Vitamin B12 deficiency can affect the nervous system at all levels, from central to peripheral. However, when patients present with rapidly progressive dementia, inflammatory or infective causes are considered more likely. Our patient presented with a rapidly progressive Fronto Temporal syndrome who had a unique food faddism for non-vegetarian food from his vegetarian habit. He had a very poor MMSE score of 7/31, indicative of poor outcome generally. Our patient had extensive hyper pigmentation of skin of the back, both legs and extensor surface of the upper limb, and lower limbs and axilla but not the classical knuckle pigmentation. Investigations showed megaloblastic anemia with hyper-segmented neutrophils; Vitamin B12 was 297pg/ml with normal homocysteine levels. MRI Brain showed bilateral T2W and FLAIR periventricular hyperintensities, dorsal column signal changes in the cervical spine. With six weeks of treatment, his MMSE improved to 30/31, and he resumed routine work. It was interesting to note the new food faddism to non-vegetarian food and less typical skin changes.