How Should You Use Spirulina? What the Research Says

Spirulina is a blue-green algae cultivated from lakes or farmed in ponds. Its nutritional benefits and antioxidant properties may help with health conditions like ulcerative colitis, or offer a boost when managing weight, cholesterol levels, skin health, and more.

Long used in traditional medicine, spirulina is usually taken as a supplement and is available in powder, capsule, tablet, and liquid form. More research is needed, however, to identify and understand the potential health benefits of spirulina.

Nutrition

Spirulina is a rich source of protein and several fatty acids, vitamins, and minerals. It also contains phycocyanins (a protein with a bluish pigment and antioxidant properties).

One tablespoon (seven grams) of spirulina contains the following nutrients:

• Calories: 20.3
• Protein: 4 grams (g)
• Fat: 0.5 g
• Carbohydrate: 1.7 g
• Fiber: 0.3 g
• Calcium: 8.4 milligrams (mg)
• Iron: 2 mg
• Magnesium: 13.6 mg
• Phosphorus: 8.3 mg
• Potassium: 95 mg
• Sodium: 73.5 mg
• Folate: 6.6 micrograms (mcg)
• Manganese: 0.1 mg
• Choline: 4.6 mg
• Vitamin K: 1.8 mcg
• Vitamin A: 2 mcg
• Beta-carotene: 24 mcg
  

Since spirulina comes from bacteria (cyanobacteria), it may be considered a protein source for vegans. Spirulina contains more protein than most vegetables. However, it lacks high enough levels of some amino acids that your body needs to function at its best.

Potential Benefits

Some people claim that spirulina has a range of health benefits. More extensive studies are needed before recommending spirulina for any condition. However, the following explores what science says about spirulina's effects on different health outcomes.

1. Ulcerative Colitis

Ulcerative colitis is an inflammatory bowel disease (IBD) that mainly impacts the large intestine. It can increase the risk of anemia and other nutrient deficiencies, colon cancer, and other conditions.

Anemia (low red blood cell function) is a serious condition that can cause an array of symptoms, from poor sleep to anxiety. A study using 1 gram (g) a day of spirulina for eight weeks in people with UC suggested spirulina benefited their labs associated with anemia.

Spirulina also improved antioxidant capacity status and health-related quality of life in patients with UC.

Further study is needed to confirm these results.

2. Antioxidant Capacity

According to research, 1 to 8 grams of spirulina per day increased superoxide dismutase (SOD) and total antioxidant capacity (TAC). Antioxidant effects include preventing cellular damage and protecting overall health. They were greater when people took 5 grams of spirulina or more daily.

However, you may not want to rely on spirulina alone to increase your TAC. Many foods are great sources of antioxidants and can help reduce inflammation. To increase antioxidants in your diet, try including various nutrient-dense foods, such as:

• Fruits: Including apples, berries, citrus fruits, cantaloupe, and tomatoes
• Vegetables: Dark leafy greens, broccoli, cauliflower, bell peppers, carrots, and sweet potatoes
• Whole grains: Oats, barley, brown and wild rice, quinoa, and whole wheat bread

Eating a variety of fruits and vegetables has been linked to improved emotional well-being, vision health, and immune function. Keep in mind that these foods do not have to be organic.

3. Athletic Benefits

Intense exercise can impact physical processes such as inflammation, immune function, and performance. Spirulina has been studied for its impact on these factors and outcomes.

In a study of elite rugby players, spirulina (5.7 g daily) for seven weeks reduced exercise-induced lipid peroxidation (potentially harmful cell changes), inflammation, and skeletal muscle damage. It may also have helped speed recovery.

A different study in cyclists suggested that 6 grams of spirulina a day for 14 days improved hemoglobin concentration. However, it did not significantly improve physical performance.

4. Blood Pressure

In a collection of studies, 1 to 8 grams of spirulina a day for up to 12 weeks lowered systolic (the top number) blood pressure by about 4.59 millimeters of mercury (mmHg) and diastolic (the bottom number) blood pressure by 7.02 mmHg.

The most significant blood pressure-lowering occurred in people with high blood pressure.

5. Blood Sugar Control

Rapidly changing, uncontrolled blood sugar levels over time can negatively impact people with type I or 2 diabetes, eating disorders (including diabulimia, an intentional misuse of insulin to manipulate weight), and more.

Over time, uncontrolled blood sugar spikes can lead to complications such as:

• Amputation
• Heart attack
• Kidney failure
• Stroke

A study published in 2023 shows that spirulina lowered blood sugar levels. It may have additive effects with metformin, a medication used to lower blood sugar in people with type 2 diabetes.

Results showed that 2 grams a day of spirulina (S. platensis) achieved these results compared with metformin alone:

• Lowered HbA1c (-1.43)
• Lowered fasting blood sugar levels (-24.94 mg/dL)
• Total and low-density cholesterol (LDL) decreased (-41.36 mg/dL and -38.4 mg/dL, respectively)
• A small increase of 3 mg/dL in high-density lipoprotein (HDL) was seen

The protein and fiber content of spirulina may be responsible. Phycocyanin may lower inflammation, which may help reduce complications. However, scientists are still figuring it out.

6. Cancer

Very few well-designed human studies have examined spirulina's effects on cancer. Some studies have been conducted in the laboratory (in vitro) and on animals. However, more studies are needed to examine its impact on humans.

7. Cholesterol Levels

Your body needs cholesterol to function properly. The two main kinds are low-density lipoprotein (LDL), or "bad" cholesterol, and high-density lipoprotein (HDL), or "good" cholesterol.

A collection of studies on cholesterol levels found that spirulina:

• Lowered total cholesterol
• Lowered LDL
• Increased HDL
• Lowered triglycerides
  

Healthcare providers generally do not suggest spirulina as a first-line treatment for lowering cholesterol and may suggest medication to manage your condition. While supplements may help, larger clinical trials and more research are needed to confirm benefits for managing cholesterol.

8. Liver Health

Your liver supports your body's natural detoxifying processes, digestion, immune system, and more. Most studies of spirulina's effects on the liver are done in animals or the lab.

However, a 2024 review of studies suggests a role in preventing lipid buildup in the liver. More research is needed to understand any benefits or protective effects of spirulina.

9. Metabolic Syndrome

Scientists have studied spirulina's effects on metabolic syndrome. Metabolic syndrome happens when a person has the following:

• High blood pressure
• High blood sugar
• High cholesterol
• Excess fat around the waist (excess abdominal fat)

Metabolic syndrome can negatively impact your health and increase your risk of heart attack, stroke, and type 2 diabetes.

As with some of the other research, a collection of studies suggested that spirulina could help lower high blood pressure, high blood sugar, and high cholesterol.

More studies are needed to confirm whether spirulina may be a helpful addition to other methods of managing metabolic syndrome, including healthy eating, exercise, and medications.

Studies in people with metabolic syndrome taking 1 to 8 grams of spirulina per day showed reduced blood sugar and insulin levels.

10. Obesity

Scientists reviewed spirulina's effects on weight management in people with obesity.

Spirulina was associated with a weight loss of 4.55 pounds in participants with obesity and a weight loss of 2.82 pounds in people diagnosed as overweight.

However, clinically speaking, these results are not enough to make a solid recommendation for using spirulina for obesity treatment.

11. Skin Health

Although more research is needed, spirulina may be good for the skin due to the many bioactive compounds it contains. It is thought that spirulina may:

• Promote fibroblasts, keratinocytes, and collagen needed for skin repair and to reduce skin inflammation and damage
• Have skin protective and wound-healing effects
• Provide UV protection
• Prevent acne

Side Effects

Spirulina is generally safe, but some people have reported the following with its use:

• Nausea and vomiting
• Diarrhea
• Headache
• Dizziness

An allergic reaction such as rash, swelling, throat swelling, or other symptoms of anaphylaxis (severe allergic reaction) may be possible in those allergic to spirulina.

If you experience side effects, stop using spirulina and contact your healthcare provider immediately.

How to Use Safely

People choosing spirulina supplements need to consider the correct dosage, as well as side effects, potential drug interactions, and other concerns.

Precautions

When considering spirulina use, be aware of the following:

• The safety of spirulina in pregnant or nursing people has not been established. Speak with your healthcare provider before using spirulina if you're pregnant, plan to get pregnant, or are breastfeeding.
• The safety of spirulina has not been established in children. Talk with your child's pediatrician before giving them spirulina.
• Spirulina is grown in lakes and can sometimes be contaminated with lead, other heavy metals, or toxins found in polluted water. These include microcystins in the algae.

People diagnosed with certain conditions also may need to avoid spirulina. These conditions include disorders affecting how the body uses proteins or amino acids, such as phenylketonuria (PKU) or maple syrup urine disease (MSUD). They also include autoimmune conditions, such as lupus and multiple sclerosis.

Dosage

There's currently no recommended "effective" dosage of spirulina, and manufacturer recommendations might vary.

Studies have used 1 to 10 grams a day for up to six months and 19 grams a day for up to two months, with a relatively good safety profile in people with different conditions. Less is known about the long-term use of spirulina.

As a general guideline, don't take more than the amount listed on the product label. A standard dose is 4 to 6 tablets (500 mg each) per day.

The types of blue-green algae used in spirulina supplements are typically Spirulina maxima, Spirulina platensis, or Aphanizomenon flos-aquae. Keep in mind that no supplement is intended to treat, cure, or prevent disease.

Interactions

The following are interactions to consider when taking spirulina:

• Blood thinners: There is a small amount (0.26 micrograms) of vitamin K in each gram of spirulina. Taking large amounts of spirulina could theoretically impact the blood-thinning effects of some medicines like Jantoven (warfarin).
• Diabetes medication: Spirulina may have additive effects with metformin, a medication used to lower blood sugar in people with type 2 diabetes. Caution should be used when taking spirulina with diabetes medications so that blood sugar isn't lowered too much, which may cause complications.
• Immune system drugs: Adalimumab (Humira), Etanercept (Enbrel), and methotrexate may interact with spirulina, although there is limited evidence on drug interaction.

It is essential to carefully read a supplement's ingredient list and nutrition facts panel to know which ingredients and how much of each ingredient is included. Please review this supplement label with your healthcare provider to discuss potential interactions with foods, other supplements, and medications.

How Do I Add Spirulina to My Diet?

Several ways to include spirulina in your diet include the following:

• Add spirulina powder to your smoothies or smoothie bowls.
• Mix the powder into energy bites or chocolate truffles.
  
• Take it as a supplement (capsule, tablet, or liquid form).

Not everyone tolerates or likes the taste of spirulina, which is described as earthy or fishy. If you don't like the taste, consider mixing it with foods with intense taste profiles (e.g., garlic-heavy pesto).

Summary

Spirulina is an edible blue-green algae that contains several important nutrients.

Research shows spirulina has some effects on increasing antioxidant levels in the body and reducing blood pressure, blood sugar, and cholesterol levels.

However, the most effective way to manage chronic conditions is to address lifestyle habits, such as your eating patterns and activity level, which can significantly affect your health and well-being.

Working with your healthcare provider and a registered dietitian nutritionist (RD/RDN) is one way to achieve your nutrition and health goals.