Asparagus Cancer Connection?

I will let the headlines speak for themselves:

  • Asparagus – a cancer cure?
  • Spread of breast cancer linked to compound in asparagus
  • Will asparagus cure cancer?
  • Asparagus will not give you cancer
  • Are asparagus and cancer really enemies?
  • Could asparagus increase your risk for breast cancer
  • Does asparagus help with cancer prevention?
  • Should I stop eating asparagus to halt cancer’s spread?

Confused?  Not that long ago, asparagus was supposed to cure cancer.  Now quite the opposite.  The headlines last week were all about a study linking an amino acid found in asparagus to the spread of a certain type of breast cancer in mice.  When cancer cells metastasize beyond the original tumor site, treatment becomes far more difficult.  Obviously a dietary substance that encourages that cancer cell behavior is highly undesirable.  So what’s the story behind all the latest headline hysteria?

The substance in question — asparagine —  is an amino acid, a building block of all proteins.  It’s not an essential amino acid to humans, meaning our bodies can synthesize asparagine from other amino acids as needed.  And in fact, humans manufacture plenty of asparagine every day for that purpose.  Unfortunately it turns out certain cancer cells like asparagine, too.  For some reason, asparagine encourages those cells to metastasize to other tissues.  In the case of a particular line of breast cancer cells, mice fed low asparagine diets did not experience metastases.  Which led directly to the anti-asparagus hysteria.  Why asparagus?  The amino acid asparagine is found in all high protein foods, from meat to dairy to high protein plant foods.  It happens to be higher in asparagus than some other vegetables, but high protein foods are the main source.  Why wasn’t beef or cheese mentioned in these main stream media reports?  Probably because lazy “journalists” thought the words asparagus and asparagine were interchangeable.

There’s another twist rarely mentioned: cancer specialists already know about the effect of asparagine on cancer cells.  In fact one common anti-cancer drug blocks asparagine so cancer cells can’t use it.  The scientists who did this study were more interested in evidence for use of anti-asparagine chemotherapy drugs than in telling people to give up asparagus.  Given that (1) protein foods contain asparagine and (2) humans also synthesize asparagine, avoiding only asparagus and hoping for a miracle cure seems rather pointless.  How much asparagus do people eat anyway?  Do cancer patients even want to eat asparagus, given the rather bitter flavor?

If you’re hoping to find good data on the amount of asparagine in foods, good luck.  Even the very large and comprehensive USDA nutrient database does not list asparagine, although all of the essential amino acids are listed.  If you had breast cancer and wanted to cut back on asparagine, you’d have to avoid all high protein foods, eating mostly fruit, a few low protein vegetables and perhaps refined grains, fats and perhaps sugary foods like candy.  Protein deficiency is one likely outcome, whether or not your cancer spreads.

The most effective way to deal with the asparagine-cancer cell connection is drugs that block asparagine so the cancer cells are starved of it, so to speak.  Cancer experts may also include lower asparagine diets as part of therapy someday, when such a diet can be better defined.  Perhaps some company will devise special medical foods that are low asparagine, to be used during treatment.  And you might be advised to avoid vegetables like asparagus and many high protein foods as well.  Simply avoiding asparagus isn’t going to be very helpful.  And there is nothing in any of these studies to suggest that either asparagine or asparagus cause cancer.

Perhaps the most important Take Away: “journalists” who don’t understand medical research and write this misleading nonsense to attract readers are not helping anyone.  As I’ve said before, don’t get your nutrition news from headlines.

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