Well, I'm certainly not an expert in this area. All that I know is from medical websites, and they've said nothing about different shades of brown. However, I would hypothasize that perhaps you have a lower than normal level of beneficial bacteria in your colon. Then again, maybe it's normal to have pale brown feces. However, after taking lots of bifidus and acidophilus bacteria supplements my feces turned dark brown.
Last year, after too many courses of Antibiotics , my stool became bright yellow and sometimes green! Also, my urine was always completely clear! I've since learned that the yellow color of urine is actually produced by the same bacteria that turn feces brown. The healthy bacteria produce B vitmains in your bowel, which are then absorbed. The excess of B vitamins (above what your body needs) is then excreted in the urine. However, with lower levels of these bacteria, the more clear your urine well become.
My suggestion would be to take a supplement called "Acidophilus Pearls" by Enzymatic Therapy, or "Bifa-15" by Eden Foods. You can find them at some health food stores and online stores. I've only tried the Acidophilus Pearls, and they are VERY effective. They are manufactured by a Japanese company, and they have a lot of research behind them. They contain bifidus bacteria (which is what turns your stools brown), and acidophilus bacteria as well. I (and many other people I've talked to on message boards) were never able to restore their intestinal flora until they started using one of these two probiotics (and I tried lots of others.) Bifa-15 is very expensive, so I haven't tried it. But the Acidophilus Pearls have worked very well, and they use a similar manufacturing process... Also, eating yogurt is always helpful...
From the Enzymatic Therapy www.enzy.com website:
>>Acidophilus Pearls™ use a proprietary coating process called True Delivery™ Technology. This technology produces a seamless, three-layered pearl that guarantees delivery of the probiotics into the intestine where they are released intact and healthy to increase intestinal flora.†
The inner layer is a paste of healthy probiotics suspended in a protective oil mixture. The second layer seals the microflora in the capsule, and protects them from air and moisture. Probiotics are anaerobic organisms and the presence of oxygen can actually injure, weaken, or kill them.
The third layer is a patented coating that protects the probiotics from the acid environment of the stomach, so they can successfully reach the intestine where they are needed. Probiotic microflora are not resistant to stomach acids, so the outermost layer of the pearl is specially developed to dissolve only in the alkaline environment of the intestines.
A scientific study showed patented Acidophilus Pearls™ delivered up to 900% more intact microflora to the intestine in relation to label claim than 4 leading competitors, including those with enteric coatings.