If you keep cod liver oil in the fridge, you may notice it becomes cloudy or develops a ‘bitty’ suspension in the oil. Whilst this might look odd, it is normal. These solids are called stearin and are long-chain fatty acids that solidify at low temperatures, similar to how coconut oil is liquid when warm but solidifies on a cold day.
Stearin
Stearin is a broad term that refers to the solid fatty fractions in an oil. It fully solidifies at approximately -7°C, but small solids can appear from around 4°C, forming visible bits in cod liver oil. Conventionally produced cod liver oil removes stearin for aesthetic reasons. However, stearin is an important part of what makes cod liver oil so nutritious and can make up to 20% of raw cod liver oil.
Health Benefits of stearin
Soluble nutrients
Due to the long-chain fatty acids in stearin, it retains a significant amount of fat-soluble nutrients, including vitamin D3. Removing stearin from cod liver oil also removes these nutrients. In the case of vitamin D, it is typically replaced with vitamin D from another source, but this can be nutritionally inferior. Many of the other nutrients held in the stearin, such as antioxidants and vitamin co-factors, are not replaced, despite their benefits to the body.
Ironically, the stearin removed from conventionally produced cod liver oil is often repurposed as an animal supplement to prevent vitamin D deficiency diseases such as rickets.
Stearin
Unlike the omega-3 fatty acids found in cod liver oil, the fats that make up stearin are much less researched. Stearin consists of a wide range of fats, and some evidence suggests that these long-chain fatty acids may contribute to gut health, cardiovascular health, and brain function. These benefits are often associated with cod liver oil but are typically attributed only to omega-3 fatty acids.
Summary
Stearin is a fraction of cod liver oil made up of long-chain fatty acids that become solid at cold temperatures. Conventional cod liver oil removes this stearin for aesthetic reasons, but at the cost of its nutritional value. Stearin contains many of the important fat-soluble nutrients that contribute to cod liver oil’s health benefits, such as vitamin D3. The fats in stearin itself may also offer additional nutritional benefits, but more research is needed.