Diet Diet &Cardiovascular &Cardiovascular

SystemSystem

ObjectivesObjectives

Importance of fatsImportance of fatsFats and CHDFats and CHDDifferent types of dietary FatsDifferent types of dietary FatsMediterranean DietMediterranean DietDietary factors affecting plasma Dietary factors affecting plasma

cholesterolcholesterolRecommendationsRecommendations

Fats in the DietFats in the Diet

A concentrated source of energy (9 A concentrated source of energy (9 kcals/gram)kcals/gram)

Supply essential fatty acids such as Supply essential fatty acids such as linoleic and linolenic acidslinoleic and linolenic acids

Provide phospholipids for membrane Provide phospholipids for membrane functionfunction

Source of fat-soluble vitamins (A, D, E, Source of fat-soluble vitamins (A, D, E, K) and help in their absorptionK) and help in their absorption

RDA (gm/day): Total fats: 65, Saturated: RDA (gm/day): Total fats: 65, Saturated: 2020

Excessive fat intake can causeExcessive fat intake can causeAtherosclerosis/heart diseaseAtherosclerosis/heart diseaseObesityObesity

• Chronic diseases are significantly influenced by the kinds and amounts of nutrients consumed.

risk of CHD: in• Dyslipidemias• Smoking• Obesity• Sedentary

lifestyle.• Male gender• homocystenemia

Dietary lipids most strongly influence the incidence of

CHD

DIETARY DIETARY FAT:FAT:

• In the past dietary recommendations emphasized decreasing the total amount of fat in the diet.

•Research now indicates that the type of fat is more important than the total amount of fat consumed.

•A. Plasma lipids and CHD :A. Plasma lipids and CHD :Plasma cholesterol may arise from the Plasma cholesterol may arise from the diet or from endogenous biosynthesis. diet or from endogenous biosynthesis.

1.1. LDL and HDL:LDL and HDL: Plasma cholesterol level varies in response to the Plasma cholesterol level varies in response to the

diet. diet.

total plasma cholesterol levels total plasma cholesterol levels risk for risk for Coronary heart diseases (CHD). Coronary heart diseases (CHD).

High levels of LDL cholesterol High levels of LDL cholesterol risk for CHD. risk for CHD.

High levels of HDL cholesterol High levels of HDL cholesterol risk for CHD. risk for CHD.

2. Beneficial effect of lowering plasma 2. Beneficial effect of lowering plasma cholesterol:cholesterol: Dietary or drug treatment of Dietary or drug treatment of

hypercholesterolemia hypercholesterolemia decreasing LDL & decreasing LDL & HDL HDL the risk for cardiovascular events. the risk for cardiovascular events.

Dietary treatment Dietary treatment 10 - 20 % reduction in 10 - 20 % reduction in

plasma lipoprotein concentrations. plasma lipoprotein concentrations.

Treatment with Treatment with “statin”“statin” drugs drugs 30 - 40 % 30 - 40 % reduction in plasma cholesterol.reduction in plasma cholesterol.

B. B. Dietary fats and plasma Dietary fats and plasma lipidslipids

Triacylglycerols are quantitatively Triacylglycerols are quantitatively the most important class of dietary fats.

The influence of triacylglycerols on blood lipids is The influence of triacylglycerols on blood lipids is determined bydetermined by ::

The chemical nature of the constituent fatty acids. The chemical nature of the constituent fatty acids.

The presence or absence of double bonds (saturated The presence or absence of double bonds (saturated vs. mono- and polyunsaturated).vs. mono- and polyunsaturated).

The number and location of the double bonds (n-6 vs The number and location of the double bonds (n-6 vs n-3).n-3).

The cis vs trans configuration of the unsaturated fatty The cis vs trans configuration of the unsaturated fatty acids.acids.

1. Saturated fat:1. Saturated fat: Saturated fats are Saturated fats are triacylglycerols containing

fatty acids with no double bonds in its side in its side chains. chains.

• Dairy and meat products. • Vegetable oils, such as coconut & palm oils

Sources

• levels of total plasma cholesterol • LDL cholesterol • Risk of CHD.

Limitation of saturated fats intake risk of CHD.

Effects

2. Monounsaturated fats:2. Monounsaturated fats:

Monounsaturated fats are Monounsaturated fats are triacylglycerols containing primarily fatty acids with one double bond.

Unsaturated fatty acids are generally derived from Unsaturated fatty acids are generally derived from vegetables and fish. vegetables and fish.

When substituted for saturated fatty acids in the diet,When substituted for saturated fatty acids in the diet, monounsaturated fats monounsaturated fats total plasma cholesterol & LDL total plasma cholesterol & LDL cholesterol and cholesterol and HDLs. HDLs.

Mediterranean cultures, with diets rich in olive oil (Mediterranean cultures, with diets rich in olive oil (high in high in monounsaturated oleic acidmonounsaturated oleic acid), show a low incidence of ), show a low incidence of coronary heart disease. coronary heart disease.

The Mediterranean diet:The Mediterranean diet: rich in: rich in: - - monounsaturated fatty acidsmonounsaturated fatty acids ( (from olive oilfrom olive oil) )

- - n-3 fatty acidsn-3 fatty acids ( (from fish oils and some nutsfrom fish oils and some nuts) ) low in: low in: -- saturated fat saturated fat. .

The Mediterranean diet The Mediterranean diet serum total cholesterol and serum total cholesterol and LDLLDL - but little change in HDL. - but little change in HDL.

Plasma triacylglycerols are unchanged.Plasma triacylglycerols are unchanged.

• Seasonally fresh food• Abundance of plant material• Low amounts of red meat• Olive oil as the principal source of fat.

Mediterranean diet contains :

3. Polyunsaturated fats3. Polyunsaturated fats::

Polyunsaturated fats are Polyunsaturated fats are triacylglycerols containing triacylglycerols containing primarily fatty acidsprimarily fatty acids with with more than one double-bond.more than one double-bond.

The effects of polyunsaturated fatty acids The effects of polyunsaturated fatty acids (PUFAs)(PUFAs) on on cardiovascular disease is influenced by the location of the cardiovascular disease is influenced by the location of the

double bonds within the molecule.double bonds within the molecule. a. n-6 Fatty acids: (omega 6)

• long-chain, polyunsaturated fatty acids with the first double bond beginning at the sixth carbon atom

Sources• Nuts• Avocados• Olives• Soybeans• Various oils (sesame, cottonseed & corn oil).

plasma cholesterol• LDL• HDL

Effects

The powerful benefits of LDL are only partially offset because of the HDL

a. n-6 Fatty acids …… cont’d

b. n- 3 Fatty acids (omega -3) b. n- 3 Fatty acids (omega -3) Long-chain, polyunsaturated fatty acidsLong-chain, polyunsaturated fatty acids, with the , with the first first

double bond beginning at the third carbon atomdouble bond beginning at the third carbon atom

• suppress cardiac arrhythmias• serum triacylglycerols• tendency to thrombosis• Lowers blood pressure• risk of cardiovascular mortality• little effect on LDL or HDL cholesterol levels.

Effects

• Plants (mainly α-linolenic acid—an essential fatty acid). • Fish oil containing docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).

Sources

Linoleic acid (n-6 )Linoleic acid (n-6 ), and , and linolenic acidlinolenic acid (n-3 ) (n-3 )

are essential fatty acidsare essential fatty acids fluidity of membrane fluidity of membrane

structure and synthesis of eicosanoids .structure and synthesis of eicosanoids .

Deficiency of essential fatty acids

• Scaly dermatitis.• Hair loss.• Poor wound healing

Recommendations for Omega-3 Fatty Acid IntakeRecommendations for Omega-3 Fatty Acid IntakeAmerican Heart Association GuidelinesAmerican Heart Association Guidelines

PopulationPopulation Patients without Patients without

coronary heart coronary heart disease (CHD)disease (CHD)

Patients with CHDPatients with CHD

Patients who need Patients who need to lower to lower triglycerides (fats) triglycerides (fats)

RecommendationRecommendation Fatty fish twice a weekFatty fish twice a week Include oils and foods Include oils and foods

rich in rich in -linolenic acid -linolenic acid (flaxseed, canola and (flaxseed, canola and soybean oils; flaxseed soybean oils; flaxseed and walnuts)and walnuts)

------------------ 1 gm of EPA+DHA per 1 gm of EPA+DHA per

day from fatty fishday from fatty fish EPA+DHA supplementsEPA+DHA supplements------------------2 to 4 grams of 2 to 4 grams of

EPA+DHA per day EPA+DHA per day provided as capsules provided as capsules under a physicianunder a physician’’s s carecare

4. Trans fatty4. Trans fatty acids:acids:

Trans fatty acidsTrans fatty acids are chemically classified as are chemically classified as “ “ unsaturated fatty acids, behaving more unsaturated fatty acids, behaving more like saturated fatty acids in the bodylike saturated fatty acids in the body, i.e. they , i.e. they serum LDL (but not HDL) serum LDL (but not HDL) the risk of CHD the risk of CHD ” ”

Trans fatty acidsTrans fatty acids do not occur naturally in do not occur naturally in plantsplants and and only occur in small amounts in only occur in small amounts in animalsanimals. .

Trans fatty acids are formed during the Trans fatty acids are formed during the hydrogenation of liquid vegetable oils, in the hydrogenation of liquid vegetable oils, in the manufacture of margarine.manufacture of margarine.

Trans fatty acids are a major component of many Trans fatty acids are a major component of many commercial baked goods, such as cookies and commercial baked goods, such as cookies and cakes, and most deep-fried foodscakes, and most deep-fried foods

A key to the presence of trans fatty acids in a food is the words ‘partially hydrogenated’ on the list of package ingredients.

Sources :Animal products: milk, meat, eggs

5. Dietary Cholesterol:

The effect of dietary cholesterol on plasma cholesterol is less important than the amount and types of fatty acids consumed.

Dietary Factors affecting Blood Cholesterol Levels

(I) Factors which increase blood cholesterol1. Dietary cholesterol (play a minor role)2. High fat (enhance intestinal cholesterol absorption 3. Saturated fat: (except 18:0)

- enhance production of LDL and cholesterol - depress LDL uptake- TG high in 18:0 are digested and absorbed more

slowly and less efficiently than those of other fatty acids

4. Lower P/S ratio (polysaturated / saturated fatty acid)5. Trans-unsaturated fatty acids: ↑LDL-cholesterol ↓HDL-cholesterol 6. Sucrose, fructose7. Animal protein: ↑lysine/arginine ratio ↑cholesterol8. Iron (Fe): ↑free radical ↑atherosclerosis

(II) Factors which decrease blood cholesterol

1. Polyunsaturated fatty acid: eicosanoids (prostaglandin)

2. Omega-3 fatty acid: ↓Apo B,↓LDL, VLDL formation

↑VLDL, LDL turn over

3. Omega-6 fatty acid: ↓LDL-C

4. Antioxidants: beta carotene, vitamin E and C

5. Plant protein

6. Fiber ( decrease absorption of cholesterol and fat ,increase fecal loss of cholesterol)

ReferenceReference See Dietary Fat : Lippincott See Dietary Fat : Lippincott

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