Amongst the B group of vitamins, biotin is often overlooked, possibly because it isn’t numbered like its more familiar stable mates such as vitamin B6 and vitamin B12. If biotin were numbered, it would be B7, although interestingly it was once also known as vitamin H.
In essence, biotin is a coenzyme - a helper molecule if you like – as it assists enzymes that enable the body to process fats, carbohydrates and proteins. It contributes to normal macronutrients metabolism and so plays an important role in deriving energy from the food we eat.
In addition, biotin is important for normal functioning of the nervous system. It helps to maintain the myelin sheath - that’s the protective covering around nerve fibres — which is crucial for the efficient transmission of signals in the brain and body. There's also evidence to suggest that biotin contributes to blood sugar regulation, particularly in supporting enzymes involved in glucose metabolism.
Perhaps most famously, biotin is associated with healthy hair, skin and nails. This connection – its role in the normal maintenance of skin and hair – is why its included in supplements marketed as such, although biotin is often already in a multi-vitamin anyway.
A deficiency in biotin, although rare, can lead to symptoms such as hair thinning, brittle nails, and scaly skin - particularly around the eyes, nose, and mouth. So, while biotin supplements won’t necessarily transform your appearance if your levels are already sufficient, ensuring you have enough in your diet is certainly a good idea for overall skin and hair health. That said, sometimes it helps to take a supplement in addition when you have specific goals in mind.
Biotin is present in a wide variety of commonly eaten foods. Eggs are one of the richest sources, particularly the yolk - although, interestingly, raw egg whites contain a protein called avidin that binds to biotin and prevents its absorption. This is generally only an issue for people who consume raw egg whites in large amounts over time.
Other good sources include liver, nuts (especially almonds and walnuts), seeds, salmon, dairy products, and legumes such as lentils and soybeans. Whole grains also provide a decent amount of biotin, though the refining process can somewhat reduce inherent levels. For those following a plant-based diet, a mix of nuts, seeds, pulses, and whole grains will usually provide more than adequate amounts.
It’s worth noting that the body’s gut bacteria can also produce biotin in small amounts, though it's unclear how much of this is absorbed and utilised.
As ever, the goal isn’t to chase one nutrient in isolation, but to focus on the overall pattern of eating. Biotin plays its part, quietly and efficiently - and like so many aspects of nutrition, it’s the sum of the parts that really matters.