Bacterially-synthesized Folate Absorption Across the Large Intestine

Inclusion Criteria: 1. 18-65 years; 2. overall healthy Exclusion Criteria: 1. \<18 years or \>65 years 2. chronic disease (eg. history of hepatic, gastrointestinal, renal, vascular, haematological or neuropsychiatric disease) or surgery affecting gastrointestinal motility, pH or folate absorption/metabolism 3. regular use of medications affecting gastrointestinal pH, motility or folate absorption/metabolism (eg. antiacids, laxatives, phenytoin, sulfasalzine, phenobarbital, primidone, cimetidine, proton pump inhibitors \[such as Nexium\] and antibiotics \[such as Sulfonamides\] or nonsteroidal anti-inflammatory drugs \[NSAIDS, such as aspirin/ibuprofen\]) 4. consumption of \>1 drink/day of alcohol on a regular basis or current smoking (last 6 months) 5. planning a pregnancy, pregnant, breast feeding or the use of high-dose estrogen oral contraceptives/hormone replacement therapy 6. known sensitivity to sunscreens containing ultraviolet B filters and/or PABA 7. difficulty with swallowing large pills or providing venous blood samples