Scurvy believed to be more effective because they were more acidic. It was the acid, not the (then-unknown) Vitamin C that was believed to cure scurvy. In fact, the West Indian limes were significantly lower in Vitamin C than the previous lemons and further were not served fresh but rather as lime juice, which had been exposed to light and air, and piped through copper tubing, all of which significantly reduced the Vitamin C. Indeed, a 1918 animal experiment using representative samples of the Navy and Merchant Marine's lime juice showed that it had virtually no antiscorbutic power at all. The
Vitamin B12 deficiency anemia its first step, of taking an oral dose of radiolabelled vitamin B, followed by quantitation of the vitamin in the patient's urine over a 24-hour period via measurement of the radioactivity. A second step of the test repeats the regimen and procedure of the first step, with the addition of oral intrinsic factor. A patient with PA presents lower than normal amounts of intrinsic factor; hence, addition of intrinsic factor in the second step results in an increase in vitamin B absorption (over the baseline established in the first). The Schilling test distinguished PA from other forms of B deficiency,