Chlorella is a bright green algae that is rich in nutrients. It is considered a "superfood" because it is rich in protein, iron, dietary fiber, B vitamins and complex carbohydrates.

Chlorella also contains high levels of antioxidants, such as vitamin C, omega-3 fatty acids, and carotenoids, such as beta carotene, which fight free radicals.

Chlorella has been studied for its potential to lower cholesterol levels and help reduce the risk of anemia during pregnancy. Some claim it can treat a range of health conditions. However, there is insufficient evidence to support most of these claims.

As a supplement, chlorella is available in tablet, powder, and extract forms.

This article describes the uses and benefits of chlorella as a dietary supplement, as well as its possible risks, side effects, and interactions.


Dietary supplements are not regulated in the United States, which means the Food and Drug Administration (FDA) does not approve a product's safety and effectiveness before it is marketed. If possible, choose supplements that have been tested by a trusted third party, such as USP, ConsumerLab, or NSF.

However, even if supplements are third-party tested, that doesn't mean they are safe for everyone or effective overall. It's important to discuss any supplements you plan to take with your healthcare provider and check for any potential interactions with other supplements or medications.

What is chlorella used for?

Supplement use should be individualized and reviewed by a health care professional such as a registered dietitian, pharmacist, or physician. No supplement is intended to treat, cure, or prevent disease.

Chlorella is a good source of many nutrients such as protein, iron, fiber, carbohydrates, antioxidants, and more. Due to its nutritional content, some claim it can treat various health conditions. However, there is insufficient evidence to support most of its claims.

Here are some possible uses for chlorella.

Reduce high cholesterol

High cholesterol is a risk factor for heart disease. When cholesterol levels are high, it is recommended to adjust your diet to lower cholesterol levels. Medications are also often prescribed to treat high cholesterol levels. However, there is a lot of interest in alternative ways to lower cholesterol.

Chlorella has been studied as a cholesterol-lowering aid.

According to a 2014 study published in the Journal of Nutrition, taking 416 mg of chlorella daily improved blood lipid levels in 62 adults with moderately elevated cholesterol. Not only do total cholesterol, triglycerides, and LDL ("bad") cholesterol decrease, but HDL ("good") cholesterol also increases.

A meta-analysis published in 2018 found that taking 4 grams of chlorella supplements daily for at least eight weeks significantly reduced total cholesterol, LDL cholesterol, blood pressure, and blood sugar compared with placebo.

A recent trial published in 2021 found that a smaller dose (1,500 mg per day) in people with diabetes had a positive impact on blood lipids and blood sugar levels.

Another meta-analysis published in 2022 concluded that chlorella supplementation reduced total cholesterol and LDL cholesterol but did not improve triglycerides or HDL cholesterol. Taking 1,500 milligrams per day can produce effects, while higher doses have no effect.

More research is needed before chlorella supplementation can be recommended to treat high cholesterol. Before starting any supplements, talk to your healthcare provider.

Reduce the risk of anemia during pregnancy

Iron requirements increase during pregnancy, and if a pregnant woman is iron deficient, anemia can sometimes result. Chlorella happens to be a great source of iron.

In a 2010 study in the journal Plant Foods for Human Nutrition, Japanese researchers gave 70 pregnant women a daily dose of 6 grams (6,000 mg) of chlorella supplements or a placebo. Treatment begins at 12-18 weeks of gestation and continues until delivery.

People in the study who took chlorella had significantly higher heme levels in their second and third trimesters compared to the placebo group. Low heme levels may indicate the possibility of a diagnosis of anemia.

Interestingly, people who took chlorella also had lower rates of edema (swelling of tissues), proteinuria (protein in the urine), and pregnancy-induced hypertension (high blood pressure).

Chlorella side effects

Chlorella is generally considered safe and well tolerated. That said, chlorella can cause side effects, especially in the first few weeks of treatment. These include:

  • stomach cramps
  • nausea
  • gas
  • diarrhea
  • green stool

Additionally, some people have reported allergic reactions, including wheezing and anaphylaxis.

Most side effects will go away as your body adjusts to the treatment.


Chlorella is not expected to cause adverse effects on breastfed infants. However, it can cause breast milk to turn green. If you are breastfeeding or plan to breastfeed, it is best to talk to your healthcare provider about chlorella use.

The safety of chlorella in children has also not been established.

People who are allergic to mold may also be allergic to chlorella. To be safe, take a smaller "test" dose of chlorella and wait 24-48 hours to see if any allergy symptoms appear. The same problem can arise if you are allergic to iodine, since chlorella is particularly high in iodine.

Chlorella can also cause adverse reactions in patients with thyroid disease, as excessive intake of iodine can aggravate the symptoms of hyperthyroidism or cause "iodine crash" in patients with hypothyroidism.

How to take chlorella

There are no guidelines for the correct use or dosage of chlorella.

Typical daily oral intake ranges from 3 g to 10 g9.

Never exceed the manufacturer's recommended dosage. If so, start with the smallest possible dose and gradually increase it. Doing this can help you avoid gastrointestinal side effects.

Tablets are the easiest form of chlorella to take because the dosage remains controllable and consistent. If taking it in powder or liquid form, stick to precise measurements to avoid underdosing or overdosing.

Chlorella powder can be mixed with water, juice, yogurt, and smoothies, but be aware that it has a slight seaweed smell and taste. Some people find that adding it to vinaigrette, miso soup, stir-fries, or wheatgrass can mask its smell and taste. Cooking chlorella does not reduce its nutritional value.

What happens if I take too much chlorella?

There's not a lot of information about chlorella and dosage, but you may be more likely to experience side effects when you take too much.


Chlorella contains high amounts of vitamin K, which can promote blood clotting and reduce the effectiveness of blood thinners like Jantoven (warfarin). If your healthcare provider prescribes warfarin, discuss with them any supplements you are taking (or plan to take), including chlorella. Healthcare providers should perform blood tests to monitor the effects of warfarin and adjust the dose if necessary.

Chlorella may amplify the effects of any photosensitizing medications (drugs that increase sensitivity to sunlight), putting you at greater risk of sunburn. Be sure to use sunscreen or stay out of the sun.

How to Store Chlorella

Please store according to the manufacturer's instructions on the product label. Always store out of the reach of children.

Similar supplements

Spirulina and kelp are two other popular algae supplements.

Spirulina is a type of blue-green algae that contains nutrients such as fat-soluble vitamins, beta-carotene, and minerals.

Kelp is a type of brown seaweed that often grows in underwater forests. It provides nutrients to marine life and is a staple food for humans. As a supplement, it often serves as a source of iodine.

Sources and precautions for chlorella

In the United States, chlorella is primarily available in supplement form. You can easily buy it online as well as in many natural food stores and stores that specialize in dietary supplements.

Tablets are the easiest form of chlorella to take because the dosage remains controllable and consistent. If taking it in powder or liquid form, use precise measurements to avoid underdosing or overdosing.

To ensure quality and safety, choose brands that have been tested and certified by independent organizations such as the United States Pharmacopeia (USP), ConsumerLab, or the National Science Foundation (NSF). Contamination often occurs with algal components. The presence of the USP, NSF, or ConsumerLab seal indicates that the product has been tested for contaminants such as arsenic and lead, and no contaminants were found.

A type of algae called Anaplasma is known to contain toxins and is best avoided.


Chlorella is an algae-based supplement that is rich in vitamins, minerals, fiber and antioxidants. It is often promoted as a good source of these nutrients for people who don't get enough fruits and vegetables in their diet. However, research does not support many of the health benefits touted by chlorella.

A diet that provides at least five servings of fruits and vegetables each day will provide many of the vitamins, minerals, fiber and antioxidants you need. You should not consider green powders and algae supplements as a substitute for a diet rich in fruits and vegetables.

Frequently asked questions

  • Does Chlorella Help Alkalize the Body?

    Although marketing uses this term to promote products, no food or drink can significantly change your blood pH levels (pH refers to whether a substance is acidic, alkaline, or neutral). The idea that many of the foods we eat in our diets are acidic and can cause disease is theoretical and has no evidence. No matter what we eat, our lungs and kidneys are involved in tightly regulating blood pH. Abnormalities in blood pH are undesirable and may lead to further health problems.

  • Can chlorella help reduce symptoms associated with fibromyalgia?

    Some preliminary (early) evidence suggests that chlorella supplementation can help reduce pain symptoms associated with fibromyalgia. Pain symptoms associated with fibromyalgia. Pain symptoms associated with fibromyalgia. In one study, a combination of chlorella tablets and liquid extract helped reduce pain symptoms compared to a placebo. More research will help determine the best supplement form and appropriate dosage. If you are considering using chlorella, be sure to talk to your healthcare provider.

  • Are chlorella supplements good for the liver?

    Some preliminary (early) evidence suggests that chlorella supplementation reduces liver enzymes and markers of inflammation (compared to placebo) in people with non-alcoholic fatty liver disease (NAFLD). Further research is still needed. If you are considering supplementing with chlorella, discuss the pros and cons with your healthcare provider first.


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