Arthrospira Platensis: Nutrition, Uses, and Safety Risks

Arthrospira platensis is a species of cyanobacteria, a group of photosynthetic bacteria often called blue-green algae. It is characterized by its swirling, helical filaments. A. platensis is the primary species cultivated and sold commercially as “spirulina.” Its name comes from the Latin word for “spiral,” describing its corkscrew shape. While consumed by humans for centuries, it has gained widespread global attention in recent decades.

Biological Characteristics and Habitat

As a prokaryote, A. platensis has a simple cellular structure that lacks a nucleus, distinguishing it from eukaryotic algae. This cyanobacterium thrives naturally in specific environments. It is found in tropical and subtropical lakes with highly alkaline water (pH 9-11) and high concentrations of carbonate and bicarbonate. These conditions inhibit the growth of many other microorganisms.

Historically, dense populations were found in locations like Lake Texcoco in Mexico and Lake Chad in central Africa, where it was a traditional food source. These natural blooms occur in warm, sunlit waters where the organism can efficiently perform photosynthesis. Its ability to flourish in extreme alkaline and saline conditions gives it a competitive advantage, allowing it to dominate the aquatic ecosystem.

Modern production has shifted from harvesting wild blooms to commercial cultivation. This cultivation occurs in large, man-made, shallow ponds that replicate its natural alkaline habitat. By controlling nutrient levels, water chemistry, and light exposure, producers can optimize growth and harvest the biomass for processing.

Nutritional Profile

Arthrospira platensis has a high protein content, ranging from 60% to 70% of its dry weight. This high-quality protein contains all essential amino acids that the human body cannot produce on its own. The protein’s digestibility is also high because its cells lack tough cellulose walls.

Beyond protein, it is a dense source of micronutrients. It contains B vitamins like thiamine (B1), riboflavin (B2), and niacin (B3). While often cited as a source of vitamin B12, it contains a pseudovitamin B12 analogue that is not bioavailable to humans and cannot correct a B12 deficiency. The organism is also rich in beta-carotene, which the body converts into vitamin A, and supplies minerals such as iron, manganese, copper, and potassium.

It also contains several unique bioactive compounds. The most prominent is phycocyanin, a pigment-protein complex that gives the organism its blue-green hue and is studied for its antioxidant properties. It also contains chlorophyll and gamma-linolenic acid (GLA), an omega-6 fatty acid investigated for its role in inflammatory processes.

Applications in Food and Research

Arthrospira platensis is used as a nutritional supplement and food ingredient, sold globally in powder, tablet, or capsule form. The powder is often blended into smoothies, juices, and energy bars to enhance their nutritional value. Its high protein and amino acid profile make it a popular supplement for those on vegetarian or vegan diets.

An extract from A. platensis is also used in the food industry. The blue pigment, phycocyanin, is isolated and used as a natural food colorant. This water-soluble extract provides a stable blue hue for products like candy and beverages, serving as a popular alternative to synthetic dyes.

The organism is also a subject of scientific research. Studies investigate its potential antioxidant and anti-inflammatory effects, attributed to compounds like phycocyanin and beta-carotene. Researchers are also exploring its capacity to modulate immune system responses and its effects on metabolic health markers like blood glucose and lipid levels.

Consumption and Safety Considerations

Arthrospira platensis is available as a fine, dark green powder, tablets, or capsules. The powder has a distinct, seaweed-like flavor and is often mixed into smoothies, juices, or foods like yogurt to mask its taste. The recommended daily dose ranges from one to five grams, though this can vary by manufacturer.

The quality of the growing environment directly impacts the safety of the final product. If not grown in properly controlled conditions, A. platensis is susceptible to contamination. One risk is the absorption of heavy metals like lead, mercury, and arsenic from the water supply.

Another concern is contamination by different species of cyanobacteria. Poorly managed cultivation ponds can be colonized by toxin-producing algae that release harmful cyanotoxins, such as microcystins. Arthrospira platensis does not produce these toxins itself. Consumers should purchase spirulina from reputable manufacturers that use third-party testing to verify the absence of heavy metals and cyanotoxins.