Does Salmon Provide Sufficient Vitamin B12?

The Effect of Fish Protein Supplementation on Micronutrient Levels

In this study, we investigated the impact of including a fish protein supplement derived from Atlantic salmon by-products in the daily diet for 8 weeks on blood micronutrient levels. The results showed that the supplementation of fish protein, which is rich in micronutrients and low in contaminants, led to increased concentrations of B12 and selenium in the blood of adults. To our knowledge, this is the first clinical trial to examine the effects of a fatty fish protein supplement on blood micronutrient levels.

No Impact on Vitamin D and Omega-3

Despite the fact that the study product was made from fatty fish, we did not observe any effects on vitamin D and omega-3 levels. Omega-3 is a well-established biomarker of fatty fish consumption, but most studies that have explored this relationship utilized higher doses of EPA and/or DHA than what was provided in the study product. Additionally, approximately one third of the participants in our study regularly consumed omega-3 supplements prior to and during the intervention. As the daily dose of the study product only provided a minimal amount of vitamin D, we did not expect an increase in its levels. Furthermore, since many participants were already using vitamin D supplements regularly, we did not anticipate a decrease in its levels. In a previous 8-week study involving adults with overweight or obesity, the intake of 750 g/week of salmon was not sufficient to prevent a decrease in vitamin D levels during autumn, despite a median intake of 11.9 μg/d, which exceeded the recommended daily intake of 10 µg/d.

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Consistent Findings on B12 and Selenium

Our findings regarding increased B12 and selenium concentrations are consistent with intervention studies that examined the intake of fish consumed as a whole filet. For instance, a randomized cross-over study involving overweight men found that the inclusion of herring in the diet led to an increase in B12 and selenium levels. In the same study, only cod increased selenium levels when compared to the control group. We previously conducted a post-prandial analysis of serum amino acids in healthy adults after consuming the study product and found a non-significant increase in most amino acid levels, thereby supporting the absorption of the fish protein supplement. B12 and selenium have high bioavailability, and their serum and plasma concentrations reflect dietary exposure.

Improved B12 Status

In addition to the increased serum B12 levels, participants in the salmon fish protein group also experienced an improvement in their B12 status during the intervention period. Although none of the participants in our study were found to be deficient in B12, 11% had low B12 status at the beginning of the study. However, it is worth noting that while serum B12 is a useful indicator of B12 status, it lacks sensitivity and specificity in diagnosing B12 deficiency. The worldwide prevalence of B12 deficiency remains uncertain, but it is estimated to exceed 40% in certain subpopulations, such as children, women of childbearing age, and older adults in low- and middle-income countries. In Europe, prevalence data on B12 deficiency primarily focus on the elderly and range from 5.9% in Norway to 24% in the Netherlands. Selenium status is less well-known, but several European countries report low selenium intake due to the generally low selenium content in European soil.

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Balancing the Benefits and Risks

A study involving preschool children found that consuming fatty fish three times a week for 16 weeks led to higher concentrations of hair mercury compared to meat. However, the exposure to fish mercury from the intervention did not exceed the tolerable weekly intake. Similarly, the weekly dose of capsules in our study also did not surpass the tolerable weekly intake. Benefit-risk assessments of seafood consistently conclude that the benefits outweigh the potential harmful effects of contaminants. Furthermore, the study product in our research contained ample amounts of selenium and zinc, which have the potential to counteract the toxic effects of heavy metals.

Study Strengths and Limitations

The strengths of our human intervention study on fish protein supplementation include its randomized controlled double-blind design. However, a limitation is that the power calculation was conducted for the primary endpoint in the original study and not for the outcomes in our study. To avoid overestimating the contribution of micronutrients to the reference intake from the daily dose of capsules, we used adult males as the reference population, as the reference intakes for most micronutrients are the same or higher for men than for women, except for iron. Additionally, the reference intakes for several micronutrients are higher during pregnancy and breastfeeding. Therefore, further assessments are necessary to evaluate the potential use of the study product in other populations.

Utilizing Fish By-Products for Optimal Nutrition

Low overall food intake or insufficient intake of foods of animal origin can lead to inadequate consumption of several nutrients present in the study product, such as vitamin B12, zinc, and selenium. To address this issue in vulnerable populations, one option is to utilize fish by-products as a dietary supplement or food ingredient. A study evaluating the sensory acceptance of bread baked with added fish flour demonstrated that the acceptance was equal to or better than that of bread without fish flour. Additionally, the bread with fish flour had higher protein, essential fatty acid, and mineral contents, but lower carbohydrate content.

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In Conclusion

In this study, we observed that the inclusion of a fish protein supplement derived from Atlantic salmon by-products in the daily diet for 8 weeks resulted in increased serum vitamin B12 and selenium concentrations. From a sustainability standpoint, by-products that contain high levels of micronutrients and low levels of contaminants, as demonstrated in our study, could serve as valuable dietary supplements or food ingredients in populations with suboptimal intake. Further exploration is warranted to fully understand the potential utilization of by-products from the aquaculture and fishery industry for human consumption.

Image source: Hook’d Up Bar and Grill