Nutrition Cardiovascular Disease (15)
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often synonymous with coronary heart disease (atherosclerosis and thrombosis of the blood vessels of the heart), but also includes other conditions such as sudden cardiac death, congestive heart failure, stroke (cerebrovascular disease), & peripheral artery disease (atherosclerosis and thrombosis of the arteries of the extremities)
Coronary Heart Disease (CHD)
- narrowing of arteries leading up to the heart causing a blockage & subsequently a myocardial infarction (MI)
- the most common source of death in the U.S.
What are some major risk factors for CHD?
- Sedentary lifestyle
can be caused by hypertension & cardiovascular risk factors, it can also be caused by hemorrhage, which wouldn't necessarily be related to
- persistently elevated arterial blood pressure
- affects one in three U.S. adults
- if untreated can lead to heart failure, chronic kidney disease, & peripheral vascular disease
- is often known as a “silent killer” since afflicted individuals are often asymptomatic
What are normal biochemical levels related to heart health?
- BP: 120/80 or lower [systolic/diastolic]
- total cholesterol: 200 mg/dL or lower
- LDL cholesterol: 100 mg/dL or lower
- HDL cholesterol: 60 mg/dL or higher
- BMI: 18.5 – 24.9
Essential (Primary) Hypertension
- persistently elevated arterial blood pressure in which a cause cannot be determined
- Secondary hypertension results from another disease (eg. cardiovascular disease)
What are some benefits of lowering blood pressure?
- risk of heart failure decreases by 50% when it's effectively treated
- risk of stroke decreases by 35-40%
- risk of myocardial infarction decreases by 20-25%
What are 2 mechanisms implicated in the development of hypertension?
- 1. dysregulation of the angiotensin & ADH hormone systems
- 2. exaggerated sympathetic nervous system stimulation and/or sympathetic/parasympathetic imbalance
- DIETARY + lifestyle factors can exacerbate or ameliorate hypertension when these abnormalities are underly the disease
What 2 categories do risk factors for hypertension fall into?
- 1. factors that cannot be modified
- 2. lifestyle factors - factors that can be modified
What are the primary lifestyle strategies for the control of hypertension?
increasing physical activity, quitting smoking, weight loss, & a reduction of sodium and alcohol intake
What two non-pharmacological interventions MOST effectively decrease blood pressure?
- 1. increasing physical activity
- 2. reducing sodium intake
- ~decreasing alcohol intake & taking potassium supplements also has a modest effect
Sodium & Hypertension
~50% of individuals w/ hypertension are thought to be salt sensitive: their BP increases in response to salt intake
a reduction in BP can be seen across all ages & ethnicities when sodium is restricted
UL: 2300 mg/daycomes mainly from processed foods (NOT table salt) → should be restricted
- there is a consistent relationship between saturated fat intake & risk for CHD
- saturated fat increases LDL & HDL but LDL more so
- saturated fat sources in the U.S. are primarily meat & dairy → if a fat is solid at room temp = SAT
- trans fat, now markedly reduced in the food supply, increases LDL but not HDL
- poly & monounsaturated fat tend to have a neutral effect on lipoproteins but favorably affect lipoprotein profiles when SUBSTITUTED for saturated fat (these are liquid at room temp.)
Trans Fatty Acids
- these are created during the hydrogenation of fats & naturally occur in ruminant animals (eg. cows)
- there is a small amount found in meat & dairy
- trans fats increase LDL, either decrease or do nothing to HDL, & increase risk for CVD
- WORSE than saturated fat
Omega-3 Fatty Acids
- examples include eicosapentaenoic acid (EPA) & docosahexaenoic acid (DHA) (found in oily fish & fish oil capsules)
- they're associated w/ reduced risk for sudden death due to cardiac arrhythmia
- this is the basis of current recommendations to increase seafood intake & previous recommendations to consume fish at least 2x weekly
- α-Linolenic (ALA) (found in flaxseed oil, canola oil, & soybean oil), a plant based omega-3 FA doesn't have the same benefits
Which fish, farmed or wild, has more omega-3 fatty acids?
- except not consistently & depending on the study
- is more dependent on what the fish are eating rather than where they were raised
- if they're eating a high omega-3 FA diet, they'll have high omega-3 content
Omega-6 Fatty Acids
- lineoleic acid (C18:2 ω-6) is found in corn oil, safflower oil, & sunflower oil
- in the body it's a component of cell plasma membranes & is used in the biosynthesis of arachidonic acid (AA), a precursor for both inflammatory mediators PG & LT
What happens to a person's risk of CHD when carbohydrates are substituted for different types of dietary fat?
- sat fat → CHO: CHD risk decreases
- MUFA → CHO: CHD risk increases
- PUFA → CHO: CHD risk increases even MORE than w/ MUFA
- triglyceride concentrations go up because excess carbs are stored as fat, increasing risk of Coronary Heart Disease
- whole grain intake decreases risk for CVD but it remains unclear if benefits are due to the greater fiber content of whole grain foods or phytonutrients & minerals
- whole grains also help decrease risk of DIABETES; are helpful in managing glucose control
- whole wheat is better than whole grain because whole grain products may have anywhere from 50-100% of the grain they're advertising
Why is increased fiber intake associated with a decreased risk of coronary heart disease?
- it decreases the total & LDL cholesterol
- it has a reduced glycemic index & insulinemic response → diabetes itself is a risk for CHD
- foods with fiber often contain micronutrients, antioxidants, phytochemicals, & MINIMAL saturated fat
- they reduce total & LDL cholesterol by binding bile acids in the small intestine, preventing bile acid reabsorption (decreasing their enterohepatic recirculation)
- as the bile acid pool in the liver is depleted, cholesterol synthesis is redirected towards bile acid synthesis
- soluble fiber might also bind FAs in the SI lumen, preventing their absorption!
- eg. beta-glucan found in oats & barley
Alcohol & CVD
- as alcohol intake increase above two drinks/day for men & one drink/day for women, the risk of hypertension also increases
- even though alcohol is a vasodilator, increased intake causes more thromboxane (a vasoCONSTRICTOR) to be produced
- intake should be < 2 drinks for men & <1 drink for women daily
- contribute to weight gain & obesity
- have little nutritional value
- notably high fructose corn syrup, ingestion of which can cause excess weight gain, increased TAGs, & insulin resistance
- SoFAS: solid fat & added sugar
- its metabolism bypasses a key step (the rate limiting step) in glycolysis & goes straight to hepatic metabolism
- because of this, high amounts of fructose can increase levels of TAGs → increasing risk of CVD
- fructose can also increase postprandial TAGs (SOMETIMES) → bottom line is it's better to get fructose from natural sources (fruit) as opposed to foods with high fructose corn syrup
Obesity & CVD
- is a major risk factor for hypertension, dyslipidemia, diabetes, & CVD independent of traditional risk factors due to its associated with chronic inflammation
- weight loss in the range of 5-10% of initial weight can improve cardiovascular risk factors in the setting of obesity
- obesity also contributes to CVD by causing sleep apnea (resulting in hypertension), & contributing to cardiac arrhythmias and congestive heart failure
What kind of relationship exists between the degree of obesity and the severity of hypertension?
- a linear one
- a weight loss regimen is a standard component of nutrition therapy for hypertension treatment
- a 5–9.2kg (11–20 lbs) weight loss reduced systolic & diastolic blood pressure
- as little as a 10% weight change can reduce BP
Nutrition-wise, what is most effective in preventing CVD?
- having a healthy diet PATTERN, as opposed to focusing on the individual constituents of a
- in general, effective diets are based on whole grains, fish, low fat or non fat dairy, & are rich in vegetables and fruit
- eg. DASH or Mediterranean diet are protective against CVD
The Dietary Approaches to Stop Hypertension (DASH)
- established by the National Heart, Lung, and Blood Institute as a comprehensive dietary approach in the treatment of hypertension
- it was first designed for blood pressure control but is now recommended more broadly
- is based on intake of whole grains, fish poultry, nuts, vegetables fruits, vegetables, & nonfat or low fat dairy
- it discourages intake of salt/sodium (no more than 2300 mg), meat, foods high in saturated fat or cholesterol, & foods or beverages w/ added sugar
What 3 additional minerals are recommended in the DASH to control BP?
- 1. Calcium through low fat dairy products
- 2. Magnesium through nuts
- 3. Potassium through fruits & vegetables
Effects of DASH Diet
- clinical trials show the DASH diet lowers systolic & diastolic blood pressure similar to that of a single agent anti-hypertensive therapy & reduces risk for CVD risk factors + CVD itself
- the diet can take effect after as little as 14 days
- African Americans seem to be more sensitive (experience a greater reduction in BP) to the low sodium component of DASH, especially women
The Mediterranean Diet
- not one diet
- the diet pattern is characterized by intake of whole grains, legumes, vegetables, fruit, some poultry, use of olive oil as the main source of fat, low fat dairy, nuts, red wine, occasional eggs, rare meat, & minimal sweets
- it has been observed to favorably influence mortality & risk for some chronic diseases (eg. prediabetics on this diet reduce their progression to type 2 diabetes)
Very Low Fat Diets
- developed to reverse coronary artery disease
- these diets have 10-15% of energy from fat derived from vegetable oils
- the diet consist of vegetables, fruit, grains, legumes, high fiber, & low energy density
- weight loss often occurs even though intake is not limited, however these diets may be insufficient in fat soluble vitamins & zinc
What is the main difference between American Heart Association dietary guidelines versus the Dietary Guidelines for Americans?
- DGA: NOT specifically targeted toward heart health, more generally aimed at reducing the risk of chronic disease
- AHA: specifically targeted toward cardiovascular health
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