In an ideal world, we would get everything our body needs from food alone. But when appetite is reduced, whether due to surgery, injections, or major lifestyle changes, it can be difficult to consume enough essential fatty acids, vitamins, and nutrients consistently.

Vitamin D is one of the most important nutrients for human health, yet around 1 billion people worldwide are deficient, and in the UK, this rises dramatically during autumn and winter. Sunlight, lifestyle, hormones, weight, genetics, work patterns and even pollution all determine how much vitamin D our body can make.