BMS1064: Wk1 - Alcohol and DRVs Flashcards by Anya Anderson

What is the equation to calculate nutrient requirement?

Metabolic demand / efficiency of utilisation

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What are Dietary Reference Values?

They are a set of values that give the average requirement of a particular nutritient needed for a population.

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What is the purpose of DRVs?

To avoid deficiency, optimise body stores and set safe upper limits of nutrients for a population.

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What are the different DRVs?

EAR, RNI, LRNI and Safe intake

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What does EAR stand for and what is it?

Estimated Average Requirement
- Where 50% of the population’s nutrient requirement is met. Assumes normal distribution.

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What does LRNI stand for and what is it?

Lower Reference Nutrient Intake
- aims to define minimum requirements
- 2 SD below EAR
- meets the nutritional needs of 2.5% of the population

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What does RNI stand for and what is it?

Reference Nutrient Intake
- 2SD above EAR
- meets the nutritional needs of 97.5% of the population

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What is the ‘safe intake’?

The intake of a nutrient which there is insufficient info to determine the distribution of requirements within a population.

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How are DRVs determined?

Observation of intakes
Balance Studies (intakes known to match losses)
Physiological estimates (e.g. to meet tissue growth during pregnancy)
Clinical studies
Functional tests

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What are the limitations of DRVs?

There are averages and don’t apply to inviduals.
DRVs apply to healthy people - not ppl with disease/metabolic abnormalities
Don’t always consider that not all of the ingested nutrient is actually absorbed
Limited info on certain groups (children, race, elderly)
Often based on survey data -> people don’t give accurate data on dietary intake

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Why might alcohol sometimes be counted as a macronutrient?

Because it can be a source of energy

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Where are no DRVs set for alcohol?

Alcohol is not an essential nutrient (not needed for health)

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Which macronutrients is alcohol most structurally and functionally similar to?

Structurally similar to carbohydrates.
Functionally similar to fats (+energy content similar)

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Does alcohol contain calories? Explain

Contains ‘empty’ calories - has energy content value but few vitamin and minerals.

However, bear in mind that ethanol is not the only source of calories in alcoholic drinks.

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What do UK DRVs for energy assume about alcohol?

That 5% of a person’s energy intake is alcohol in the UK.

However, it is actually closer to 7.5%.

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What are is the general guidance when it comes to alcohol intake in the UK?

What is 1 unit of alcohol equal to?

No more than 14 units per week and spread it out.

1 unit = 10ml / 8g ethanol

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How/where is alcohol absorbed, transported and metabolised?

Readily absorbed along the entire GI tract (straight into blood).

Transported in blood unaltered.

Metabolised in the liver via two main pathways.

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Name the 2 main pathways in which alcohol is metabolised in the liver.

Alcohol Dehydrogenase pathway (ADH)
and
Cytochrome p450 pathway - Microsomal Ethanol Oxidising System (MEOS)

Describe the ADH pathway:

Ethanol -> Acetaldehyde -> ethanoic acid

Describe the MEOS pathway:

Induced by Chronical alcohol consumption
Ethanol -> Acetaldehyde

What are the diseases caused by alcohol consumption?

Fatty liver disease
Liver Cirrhosis
Lactic Acidosis
Metabolic Tolerance

What are the ST effects of alcohol?

Slow reaction time (low levels), sensory loss, muscle incoordination (mid levels), blurred vision, unconsciousness, slow respiration (high levels)

What are other adverse affects of alcohol consumption?

Increased risk of injuries, poor mental health, cancer and strokes.

What causes a metabolic shift in heavy drinkers? equation?

What are the issues that come with this shift?

High NADH levels, low NAD+ levels due to ADH pathway.

Pyruvic Acid + NADH + H+ –> Lactic acid + NAD+

… to try and restore levels

Issues:
- promotes fatty acid synthesis -> fatty liver
- causes lactic acidosis -> abdominal pain, vomiting etc

The ADH and MEOS pathway can lead to Acetaldehyde toxicity. How does this occur? What does acetaldehyde do?

Too much acetaldehyde. Binds covalently to proteins - impairing their function. Causes formation of microtubules in liver -> cirrhosis.

What is another issue that comes with heavy drinking (in relation to the ADH and MEOS pathway)?

Both the ADH and MEOS pathways are not specific only for alcohol (example below for ADH). Heavy drinking induces the MEOS pathway. Excess retinol is usually oxidised by MEOS. --> vitamin deficiencies --> hepatic retinol depletion

What is the relationship between alcohol consumption and cancer?

The relationship between the two is complex (conflicting data). However, consistent relationship found with cancer of upper GI tract, liver, colon and breast.

Are there any benefits of consuming alcohol? Explanations?

Important social factor - improves mental health/wellbeing? Mod consumption linked to decreased cardiovascular disease. Maybe because... - 'Hormeis' - low level physiological challenges to body promotes adaptive responses. - Other components in alcoholic beverages - e.g. phenolic compiunds in wine.

How is ethanol produced? What is the equation and enzyme?

By the fermentation of sugars by yeasts.

Where is the hexose sugar derrived from to make ethanol?

Either juice extraction from fruit, honey, sugar cane or palm sap OR Saccharification of cereals, root crops or tubers. (Saccharafication by malt, mould or salivary enzymes)

Name the main ingredients in beer.

Water Malted Barley Hops

How does water affect beer production?

Makes up 90-95% of the beer. Mineral content determines flavour.

How is malted Barley used in the beer production process?

Barley selected for its brewing properties. Barley is malted to release ENZYMES to convert STARCH granules to GLUCOSE. [The degree to which the barley structure is degraded during malting is called 'modification'.] Malt provides: - Flavour, starch for fermentation, protein for yeast nutrition, and colour

How are Hops (Humulus Lupulus) used in brewing?

Hops produced soley for brewing. The cone part contains LUPULIN GLAND that holds the hop resin. Hops give the beer a bitter taste, characteristic aroma and a longer shelf-life.

Name the stages of beer production

Malting of Grain Mashing of Grist Wort Drained off Hops added Fermentation Racking Refining Filtration (refer to notes for further details)

Name the stages of wine production

Picking Stemming and Crushing Pressing Fermentation Aging Bottling

What is the need for the pressing step after crushing in wine production?

To remove as much juice as possible. Note: seeds not crushed

What is the difference in the making of red vs white wine?

White wines are made by pressing out the juice from the grapes, and fermenting only the juice. [Fermentation = 2-8 weeks] Red wine is made by the fermentation of grape juice, which often also contains the skin, pieces of the grapes, and sometimes even their seeds. [Fermentation = 10-14 days]

What happens in fermentation when making wine?

Yeast and sugar added to juice (or juice + skins). Sulphur dioxide used to restrict bacterial cell growth. Differs in time depending on white/red wine.

What happens in the ageing process when making wine?

- Sedimentation of yeast cells occurs. - Wine transferred across a series of tanks to remove sediment. - Filtered at high pressure. Wooden casks provide unique character to the wine. Bottling 12 months after grape harvest. Ageing is variable - white = 12-18 months. red = up to 5 years (or more)

How are distilled spirits made?

- Ethanol concentrated by distillation. - Max conc achievable by distillation is 95.6% (azeotrope). - Often diluted with water to around 40% alcohol by volume (ABV)

What is an Azeotrope?

A mixture of liquids that has a constant b.p. because the vapour and the liquid mixture have the same composition.