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Type of vitamin D in salmon found to be better for immune system

A portion of Scottish salmon can provide up to 71% of a person's daily vitamin D requirement.
A portion of Scottish salmon can provide up to 71% of a person's daily vitamin D requirement.

Researchers have discovered that the type of vitamin D found in oily fish such as salmon helps boost the human immune system against bacteria and viruses.

A study said vitamin D₃ from animal-based foods is more effective at boosting vitamin D levels in the blood than D₂, which is found in plant foods like mushrooms and added to some brands of bread, cereal and yogurts.

The three-month research, conducted in British women and published in the journal Frontiers in Immunology, also found that vitamin D₃ activated genes linked with “interferon activity” which is a crucial part of the immune system’s defence against viruses and disease-causing bacteria. It reported that vitamin D₂ had the opposite effect and instead appeared to suppress the interferon genes. 

A healthy choice

A recent analysis by the University of Stirling’s Nutritional Analytical Service collected 15 samples of farm-raised Scottish salmon, representative of typical Scottish produce, and put them through a variety of laboratory tests to assess nutrient levels.

The percentages of an adult’s daily recommendation from one serving were as high as 71% for vitamin D.

The study also showed salmon has 4.5 times the daily recommendation for special omega-3 fats found in marine foods, more than half our protein needs, and 42% of the vitamin E recommendation. 

The new figures for vitamin D and omega-3s were 7% to 8% higher than in previous tests conducted in 2003 and 2020. 

Despite the benefits of eating fish, a study commissioned by Food Standards Scotland and conducted by Abertay University found that Scots are eating less than a quarter of the recommended serving of oily fish per week.

The average intake was 33g per person per week – 76 % lower than the 140g serving set out in the Scottish Government’s Scottish Dietary Goals.

Vitamin deficiency

Dietitian Dr Carrie Ruxton said: “For years, we’ve believed that the two main types of vitamin D are equal, but this study throws that into doubt and suggests that vitamin D₃ is more effective at preparing our immune system to tackle the threat of viruses and bacteria. 

“Many people in the UK don’t get enough vitamin D from their diets, or from regular, safe exposure to summer sunshine. That’s why around a quarter of Scots are deficient in vitamin D, according to government estimates.

“A single portion of Scottish salmon provides more than 70% of our daily vitamin D recommendation, and is also high in protein and other important nutrients.

“Experts recommend that we all have one serving of oily fish a week and take a vitamin D supplement in autumn and winter to ensure we are meeting our vitamin D needs.”

Nutritional value

Tavish Scott, chief executive of trade body Salmon Scotland, said: “This latest study from Frontiers in Immunology adds to our knowledge that salmon is healthier than ever, showing that the type of vitamin D₃ found in salmon can help enable a critical immune system response to bacterial and viral infections. 

“Recent findings indicating an increase in the nutritional value of farm-raised salmon have coincided with year-on-year improvements in the way producers are rearing and feeding their stock.”