Alcohol

Alcohol Overview

• Focus on absorption, metabolism, benefits, and consequences of alcohol in nutrition.

Alcohol Consumption in Canada

• Prevalence: A significant portion of the Canadian population consumes alcohol.

  • ~3-9% of total calories for drinking adults come from alcohol.

• Average Consumption:

  • Average Canadian (>= 15 years) consumed around 7.9 kg (~55,230 kcal) of pure alcohol in 2016.

• Density of Alcohol: Alcohol has a density of 0.789 g/ml.

Alcohol Absorption

• Absorption Process: Alcohol is absorbed through simple diffusion along the gastrointestinal (GI) tract.

  • About 20% is absorbed in the stomach.

  • Rate of absorption is slowed if food is present in the stomach.

• Distribution: Alcohol is quickly distributed throughout all body water compartments.

• Metabolism:

  • Approximately 90% metabolized by the liver; the rest is excreted via urine and exhaled.

  • The body prioritizes the metabolism of alcohol due to its toxic nature.

Factors Affecting Blood Alcohol Level

• Weight: Higher body weight results in more body water, diluting alcohol concentration in the blood.

• Gender: Men typically have more body water and stomach ADH activity, resulting in lower blood alcohol levels than women of the same size.

• Food Intake: Presence of food in the stomach reduces the rate of alcohol absorption.

• Drinking Rate: Increased rate of consumption leads to higher blood alcohol levels.

• Type of Drink: Carbonated mixers can speed up alcohol absorption.

Physiological Effects of Alcohol

• Acute Effects:

  • Alcohol impacts the central nervous system, breathing, heart rate, mood, judgment, memory, coordination, and vision.

  • Acts as a depressant, enhancing inhibitory signals and inhibiting excitatory ones.

  • Increases dopamine release in brain reward centers and prevents the release of Antidiuretic hormone (Vasopressin).

Alcohol Metabolism

• Main Enzyme: Alcohol is mostly broken down by Alcohol Dehydrogenase (ADH), primarily in the liver.

  • Small amounts metabolized in the stomach; some bacteria in the colon can also produce ADH.

• Byproducts: The metabolism of alcohol yields acetaldehyde, a toxic compound.

  • The conversion of acetaldehyde further produces harmful byproducts like free radicals, leading to oxidative stress.

• Processing Rate: The liver can generally process 1 drink (~14ml ethanol) per hour.

Long-term Effects of Alcohol Metabolism

• Fat Accumulation: Increased fat accumulation in the liver can lead to fatty liver disease, malnutrition, and reduced nutrient absorption.

• Nutrient Deficiency: Linked to lower levels of vitamins A, C, iron, calcium, etc.

• Cancer Risk: Higher alcohol consumption elevates the risk for various cancers (throat, esophagus, stomach, colon, liver).

Metabolic Benefits of Moderate Alcohol Consumption

• Cardiovascular Health: Moderate intake (up to 2 drinks/day for women; 3 drinks/day for men) linked to a reduced risk of heart disease in older adults.

  • Increases HDL, reduces blood clotting and platelet aggregation.

Overlooked Caloric Contribution to Obesity from Alcohol

• Binge Drinking Statistics:

  • ~30% of Grade 12 students in Ontario and Alberta binge drink monthly, contributing 6000-13,200 kcal/year (0.78-1.71 kg of fat).

  • Weekly binge drinking could lead to 52,000-114,000 kcal/year (6.74-14.83 kg of fat).

Energy Intake and Alcohol

• Effect on Appetite: Drinking wine before meals showed significant increases in energy intake (Caton et al., 2007).

Canadian Guidance on Alcohol and Health

• Health Benefits of Abstinence: No alcohol consumption leads to better health outcomes and sleep.

• Low-Risk Guidelines:

  • 1-2 standard drinks/week avoids alcohol-related consequences.

  • 3-6 drinks/week increases risk of various cancers.

  • 7+ drinks/week markedly raises heart disease risks and other alcohol-related issues.

• Standard Drink Conversions:

  • Beer: 341 ml (12 oz) of beer (5% alcohol)

  • Wine: 142 ml (5 oz) of wine (12% alcohol)

  • Spirits: 43 ml (1.5 oz) spirits (40% alcohol)

Implications of Alcohol for Athletes

• Impaired Metabolism: Alcohol can hinder gluconeogenesis, glucose metabolism, and muscle protein synthesis, complicating recovery.