Chapter 9

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Questions and Answers

What percentage of total energy intake may come from discretionary food sources in a 2000-kcal-per-day diet?

14% (correct)

10%

20%

25%

How should energy from alcohol be considered when planning a healthy diet?

It is not important to consider at all.

It must be accounted for along with discretionary calories. (correct)

It should replace energy from solid fats.

It should displace energy from other food sources.

What is the impact of excess acetate produced during ethanol metabolism on fat oxidation?

It has no effect on fat oxidation.

It converts fat directly into muscle.

It suppresses normal fat oxidation. (correct)

It enhances normal fat oxidation.

Which of the following best describes discretionary energy?

Calories left over after meeting nutritional requirements. Signup and view all the answers

What factor does not play a role in the oxidation of acetate in peripheral tissue?

Insulin Signup and view all the answers

What challenge is often faced when reducing discretionary calories from fat, sugar, and alcohol?

It is difficult to reduce them together. Signup and view all the answers

Which substance is stored as fat in the body according to NCAA findings?

Ethanol Signup and view all the answers

What is typically true regarding the consumption of alcoholic beverages in a diet?

They contribute to meeting daily energy requirements. Signup and view all the answers

What is the most commonly consumed form of alcohol globally?

Ethyl alcohol (ethanol) Signup and view all the answers

What is the estimated annual consumption of pure ethanol per person in the United States?

2.35 gallons Signup and view all the answers

Which statement is true regarding the toxicity of different alcohols?

Ethanol is the only form of alcohol tolerated within the body in appropriate amounts. Signup and view all the answers

How does ethanol compare structurally to glucose?

Ethanol consists of two carbons and one hydroxyl group, while glucose has six carbons and five hydroxyl groups. Signup and view all the answers

What role does alcohol play in sports nutrition according to the content?

Alcohol is often overlooked despite its physiological effects. Signup and view all the answers

What is one of the learning objectives related to alcohol in the provided content?

Explain key myths or hot topics related to alcohol. Signup and view all the answers

Which of the following statements about alcohol consumption is incorrect?

Alcohol can always fit into a healthy diet without restrictions. Signup and view all the answers

Which type of alcohol is considered extremely toxic and can cause serious harm?

Both B and C Signup and view all the answers

What is the criterion for classifying high-risk alcohol consumption for males?

5 or more drinks per day or 15 or more drinks per week Signup and view all the answers

Which enzyme deficiency is particularly significant for individuals of Asian descent concerning alcohol metabolism?

Acetaldehyde dehydrogenase Signup and view all the answers

What constitutes binge drinking for males?

More than five drinks in a single occasion Signup and view all the answers

Which group is advised against alcohol consumption due to potential risks?

Individuals who are or may become pregnant Signup and view all the answers

What defines a standard drink in the United States?

0.6 ounces of ethanol Signup and view all the answers

What is the primary concern of consuming two Long Island Iced Teas in a short duration?

Exceeding recommended alcohol consumption levels Signup and view all the answers

Which alcoholic beverage typically contains the highest ethanol content?

Spirits Signup and view all the answers

Why is it misleading to only count the number of drinks consumed?

Ethanol content can differ significantly between drinks Signup and view all the answers

What is the typical ethanol content range for beer?

4 to 5% ethanol Signup and view all the answers

What health risks are associated with binge drinking?

Physical, mental, and societal harm Signup and view all the answers

What constitutes moderate drinking for males according to dietary guidelines?

Two standard drinks per day Signup and view all the answers

What is one of the side effects associated with acetaldehyde accumulation?

Acute flushing of the skin Signup and view all the answers

How many grams of ethanol are contained in a standard drink in Canada?

13.5 grams Signup and view all the answers

What is the primary function of alcohol dehydrogenase (ADH) in the body?

To metabolize ethanol Signup and view all the answers

What is the recommended maximum alcohol consumption per week for females?

10 drinks Signup and view all the answers

How does the presence of food in the stomach affect ethanol absorption?

It slows the absorption process Signup and view all the answers

Why is ethanol often considered a homeostatic threat?

It must be metabolized before other nutrients due to its toxicity Signup and view all the answers

What factor does NOT influence blood alcohol content (BAC)?

Type of carbohydrate consumed Signup and view all the answers

When consuming alcohol, what impact does carbonation have on absorption?

It increases the rate of absorption Signup and view all the answers

Compared to males, how do females typically respond to ethanol consumption?

They have a greater BAC from the same amount of ethanol Signup and view all the answers

What is the energy yield of metabolized ethanol?

7.1 kcals per gram Signup and view all the answers

What role do NAD+ and NADH play in metabolism?

They provide majority of electrons for ATP production Signup and view all the answers

What is the main enzyme responsible for ethanol metabolism in the liver?

Alcohol dehydrogenase Signup and view all the answers

Which pathway becomes more active in individuals who consume large amounts of ethanol?

Microsomal ethanol-oxidizing system (MEOS) Signup and view all the answers

What happens to the rate of ethanol absorption when food is present in the stomach?

It decreases Signup and view all the answers

In what scenario would a concentrated alcoholic beverage typically produce a greater rise in BAC?

With an empty stomach Signup and view all the answers

What is the effect of ethanol on the NADH to NAD+ ratio in the liver during increased consumption?

It increases the ratio, causing metabolic disruptions. Signup and view all the answers

Which factor is critical in determining the absorption rate of ethanol?

The presence of other foods in the stomach Signup and view all the answers

What is the primary toxic byproduct formed during ethanol metabolism?

Acetaldehyde Signup and view all the answers

What is the estimated metabolic rate of ethanol in the liver per hour?

0.25 ounces Signup and view all the answers

What critical characteristic distinguishes ethanol from carbohydrates and fats in the context of metabolism?

Ethanol metabolism is prioritized over other macronutrients Signup and view all the answers

How does habitual ethanol consumption affect body fat management?

Inhibits fat loss due to efficient energy utilization from acetate. Signup and view all the answers

In what way does body composition affect BAC levels post-consumption of ethanol?

Lean muscle mass leads to lower BAC Signup and view all the answers

What is the maximum ATP produced from one molecule of ethanol when metabolized via the ADH pathway?

13 ATP Signup and view all the answers

Which enzyme facilitates the conversion of acetate into acetyl-CoA?

Acetyl-CoA synthetase Signup and view all the answers

What can excessive consumption of ethanol lead to in terms of liver health?

Fatty liver disease and cirrhosis. Signup and view all the answers

How does the MEOS pathway impact energy coupling during ethanol oxidation?

It alters energy coupling and generates heat. Signup and view all the answers

What recommendation is made for moderate alcohol consumption per day for males?

Up to two drinks. Signup and view all the answers

What is a potential consequence of an altered NADH/NAD+ ratio in the liver?

Increased lactate and potential lactic acidosis. Signup and view all the answers

Which enzyme plays a minor role in ethanol metabolism by breaking down hydrogen peroxide?

Catalase Signup and view all the answers

What is the importance of considering alcohol consumption in a healthy diet?

Alcohol has no nutritional value. Signup and view all the answers

Study Notes

Alcohol Structure and Function

Ethanol is the most common drug globally, with an estimated 1.6 gallons consumed per person (over the age of 15) annually.
It's not essential for health, but it's important to understand its effects on the body.
Ethanol is structurally similar to glucose, with each composed of carbon, hydrogen, and oxygen.
Ethanol metabolism is not regulated by hormones, making it a homeostatic threat.
The metabolism of ethanol takes priority over other macronutrients to remove it from the body.
Ethanol provides 7.1 kcals per gram, but it is better to think of it as a psychoactive drug rather than a macronutrient.

Alcohol Absorption

First-pass metabolism: A small amount of ethanol is initially metabolized in the stomach by alcohol dehydrogenase (ADH).
Majority of ethanol passes unaltered into the bloodstream through the stomach and small intestine by simple diffusion.
Rate of absorption and blood alcohol content (BAC) are influenced by factors such as sex, body mass, beverage type, stomach content, and consumption speed.

Food and Alcohol Absorption

Absence of food in the stomach accelerates ethanol absorption into the bloodstream.
The type of food doesn't significantly affect absorption rates.
Food slows alcohol absorption, increasing ethanol metabolism through first-pass and liver metabolism.
Increased liver blood flow, ADH activity, and NADH re-oxidation contribute to increased metabolism.
Concentrated beverages like spirits lead to a greater BAC compared to dilute beverages like beer due to higher ethanol content.
However, this effect is determined by the fed/fasted state.
Ethanol from concentrated beverages may be absorbed faster than dilute beverages when the stomach is empty.
This relationship reverses when food is consumed prior to or during alcohol consumption.
Carbonated beverages may lead to faster absorption compared to non-carbonated ones.

Sex and Body Composition

Ethanol absorption and metabolism are similar in females and males.
However, a specific amount of ethanol will result in a higher BAC in females due to physiological differences.
Females have less total body water, resulting in a higher BAC.
First-pass metabolism is lower in females due to less ADH activity in the stomach.
This means less ethanol is metabolized before entering the bloodstream.

Metabolism of Ethanol

90% of ethanol is metabolized in the liver by ADH at a rate of approximately 0.25 ounces per hour.
10% is excreted through breath, sweat, and urine.
The rate of metabolism doesn't increase with higher ethanol levels, so if consumption exceeds metabolism, BAC will rise.
ADH metabolizes ethanol into acetaldehyde and NADH.
Acetaldehyde is toxic and is immediately metabolized by acetaldehyde dehydrogenase (ALDH2) to acetate.
Acetate is released into the bloodstream and converted to acetyl-CoA for use in the Krebs cycle for energy production.

Microsomal Ethanol Oxidizing System (MEOS)

An alternative pathway primarily activated with heavy alcohol consumption.
Used when the ADH pathway is saturated.
Also produces acetaldehyde and utilizes NADPH, altering energy coupling and generating heat.
Catalase contributes to ethanol metabolism in a small, indirect manner.

Impact of Ethanol Metabolism on Other Metabolic Processes

Disrupting the NADH/NAD+ ratio can lead to:
- Lactic acidosis: Increased lactate production due to limited NADH re-oxidation, affecting lactate dehydrogenase activity.
- Hypoglycemia: Reduced pyruvate levels may impact hepatic gluconeogenesis, causing glucose depletion.
- Fatty liver disease: Shift toward lipogenesis, increased hepatic fatty acid accumulation, and reduced fatty acid oxidation.

Dietary Impact of Alcohol

While alcoholic beverages may contribute to macronutrients and micronutrients, ethanol itself provides no additional nutritive value.
It's considered an empty source of energy.

Alcohol Intake Guidelines for Moderation

The 2015-2020 Dietary Guidelines for Americans recommends moderate alcohol consumption.
Moderate drinking: 1 standard drink per day for females, 2 standard drinks per day for males.
High-risk drinking: 4+ drinks per day or 8+ drinks per week for females; 5+ drinks per day or 15+ drinks per week for males.
Binge drinking: 4+ drinks by females or 5+ drinks by males in a single occasion.

Considerations for Alcohol Consumption

Pregnant or potentially pregnant females, those under 21, and those driving or planning to drive should abstain from alcohol.
Be aware of the ethanol content in beverages and total ethanol consumed.
Be mindful of binge drinking, especially with multiple drinks or beverages containing more than one standard drink.

Defining a Drink

Standard drinks, or drink equivalents, are used to quantify alcohol intake.
In the US, 1 standard drink contains 0.6 ounces (14 grams) of ethanol.
Different countries have different standard drink definitions, ranging from 8g to 18g of ethanol.
Relying solely on counting drinks can be misleading due to varying ethanol content and volumes.

Accommodating Alcohol Into a Healthy Diet

While some alcoholic beverages may contain nutrients, ethanol itself has no additional nutritive value.
It's an empty source of energy, so consider its impact on calorie intake and overall diet.
Focus on providing a balanced, nutrient-dense diet and prioritize other essential nutrients.

Caution Regarding Alcohol Consumption

Pay attention to variations among individuals in response to alcohol.
Individuals with a deficiency in acetaldehyde dehydrogenase may experience adverse reactions due to acetaldehyde accumulation.
This includes flushing, nausea, and increased risk of esophageal cancer.
Alcohol consumption can influence other important factors of health and performance, such as hydration, sleep, and exercise recovery.
Consult with a healthcare professional to determine individual risk levels and ensure safe and healthy alcohol choices.### Energy from Alcoholic Beverages
Ethanol in alcoholic beverages contributes approximately 99.4 kcal of energy.
The energy content in alcoholic beverages is further increased by the carbohydrate content of the alcohol itself and any mixers used.
The energy from alcoholic beverages should be considered as part of a healthy diet.
It is recommended to consume alcoholic beverages in addition to, rather than as a replacement for, other food sources.
Alcoholic beverages can contribute to discretionary energy intake, which refers to calories consumed from sources like solid fat, added sugars, and alcohol.
Discretionary energy intake should not exceed 270 kcal per day, according to the 2000-kcal-per-day U.S.-style eating pattern.
If consuming alcohol, reduce intake of fat and added sugars accordingly to stay within discretionary calorie limits.

Alcohol and Body Composition

According to the NCAA (2013), ethanol consumption can influence body composition, specifically by being stored as fat.
However, the relationship between ethanol and body composition is more complex.
Excess acetate, produced during ethanol metabolism, can alter whole-body fat oxidation.
Acetate is transported and oxidized in peripheral tissues, reducing normal fat oxidation.
This process is not dependent on insulin, unlike the distribution of glucose.
Up to 80% of acetate is oxidized in peripheral tissues, with a small amount used for other processes.

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Explore the structure, function, and metabolism of ethanol in this quiz. Understand the effects of alcohol on the body and how it is absorbed and metabolized. This quiz is essential for those studying health or chemistry related to psychoactive substances.