Ferrous sulfate from Costco can lead to constipation, while ferrous fumarate is often converted to elemental iron. Additionally, ferrous gluconate is another option that some may consider. Ferrous fumarate combined with folic acid tablets can be beneficial, as noted in Malayalam resources. When looking for the best calcium citrate, it is essential to compare different supplements to find the most effective one. Remember, if you’re experiencing constipation from ferrous sulfate, you might want to try ferrous fumarate or ferrous gluconate instead. Ultimately, selecting the best calcium citrate can help enhance your overall health and well-being.