Prudent Diet and Preventive Nutrition From Pediatrics to Geriatrics: Current Knowledge and Practical Recommendations
(Part 3 of a Multipart Series)
Enas A Enas, A Senthilkumar, Hancy Chennikkara, Marc A Bjurlin
Coronary Artery Disease in Asian Indians (CADI) Research Foundation, and University of Illinois, Chicago, USA
Whole Grains: The Foundation of Healthy Food
Whole grains have been the staple food worldwide for centuries, especially among vegetarians.187,188 Whole grain and legume consumption not only decreases blood sugar and insulin resistance but also prevents the development of diabetes, particularly in people with the metabolic syndrome.185,186 Whole-grain products are a good source of fiber, minerals, as well as several vitamins, including vitamins B and E. In a 12-year follow-up of 42 898 men, the risk of developing diabetes was 42% lower in those with the highest intake of whole grains. The risk was reduced by 52% in those who also engaged in physical activity, and 87% in those who also had a low BMI.189 The risk reduction was attributed to higher intakes of cereal fiber and magnesium. Intake of whole-grain cereal is inversely associated with hypertension, CAD, stroke, and CVD mortality190,191 (Table 7).192–206 In another study, 25% –30% reduction in stroke was observed with the intake of whole grains—similar in magnitude to that of statins.206–208 In sharp contrast, intake of refined grains increases the risk of diabetes, stroke and CVD.191,205–212 These prospective data highlight the importance of distinguishing whole-grain from refined-grain cereals in the prevention of CVD and diabetes.209 Efforts should be made to replace refined-grain with whole-grain foods.189
A whole-grain food includes all the edible parts of the grain: the bran, the germ, and the endosperm.213 Grinding or milling, using modern technology, leads to the loss of many beneficial micronutrients, antioxidants, minerals, phytochemicals, fiber, and much of the germ.214 As a result, refined grain products are devoid of most vitamins and essential fatty acids, and contain more starch.215 Because of the loss of bran and pulverization of the endosperm, refined grains are digested and absorbed rapidly, resulting in a large increase in the levels of blood sugar and insulin.215 The common grains consumed in the West include wheat, oats, rye, rice, barley, and corn.213 In the USA, rye bread is an important source of whole grain consumption, and results in a lower glucose response than white bread.152,212 Whole-grain, ready-to-eat cereal contains >25% whole grain content by weight.189 The recommended intake is at least 6 servings of grain (but not more than 11) with at least 3 being whole grains. The current intake of whole grains is less than half a serving/day or 15% of the grain intake. Only 2% of the 150 lb of wheat flour consumed per capita in the USA is whole-grain flour.216 Commonly consumed refined grain foods include white rice (idli, dosa), refined wheat and flour (white bread), pancakes, cakes, sweet rolls, English muffins, muffins, waffles, rolls, biscuits, pizza, and refined-grain ready-to-eat breakfast cereal, and their use should be minimized.
Nuts: A Wholesome Food and Powerhouse of Healthy Fats and Nutrients
Extensive studies during the past decade have transformed the image of nuts from fattening snacks to a wholesome and heart-healthy food to be consumed daily.198–202,215 Nuts are rich sources of protein, antioxidants, fiber, vitamins and minerals (especially potassium and magnesium). Nuts yield 5%–10% fiber, and 12%–25% protein. The consumption of nuts is also associated with a reduced risk of CAD in several studies.198–202,217,218 Yet, nuts are not generally recommended as snacks because of their high fat content. Although nuts contain 45%–80% fat, most of the fats are the highly beneficial MUFA and PUFA (Table 8).65
Nuts, particularly almonds, significantly improve lipid profiles because of the high fiber and MUFA component. The dose–response effects of almonds were compared with low-SAFA (<5% energy), whole-wheat muffins used as the control diet in a randomized crossover study involving 27 dyslipidemic men and women. Three isoenergetic supplements each (mean 423 kcal/day; 22% of energy) were consumed for 1 month. The supplement consisted of full-dose almonds (73 g/day), half-dose almonds plus halfdose muffins, and full-dose muffins. Full-dose almonds produced a highly significant decrease in the Lp(a) level (8%), LDL:HDL ratio (8%), and oxidized LDL (14%) compared to the control diet.219 A 9% decrease in the LDL level occurred with 73 g/day of almonds, and 4% decrease with 37 g/day (handful) of almonds. This result translates to a 1% reduction in LDL for every 7 g/day of almonds, and is consistent with other studies.220,221 More importantly, there was no difference in body weight between the almond and muffin diet.222 Nuts are energy-dense, and contain 160–200 cal/oz. It cannot be overemphasized that energy from nuts should replace the unhealthy calories from SAFA and refined grains to prevent weight gain.
Consumption of other nuts (except coconuts) is equally beneficial. For example, a 10% reduction in the LDL level can be achieved by the daily consumption of 40 g of walnuts, peanuts or pistachios, 70 g almonds, 100 g macadamia nuts, and 110 g of pecans.223–230 Nuts are as effective as increasing physical activity and trimming calories to increase HDL levels. Adding 2 oz or 60 g of nuts to a diet is a delicious way to decrease the TC/HDL ratio and CAD risk.8,14,23,231,232 Nuts also improve insulin sensitivity and prevent diabetes.233 In a prospective study of 83 818 women, 3206 new cases of type 2 diabetes were observed during a follow-up of 16 years.203 Consumption of nuts was inversely associated with the risk of type 2 diabetes after adjustment for age, body mass index (BMI), physical activity, smoking, alcohol use, and dietary factors (total calories, fat calories, and fiber). The risk of diabetes was reduced by 27% in those who consumed >5 oz/week of nuts or peanut butter compared to those who almost never ate these products.203 The proscription of nuts can no longer be justified. In fact, regular nut consumption as replacement for refined grains and high-fat meats is strongly recommended.161,234