Our bodies digest food using enzymes that have evolved to convert food here on Earth. Could we even possibly get nutrients from something we haven't evolved alongside? - Is it possible for humans to digest and live on food that isn't based on DNA or RNA?


closed as primarily opinion-based by anongoodnurse, fileunderwater, Amory, Chris, WYSIWYG Apr 3 '15 at 8:33

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ Welcome to biology.SE! I vote for not closing this question. Yes it is going to be speculative and probably breaks half of the "how to ask" rules (that you can find here) but an answer along the lines of non-carbon based life (e.g. sulfur-based organisms) might be interesting. $\endgroup$ – cagliari2005 Apr 2 '15 at 21:29
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    $\begingroup$ @cagliari2005 How do you want to answer this in a scientific way? $\endgroup$ – Chris Apr 2 '15 at 21:32
  • $\begingroup$ @Chris. Was reading the question as "Is there digestive enzymes for non-carbon based nutrients?". Someone might know something about that. $\endgroup$ – cagliari2005 Apr 2 '15 at 21:34
  • $\begingroup$ I was thinking of both carbon and non carbon based life - could we even possibly get nutrients from something we haven't evolved 'with'. $\endgroup$ – jane Apr 2 '15 at 21:36
  • $\begingroup$ Then you should edit your question and add these information. $\endgroup$ – Chris Apr 2 '15 at 21:40

This might be flagged for being somewhat of a subjective question, but to survey human diet:

Mnemonic SPONCH can be used to sum up the necessary building blocks of life, in the elements Sulfur, Phosphorus, Oxygen, Nitrogen, Carbon, Hydrogen. There are others, trace elements, which are necessary and come from diet (selenium, for example). These elements are used in building our biological macromolecules: Carbohydrates, lipids, nucleic acids, and proteins. The molecular interactions between these macromolecules, their cofactors, etc. are essential for life. Some of these compounds, however, can't be made in the human body from scratch; hence essential amino acids, and the necessity to consume foods which provide metals, carbohydrates, fats/triglycerides, etc.

So, at this point our body is optimized to incorporate terrestrial foods. Sometimes, though, we can see that the body will sometimes accept analogs to normal compounds, although this is often to disastrous effect (like chemotherapy in cancer). The real question, then, would be: does said extraterrestrial food compose of necessary biological elements or analogs in a way our body can actually use this food for sustenance? That, however, is 100% speculation as we have no reference in even a single case to base our assumptions.

  • $\begingroup$ Thanks for your reply! I've altered the question to try to make it less opinion based. Any extra thoughts based on the change? $\endgroup$ – jane Apr 3 '15 at 10:30
  • $\begingroup$ @jenga So, here's my thoughts, in part: We can only extract energy from sources we can break apart, absorb, and transport efficiently. We have specific proteins that get this job done. If we have an enzyme to do the job, the job gets done, and if we don't.. well, vice versa. How can we make sources of nutrients we wouldn't otherwise be able to process usable? Perhaps a system of ingesting exogenous enzyme.. but it's again mostly speculation. $\endgroup$ – CKM Apr 3 '15 at 20:08

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