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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 52 year old female patient complains of pain in her abdomen. General examination reveals BMI 30 Kg/m2. X-ray examination reveals osteoporotic changes. Doctor suspects impaired absorption of calcium in this patient. All of the following could be the reason for this except:
assistant
The correct answer is  Phytic acid (inositol hexaphosphate) in cereals binds calcium in the intestinal lumen, preventing its absorption. Other minerals, including zinc are also chelated by phytate.
This is mainly a problem among people who consume large amounts of unleavened whole-wheat products; yeast contains an enzyme, phytase, that dephosphorylates phytate, so rendering it inactive.
High concentrations of fatty acids in the intestinal lumen, as a result of impaired fat absorption, can also reduce calcium absorption by forming insoluble calcium salts; a high intake of oxalate can sometimes cause deficiency since calcium oxalate is insoluble.

Reference:  HARPERS ILLUSTRATED BIOCHEMISTRY30th, Page No: 541