Vitamin B1 (thiamine) deficiency in wildlife was previously described as a problem among certain species within relatively limited geographical areas. Now, researchers from Stockholm University and several other research institutions in Europe and North America have shown that thiamine deficiency is far more widespread than previously thought. The results were recently published in the highly ranked science journal Scientific Reports.

By studying thousands of mussels, birds and fish in 45 areas in the Northern Hemisphere, the researchers have found that the problem of thiamine deficiency in wildlife is much more extensive than previously thought. The research pays special attention to the high prevalence of such effects of thiamine deficiency that, though not directly fatal, cause poor health and reproductive problems. This impact is very serious, as these effects will cause populations to decline and disappear in the long term. Another important conclusion is that thiamine deficiency appears episodically, i.e. with varying intensity in time and space.

“The symptoms often appear in an area for a period of time, perhaps a couple of years, after which they disappear for some time and then reappear,” says Professor Lennart Balk, who coordinated the research.

Thiamine deficiency in the studied species – blue mussels, common eiders, American and European eels, Atlantic salmon and sea trout – has been proven using chemical and biochemical analysis. Examples of effects that are not directly fatal, but have been associated with thiamine deficiency, include reduced growth, changes in organ size, general decline in nutritional status, poor blood values, increased likelihood of infections, altered behaviour, impaired swimming ability and very serious effects on reproductive health. The link between these effects and thiamine deficiency has previously been demonstrated in laboratory experiments, but now also in wildlife in the field. In addition, previously published findings have been revisited in light of the new results, which has further confirmed the presence of thiamine deficiency in the Pacific Ocean, North America, the Atlantic Ocean and Northern Europe.

The ultimate aim of the research is to find the underlying cause of thiamine deficiency, i.e. how it has appeared in our ecosystems. The presented results constitute the necessary knowledge to move forward and explore possible biochemical mechanisms.

“We cannot rule out the possibility that the observed thiamine deficiency is so serious that it contributes significantly to the ongoing global extinction of many animal species,” says Lennart Balk. Other researchers have identified this loss of biological diversity as the most serious of all threats to life on Earth today.

The article ”Widespread Episodic Thiamine Deficiency in Northern Hemisphere Wildlife” (DOI: 10.1038/srep38821), written by researchers from 5 countries and 13 universities and other research institutions under the leadership of Professor Lennart Balk from Stockholm University, has been published in Scientific Reports within the Nature Publishing Group (NPG) and is freely available at:

Most of the research has been funded by the BalticSea2020 foundation and the Engkvist foundations.