Friday Pearl

Thiamine, Alchohol Intake, Brain Health

Friday, February 22, 2019


A deficiency in the essential nutrient thiamine resulting from chronic alcohol consumption is one of the factors linked to brain damage. 


Thiamine is a helper molecule (cofactor) required by three enzymes involved in carbohydrate metabolism.


Chronic alcohol consumption can cause inadequate nutritional thiamine intake, decreased absorption of thiamine from the gastrointestinal tract, and impaired thiamine utilization in the cells.


Given that intermediate protein blocks and DNA, as well as brain chemicals, are needed for the generation of all essential molecules in neuronal cells, a thiamine deficiency can interfere with numerous cellular functions, possibly leading to alcohol-related brain problems.


Unfortunately, the human body cannot produce thiamine and must ingest it through the diet. Thiamine-rich foods include pork and poultry; whole grain cereals such as brown rice and bran; nuts; and dried beans, peas, and soybeans.


The three enzymes that require thiamine as cofactors are transketolase, pyruvate dehydrogenase, and alpha-ketoglutarate dehydrogenase: They all participate in the metabolism of carbohydrates in the body.


Each of these enzymes consist of several components that must be assembled to produce functionality, and the addition of thiamine is a critical step in this assembly process, as well as the thiamine production of the neurotransmitter acetylcholine and for the synthesis of myelin, which forms a sheath around many neurons, ensuring the ability of these neurons to conduct signals.


Thiamine-dependent enzyme information from the National Institute on Alcohol Abuse for physicians and biochemistry geeks


Transketolase is an important enzyme in the breakdown of glucose through a biochemical pathway called the pentose phosphate pathway. Glucose is first converted to a molecule called glucose-6-phosphate, which enters the pentose phosphate pathway where it is further modified by transketolase.


During that reaction, two products are formed—the sugar ribose-5-phosphate and a molecule called reduced nicotinamide adenine dinucleotide phosphate (NADPH).


Ribose-5-phosphate is needed for the synthesis of nucleic acids, complex sugar molecules, and other compounds called coenzymes that are essential for the functioning of various enzymes.


NADPH provides hydrogen atoms for chemical reactions that result in the production of coenzymes, steroids, fatty acids, amino acids, and neurotransmitters. In addition, NADPH plays an important role in the synthesis of glutathione, a compound essential to the body’s defense against damage from oxidative stress.


Reduced transketolase activity interferes with all these essential biochemical processes.


The other two enzymes requiring thiamine, pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase, also participate in different steps of the breakdown and conversion of glucose-6-phosphate through two consecutive chains of biochemical reactions called glycolysis and the Krebs citric acid cycle.


The main function of these pathways is the generation of a molecule called adenosine triphosphate (ATP), which provides energy for numerous cellular processes and reactions.


Decreases in the activities of pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase can result in reduced ATP synthesis, which in turn can contribute to cell damage and even cell death. 


In addition, proper functioning of pyruvate dehydrogenase is essential for the production of the neurotransmitter acetylcholine, as well as myelin synthesis, as mentioned above.


The citric acid cycle and alpha-ketoglutarate dehydrogenase play a role in maintaining the levels of the neurotransmitters glutamate, gamma-aminobutyric acid (GABA), and aspartate, as well as in protein synthesis.


As you can see, these thiamine-using enzymes play numerous vital roles in the functioning of cells, particularly neurons.


When thiamine levels decrease, the activity levels of all three enzymes are reduced to some extent. The specific reductions depend both on the enzyme and on the cell type. 


Overall, transketolase activity may be the most sensitive measure of thiamine deficiency. Substantial decline in transketolase activity resulting from thiamine deficiency has been found in various brain areas of alcoholics who do not exhibit the clinical and neuropathological signs of problems, suggesting that thiamine deficiency can cause adverse effects even before severe brain damage becomes obvious.


Unfortunately, lack of detection and treatment of thiamine deficiency in both chronic alcohol abusers and nonalcoholics, is first diagnosed postmortem in over 80 percent of cases. 


Ellen Troyer, Spencer Thornton, MD, David Amess and the Biosyntrx staff


PEARL: The obvious question: How much alcohol is too much? According to extensive research by the National Institute on Alcohol Abuse and Alcoholism (NIAAA), less than 2 percent of drinkers who fall within the following guidelines develop alcohol- use disorders. 


For men, low-risk alcohol consumption is considered drinking four or fewer standard drinks on any single day and less than 14 drinks during any given week. 


For women, low-risk is three or fewer drinks on any given day, with no more than seven drinks per week. 


Low risk does not mean no risk. There are situations in which no level of drinking can be considered low risk. 

  • You plan to drive or operate heavy equipment.
  • You are pregnant or planning to become pregnant.
  • You have certain medical conditions, including cirrhosis of the liver, hepatitis C, and chronic pain, as well as some heart conditions and mental disorders.
  • You are taking medications that negatively interact with alcohol. 

  

The public service science information above is not meant to diagnose, treat, cure, or prevent any disease.