Lifestyle: CVD - risk factors 1.2-1.3

Question 1

What is risk?

Answer 1

The mathematical probability of an event occurring (in a period of time)

Question 2

How to calculate ‘1 in x’ risk

Answer 2

Eg., 19900 fatalities from injuries out of population of 62,262,000

divide the population by incidence

62,262,000 by 19990 = 3128.7

or 1 in 3129.

Question 3

What is perception of risk?

Answer 3

A belief that can be an overestimation or underestimation of statistical risk due to

• something not being natural

something being outside of people’s control

something unfamiliar

something ‘dreaded’ - fear based

something deemed ‘unfair’

something deemed very unlikely

Question 4

What are the types of risk factors?

Answer 4

age

heredity

physical environment

social environment

lifestyle and behaviour choices

Question 5

Define correlation

Answer 5

A change in one variable is associated with a change in a second variable

Question 6

What is a cohort study?

Answer 6

Studying a group of people over time;

at the start of the study, none have the disease;

exposures to known risk factors (say, smoking) are then noted.

Since they take a long period of time, they can be very expensive

Question 7

What are the findings of the on-going Framlingham Heart Study in the US?

Answer 7

High bp, high blood cholesterol, smoking, obesity, diabetes and lack of physical activity are all major CVD risk factors

UPDATE: lung size (capacity) correlates strongly with longevity!!! Hot of the press that one - ed.

Question 8

What are case-control studies?

Answer 8

A survey of people who are deemed representative of the population.

E.g., A group with a disease are compared with a control group without the disease.

Data is collected on risk factors ppts (participants) have been exposed to in the past.

Both groups are matched according to sex and age.

* Doll and Hill in the 1950s showed a positive correlation between smoking and lung cancer.

* INTERHEART screened 15000 cases and 14800 controls across 52 countries and matched by gender and age noted the nine risk factors were the same for men and women and in almost all regions and for all ethnicities.

Question 9

What are the features of a good study?

Answer 9

Clear aim - the hypothesis

Representative sample

Good sample size

Valid and reliable results

Clearly identified control variables

Question 10

What is hypertension?

Answer 10

High blood pressure

Question 11

What is a sphygmomanometer?

sphygmos = pulse

manometer = measures pressure

Answer 11

Device to measure blood pressure

Question 12

What does mmHg mean?

Answer 12

millimetres of mercury - the millimetres a column of mercury rises in a taking pressure readings

Mercury is Hg.

(elsewhere in physics, pressure is measured in kilopascals, but the medical sciences do hold on to outdated methds…)

Question 13

What does a blood pressure reading of 140/85 mean?

Answer 13

Systolic pressure of 140 mmHg

Diastolic pressuce of 85 mmHg.

Question 14

What determines blood pressure?

Answer 14

Peripheral resistance (friction) between the blood flow and vessel walls

surface area of the vessel walls (there is more surface area in the capillaries so flow slows and BP drops)

BP fluctations due to contraction and contraction of heart (high BP when heart contracts)

during diastole, the elastic recoil of vessels maintains BP

narrowing of vessels causes BP to rise (contraction of lumen but also physiological issues - aging, release of adrenaline, high salt diet)

Question 15

What is an oedema

Answer 15

sign of high BP (build up of fluid causing swelling)

Question 16

Why do fluid and small molecules leave capillaries and enter interstitial space?

Answer 16

Blood is under relatively high pressure at the end of a capillary.

The high pressure forces molecules and liquid out (blood cells and plasma proteins) - this is called tissue fluid

Under elevated BP, more fluid may seep out and cause oedema

Question 17

Tissue fluid (instititial fluid) goes where?

Answer 17

Carries nutrients and O₂ to the cells and picks up waste and CO₂

Under normal circumstances, any excess goes into lymph system (lymph clears out debris and rubbish)

Under high BP conditions, it pools in intercellular space

Question 18

If the left hand side of the heart begins to fail, where does blood pool?

Answer 18

In the lungs

Question 19

What is a calorie?

Answer 19

The quantity of heat required to raise 1cm³ by 1 degree

Question 20

What unit is used by scientists to measure food energy?

Answer 20

The kilojoule (1000 joules)

4.14 J = 1 calori

Question 21

Why is measuring food energy in kilojoules rather strange (-ed)?

Answer 21

Biology is not the same as physics.

A block of wood may contain 4000kJ but would not be very good for compared to the same amount of energy released by potatoes….

(this is not on the A-level…it’s more about thinking about biology; biologists, like many scientists and social scientists, have suffered from ‘physics envy’ - trying to make their subject fit the methods of physics!)

Question 22

For notes on carbs and fats - see biological molecule quizzes

Answer 22

ok…

Question 23

Describe Dietary Reference Values (DRVs)

Answer 23

Created by the Dept of Health they indicate a range of nutrient intake:

EAR - estimated average requirement

LRNI - lower reference nutrient intake

HRNI - higher reference nutrient intake

Question 24

What is a basal metabolic rate? (BMR)

Answer 24

Energy required for essential processes

higher in males, heavier people, younger people, and more active people

Question 25

Describe ‘the energy balance’

Answer 25

Eating fewer kJ per day than you use creates a negative energy balance and energy stored in the body will be used to meet the demand - hence weight loss.

If you eat more than needed, you create a positive energy balance - hence weight gain.

NB - this is now questioned - it depends on what foods are being eaten; the old adage ‘eat less, do more’ is being rejected by scientists (notably functional medical researchers) - ed.

Question 26

What is the current % of men and women who are defined as obese?

Answer 26

About 25% are obese

65% of men are overweight and 55% of women

Question 27

What is a BMI?

Answer 27

Body Mass Index which relates weight to height.

BMI = mass Kg / height m^2

So if you’re 79Kg and height 1.7m

BMI = 79/1.7^2 = 27.3

(Ttis is mine - I’m apparently overweight…actually, I weight train, have low fat levels and my abs are decently six packed, hah hah! - ed)

Question 28

For whom is the BMI not very accurate?

Answer 28

Atheletes

Children

People > 60

People with long term health conditions

Question 29

Instead of BMI, what alternative measure could be used?

Answer 29

Waist to hip ratio

Positive correlation between hip circumferences and hip circumference and heart attacks

Measure waist then divide by hip.

(Mine was 90cms / 100cms after lunch; so 0.90)

Question 30

What problems were there with waist to hip measurements?

Answer 30

Different people put on weight in different areas.

Ratio can stay the same though weight is put on/lost:

A woman who measures 90cm to 100cms (0.9 ratio) puts on weight during the menopause and now measures 108cms and 120cms, which is still 0.9.

Question 31

What are the consequences of obesity?

Answer 31

coronary heart disease

stroke

type II diabetes

high BP

increase blood lipid levels

(and recent research from the Amen clinics shows brain shrinkage!)

Question 32

Why is cholesterol a problem? (1pt)

Answer 32

Positive correlation between high blood cholesterol levels and coronary heart disease

eg in Europe, 45% of heart attacks relate to high blood cholesterol

Question 33

What are lipoproteins

Answer 33

cholesterol is not soluble, so it forms with proteins to be transported around the bloodstream

Question 34

What are LDLs? (1pt)

Answer 34

Low-density lipoproteins

Question 35

What do LDLs do?

Answer 35

Cholesterol plus triglycerieds form LDLs which transport the cholesterol to body cells

LDLs bind to cell membranes where they are taken in

the cholesterol helps maintain cell membranes

EXCESS LDL overwhelm membrane receptors hence high LDL in blood

High LDL in blood can cause atheromas (plaque build up on arterial walls)

Question 36

What do HDLs do?

Answer 36

Higher % of protein to cholesterol than LDLs

transport cholesterol from body tissues to the liver to break it down

this lowers blood cholesterol levels and helps remove fatty plaques

Question 37

What is the traditional view on saturated versus unsaturated fats?

Answer 37

1) saturated fats increase LDL and HDL cholesterol
2) swapping saturated for polyunsaturated fat decreases LDL and HDL increases HDL:LDL ration and improves the protective effects
3) low fat diet can reduce CVD risk
4) saturated fats may reduce activity of LDL receptors so LDL is not removed from the blood, increasing blood cholesterol levels and hence CVD risks

Question 38

What is the conflicting evidence regarding high cholesterol in the blood?

Answer 38

1. In France, research indicated that CHD (coronary heart disease) was low despite high cholesterol and saturated fat in diet.
2. 2014 research noted no significant correlation between saturated fat and CHD or evidence that polyunsaturated fats are protective.
3. More risk was associated with trans-fats (polyunsaturated oils hydrogenated for processing). Since 2008 UK food manufacturers have dropped trans-fats.
4. Other researchers argue that the culprit is sugar, “Sugar drives the good cholesterol down and increases small dangerous cholesterol particles and causes pre-diabetes and diabetes (diabesity). THAT is the true cause of most heart attacks, NOT LDL cholesterol.” Dr Mark Hyman

For personal reading, here’s a functional medicine view on cholesterol bringing the science up to date.

Question 39

How does smoking relate to cardiovascular disease? (5 pts)

Answer 39

50 yr cohort study found CHD mortality 60% higher in smokers than non-smokers.

Reasons:

1. CO in smoke binds to haemoglobin instead of O₂
2. heart rate increases to provide more O₂ to the body
3. nicotine stimulates adrenaline production, which increases heart rate, constricts arterial vessels and hence BP increases
4. chemicals in smoke damage lung lining
5. smoking can reduced ‘good’ HDL cholesterol

Question 40

How does inactivity relate to CVD? (3 pts)

Answer 40

research indicates that an active lifestyle can lower CHD risk by 50%

1. moderate exercise prevents and even lowers BP
2. exercise increases ‘good’ HDL cholesterol and reduces risk of type II diabetes
3. active person is more likely to survive a heart attack

Question 41

How does genetics relate to CVD risks?

(2pts + 3pts for any details)

Answer 41

No clear cut relationship between single and multiple inherited genes and risk of disease

• Single genetic causes:

FL: familial hypercholesterolaemia causes LDL receptors not to form (but diet and lifestyle also seem to play a role); FL seems to affect around 5-10% of CHD patients

• Gene clusters - the apolipoprotein clusters APOA, APOB, APOE

APOA - the major protein in HDL which helps remove cholesterol from blood stream; mutations thwart this removal and hence increase risk of CHD

APOB: main protein in LDL which helps transfer cholesterol from blood to cells; mutations mean more LDL in blood hence increases CVD risk.

APOE: major component of HDLs - help remove excess cholesterol from blood; the APOE4 allele can slow removal hence increase riks of CHD.

Question 42

Why is it difficult to reduce heart disease issues to one gene or one set of genes? (2pts)

Answer 42

1. genetic mutations can be affected by different environments
2. and when they combine, it is difficult to assess the effect of one gene or one cluster

Question 43

Regarding disease in general, what does “multifactorial” mean?

Answer 43

There are many potential causes.

hereditary (genes)

physical environment (think of sunlight exposure, access to fresh water)

social environment (peer pressure to drink, smoke, do drugs)

lifestyle choices (personal psychology about how to live, exercise, sleep)

Question 44

What is the role of antioxidants in CVD?

Answer 44

Free radicals, e.g., O₂⁺ can damage cells, enzymes, and genetic material and correlates with cancer, CHD, premature ageing.

Vit C, beta-carotene, and Vit E can protect against free radicals by offering hydrogen atoms to pair up with unpaired electrons e^-

Sources of antioxidants: basically,”eat the rainbow”

Vitamin C: Broccoli, Brussels sprouts, cantaloupe, cauliflower, grapefruit, leafy greens (turnip, mustard, beet, collards), honeydew, kale, kiwi, lemon, orange, papaya, snow peas, strawberries, sweet potato, tomatoes, and bell peppers (all colors)

Vitamin E: Almonds, avocado, Swiss chard, leafy greens (beet, mustard, turnip), peanuts, red peppers, spinach (boiled), and sunflower seeds

Carotenoids including beta-carotene and lycopene: Apricots, asparagus, beets, broccoli, cantaloupe, carrots, bell peppers, kale, mangos, turnip and collard greens, oranges, peaches, pink grapefruit, pumpkin, winter squash, spinach, sweet potato, tangerines, tomatoes, and watermelon

Selenium: Brazil nuts, fish, shellfish, beef, poultry, barley, brown rice

Zinc: Beef, poultry, oysters, shrimp, sesame seeds, pumpkin seeds, chickpeas, lentils, cashews, fortified cereals

Phenolic compounds: Quercetin (apples, red wine, onions), catechins (tea, cocoa, berries), resveratrol (red and white wine, grapes, peanuts, berries), coumaric acid (spices, berries), anthocyanins (blueberries, strawberries)

Source for the above for review by Harvard science writers (NB, from other studies, it is noted that alcohol can seriously damage brain metabolism)

Question 45

What is the role of salt in CHD?

Answer 45

Basic science:

High salt diet can cause kidneys to retain water, which increases BP and hence CVD risks.

It’s more complicated:

We need salt, active people more than others; a lot of salt today is processed or hidden and devoice of mineral content; reducing CHD to salt intake has not been properly established since mineral salts also offer a lot of other benefits for the body.

More reading for the interested.

Question 46

What is the role of stress in CVD? (2 pts)

Answer 46

1. Stress leads to release of adrenaline causing arterial constriction and raised BP
2. Psychologically it can also lead to overeating, higher alcohol consumption, and poor diet (snacking on sugary foods!)

For the interested - more detail than the book provides on this important area

The relationship between stress and inflammation has been studied rigorously in the past decade, with researchers finding evidence that the inflammatory pathway is pivotal in the pathogenesis of many chronic diseases. In fact, 75% to 90% of human disease is related to stress and inflammation, including cardiovascular and metabolic diseases and neurodegenerative disorders.

Studies suggest that chronic stress results in glucocorticoid receptor resistance that, in turn, results in failure to downregulate inflammatory responses…Large bodies of research indicate that chronic stress, whether experienced in early life or as an adult, is linked to increased coronary heart disease risk. In particular, childhood adversity, including physical and sexual abuse in childhood, has been shown to relate to higher morbidity of cardiovascular events in women. Work-related stressors, poor sleep, and emotional disturbances have been correlated with adult-related cardiovascular disease.

SOURCE

Question 47

What is the relationship of alcohol consumption with CHD?

Answer 47

1. Heavy drinking raises blood pressure, contributes to obesity, can cause irregular heart beat, liver damage, brain and heart damage.
2. An impaired liver means it cannot remove glucose and lipids from the blood. Alchohol turns to C3 carbohydrate (ethanal) which is used in respiration but some can turn into Very Low Density Lipoproteins (VLDLs) that increase risk of arterial plaque formation.

BONUS RESEARCH

Though the UK govt accepts moderate drinking at 2-3 units DAILY for women and 3-4 units for men (see textbook), even this “moderate drinking” has been found to:

1. shrink the brain
2. reduce blood flow to the brain
3. 1-2 glasses of wine a day diminishes the memory centres
4. reduces the number of new brain cells produced
5. increased risk of dementia
6. prematurely ages the brain

SOURCE

Question 48

What is the role of coffee and CVD risk?

Answer 48

Studies show both positive and negative correlation.

NEGATIVE CORRELATION (or health benefits of coffee)

1. In … three studies, people who reported drinking one or more cups of caffeinated coffee had an associated decreased long-term heart failure risk.
2. In the Framingham Heart and the Cardiovascular Health studies, the risk of heart failure over the course of decades decreased by 5-to-12% per cup per day of coffee, compared with no coffee consumption.
3. In the Atherosclerosis Risk in Communities Study, the risk of heart failure did not change between 0 to 1 cup per day of coffee; however, it was about 30% lower in people who drank at least 2 cups a day.
4. Drinking decaffeinated coffee appeared to have an opposite effect on heart failure risk – significantly increasing the risk of heart failure in the Framingham Heart Study. In the Cardiovascular Health Study however; there was no increase or decrease in risk of heart failure associated with drinking decaffeinated coffee. When the researchers examined this further, they found caffeine consumption from any source appeared to be associated with decreased heart failure risk, and caffeine was at least part of the reason for the apparent benefit from drinking more coffee.

SOURCE

POSITIVE CORRELATION WITH HEALTH RISKS

When you drink caffeine, however, the adenosine receptors mistake the caffeine for adenosine and bind to it. When caffeine is attached to the adenosine receptors, it does just the opposite of adenosine. It constricts the brain’s blood vessels, speeds up neuronal activity, and signals your body to go on high alert by producing adrenaline.

This gives you that java jolt, which makes your heart beat faster, your breathing become more shallow, and your muscles tense up. It also boosts dopamine levels, which activates the pleasure centers in your brain.

What happens to the adenosine receptor system when you consume large amounts of caffeine on a regular basis?

What they found is that habitually high caffeine intake (about 950mg a day) results in diminished blood flow to the brain, showing that the adenosine receptor system, in fact, does NOT learn to compensate for the effects of caffeine.

After years of studying brain scans, I can assure you that reduced cerebral blood flow leads to brain drain. It lowers cognitive function and can exacerbate emotional and mental health problems.

SOURCE