B12 & Folate: Requirements for Blood Flashcards
explain the importance of folate (vitamin B9), vitamin B6, and vitamin B12 in red blood cell (RBC) DNA synthesis and their broader roles in various metabolic processes
You’ve highlighted an important point regarding the haematological presentations of vitamin B12 and folate deficiencies. While the hematological manifestations (e.g., megaloblastic anemia) of these deficiencies are similar due to their shared role in DNA synthesis, the key clinical difference lies in the neurological symptoms seen with vitamin B12 deficiency. Vitamin B12 is necessary for maintaining the integrity of nerves, and its deficiency can lead to peripheral neuropathy and other neurological issues.
Deficiencies in vitamin B12, folate, or vitamin B6 can occur due to various reasons, including:
Poor Diet: Inadequate dietary intake of these vitamins can lead to deficiencies, especially in individuals with restricted diets, such as vegans who may lack folate (vitamin B9), vitamin B6, and vitamin B12 for red blood cell (RBC) DNA synthesis and their broader roles in various metabolic processes. These vitamins are essential for overall health and play crucial roles in maintaining normal cellular functions.
Malabsorption: Conditions affecting the gastrointestinal tract, such as celiac disease, Crohn’s disease, or surgical procedures that alter nutrient absorption, can lead to malabsorption of these vitamins.
Gastric Surgery: Some weight loss surgeries, like gastric bypass surgery, can interfere with the absorption of vitamin B12.
give an overview of water-soluble and fat-soluble vitamins
Water-Soluble Vitamins (B-complex and C):
There are nine water-soluble vitamins, including the B-complex vitamins (B1, B2, B3, B5, B6, B7, B9, B12) and vitamin C.
These vitamins cannot be synthesized in the body and must be obtained from food or supplements.
Water-soluble vitamins are not stored in significant quantities and are easily excreted in urine, with the exception of vitamin B9 (folate) and vitamin B12 (cobalamin), which have some reserves in the body (3-4 months for B9 and 3-4 years for B12).
Deficiencies can occur, particularly for vitamin B12 and vitamin C.
Toxicity from water-soluble vitamins is unlikely because excess amounts are excreted in urine.
Water-soluble vitamins are readily absorbed from the diet.
Fat-Soluble Vitamins (DAKE - D, A, K, E):
There are four fat-soluble vitamins: vitamins D, A, K, and E.
These vitamins are stored in the body’s fat tissues and the liver and are not as readily excreted in urine.
Deficiencies in fat-soluble vitamins are less common, especially for vitamins K, E, and D (KED).
However, fat-soluble vitamins can be toxic when consumed in excessive amounts, particularly vitamins D and A.
The absorption of fat-soluble vitamins depends on the gastrointestinal tract (GIT) and pancreas.
explain vitamin B12 (Cobalamin) and its dietary requirements and storage in the body
Vitamin B12 is often referred to as Cobalamin due to the presence of cobalt in its chemical structure.
The daily dietary requirement for vitamin B12 is relatively low, typically around 1 to 2 micrograms (µg) per day. During pregnancy, this requirement increases to 3 to 4 µg per day.
A healthy diet may provide well over 5 µg of vitamin B12 per day, as it can be found in various animal products such as meat, fish, eggs, and dairy.
Vitamin B12 is largely absent from plant-based foods, and it is primarily concentrated in the tissues of animals higher up the food chain, such as predators. This makes vitamin B12 less readily available to individuals following strict vegetarian or vegan diets.
The liver can store several milligrams of vitamin B12, and it has a relatively long half-life of about 12 months. As a result, a deficiency in vitamin B12 typically takes a considerable period of time to develop, requiring a prolonged absence of dietary B12. This means that a person can maintain adequate stores of vitamin B12 in the liver for well over a year before experiencing a deficiency that affects processes like erythropoiesis (red blood cell production).
explain how certain medications can interfere with the absorption, metabolism, or storage of vitamin B12
Proton Pump Inhibitors (PPIs): PPIs are used to reduce stomach acid production and may affect the absorption of B12 from food.
Histamine-2 Receptor Antagonists (H2 Blockers): These drugs, often used to treat acid reflux and ulcers, can also reduce stomach acid production and potentially impact B12 absorption.
Metformin: Metformin is a medication commonly prescribed for people with type 2 diabetes. Long-term use of metformin has been associated with reduced B12 absorption.
Certain Antibiotics: Specific antibiotics can affect the balance of gut bacteria and, in some cases, may influence B12 absorption.
Bile Acid Sequestrants: Medications that bind to bile acids can interfere with fat absorption, which, in turn, may affect the absorption of fat-soluble vitamins like B12.
give an overview of the complex process of vitamin B12 absorption within the gastrointestinal system
Attachment to Animal Protein: Vitamin B12 is tightly bound to animal protein, primarily found in meat and other animal-derived food sources.
Saliva Containing R-binder: Saliva contains R-binder, also known as haptocorrin and transcobalamin 1. R-binder plays a role in protecting B12 from the acidic environment of the stomach.
Mechanical Digestion: During the process of eating, food is cut and chewed by the teeth and mixed with saliva, which initiates the digestive process.
Pepsin Action: Pepsin, an enzyme produced in the stomach, starts to separate B12 from meat proteins and allows it to bind with R-binder.
Parietal Cells: Parietal cells in the stomach secrete hydrochloric acid (HCl) and intrinsic factor (IF), which is essential for B12 absorption.
Pancreatic Proteases: In the small intestine, pancreatic proteases break down B12-R-binder complexes. B12 is then released and binds with Intrinsic Factor (IF).
Chief Cells: Chief cells in the stomach secrete pepsinogen, which is converted to pepsin and further aids in protein digestion.
IF Receptors in Ileal Cells: In the ileum (the last part of the small intestine), receptors on the apical surface of ileal cells collect Intrinsic Factor (IF) and B12 and transport them into the cells.
Binding with Transcobalamin 2: In the blood of the portal vein, approximately 20% of B12 combines with transcobalamin 2 (TCN2) and is transported to various body tissues where it is available for cellular use.
Remaining B12 Circulating with Transcobalamin 1: The remainder of the B12 circulates with transcobalamin 1 (TCN1) and is not readily available to body cells for utilization.
outline the various problems and potential causes related to vitamin B12 deficiency
- Low B12 in Diet:
Causes: Individuals following a strict vegan or vegetarian diet, which lacks animal-derived foods, may have limited dietary sources of B12.
- Low Intrinsic Factor:
Causes: Pernicious anemia: An autoimmune condition that leads to the destruction of parietal cells in the stomach, reducing intrinsic factor production.
Gastrectomy: Surgical removal of part or all of the stomach can impact intrinsic factor production.
- Lack of Acidity:
Causes: Excessive PPI (Proton Pump Inhibitor) Use: Long-term use of PPIs, which reduce stomach acid production, can hinder B12 absorption.
Gastrectomy: Surgical removal of the stomach can result in decreased stomach acid production.
- Intestinal Malabsorption:
Causes: Ileal resection: Surgical removal of the ileum, the final part of the small intestine, can reduce B12 absorption.
Crohn’s disease: An inflammatory bowel disease that can affect the absorption of nutrients, including B12.
Tapeworm infection: Some tapeworms can consume B12, leading to a deficiency. Congenital malabsorption: Rare genetic conditions can hinder the body’s ability to absorb nutrients.
Medications: Certain medications or medical conditions may affect B12 absorption in the intestines.
explain the clinical manifestations and symptoms associated with vitamin B12 deficiency
Haematological Symptoms:
Macrocytic anemia: A type of anemia characterized by larger-than-normal red blood cells, leading to decreased oxygen-carrying capacity and fatigue.
Neurological Symptoms (Peripheral):
Paresthesia: Abnormal sensations like tingling or numbness in the extremities.
Impaired vibration sense: Reduced ability to sense vibrations, especially in the extremities.
Muscle weakness: Reduced muscle strength and coordination.
Impaired tendon reflexes: Reduced or absent reflex responses.
Loss of proprioception: A diminished sense of body position and movement.
Ataxia: Difficulty in coordinating muscle movements, leading to unsteady gait.
Optic neuritis: Inflammation of the optic nerve that can affect vision.
Headache: Frequent or severe headaches.
Neurological Symptoms (Central):
Poor memory: Memory deficits and cognitive difficulties.
Dementia: A more severe cognitive impairment involving memory, thinking, and behavior.
Depression: Mood disturbances, including persistent feelings of sadness or hopelessness.
Delirium: An acute state of confusion and disorientation.
Physiological Symptoms:
Smooth tongue: The tongue’s surface may appear smooth and lacking the normal papillae.
Change in tongue size: Alterations in tongue size or shape.
Sore tongue: Discomfort or pain in the tongue.
Dysphagia: Difficulty in swallowing.
Reduced appetite: A decrease in the desire to eat.
Weight loss: Unintentional weight loss.
GI pain: Gastrointestinal discomfort or pain.
GI disorders: Gastrointestinal problems, potentially affecting digestion and absorption.
Palpitations: Abnormal awareness of heartbeats or irregular heart rhythms.
give an overview of folate (vitamin B9), its dietary sources, absorption, storage, and crucial roles in the body
Folate and Folic Acid: The term “folate” encompasses all forms of folic acid, which is vitamin B9. Folate is essential for various biochemical processes in the body.
Role in DNA and RNA Synthesis: Folate serves as a substrate for thymidine, playing a vital role in DNA and RNA synthesis, making it crucial for cell division and growth.
Dietary Sources: Folate is abundant in fruits and vegetables, especially leafy green vegetables. It can also be found in foods like liver, kidney, and yeast.
Fortification: In many countries, flour is fortified with folic acid to ensure an adequate intake.
Daily Requirement: The recommended daily requirement for folate is typically in the range of 100 to 200 micrograms (µg). A mixed diet usually provides this daily requirement.
Absorption: Folate is absorbed in the upper jejunum of the small intestine, and approximately 50% of the ingested folate is absorbed.
Storage: A small amount of folate, around 5 to 10 milligrams (mg), is stored in the liver, providing a reserve that can last for about four months.
Loss and Excretion: Folate is lost through urine, bile, and the shedding of skin and intestinal cells.
Increased Demand in Pregnancy: During pregnancy, there is an increased demand for folate due to the rapid growth and development of the fetus. Folate deficiency is more likely to occur during this period.
Prevention of Birth Defects: Adequate folate intake, especially pre-conception and during early pregnancy, is critical for preventing neural tube defects like spina bifida.
explain folate (vitamin B9) and its key characteristics
Alcohol: Excessive alcohol consumption can interfere with folate absorption and metabolism, potentially leading to deficiencies.
Anticonvulsant Medicines: Some anticonvulsant medications can affect folate utilization in the body, potentially leading to deficiencies.
Vitamin B12 Deficiency: Vitamin B12 deficiency can trap tetrahydrofolate and prevent it from participating in essential reactions, contributing to folate deficiency.
Malabsorption Conditions: Various malabsorption conditions, such as inflammatory bowel disease (IBD), celiac disease, and short bowel syndromes, can hinder the absorption and utilization of folate.
Mutation in Methyltetrahydrofolate Reductase (MTHFR): Genetic mutations, particularly in the MTHFR gene, can impact the body’s ability to metabolize folate effectively.
Elderly Person’s Diet: Elderly individuals may have dietary patterns that lack essential nutrients, including folate, which can increase the risk of deficiency.
Haemolytic Diseases: Conditions characterized by the breakdown of red blood cells (hemolysis) can increase the body’s demand for folate, potentially leading to deficiencies.
explain the additional factors and nutrients that are essential for normal hematopoiesis
Amino Acids: Amino acids are the building blocks of proteins, including those involved in the production of blood cells.
Energy: Adequate energy is required to support the metabolic processes involved in hematopoiesis.
Growth Factors: Various growth factors, such as erythropoietin (Epo) and others, play essential roles in regulating the proliferation and differentiation of blood cell precursors.
Hormones: Normal levels of hormones like growth hormone, thyroxine, steroids, and androgens are necessary for proper hematopoiesis, as they influence cell growth, differentiation, and overall metabolism.
Copper: Copper is a trace element that plays a role in various enzymatic reactions, including those related to hematopoiesis.
Vitamin C: Vitamin C (ascorbic acid) is important for collagen synthesis and maintaining the integrity of blood vessel walls, which can affect blood cell production.
Vitamin B6 (Pyridoxine): Vitamin B6 is involved in numerous enzymatic reactions and can impact the metabolism of amino acids and other essential molecules needed for hematopoiesis.
Vitamin B2 (Riboflavin): Vitamin B2 is essential for various metabolic processes, and its role in hematopoiesis is related to energy production and enzyme activity.
explain the standard clinical practice and important consideration in the evaluation and treatment of individuals with low folate or vitamin B12 levels
Your statement is in line with standard clinical practice and an important consideration in the evaluation and treatment of individuals with low folate or vitamin B12 levels. Testing for both folate and vitamin B12 levels is crucial when addressing deficiencies in these essential vitamins, as they can share similar clinical manifestations, including certain types of anemia.
It is especially critical to address a vitamin B12 deficiency before starting folate treatment. Vitamin B12 deficiency can lead to irreversible neurological damage if left untreated. Folate supplementation alone can correct the anemia associated with B12 deficiency, but it will not prevent or treat the neurological complications. Therefore, ensuring that a B12 deficiency is ruled out or addressed is essential before proceeding with folate supplementation.
