How does aluminium amalgam work as a reducing agent?

I can't seem to find much information on this topic but how does aluminium amalgam work as a reducing agent? 


Could it be used to deoxygenate a carboxylic acid or amino acid to the corresponding alcohol or alkane? 


If not , why not?





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> Could aluminium amalgam be used to deoxygenate a carboxylic acid or amino acid to the corresponding alcohol or alkane? 
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No. Aluminium amalgam has been used to selectively reduce other groups in molecules containing a carboxylic acid group, while preserving the carboxylic acid group. 


See for example in [Industrial Organic Nitrogen Compounds](https://books.google.com/books?id=U7bQAAAAMAAJ&q=industrial+organic+nitrogen+compounds&dq=industrial+organic+nitrogen+compounds&hl=en&sa=X&ved=0CCoQ6AEwAGoVChMIyYy8xpLlyAIVAW0-Ch2CyAUk) at page 139:



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> Some pyridine-carboxylic acids have been reduced to the corresponding dihydropyridine-carboxylic acids with aluminium amalgam.
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See also the patent [Polyene carboxylic acids and esters and manufacture thereof](https://www.google.com/patents/US2175843) where aluminium amalgam is suggested as a mild reducing agent which preserves the carboxylic acid or ester group. 


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