How Many Calories in Spirulina? Nutrition Facts & Macros

Dried spirulina has 290 calories per 100 g. However, typical serving sizes are much smaller — a standard tablespoon (7 g) has only 20 kcal, and a daily dose of 3-5 g has just 9-15 kcal. The calorie content is secondary to its extraordinary nutrient density: 57.5 g protein, 28.5 mg iron, and 3.67 mg riboflavin per 100 g.

Spirulina can support weight loss indirectly. Its high protein content (57.5%) promotes satiety, and studies suggest it may reduce appetite. A typical 3-5 g daily dose adds only 9-15 calories while providing significant protein, iron, and B vitamins that support energy metabolism during calorie restriction. It is not a fat burner — but a nutrient-dense supplement that prevents deficiencies common in restrictive diets.

Standard daily doses range from 1-10 g. Beginners should start with 1-2 g per day and gradually increase to 3-5 g over 1-2 weeks. Athletes and those with higher iron needs may take up to 10 g. Take with vitamin C-rich foods to enhance iron absorption. Best consumed in the morning or before workouts. Can be mixed into smoothies, juices, or taken as tablets.

Yes — spirulina contains all essential amino acids, making it a complete protein. At 57.5 g protein per 100 g, it has more protein by weight than beef (26 g), chicken (27 g), eggs (13 g), or tofu (10 g). However, typical serving sizes (3-10 g) provide only 1.7-5.8 g of protein, so it supplements rather than replaces protein-rich foods. The protein is highly bioavailable — spirulina has no cellulose cell wall, unlike chlorella.

Spirulina is generally safe. Common side effects include mild digestive discomfort (bloating, gas) when starting — begin with small doses (1 g) and increase gradually. Its high vitamin K content (25.5 mcg per 100 g) may interact with blood thinners. People with phenylketonuria (PKU) should avoid it due to phenylalanine content. Always buy from reputable sources — contaminated spirulina (heavy metals, microcystins) is the main safety concern.

Both are nutrient-dense algae but differ significantly. Spirulina has comparable protein (57.5 vs 50-60 g), more iron (28.5 vs 6-20 mg), and no cell wall (higher bioavailability). Chlorella has more chlorophyll (detox claims), more omega-3 fatty acids, and a tough cell wall that must be cracked for absorption. Spirulina is blue-green (phycocyanin), chlorella is bright green (chlorophyll). Both are excellent — many people take them together.