Vitamins play a vital role in many biochemical functions in the human body and are essential components for maintaining optimal health. There are two main groups of vitamins – those that are fat-soluble (easily stored in fat upon absorption) and those that are water-soluble (washed out and not easily stored). Although adequate intake of all vitamins is important, due to the transient nature of water-soluble vitamins, regular intake is required to avoid deficiency. The water-soluble vitamins include Vitamin C and Vitamin B complex (thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folate, and cobalamin).
Vitamin B complex and vitamin C are found in many foods, especially vegetables and fruits, as well as dairy, meat, legumes, peas, liver, eggs, and fortified grains and cereals. In addition to serving as cofactors in biochemical reactions, vitamin B complex is vital for normal body growth and development, healthy skin, properly functioning of nerves and the heart, and red blood cell formation. The overall lack of water-soluble vitamins is rare in North America, though it can present in alcohol use disorder, malabsorption syndromes, strict veganism, and malnourished states.
As stated above, the deficiency of water-soluble vitamins is rare in North America. However, deficiency may be a presenting feature in alcohol use disorder, malnourishment, and malabsorption syndromes such as short-bowel syndrome. In short-bowel syndrome, there is the removal of a large portion of the small intestine for various reasons such as Crohn disease, necrotizing enterocolitis, traumatic injury, obstruction, or cancer. The small bowel is the site of absorption for all vitamins, and if a significant portion gets surgically removed (typically enough so that less than or equal to 200 cm of bowel remains), the body will be unable to absorb vitamins adequately. Treatment includes vitamin supplementation.
Although it is tempting to simply obtain urine or serum levels of water-soluble vitamins, these reflect only presently circulating vitamin levels and are unable to approximate storage levels. Alternate forms of testing include immunoassays, chromatographic methods, chemical methods, high-pressure liquid chromatography, and capillary electrophoresis, depending on the vitamin being tested. For vitamin B12 (cyanocobalamin) and folate deficiency, as discussed below, it is essential to obtain a complete blood cell count (checking MCV, hematocrit, and hemoglobin) in addition to methylmalonic acid and homocysteine levels.
Vitamins are classified into two categories based on how they are absorbed and if they are stored. Water-soluble vitamins dissolve in water upon entering the body. Because of this, humans cannot store excess amounts of water-soluble vitamins for later use. There are nine water-soluble vitamins: the B vitamins -- folate, thiamine, riboflavin, niacin, pantothenic acid, biotin, vitamin B6 and vitamin B12 -- and vitamin C. Deficiency of any of these water-soluble vitamins results in a clinical syndrome that may result in severe morbidity and mortality.
|||Braga CB,Vannucchi H,Freire CM,Marchini JS,Jordão AA Jr,da Cunha SF, Serum vitamins in adult patients with short bowel syndrome receiving intermittent parenteral nutrition. JPEN. Journal of parenteral and enteral nutrition. 2011 Jul; [PubMed PMID: 21628608]|
|||McLeish SA,Burt K,Papasouliotis K, Analytical quality assessment and method comparison of immunoassays for the measurement of serum cobalamin and folate in dogs and cats. Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc. 2019 Jan 13; [PubMed PMID: 30638139]|
|||Ajob L,Brännström I,Ott M,Werneke U, [Wernicke encephalopathy]. Lakartidningen. 2017 Sep 12; [PubMed PMID: 30299532]|
|||Balasubramaniam S,Christodoulou J,Rahman S, Disorders of Riboflavin Metabolism. Journal of inherited metabolic disease. 2019 Jan 24; [PubMed PMID: 30680745]|
|||Banka SS,Thachil R,Levine A,Lin H,Kaafarani H,Lee J, Randomized controlled trial of different aspirin regimens for reduction of niacin-induced flushing. American journal of health-system pharmacy : AJHP : official journal of the American Society of Health-System Pharmacists. 2017 Jun 15; [PubMed PMID: 28432049]|
|||Li L,Feng L,Jiang WD,Jiang J,Wu P,Kuang SY,Tang L,Tang WN,Zhang YA,Zhou XQ,Liu Y, Dietary pantothenic acid deficiency and excess depress the growth, intestinal mucosal immune and physical functions by regulating NF-κB, TOR, Nrf2 and MLCK signaling pathways in grass carp (Ctenopharyngodon idella). Fish [PubMed PMID: 25957886]|
|||Bhargava M,Bhargava A, Pyridoxine for patients suffering from drug-susceptible tuberculosis in India. Public health action. 2018 Jun 21; [PubMed PMID: 29946528]|
|||Poissonnier LA,Simpson SJ,Dussutour A, Observations of the [PubMed PMID: 25392989]|
|||Sanvisens A,Zuluaga P,Pineda M,Fuster D,Bolao F,Juncà J,Tor J,Muga R, Folate deficiency in patients seeking treatment of alcohol use disorder. Drug and alcohol dependence. 2017 Nov 1; [PubMed PMID: 28988003]|
|||Nagao T,Hirokawa M, Diagnosis and treatment of macrocytic anemias in adults. Journal of general and family medicine. 2017 Oct; [PubMed PMID: 29264027]|
|||Khalife R,Grieco A,Khamisa K,Tinmouh A,McCudden C,Saidenberg E, Scurvy, an old story in a new time: The hematologist's experience. Blood cells, molecules [PubMed PMID: 30704850]|