Dietary vitamin B12 deficiency is one of the most common micronutrient deficiencies worldwide, with over a billion individuals suffering from low levels of the vitamin. While ruminant-derived meat and dairy products play a crucial role in providing the recommended B12 dietary allowance (2.4 µg/day), increasing the production and consumption of meat and milk entails substantial environmental ramifications. Spirulina blue-green algae (Arthrospira platensis) has been widely proposed as healthier and more sustainable substitutes for meat, milk, and dairy products (also known as meat and milk analogues). However, previous research has shown that while Spirulina contain desirable macro- and micro-nutrients (e.g., essential amino acids, calcium, potassium, magnesium, iron), the majority of vitamin B12 found in so-called traditional Spirulina is a non-active, pseudo-form (cobamide), unavailable to humans, referred to as pseudo-vitamin B12. This renders traditional Spirulina a limited alternative to animal-source foods. As a response, in this exploratory in vitro study, we ask whether light conditions may enhance active vitamin B12 production in Spirulina. We describe the use of scalable photobioreactors, artificially illuminated, located in the Hengill area of Iceland. These systems are used to cultivate Photosynthetically Controlled Spirulina (PCS), to produce carbon–neutral and nutritious biomass containing unopposed, biologically active vitamin B12, in levels comparable to beef (1.64 µg/100g in PCS with a standard deviation of 5% versus 0.7–1.5 μg/100g in beef). In terms of mitigating global vitamin B12 deficiency, we explore production scale up scenarios. In one scenario, by re-allocating the electricity currently consumed by heavy industry, Iceland could produce 277,950 tonnes of Spirulina biomass per year, which translates into approximately 4555 g per year of active vitamin B12, able to meet the recommended dietary allowance (RDA) of over 13.8 million children aged 1–3. More ambitious production scenarios could see Iceland providing the RDA for over 26.5 million children aged 1–3, and over 50 million children aged 0–6 months.

Dietary vitamin B12 deficiency is one of the most common micronutrient deficiencies worldwide, with over a billion individuals suffering from low levels of the vitamin. While ruminant-derived meat and dairy products play a crucial role in providing the recommended B12 dietary allowance (2.4 µg/day), increasing the production and consumption of meat and milk entails substantial environmental ramifications. Spirulina blue-green algae (Arthrospira platensis) has been widely proposed as healthier and more sustainable substitutes for meat, milk, and dairy products (also known as meat and milk analogues).

The feasibility of consuming 100 g of PCS daily, compared to the same quantity of beef, involves several technical considerations, particularly in terms of palatability, nutrition, and practicality. From a palatability perspective, consuming 100 g of PCS daily may be challenging due to its taste and texture, which may not be easily adaptable to a wide variety of dishes as beef. Moreover, a high intake could also pose risks of excessive micronutrient accumulation, such as iodine, which Spirulina can contain in large amounts. While PCS could be utilized to fortify other foods, achieving the RDA for certain nutrients solely through fortification may require careful formulation to avoid under-nutrition, thus complicating its use on a large scale. Therefore, while PCS offers substantial nutritional benefits, relying on it as a primary source to meet specific nutritional requirements like vitamin B12 through high daily intake or fortification may present challenges.

While comparing the nutritional and environmental benefits of PCS with beef, we recognize that direct vitamin B12 supplementation and fortification—through tablets or liquids—may be equally effective. These supplements often contain bioactive forms of the vitamin, such as methylcobalamin and cyanocobalamin, which ensure effective absorption and physiological utility. Although not the focus of this study, this approach could help achieve adequate vitamin B12 intake, particularly in diets that limit or exclude animal products. Understanding this is crucial for making informed dietary decisions, especially for those at risk of B12 deficiency.