**4. Dietary food groups and lipoprotein**

#### **4.1. Grains and cereal**

Based on evidence from both population and intervention studies, the recommended intake of whole grains of the 2005 Dietary Guidelines for Americans, is at least three ounces per day [114]. The Dietary Guidelines Advisory Committee (DGAC) 2010 Report emphasizes fiber-rich carbohydrate foods such as whole grains and vegetables, fruits, and cooked dry beans and peas, it specifically recommends that half of the grains consumed be whole grains, hence some whole grains should replace refined grains [115]. Similar recommendations are made by the American Heart Association [116] and the American Diabetes Association [117]. Whole grains are referred to as "complex" or "high-quality" carbohydrates, mainly due to their dietary fiber content [118], which has a beneficial effect on body weight, and lipid profiles because they are usually less energy-dense and more satiating than refined-grain foods [119] may be due to their high fiber content. Among whole grains, oat and barley have an advantage over wheat and brown rice in lowering serum lipids [120,121,122], contain viscous fibres, including β-glucacon [118] that lower serum cholesterol; 3.5 g of β-glucan from oats reduces LDL-C by 5% [123,124]. β-glucan interferes with reabsorption of bile acids and cholesterol by binding to bile acids, leading to increase bile acid excretion and lowering the bile acid levels in the liver and thereby increasing the conversion rate of cholesterol to bile acids. A viscous fiber intake of 10–25 g/d is recommended by the National Cholesterol Education Program's Adult Treatment Panel III as an additional diet option to decrease LDL cholesterol; an intake of 5–10 g/d lowers LDL-C by about 5% [126].

#### **4.2. Fruit and vegetables**

The 2010 Dietary Guidelines for Americans, recommend consuming sufficient amounts (5-13 servings, depending on energy needs) and a varieties of fruits and vegetables to reduce the risk of developing chronic diseases [115]; fruits, vegetables, or both should be emphasized at each meal, being major sources of vitamins C, E, and A, beta-carotene, other vitamins, fiber, flavonoids, and some minerals. Snacks and desserts that contain fruits and/or vegetables can be low in saturated fat, total fat, and cholesterol, and are very nutritious [18]. Fruits and vegetable intakes do not significantly change HDL cholesterol concentrations, but do decrease total and LDL cholesterol [9,127-132]. The protective effect of fruit and vegetables against CVDs is from their water-soluble and also viscous fibers (e.g. pectins) [133]. Viscous fiber increases fecal bile acid losses [134] and chenodeoxycholic acid synthesis [135].

#### **4.3. Dairy products**

310 Lipoproteins – Role in Health and Diseases

**4.1. Grains and cereal** 

LDL-C by about 5% [126].

**4.2. Fruit and vegetables** 

reduce oxidized LDL due to antioxidant activity [112,113].

**4. Dietary food groups and lipoprotein** 

protein in general has little effect on lipoprotein profiles. However, substituting plant protein including wheat gluten, soy proteins for animal protein decrease serum cholesterol [104,105]. Advice on the use of soy foods to displace animal products is consistent with the AHA advisory on soy [107**],** which states that 50 g/d soy protein consumption reduces approximate 3% LDL-C with no apparent dose-response effect [108]. Maximum reduction in LDL cholesterol was achieved when ~50 g of soy protein when was replaced meat or dairy protein [109]. Soy is a complex protein with a globulin fraction to which its cholesterollowering effect has been attributed; this fraction digested to peptides with inhibitory effects on cholesterol synthesis [110]. Isoflavones or the saponins found in soy, are also responsible for the cholesterol-lowering effect of soy [111,112]. Soy and other vegetable proteins also

Based on evidence from both population and intervention studies, the recommended intake of whole grains of the 2005 Dietary Guidelines for Americans, is at least three ounces per day [114]. The Dietary Guidelines Advisory Committee (DGAC) 2010 Report emphasizes fiber-rich carbohydrate foods such as whole grains and vegetables, fruits, and cooked dry beans and peas, it specifically recommends that half of the grains consumed be whole grains, hence some whole grains should replace refined grains [115]. Similar recommendations are made by the American Heart Association [116] and the American Diabetes Association [117]. Whole grains are referred to as "complex" or "high-quality" carbohydrates, mainly due to their dietary fiber content [118], which has a beneficial effect on body weight, and lipid profiles because they are usually less energy-dense and more satiating than refined-grain foods [119] may be due to their high fiber content. Among whole grains, oat and barley have an advantage over wheat and brown rice in lowering serum lipids [120,121,122], contain viscous fibres, including β-glucacon [118] that lower serum cholesterol; 3.5 g of β-glucan from oats reduces LDL-C by 5% [123,124]. β-glucan interferes with reabsorption of bile acids and cholesterol by binding to bile acids, leading to increase bile acid excretion and lowering the bile acid levels in the liver and thereby increasing the conversion rate of cholesterol to bile acids. A viscous fiber intake of 10–25 g/d is recommended by the National Cholesterol Education Program's Adult Treatment Panel III as an additional diet option to decrease LDL cholesterol; an intake of 5–10 g/d lowers

The 2010 Dietary Guidelines for Americans, recommend consuming sufficient amounts (5-13 servings, depending on energy needs) and a varieties of fruits and vegetables to reduce the risk of developing chronic diseases [115]; fruits, vegetables, or both should be emphasized at each meal, being major sources of vitamins C, E, and A, beta-carotene, other vitamins, fiber, flavonoids, and some minerals. Snacks and desserts that contain fruits and/or vegetables can Dairy products are important sources of protein, calcium, phosphorus, and vitamin D. The recommendation for intakes of dairy products is 2-3 serving per day; fat-free milk or 1 percent fat milk, fat-free or low-fat cheese (e.g., ≤3g per 1 oz serving), 1 percent fat cottage cheese or imitation cheeses made from vegetable oils, and fat-free or low-fat yogurt are good choices. Fat-free milk and other fat-free or low-fat dairy products provide as much or more calcium and protein than whole milk dairy products, with little or no saturated fat [18].

Recent studies confirm that milk products were associated with lower small dense LDL, and triglyceride concentrations, and higher HDL cholesterol [136]. In the CARDIA study, obese subjects with more frequent consumption of dairy products showed a trend towards lower risk of dyslipidaemia [137]. Minerals (calcium, magnesium), protein (casein and whey) and vitamins (riboflavin and vitamin B-12) have the hypocholesterolaemic effect of dairy product. The possible hypolipidaemic mechanism of calcium includes decreased intestinal absorption of cholesterol, bile acids, or fat [138], decreased fatty acid synthesis, increasing lipolysis, all of which lead to decreased triacylglycerol stores [139]. Milk proteins (whey) [140] or peptides [141] may also play a role. Whey may act independently or synergistically with the calcium; attenuate lipogenesis, and accelerate lipolysis [142]. Dairy products contain SFAs that could affect the blood lipid profile. A recent meta-analysis of 21 prospective cohort studies showed that the harmful effects of SFAs on CHD are still controversial [143]. An inverse association was shown between milk-specific fatty acids in serum cholesterol esters with serum cholesterol and apolipoprotein β levels [144]. Consumption of fat-free dairy products might decrease plasma cholesterol levels, while whole milk has neither a hypo- nor hypercholesterolaemic effect [139]. SFAs in dairy products can adversely influence CHD, although the effect of SFAs on CHD risk depends on the source of calories by which it is substituted to maintain energy balance [145]. Different dairy products have different effects on the lipid profiles. The LDL-C-raising effect of cheese was less than that of butter at comparable intakes of total fat and saturated fat [146,147]. Butter fat may increase total and LDL cholesterol by down-regulation of LDL removal from the circulation [148]. Fermented dairy products may have a favourite effect on lipid profiles. The protective effect of yogurt [139,149], a fermented dairy product, was shown to reduce absorption of cholesterol and therefore prevent dyslipidemia; it is thought to increase calcium bioavailability through its high acidity [149]. Fermented milk products may decrease cholesterol levels more than non-fermented products [149-151]. Probiotic yogurt decreased total cholesterol by 4% and LDL cholesterol by 5% [149]. A meta-analysis of fermented dairy products has shown a possible cholesterol lowering property, through the high content of probiotic bacteria [152].

#### **4.4. Nuts**

Although nuts are high in fat, in most nuts the predominant fats are unsaturated. Studies over the last decade have demonstrated favourable effects of nuts in modifying lipid risk factors for CHD [153]. However, their use is not yet part of standard advice for patients with hyperlipidemia, despite recognized health benefits for the general population. Intake of nuts fits well with current American Heart Association guidelines [19] to replace dietary SFAs with unsaturated fats and with the National Cholesterol Education Program (NCEP) guidelines to increase intake of dietary MUFAs [153]. Less atherogenic plasma lipid profiles associated with long-term consumption of nuts [154,155]. Addition of nuts to the habitual diet of both normocholesterolemic and hypercholesterolemic subjects results in a significant reduction in plasma total and LDL cholesterol, whereas HDL remains unchanged or increases [155-158]. One-percent reductions in LDL cholesterol would be achieved with daily intakes of 4-11 g of walnuts, pecans, peanuts, macadamias, and pistachios [50,155,157- 161]. There are several components in nuts i.e. high MUFA, high PUFAs : SFAs ratio, proteins (specially high arginin), plant sterols, fiber, and associated phenolic substances, which may all contribute to the cardioprotective effect of nuts [154,162]. Also replacement of dietary SFAs with MUFAs due to the high MUFA content of nuts and high content of vitamin E in nuts reduce susceptibility of LDL to oxidation, a key event in the development of CVDs [233]. Consumption of almonds, either as the whole nut or the oil, lower total and LDL cholesterol concentrations. Addition of 100 g of almonds to the diets reduces total cholesterol by 9-16% and LDL cholesterol by 12-19 % in hypercholesterolemic subjects [164]; in one study almond consumption also reduced fasting triglyceride concentrations by 14%, compared with baseline [165]. Macadamia is another nut that improve lipid disturbances, and its inclusion as part of a healthy diet favourably altered the plasma lipid profile, despite the nuts being high in fat; their consumption reduced plasma total and LDL cholesterol concentrations and increase HDL cholesterol without any change in the triglyceride concentrations [166]. These changes could contribute to high MUFA intake and lower intake of PUFA and SFA consumption of macadamia nuts. Of nuts, walnuts are unique in improving dyslipidemia because they are a rich source of PUFAs, especially α-linolenic acid and linoleic acid; 100 g of walnuts contain 65.2 g fat; mainly from PUFAs (47.2 g) including α-linolenic acid (9.1 g) and linoleic acid (38.1 g) [167]. In a meta-analysis**,** consumption of walnuts resulted in decrease in total and LDL cholesterol concentrations, whereas HDL cholesterol and triglycerides were not affected [168]. Despite favourable effects of nuts on dyslipidemia, the intake of nuts should fit within the calorie and fat goal [18].

#### **4.5. Beans and legumes**

Legumes include a variety of beans such as navy, pinto, kidney, garbanzo, lima beans and peas such as split green peas or lentils. The Dietary Guidelines for Americans suggest consuming 3 cups of legumes per week [18, 169]. Legumes are a rich source of soluble dietary fiber and vegetable protein and have long been known to be hypercholesterolaemic foods [170,171 ]. One-half cup of cooked beans or peas can provide a range of dietary fiber from 4.6 g in fava beans up to 9.6 g fiber in navy beans, with a half cup of chick peas providing 6.2 g of total fiber, and 1.3 grams soluble dietary fiber [169]. In a meta-analysis both total and LDL cholesterol decreased, while HDL cholesterol did not change significantly, when diets uses supplemented with non-soy legumes [169]. The hypocholesterolaemic property of legumes is associated with the water-soluble fibre. Dietary fiber in legumes is not digested in the small intestine but be fermented in the colon and produces short chain fatty acids such as acetate, propionate and butyrate [172,173]; that inhibits hydroxy-3-methylglutaryl-CoA reductase, the limiting enzyme for cholesterol synthesis. Dietary fiber also decrease LDL cholesterol concentration by partially interrupting the enterohepatic circulation of bile acids via binding to bile acids in the intestines and preventing their re-absorption [174]. Consequently, an increase in the production of bile acids decreases the liver pool of cholesterol and increases uptake of serum cholesterol by the liver, decreasing thereby circulating cholesterol in the blood [175]. Another hypercholesterolemic component of legume is phytochemicals, which has been shown to reduce blood cholesterol levels and is present in small to moderate amounts in many types of legumes, such as chickpeas [176]. Dietary modification strategies that target the reduction of risk factors for CVDs should include an increase in legume consumption in addition to other strategies which have been of proven benefit [169].

#### **4.6. Meat, fish, poultry and eggs**

312 Lipoproteins – Role in Health and Diseases

**4.5. Beans and legumes** 

Although nuts are high in fat, in most nuts the predominant fats are unsaturated. Studies over the last decade have demonstrated favourable effects of nuts in modifying lipid risk factors for CHD [153]. However, their use is not yet part of standard advice for patients with hyperlipidemia, despite recognized health benefits for the general population. Intake of nuts fits well with current American Heart Association guidelines [19] to replace dietary SFAs with unsaturated fats and with the National Cholesterol Education Program (NCEP) guidelines to increase intake of dietary MUFAs [153]. Less atherogenic plasma lipid profiles associated with long-term consumption of nuts [154,155]. Addition of nuts to the habitual diet of both normocholesterolemic and hypercholesterolemic subjects results in a significant reduction in plasma total and LDL cholesterol, whereas HDL remains unchanged or increases [155-158]. One-percent reductions in LDL cholesterol would be achieved with daily intakes of 4-11 g of walnuts, pecans, peanuts, macadamias, and pistachios [50,155,157- 161]. There are several components in nuts i.e. high MUFA, high PUFAs : SFAs ratio, proteins (specially high arginin), plant sterols, fiber, and associated phenolic substances, which may all contribute to the cardioprotective effect of nuts [154,162]. Also replacement of dietary SFAs with MUFAs due to the high MUFA content of nuts and high content of vitamin E in nuts reduce susceptibility of LDL to oxidation, a key event in the development of CVDs [233]. Consumption of almonds, either as the whole nut or the oil, lower total and LDL cholesterol concentrations. Addition of 100 g of almonds to the diets reduces total cholesterol by 9-16% and LDL cholesterol by 12-19 % in hypercholesterolemic subjects [164]; in one study almond consumption also reduced fasting triglyceride concentrations by 14%, compared with baseline [165]. Macadamia is another nut that improve lipid disturbances, and its inclusion as part of a healthy diet favourably altered the plasma lipid profile, despite the nuts being high in fat; their consumption reduced plasma total and LDL cholesterol concentrations and increase HDL cholesterol without any change in the triglyceride concentrations [166]. These changes could contribute to high MUFA intake and lower intake of PUFA and SFA consumption of macadamia nuts. Of nuts, walnuts are unique in improving dyslipidemia because they are a rich source of PUFAs, especially α-linolenic acid and linoleic acid; 100 g of walnuts contain 65.2 g fat; mainly from PUFAs (47.2 g) including α-linolenic acid (9.1 g) and linoleic acid (38.1 g) [167]. In a meta-analysis**,** consumption of walnuts resulted in decrease in total and LDL cholesterol concentrations, whereas HDL cholesterol and triglycerides were not affected [168]. Despite favourable effects of nuts on

dyslipidemia, the intake of nuts should fit within the calorie and fat goal [18].

Legumes include a variety of beans such as navy, pinto, kidney, garbanzo, lima beans and peas such as split green peas or lentils. The Dietary Guidelines for Americans suggest consuming 3 cups of legumes per week [18, 169]. Legumes are a rich source of soluble dietary fiber and vegetable protein and have long been known to be hypercholesterolaemic foods [170,171 ]. One-half cup of cooked beans or peas can provide a range of dietary fiber from 4.6 g in fava beans up to 9.6 g fiber in navy beans, with a half cup of chick peas

**4.4. Nuts** 

Recommendation for intakes of meat, fish and poultry are up to 5 oz per day from lean meats (beef, pork, and lamb), poultry, and fish [18]. To achieve NCEP dietary goals, individuals are often counselled to reduce the amount and frequency of red meat consumption because of its hypercholestromia effects [177-179]. Cholesterol raising effects of red meats appears to result from high contents of SFAs [177,179]. Therefore, lean red meats that provide small amounts of these fatty acids do not adversely influence the blood lipid profile, compared with lean white meats. In isoenergetic low-fat diets, lean meat, fish and, poultry had similar effects on blood lipid response in both hypercholesterolemic and normocholesterolemic subjects [178,180,181]. Data available suggest that meat protein, per se, is not hypercholesterolemic [177,181,182]. The blood cholesterol-raising potential of meat products appears to be a function of their SFA fat and cholesterol contents. Therefore, substituting lean for higher fat red meat should favourably influence serum total cholesterol and LDL-C levels. Incorporating lean beef, fish, or poultry into the AHA diet can be beneficial in lower disturbances of lipid profile in patients with hypercholesterolemia [178,183]. Therefore the hypercholesterolemic subjects known to be at high risk for CVDs, could be advised to include lean fish as well as lean beef or poultry without skin in an AHA diet to reduce their lipoprotein disturbances [184,185]; normolipidemic subjects can also incorporate lean fish in an AHA diet [184], althought it is not necessary to eliminate or drastically reduce intake of lean red meat consumption because it is a rich source of iron, zinc and vitamin B12. One of the dietary recommendations in the prevention of CVDs is to limit egg consumption, because they have been shown to be a major source of dietary cholesterol (One egg contains 200 mg/cholesterol) that increases both serum total and LDLcholesterol concentrations [21,86,186]. Several epidemiologic studies however found no relation between egg consumption and risk of coronary heart disease [187,188], may be because dietary cholesterol increases not only concentrations of total and LDL cholesterol but also concentrations of HDL cholesterol [21,186,189,190]. Egg intake has been also shown to promote the formation of large LDL particles, which is less atherogenic [191]. Therefore dietary recommendations aimed at restricting egg consumption should not be generalized to include all individuals [191].

#### **4.7. Dietary pattern**

Using single nutrients or dietary food groups have some limitations in assessing their effect on lipid profiles separately because nutrients and foods are consumed in combination. To date, dietary patterns consider how foods are consumed in combination, and are used to evaluate the effects of overall nutritional habits on health status. There are two dietary patterns that demonstrate the beneficial effect on disturbances of lipoprotein concentrations; there include the dietary to stop hypertension (DASH) and the Mediterranean diet. The DASH dietary pattern, rich in fruits, vegetables, and low-fat dairy foods, emphasizes fish, poultry, and whole grains, and is reduced in total fat, SFAs and cholesterol, red meat, sweets, and sweetened beverages [192,193]; it lowers total, LDL and HDL cholesterols, without any adverse effects on triglyceride concentrations [194]; all of these coupled with decrease in blood pressure, reduce 10-year coronary heart disease risk of approximately 12% [194]. The Mediterranean dietary pattern consists of: (a) daily consumption: of non refined cereals and products (whole grain bread, pasta, brown rice, etc), vegetables (2 – 3 servings/ day), fruits (6 servings/day), olive oil (as the main added lipid) and dairy products (1 – 2 servings/day), (b) weekly consumption: of fish (4–5 servings/week), poultry (3 – 4 servings/week), olives, pulses, and nuts (3 servings/ week), potatoes, eggs and sweets (3 – 4 servings/week) and monthly consumption: of red meat and meat products (4 – 5 servings/month). It is also characterized by moderate consumption of wine (1 – 2 wineglasses/day). Mediterranean diet is a diet poor in SFAs and PUFAs but rich in MUFA (oleic acid) provided by the olive oil. The ratio of MUFAs : SFAs fat ratio is high > 2 [195]. This diet pattern is associated with reduction in total and LDL-cholesterol, and also a significant effect on triglycerides and VLDL concentrations, and a small positive or no effect on HDL-cholesterol [196-199] and improves dyslipidemia in dislipidemic patients [200]. This diet also includes antioxidant vitamins and phenolic compounds, and therefore reduces levels of circulating oxidized LDL and increases total antioxidant capacity [201]. Beside these two dietary patterns, other dietary pattern such as the western, and healthy dietary patterns affect lipoprotein profiles. The western pattern is characterized by high consumption of food such as refined grains, french fries, and red meats that have detrimental effects on lipid profiles. The healthy pattern included non-hydrogenated fat, vegetables, eggs, and fish and was negatively associated with lipoprotein disturbances [202-205]. In addition of dietary patterns, therapeutic lifestyle change is another dietary approach that ATP III recommends to reduce risks for CHD. This dietary approach includes the following: 1) Reduced intakes of dietary SFAs (<7% of total calories) and cholesterol (<200 mg/d), 2) weight reduction, 3) increased physical activity, and 4) therapeutic options for enhancing LDL lowering such as plant stanols/ sterols (2 g/d) and increased viscous (soluble) fiber (10-25 g/d) [18].
