14.9: Biotin
- Page ID
- 58110
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Biotin is made by our intestinal bacteria. And the amounts they make seem to be generally greater than our requirements. Deficiencies have been seen only under the most unusual of conditions. So, as with pantothenic acid, there’s little dietary concern about biotin.
In the 1930s, biotin was found to be a vitamin for yeast. So, in reference to the fact that the life of yeast requires it, the vitamin was christened biotin from the Greek bios, meaning life.
The essentiality of biotin for humans was determined with the help of raw egg white. In fact, for a brief time, biotin was known as “anti-egg-white-injury factor.” The reason is that raw egg white contains a substance, called avidin, which binds biotin and prevents its absorption from the intestine.
The first studies produced biotin deficiencies by feeding subjects a low-biotin, 15 to 20% egg-white diet. This required the raw whites of about 24 eggs day for each volunteer. Cooking destroys the avidin (as a protein, avidin is denatured by cooking). For the anti-biotin effect, the egg white had to be raw.
The symptoms found for biotin deficiency are good grist for the faddist mill. They include such vague and common signs as skin problems, lost appetite, depression, sleeplessness, and muscle aches—symptoms which also happen to be popular in the marketing of dietary supplements. Biotin deficiencies are practically nonexistent unless deliberately created, it’s a rare condition indeed that is relieved by biotin. It would be rare, indeed, that any of the forementioned conditions would be relieved by biotin.
There are rare genetic defects in biotin metabolism that can be overcome by massive doses of biotin.
As with pantothenic acid, the virtual absence of naturally-occurring deficiency signs doesn’t lessen the importance of biotin in body processes. Biotin coenzymes are used widely. They take part in the making of fatty acids, the breaking down of nutrients to yield energy, and in the producing of some amino acids. They are also necessary in some reactions which require Coenzyme A (the pantothenic-acid coenzyme).
The functions of biotin coenzymes seem to be closely related to those of vitamin B6, folate, and vitamin B12. In cases of severe malnutrition, it’s possible that biotin deficiencies are hidden among the more evident signs of other deficiencies.