B-vitamins and vitamin C are not stored in the body, so deficient occurs easily.

Pellagra is the late-stage of niacin deficiency characterized by the 4 D’s: diarrhea, dermatitis, dementia, and death, which usually appear in that order.  May occur in people who are generally starved, long-term alcoholics and drug-users,  or in those receiving isoniazid therapy for TB. Occurs primarily in developing nations reliant on corn and corn products as major food staples, unless the corn is specially treated.  Traditionally, in Mexico corn is soaked in a lime solution prior to cooking tortillas.  This process frees the niacin in corn and prevents niacin deficiency (and pellagra) in that population. 

Intrinsic factor (IF) is required for proper B12 digestion and absorption.  Without IF, B12 deficiency can occur.  This is most commonly seen in people over the age of 60.  B12 deficiency can also occur in patients on long-term metformin therapy.

Buvat DR.  Use of Metformin Is a Cause of Vitamin B12 Deficiency. Am Fam Physician. 2004 Jan 15;69(2):264-266. http://www.aafp.org/afp/2004/0115/p264.html

Vitamin A deficiency is a public health problem in much of southeast Asia and Africa.  An estimated 250 million preschool children are vitamin A deficient and it is likely that in vitamin A deficient areas a substantial proportion of pregnant women is vitamin A deficient.  An estimated 250 000 to 500 000 vitamin A-deficient children become blind every year, half of them dying within 12 months of losing their sight.  Promoting and supporting breastfeeding is one good way to prevent vitamin A deficiency in babies.  WHO also recommends families grow gardens with vitamin A rich fruits (e.g., mango, cantaloupe)  and vegetables (e.g., sweet potatoes, pumpkins, carrots, kale, collards, butternut squash), and consume vitamin A fortified foods (e.g., breakfast cereals or milk). http://www.who.int/nutrition/topics/vad/en/index.html  

Cooking or consuming vitamin A rich foods with some oil or fat also helps improve absorption.