Intestines and absorption of vitamins

Vitamins have important regulatory functions in the body.  They participate in various metabolic processes inside cells. If our body is deprived of the right amount of vitamins, it is not able to function. Food in well-balanced diet is the main source of vitamins. Some vitamins are produced by our own cells, such as vitamin D in the skin, or by bacteria in our intestines in case of vitamins B and K.

Absorption of digestion products mainly occurs in the small intestine with the participation of the mucosa. Mucosa is equipped with numerous intestinal villi which are small, finger-like projections that extend into the lumen of the small intestine. Each villus contains blood vessels and lymphatic vessels, thanks to which nutrients are absorbed into the circulatory system and delivered to the farthest parts of the body.

Fatty acids and fat-soluble vitamins, i.e. A, D, E, K, are absorbed into the lymphatic vessels of the small intestine, while amino acids, vitamin B12 and folic acid get into its blood vessels. Other B group vitamins, vitamin K and biotin are absorbed in the large intestine.

Sometimes the absorption of nutrients in the intestines does not occur properly. This can be caused by:

  • inflammation of the intestinal mucosa, 
  • atrophy of the intestinal villi e.g. in celiac disease, 
  • inadequate food combination, 
  • food intolerance, 
  • bacterial flora disorders, 
  • chronic diarrhea.

The correct anatomical structure of the intestinal mucosa along with proper motility and vascularization of the intestine is very important. The surface of intestinal absorption is significantly increased by intestinal villi and circular folds, which differ on individual sections of the small intestine and may change depending on the diet, composition of the intestinal microbiome and malabsorption syndrome.

We can make absorption of vitamins more efficient by improving the condition of the intestinal mucosa, using a diverse, balanced diet, as well as limiting the intake of certain drugs, stimulants and other substances. The correct microbiome and reduction of inflammation of the intestines are also of great importance.

 

Bibliography:

1. Marchesi, J. R; Adams, D. H; Fava, F; Hermes, G. D; Hirschfield, G. M; Hold, G; Quraishi, M. N; Kinross, J; Smidt, H; Tuohy, K. M; Thomas, L. V; Zoetendal, E. G; Hart, A (2015). “The gut microbiota and host health: A new clinical frontier”
2. Sánchez de Medina, Fermín; Romero-Calvo, Isabel; Mascaraque, Cristina; Martínez-Augustin, Olga (2014-12-01). “Intestinal inflammation and mucosal barrier function”. Inflammatory Bowel Diseases.
3. Maton, Anthea; Jean Hopkins; Charles William McLaughlin; Susan Johnson; Maryanna Quon Warner; David LaHart; Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall.
4. Gerald F. Combs, Jr.James P. McClungAcademic Press, 15 gru 2016 ” The VitaminsFundamental Aspects in Nutrition and Health”