Biotin (also known as vitamin B7, vitamin H or coenzyme R) is a water-soluble vitamin in the B series, and as such, is needed for energy metabolism and plays a role in protein and fat metabolism, as well as maintaining the functionality of the nervous system. B7 is also necessary for normal embryonic growth.
Biotin in particular is essential for healthy skin, hair, liver, and eyes. The first two would explain why it’s also known as Vitamin Haut & Haar (skin and hair) in German, or vitamin H in general. B7 is thus often added to beauty products.
Being water-soluble, it is stored in the liver and heart in small quantities, but excess amounts will be expelled quickly. This means we need an adequate, ongoing (daily) supply to keep Biotin levels in the optimal range.
Biotin is actually synthesized by bacteria in the intestine, but further study is needed to clarify to what extent and how reliably i.e. on what factors this depends. For now, we should assume that we need to consume biotin from dietary sources.
This article will cover the recommended intake levels, why we want to reach those levels, the dangers of overconsumption, and which foods are richest in Vitamin B7. As a twist, we sort foods by their nutrient to calorie ratios, as opposed to the more common per 100 gram values. This is because per calorie values correct for water content, and satiation, but more on that later.
Note that all recommended intake figures below are based on the needs of a 31 year old non-pregnant, non-lactating woman on a 2000 kilocalorie diet. Your personal requirements may differ (wildly). One way to figure out your individual needs, including calories per day, is the FooDosage Nutrition Calculator. It’s free, by the way.
Recommended Biotin Intake
The recommended intake range for Vitamin B6, as set by the National Academy of Sciences:
Recommended minimum intake (RDA): 30 µg per day
Upper limit: –
“No adverse effects of biotin in humans or animals were found. This does not mean that there is no potential for adverse effects resulting from high intakes. Because data on the adverse effects of biotin are limited, caution may be warranted.”
In other words: Any amount of Biotin you can get from food sources is probably fine, but don’t overdo it with supplements.
Note that your personal requirements may differ depending on your age, sex, pregnancy-, and lactation status.
Importance of an Adequate Biotin Intake (Dangers of a Deficiency)
Biotin deficiencies are rare, but not impossible. Because raw egg whites contain a substance that inhibits biotin absorption, people like Rocky Balboa may be at an increased risk of a deficiency, the symptoms of which include:
- Hair loss
- Dry, scaly skin
- Cheilitis (Cracking in the corners of the mouth)
- Glossitis (swollen and painful tongue that is magenta in color)
- Dry eyes
- Loss of appetite
Risks of an Excessive Biotin Consumption (Side Effects)
As a water-soluble vitamin, excess B7 is usually expelled without complication. As opposed to fat soluble vitamins, liver toxicity is not a danger.
There is no evidence of adverse effects from the consumption of naturally occurring Biotin in foods, or supplements. It is, however, advisable to proceed with caution when it comes to supplements, as there is not enough data from studies yet to confirm any amounts are safe.
Top Biotin Food Sources
At this point, I would usually present you with the results of sorting and filtering my nutrition database to determine the foods with the highest concentrations of Biotin. Alas, Vitamin B7 is missing from the databas (not just mine) because we simply haven’t found a practical testing method yet. Some sparse data exists, but there is no way to tell if the “top foods” in question are actually rich in Biotin or not, compared to all untested foods.
As soon as more data becomes available, I will update this post.
Also, as mentioned earlier, there are bacteria in our intestines that actually produce Biotin, though it is as of yet inconclusive how high the amounts are, and what factors this production depends on, if any. For now, we should assume we require B7 from food sources (or supplements).
Among the few tested foods, the highest per 100 gram amounts of Biotin can be found in:
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Note that only cooked eggs, or egg yolks are a good source of Biotin, as raw egg whites contain a protein that inhibits Biotin absorption.
Apart from the above specific examples, good amount of biotin can generally be found in livers, meats, sardines, nuts, legumes, whole grains, cauliflower, bananas, and mushrooms.
Bon appetit 🙂