in nature. (Panahi et al., 2016) This small but remarkable organism has been on Earth for over 2 billion years and is valued as a whole-food supplement due to its exceptional nutritional profile.
Chlorella contains an extraordinary amount of chlorophyll — more than any other plant studied — along with a wide range of vitamins, minerals, and amino acids.
Chlorella nutritional profile (per 10g):
- Protein: 5-6g (50-60% by weight — a complete protein with all essential amino acids)
- Chlorophyll: 100-250mg (10-25x more than spinach)
- Iron: 1.5-5mg — iron contributes to the reduction of tiredness and fatigue, and to normal oxygen transport in the blood (EFSA-authorized claims)
- Vitamin B12: 2-4mcg — B12 contributes to normal energy-yielding metabolism and to the reduction of tiredness and fatigue (EFSA-authorized claims; note: bioavailability from algal sources is debated)
- Beta-carotene: high content
- Chlorella Growth Factor (CGF): a unique nucleic acid complex
- Fibre: 1-1.5g (from cell wall)
- Omega-3 fatty acids: small amount
Chlorella vs spirulina — quick comparison:
Chlorella and spirulina are often confused, but they are entirely different organisms. Spirulina is a blue-green alga (prokaryote), while chlorella is a green alga (eukaryote). Their main difference: spirulina is often chosen for energy support and athletic performance, while chlorella is valued for its chlorophyll content and nutritional density.
Browse our spirulina products for an alternative algae supplement.
Why Is Chlorella Valued as a Nutritional Supplement?
Chlorella's appeal comes from its concentrated nutritional profile. As a whole-food supplement, it provides a broad spectrum of nutrients in a highly bioavailable form (when the cell wall is properly broken).
Key nutritional highlights:
1. Exceptional Protein Content
At 50-60% protein by weight, chlorella is one of the most protein-dense plant foods. It contains all essential amino acids, making it a complete protein source — particularly relevant for vegetarians and vegans.
2. Rich Chlorophyll Content
Chlorella contains more chlorophyll than any other plant studied. Chlorophyll is the green pigment responsible for photosynthesis and is a natural source of magnesium.
3. Iron and B-Vitamin Content
Chlorella is a notable source of iron and B vitamins, including B12. Iron contributes to normal formation of red blood cells and to the reduction of tiredness and fatigue. B vitamins contribute to normal energy-yielding metabolism (EFSA-authorized claims).
4. Fibre from Cell Wall
The fibre content in chlorella's cell wall supports normal digestive function.
Does Chlorella Support the Immune System and Digestion?
Beyond its nutritional value, chlorella has been studied for its effects on immune function and digestive health.
Immune system:
Kwak et al. (2012):
51 healthy participants took 5g chlorella daily for 8 weeks. The study observed increases in NK cell (Natural Killer cell) activity and immune-related markers (Kwak et al., 2012).
Otsuki et al. (2011):
26 participants took chlorella for 4 weeks. The study observed an increase in secretory IgA (mucosal immunity) levels.
Digestion and gut health:
Chlorella's chlorophyll and fibre content may support the digestive tract in multiple ways:
- Chlorophyll may support beneficial bacteria growth
- Fibre promotes regular bowel activity
- Chlorella Growth Factor (CGF) may help support gut wall integrity
- May be especially effective when combined with probiotics. Probiotic products
What Is the Best Chlorella Form and How Should You Take It?
Chlorella forms:
| Form | Advantages | Disadvantages | Recommended dose |
|---|---|---|---|
| Broken cell wall tablets | Best bioavailability | More expensive | 3-5g daily |
| Powder | Flexible use (smoothies, drinks) | Strong taste | 3-5g daily |
| Capsules | Convenient, tasteless | More capsules needed | 3-5g daily |
| Whole cells (unbroken) | Cheaper | Poor digestibility | Not recommended |
Important: Chlorella's cell wall MUST be broken for proper nutrient absorption. Without this processing step, the nutrients cannot be released in the digestive tract and absorption is minimal. Look for "broken cell wall" or "cracked cell wall" on the product.
General usage recommendations:
| Goal | Dose | Duration |
|---|---|---|
| General nutritional support | 2-3g | Ongoing |
| Increased nutritional intake | 3-5g | Ongoing |
| Immune system support | 5g | Ongoing |
| Digestive support | 3-5g | Ongoing |
Introduction schedule:
1. Week 1: 1g daily
2. Week 2: 2g daily
3. Week 3: 3g daily
4. Week 4+: desired dose (up to 5g)
Gradual introduction is recommended to allow your digestive system to adjust, as some people may experience mild gas or bloating initially.
Timing:
- Morning on empty stomach — best absorption
- OR 30 minutes before meals
- Divide larger doses into 2-3 portions daily
- Drink plenty of water throughout the day
Is Chlorella Safe and Who Is It Suitable For?
General safety:
Chlorella is generally considered safe for healthy adults when used as directed.
Possible side effects:
- Green-coloured stool (normal — due to chlorophyll content)
- Gas and bloating (especially when starting — begin with a smaller dose)
- Photosensitivity (chlorophyll may increase sun sensitivity — use sunscreen)
- Allergic reactions (rare — those with algae or mould allergies should be cautious)
Who should be cautious:
- Iodine-sensitive people — chlorella contains iodine
- Blood thinner users — chlorella contains vitamin K. Vitamin K info
- Those with autoimmune conditions — chlorella may stimulate the immune system
- Pregnant and breastfeeding women — consult your doctor before use
- Those with kidney conditions — chlorella has high protein content
Quality selection:
1. Always choose broken cell wall chlorella
2. Prefer products cultivated in controlled conditions
3. Look for third-party testing certification
4. Avoid products with unknown origin
How to Combine Chlorella With Other Supplements?
Complementary combinations:
Chlorella + fibre:
Additional fibre supports normal digestive function. Fibre products
Chlorella + vitamin C:
Vitamin C supports normal immune system function and increases iron absorption from plant sources — relevant since chlorella is rich in iron. Vitamin C products
Chlorella + magnesium:
Magnesium contributes to the reduction of tiredness and fatigue and supports normal energy-yielding metabolism. Magnesium products
Chlorella + spirulina:
These two algae complement each other nutritionally. Spirulina adds phycocyanin (an antioxidant pigment) and a strong amino acid profile, while chlorella provides chlorophyll and a broader vitamin/mineral profile. A 2:1 ratio (chlorella:spirulina) is a popular combination.
Chlorella + probiotics:
Probiotics support gut health and normal digestive function. Take probiotics at a different time than chlorella for best results. Probiotic products
Summary
Chlorella is a nutrient-dense green algae supplement valued for its exceptional nutritional profile — including high protein content, abundant chlorophyll, iron, and B vitamins.
Key points:
- Contains more chlorophyll than any other plant studied
- 50-60% protein by weight — a complete protein source
- Rich in iron (contributes to reduction of tiredness and fatigue — EFSA-authorized claim)
- Contains B vitamins including B12 (contributes to normal energy metabolism — EFSA-authorized claim)
- Always choose broken cell wall form for proper absorption
- Start with 1g and increase gradually to allow digestive adjustment
- Recommended dose: 3-5g daily for general nutritional support
- Generally safe for long-term use — use caution with autoimmune conditions and iodine sensitivity
- Combines well with spirulina, vitamin C, and probiotics
References
1. Uchikawa, T., Kumamoto, Y., Maruyama, I., et al. (2011). Enhanced elimination of tissue methylmercury in Parachlorella beijerinckii-fed mice. The Journal of Toxicological Sciences, 36(1), 121-126.
2. Merchant, R.E., & Andre, C.A. (2001). A review of recent clinical trials of the nutritional supplement Chlorella pyrenoidosa. Alternative Therapies in Health and Medicine, 7(3), 79-91.
3. Panahi, Y., Darvishi, B., Jowzi, N., Beiraghdar, F., & Sahebkar, A. (2016). Chlorella vulgaris: a multifunctional dietary supplement with diverse medicinal properties. Current Pharmaceutical Design, 22(2), 164-173.
4. Nakano, S., Takekoshi, H., & Nakano, M. (2010). Chlorella pyrenoidosa supplementation reduces the risk of anemia, proteinuria and edema in pregnant women. Plant Foods for Human Nutrition, 65(1), 25-30.
5. Kwak, J.H., Baek, S.H., Woo, Y., et al. (2012). Beneficial immunostimulatory effect of short-term Chlorella supplementation: enhancement of natural killer cell activity. Nutrition Journal, 11, 53.
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