Sea lettuce packs 29 times more vitamin B12 than beef, research finds

Scientists have discovered that sea lettuce is a rich source of true vitamin B12. The protein extracted as a dried ingredient contained 29 times more B12 than cooked beef. 

Vitamin B12 is largely found in animal products and is essential for the functioning of the nervous and immune systems, the production of red blood cells, and DNA synthesis. 

Ulva fenestrata and Palmaria palmata, but not dulse or sugar kelp, were found to contain vitamin B12. The study found that blanching (60 °C, 3 min) reduced B12 content by 45% (Ulva) while retaining the claim threshold. 

Additionally, sea lettuce storage at room temperature in the dark for up to 4.8 months preserves B12 content. Oven-drying, freeze-drying, and soaking it in freshwater also preserve the vitamin.

“Protein extraction via a new method resulted in a dried ingredient containing 60% more B12 than untreated Ulva and 29 times more than red meat on a moisture-equivalent basis. All Ulva samples — including the protein ingredient — qualified for the EU nutritional claim ‘High in Vitamin B12,’” reveals the paper.

“However, considerable losses of B12 were observed during the preparation of the protein ingredient.” But, just 2.9 grams of the Ulva protein powder would meet the recommended daily vitamin B12 intake. 

Spotlight on seaweed

Scientists point out that plant-based alternatives to animal-based foods are more environmentally friendly, with dramatic cuts to greenhouse gas emissions and land use. However, the shift risks lower levels of vitamin B12 intake.

Sea lettuce protein extract contains 29 times more vitamin B12 than cooked red meat.They explain that seaweeds are unable to synthesize vitamin B12, but some do contain it due to symbiotic relationships with cobalamin-producing bacteria.

The study, published in Food Chemistry, suggests: “Integrating seaweed into plant-based diets — whether as a whole food or a protein ingredient — can help maintain a positive environmental impact of these diets and, in parallel, contribute to the intake of vitamin B12.”

Last year, researchers cultivated the algae spirulina to produce carbon-neutral biomass with biologically active vitamin B12 in levels similar to beef.

Addressing data gap

Previous studies suggest that Ulva sp. (4.7 g dry weight) and Porphyra sp. (3.0–7.7 g dry weight) meet the adequate intake of 4 μg of B12 daily set by the EU Food Safety Authority. However, the researchers note that tools (microbiological assays) used to measure the active vitamin can overestimate the content.

Storing sea lettuce in the dark at room temperature for nearly five months preserves its B12 levels.They note highly selective and sensitive liquid chromatography (LC)-based methods are recommended to measure biologically active vitamin B12. But this technique has only been used for U. intestinalis, signaling a gap in data.

“Besides the limited data on vitamin B12 in seaweed, it remains unclear how its content is affected by industrial practices, such as seaweed post-harvest and preservation treatments as well as storage,” the paper flags.

“Gaining insights into such effects would help the seaweed industry to ensure optimal preservation of B12 in the produced biomasses. Regarding post-harvest treatments of seaweed, soaking is commonly used to remove sand and epiphytes. Meanwhile, blanching is primarily applied in kelp species to lower iodine content to levels safer for consumption.”

According to this study, B12 was equally preserved by oven-drying and freeze-drying, and it was also preserved by dark storage for up to 4.8 months, irrespective of the drying method. 

“Altogether, food products developed from whole U. fenestrata and its protein ingredients show strong potential as dietary sources of vitamin B12. Nevertheless, bioavailability trials are necessary to determine the extent to which vitamin B12 from these products is absorbed and reaches systemic circulation,” concludes the study.