Tag: Vitamin A
Written By: Maria Vardapetyan, Eric Baghdasaryan, Osheen Abnous
Vitamins are chemicals that facilitate many processes in the human body such as blood clot formation, good vision, fight infections etc. There are two classes of vitamins. Water soluble vitamins and fat soluble vitamins. Water soluble vitamins dissolve in water. This makes it possible for them to be absorbed through all mucous membranes. Fat soluble vitamins on the other hand do not dissolve or pass through mucous membranes. Fat-soluble vitamins are absorbed in the intestine along with fats in the diet. These vitamins have the ability to be stored in the fat tissues of the human body. Water-soluble vitamins are not stored in the body and have to be taken in daily with the food and dietary supplements. Solubility of a vitamin is not a function of its physical state. There are fat soluble vitamins that have a liquid form and almost all of the water soluble vitamins come in form of pills or powders.
In this article, we are going to focus on fat soluble vitamins. They are all complex molecules made of carbon, hydrogen, and oxygen in different arrangements (see figures 1, 2, 3 and 4). These fat soluble vitamins are vitamin A, D, E and K.
Vitamin A has a major role in vision, immune function, cell growth, and maintenance of organs such as heart, kidneys, lungs, etc. It plays a pivotal role in the health of our eyes, specifically the retina1. Rhodopsin protein, a major protein that has the leading role in the process of vision, is found in the retina where it allows us to perceive light. This protein requires vitamin A to function properly. Without vitamin A, rhodopsin cannot sense light and thus cannot initiate the process by which vision occurs.
Figure 1: Chemical structure of Vitamin A molecule
Vitamin D regulates different chemical reactions that are associated with bones, muscles, and the immune system. The simplified way it does this regulation is it helps absorb calcium from dietary nutrients which in turn strengthens the bones, helps neurons exchange signals to move muscles and helps the immune system to fight against viruses and bacteria2.
Figure 2: Chemical structure of Vitamin D molecule
Vitamin E acts as an antioxidant. Antioxidants are naturally occurring chemicals that neutralize toxic byproducts of many chemical reactions in the human body. When food is consumed and digested, the human body converts it into energy. As a result of metabolism free radicals (toxic byproducts) are formed and are neutralized with the help of vitamin E. In addition, free radicals are also in the environment. Furthermore, vitamin E stimulates the immune system to fight against bacteria and viruses3.
Figure 3: Chemical structure of Vitamin E molecule
Vitamin K can be obtained from food and dietary supplements. There are two forms of vitamin K: phylloquinone (Vitamin K1), which is found in spinach, kale and other greens and menaquinone-4 (Vitamin K2), which is found in animal products. Vitamin K1 is involved in blood clotting, and Vitamin K2 is involved in bone tissue building. Vitamin K1 is the main Vitamin K in human diet (75-90% of all vitamin K consumed), however, it is poorly absorbed in the body4,5.
Figure 4: Chemical structures of Vitamin K1 and K2 molecules
Absorption of fat soluble vitamins
Polarity describes the inherent charge(positive or negative) or lack of charge for any given substance or molecule. Molecules that are charged are referred to as “polar”, while those that lack charge are “nonpolar”. When discussing solubility, it is important to remember the phrase “like dissolves like”. That means polar (charged) substances like to interact with a polar environment like water, since water contains a slight negative charge. Hence, charged substances are water-soluble. Nonpolar substances on the other hand readily interact with nonpolar environments such as fat, which contains no charge. Therefore, molecules that lack a charge such as vitamins A, D, E, and K are referred to as fat soluble.
Due to their water fearing nature, these fat soluble vitamins cannot simply be absorbed directly into the bloodstream (which is mostly water) like the sugars and amino acids in our diet. As their name suggests, these fat soluble vitamins like to be embedded in fatty droplets, which facilitate their absorption in the following way. Fat soluble vitamins group together with other fat molecules to form fatty droplets, effectively reducing the amount of interaction with the watery environment of the intestines. Therefore, without an adequate amount of fat in your diet, your body is unable to effectively absorb these fat-soluble vitamins. This may be true in an intact anatomy, however, post weight loss surgical patients can not increase their fat soluble vitamin levels by increasing their fat intake. This is due to the fact that a high fat diet causes excessive bowel movement which in turn washes away any vitamins taken by mouth. DS limits fat absorption (thus the great weight loss) which can cause vitamin A and D deficiency that can not be easily corrected with oral supplementation.
As mentioned before, fat soluble vitamins are hydrophobic and nonpolar, which means they are also fat loving or lipophilic. Excess fat soluble vitamins can be stored in the liver and fat tissue. Therefore, these vitamins do not need to be eaten every single day since stores of these vitamins can sustain a person for some time. It may take several weeks or months for our body to deplete these stores of fat soluble vitamins which is why it generally takes a longer amount of time for fat soluble vitamin deficiencies to manifest themselves. The ability to store these fat soluble vitamins in tissues can also lead to vitamin toxicity – marked by an excess of vitamin stores in our body.
Clinical manifestations of A, D, E, K deficiency
|Vitamin||Clinical Deficiency manifestations|
|Vitamin A||Vision Problems
Dryness of the eye
|Vitamin D||Softening and weakening of the bones
Bone shape distortion
Bowed legs (generally in children)
|Vitamin E||Damage to red blood cells
Tissue/organ damage due to inability to supply enough blood
Nervous tissue malfunction
|Vitamin K1||Excessive bruising
Increased bleeding time
Small blood clots under nails
Increased bleeding in mucous membrane
|Vitamin K2||Weak bones
Increased plaque deposits along gumline
- Office of Dietary Supplements – Vitamin A. NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/#. Accessed April 26, 2020.
- Office of Dietary Supplements – Vitamin D. NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/VitaminD-Consumer/. Accessed April 26, 2020.
- Office of Dietary Supplements – Vitamin E. NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/VitaminE-Consumer/. Accessed April 26, 2020.
- Vitamin K. The Nutrition Source. https://www.hsph.harvard.edu/nutritionsource/vitamin-k/. Published July 2, 2019. Accessed April 26, 2020.
- Beulens JWJ, Booth SL, van den Heuvel EGHM, Stoecklin E, Baka A, Vermeer C. The role of menaquinones (vitamin K₂) in human health. The British journal of nutrition. https://www.ncbi.nlm.nih.gov/pubmed/23590754. Published October 2013. Accessed April 26, 2020.
Obesity is related to as many as 400,000 deaths each year in the US and it has increasingly been recognized as a risk factor for several nutrient deficiencies. This may seem surprising given the likelihood of over consumption of calories, however these additional calories are not from nutritious sources. One of the main reason for these nutritional deficits is the greater availability of inexpensive foods that are rich in calories and are nutrient deficient. This has led some medical professional to conclude that there is a certain group of people who are overfed but undernourished. Even with the epidemic of the obesity, there is significant nutritional deficiencies noted.
Obese subjects have increased blood volume, cardiac output, adiposity, lean mass and organ size all of which can influence volume of distribution, in addition, treatment for severe obesity involving surgical procedures can worsen these nutrient deficiencies and in some cases may cause new ones to develop.
This table shows the percentage of population below the estimated average requirement (EAR) by body weight status in adults more tan 19 years old, showing that almost 90 to 100 percent of people including normal weight (NW) are below the EAR of vitamin D and Vitamin E.
Nutritional deficiencies in obese patients may promote the development of chronic diseases including increased insulin resistance, pancreatic B-cell disfunction and diabetes, this is because specific micronutrients are involved in glucose metabolic pathways; There are other chronic diseases related to obesity that are being investigated such as decrease in focal grey matter volume and cognitive impairment or inadequate sleep due to low intake of antioxidant vitamins.
We would like to thank Miguel Rosado, MD for his significant contribution provided for this Blog.
Vitamin A is one of the 4 fat soluble vitamins along with vitamin D, Vitamin E and Vitamin K. It is multifunctional and essential which means that it is not produced by the body. In this article we will touch on aspects of Vitamin A absorption and it’s effect on wound healing as well as its metabolism.
We often think of Vitamin A as the critical vitamin for vision, however it has several other roles that related to immune function, protein synthesis, and cellular communication. Vitamin A deficiency is a concern world wide because of the natural of the side effects. Vitamin A deficiency is the leading cause of preventable childhood blindness in the world according to UNICEF and sometimes it may be undetected until there is irreversible damage.
There are 2 chemical forms of vitamin A in diet:
Retinoids (Preformed vitamin A) This group include retinol, retinyl esters, and retinal they are mostly found in animal sources like liver, egg yolk or fish oils.
Carotenoids (Provitamin A) This group includes beta-carotene, alpha-carotene and lycopene, mainly found in plant sources like leafy vegetables or yellow/orange vegetables and fruits.
1.- Ingested food is digested in the stomach where retinyl palmitates (esters) are released from proteins. Retinol and beta-carotene are absorbed directly into the small intestine where retinyl esters and betacarotene are transformed into retinol . Retinol is the most easily absorbed form of vitamin A.
2.-That retinol absorbed by the enterocytes in the ileum (small intestine) along with bile is then transported to the liver with the help of chylomicrons a protein that transports fat.
3.-Fifty to 80% of the vitamin A is stored in the liver and the remaining is deposited into adipose tissue, lungs and kidneys.
4.-When stored retinol is released from the liver into the circulation to target organs, it is bound to plasma retinol-binding protein (RBP4) a transporting protein produced by the liver that requires ZINC, which is synthesized by the liver; This complex is stabilized by transthyretin (TTR), which reduces renal excretion.
Retinol is a crucial component for reproduction, embryological development, cellular differentiation, growth, protein synthesis, and immunity in the form of retinoic acid and vision in the form of retinal.
One of Vitamin A additional roles is in epithelial health of skin and mucous membranes. It increases epithelial turnover which is crucial during would healing. It also has anti-oxidative effects which prevent cell damage and can prevent or reverse the effects of other damaging agents. In addition to these benefits it has also been associated with increasing collagen, fibronectin, keratinocytes and fibroblast, all important in wound tissue structure. There have been some studies that suggest giving higher doses of Vitamin A in patients with non or slow healing wounds.
It is important to remember that we have documents delayed diagnosis of adult vitamin A deficiency leading to significant night blindness in adults. It is critical that the patients and their primary care physicians are acutely aware of this possibility. In majority of the patients with low vitamin A, post weight loss surgery, aggressive supplementations, including injections need to be considered as a part of the treatment regimen.
We would like to thank Miguel Rosado, MD for his significant contribution provided for this Blog.
New FDA regulations for compounding pharmacies has spurred changes in our pricing and ability to provide injectable Vitamin A and Vitamin D. The compounding pharmacies are no longer compounding injectable Vitamin A and there is a nationwide shortage of the national brand of injectable Vitamin A. We have a tentative date of February 2018 when we may be able to obtain injectable Vitamin A. We won’t be able to quote pricing on Vitamin A injections until we are able to orders.
We are able to obtain and supply our patients with injectable Vitamin D but with a price increase.
The following is the letter we received from our compounding pharmacy.
“The healthcare industry has continuously undergone changes in regulations and legislation. The compounding industry is no exception and has faced rigorous regulatory requirements this past year such as new testing specifications and compliance standards.
We are set on facing these demanding challenges by meeting and exceeding these new regulatory requirements. We want to assure you we will continue to provide the best products on the market for you and your patients. Quality and safety remain a top priority. We understand that our pharmacy plays a vital role in providing care to your patients. The increase in pricing is a reflection of the additional cost in producing and testing the product based on regulatory specifications.”
Vitamin A and D are fat soluble vitamins. This means that in order for them to be absorbed by the GI track, them need to be absorbed by fat globules (chylomicrons). These are then taken up by the lymphatics of the GI track and taken to the blood stream. With the anatomical changes of the Duodenal Switch, the fat absorption capacity is significantly reduced. This results in excellent weight loss. It also results in much diminished absorption of the Fat soluble vitamins A, D, E and K. It is essential to use Dry Water Soluble forms of Vitamins A, D, E, and K. Bio-Tech is a brand that is formulated in this manner.
The Biotech D3-50 has 50,000IU of Vitamin D.
We recommend specific dosages of dry (water soluble) Vitamin A and D. These are not available at most pharmacies. In fact when our recommendations are presented at most pharmacies they are incorrectly dispensed with the fat soluble variety with is worth less becasue it is not absorbed by the duodenal switch patients. It is also important to not that this type of vitamin should not be taken with any dietary fat. Fat can inhibit the absorption of this type of vitamin. When ordering online, please make sure that the “Dry” or “Water Soluble” formulary is ordered.