I think the low ferritin is typical, but I think you should still get the colonoscopy. If you get a clean bill of health there you probably won't need another one for 5 years.

The vitamin C is 500 mg. The proferrin is 10.5 mg per tablet. Expensive, but it worked for me.

No question that this is a major change to your digestion and it will affect the rest of your life. Your concerns:

malabsorption. If you have the DS you are going to malabsorb many nutrients, such as protein, fa****er, vitamins, minerals etc. You will perfectly absorb sugar. Malabsorption is one of the key reasons DS works. Its your responsibility to eat a diet high in protein, relatively low in carbs, and healthy in other nutrients to counteract some of the malabsorption. Some people have encountered bad surgeons and have had greater problems with getting enough nutrition than most, but it does happen.

vitamin deficiency. You are committing yourself to a lifetime of blood tests, at least annually and more often for some people. You will have probably have deficiencies that can be corrected by changing your doses in most cases. You are responsible for studying what vitamins and minerals you will need, because most nutritionists aren't very good when it comes to this surgery. The blood tests will pick up what you need to change. Most people have to tweak their doses over time. Those that stop doing blood tests and taking daily vitamins get into trouble.

other worrisome effects. For the first year or so I felt like my gut was ruling my life. If I made bad food choices, I paid for it in putrid gas, stinking poop and urgent diarrhea and multiple daily poops. I tested the limits sometimes and paid for it. Now, I know the limits, my gut is more accepting of food adventures and those problems are much less frequent. Something that I didn't appreciate starting out was that the cost of groceries would be higher because carbs are cheaper than protein, multiple daily vitamins are a new monthly expense for our budget, and health insurance copays and deductibles can add up for 20+ blood tests and doctors visits and infusions. The good news was that I was hired for a much better job with better benefits because I wasn't morbidly obese!

Don't take this surgery lightly. It's a lifetime decision. I had worsening diabetes and arthritis and that was the tipping point for doing it. Losing diabetes for me was worth every little post-op aggravation.

Expect some regain of your weight lost to the tune of 15-20%. Lose as much as you can the first year to have some buffer for that.

I am 13.5 years out and hover around 15% regain effortlessly and I don't diet. Every year, I usually do a detox of sorts when I find myself actually craving carbs. With that, I cut back simple carbs for a few weeks, focusing on meat veggies and cheese.

It is true we have an impaired ability to absorb iron. After having infusions every year or so starting about 5 years into my DS life, I have not needed an infusion for 2 years now because I changed the type of iron I take, heme iron (Proferrin), take it with vitamin C on an empty stomach, and do not take it with copper, calcium, zinc, or milk products. My last ferritin test was normal. In my low-ferritin years, I was advised to get a colonoscopy to rule out colon cancer, and it was completely normal. My obese sister currently has stage 4 colon cancer. The doc said losing large amounts of weight is protective for colon cancer and he felt I was now at low risk, despite my family history. Visible blood in the stool or black tar-like poop are more obvious symptoms of colon cancer, more than diarrhea or constipation.