Color-Blind People May Not Notice That They’re Bleeding!

Unusu­al bleed­ing or dis­charge is one of the clas­sic sev­en warn­ing signs of can­cer. Blood in the stool could be a sign of colon can­cer. It’s also a com­mon sign of diver­tic­u­lo­sis of the colon. Unfor­tu­nate­ly, peo­ple with red-green col­or blind­ness might not notice that they are pass­ing blood with their bow­el move­ments. Here’s an arti­cle about three col­or-blind men who didn’t notice that they were pass­ing blood with their stool. One of them had colon can­cer. Anoth­er had diver­tic­u­lo­sis; he was bleed­ing heav­i­ly but mis­took the blood for diar­rhea. The third patient had bleed­ing from hem­or­rhoids. The men didn’t notice the blood because they can’t see the col­or red. For­tu­nate­ly, their wives saw the blood and had them seek med­ical atten­tion.

Red-green col­or-blind­ness is far more com­mon in men than in women. That’s because men have only one copy of the X chro­mo­some in each of their cells. If one of the genes on their X chro­mo­some is defec­tive, they don’t have a spare X chro­mo­some to serve as a back­up. Women don’t get red-green col­or-blind­ness unless they inher­it a defec­tive ver­sion of the gene from both par­ents. That’s why women rarely get red-green col­or-blind­ness, but even a woman with nor­mal col­or vision can have col­or-blind sons.

For­tu­nate­ly, the intesti­nal prob­lems that these men had are pre­ventable by diet. Colon can­cer is rare in pop­u­la­tions that eat a low-fat, plant-based diet. So are diver­tic­u­lo­sis and hem­or­rhoids, which result from con­sti­pa­tion.

Note: Since I wrote this post, glass­es that cor­rect for red-green col­or­blind­ness have become avail­able!

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