The DASH Diet David M

CHAPTER 89

The DASH Diet David M. Lessens, MD, MPH • David Rakel, MD

WHAT IS THE DASH DIET? BESIDES LOWERING SODIUM, BY WHAT DASH stands for Dietary Approaches to Stop Hyper- OTHER MEANS MIGHT THE DASH DIET tension. This eating plan was initially developed to BENEFIT HEALTH? lower blood pressure,1 but it has since been found to modify several disease risk factors and outcomes, Oxidative stress refers to one’s ability to detoxify the including improvements in cholesterol levels and insu- products of cellular damage. Much of this damage is lin sensitivity. This diet favors meals that are low in caused by inflammation, which plays a foundational role animal and dairy fat and rich in fruits, vegetables, and in many chronic diseases, including obesity. In a small whole grains. It is a well-balanced diet that can be fol- study, investigators found that the DASH diet decreased lowed by everyone, including those in low socioeco- blood pressure and enhanced antioxidant capacity, espe- nomic strata,2 to help lead a healthy lifestyle (Table cially in obese individuals.4 In another study, researchers 89.1). It is similar to the antiinflammatory diet discussed found lower levels of proinflammatory markers, includ- in Chapter 88. ing C-reactive protein and interleukin-6, among those consuming this diet.5 Researchers have postulated the importance of potas- HOW MUCH CAN I EXPECT MY BLOOD sium, magnesium, and fiber in the DASH diet’s role in PRESSURE TO COME DOWN? lowering blood pressure. One crossover study, for example, had obese and lean individuals consume a usual diet, Two sentinel studies have investigated how adher- the DASH diet, and a usual diet supplemented with spe- ence to the DASH diet can reduce blood pressure. The cific amounts of potassium, magnesium, and fiber match- original study,1 which took place among four academic ing those of the DASH diet. Each eating plan was also health care centers, divided subjects into three groups: matched for calcium and sodium. After 3 weeks, only one ate a normal American diet, one ate an American obese individuals adhering to the DASH diet showed an diet but with more fruits and vegetables, and one ate the improvement in blood pressure and endothelial func- DASH diet. In those eating the DASH diet and with no tion. The study’s investigators concluded that nutritional high blood pressure, the average systolic value dropped factors other than these five must be contributing to the by 5.5 mm Hg and the diastolic value by 3 mm Hg. For observed health benefits, and these remain a topic of fur- those who already had high blood pressure, the systolic ther investigation.6 value dropped by 11.6 mm Hg and the diastolic value The DASH diet also contains nitrate-rich root veg- by 5.3. Blood pressure also dropped in the group eat- etable like beets, carrots, and turnips. Consuming nitrates – ing more fruits and vegetables, but not as much. Fur- (NO3 ) from such sources may increase the body’s avail- thermore, these changes occurred after just 2 weeks on able nitric oxide (NO), which may lead to vasodilation – the diet. and decreased blood pressure. Ingested nitrates (NO3 ) 3 – The second DASH trial examined the effect of a are reduced to nitrites (NO2 ) by enteral bacteria and reduced dietary sodium intake (at three separate levels: then are reabsorbed by the intestines and excreted in the 3300, 2300, or 1500 mg daily) as participants consumed stool (the reason manure is such a good fertilizer, which is a normal American diet or followed the DASH eating rich in nitrites). Nitrites are further reduced in the endo- plan. Results showed that reducing dietary sodium low- thelium to NO (Fig. 89.1). ered blood pressure for both eating plans, but at each In a study of 72 hypertensive patients, 36 were given level, blood pressure was lower for those on the DASH 250 mL of beetroot juice once daily (6.4 mmol nitrate) eating plan. These studies emphasize and highlight that and 36 were given a nitrate-free beetroot juice pla- nutritional features of the DASH diet may play a role in cebo. The 24-hour blood pressure monitoring showed reducing blood pressure, apart from reducing sodium sustained reductions of 7.7 mm Hg in systolic pres- consumption. sure and 5.2 mm Hg in diastolic pressure in the treatment group. This is just slightly less than the average blood pressure drop with single antihypertensive drug In those with high blood pressure, the DASH diet on an therapy (9.1 mm Hg/5.5 mm Hg). The nitrate-rich average lowered systolic blood pressure by 11.6 mm Hg and beetroot juice also improved endothelial function by diastolic blood pressure by 5.3 mm Hg. ∼20%.7

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TABLE 89.1 The DASH Diet

Significance of Each Daily Food Group in the Food Group Servings Serving Sizes Examples and Notes Dash Eating Plan Grains and grain 7–8 1 slice bread Whole wheat bread, English muffin, Major sources of products 1 oz dry cereal* pita bread, bagel, cereals, grits, energy and fiber ½ cup cooked rice, pasta, or oatmeal, crackers, unsalted cereal pretzels, and popcorn Vegetables 4–5 1 cup raw leafy vegetables Tomatoes, potatoes, carrots, green Rich sources of ½ cup cooked vegetables peas, squash, broccoli, turnip potassium, 6 oz vegetable juice greens, collards, kale, spinach, magnesium, and artichokes, green beans, lima fiber beans, sweet potatoes Fruits 4–5 6 oz fruit juice Apricots, bananas, dates, grapes, Important sources 1 medium fruit oranges, orange juice, grapefruit, of potassium, ¼ cup dried fruit grapefruit juice, mangoes, melons, magnesium, and ½ cup fresh, frozen, or peaches, pineapples, prunes, fiber canned fruit raisins, strawberries, tangerines Low-fat or fat-free 2–3 8 oz milk Fat-free (skim) or low-fat (1%) milk, Major sources of dairy foods 1 cup yogurt fat-free or low-fat buttermilk, fat- calcium and protein 1.5 oz cheese free or low-fat regular or frozen yogurt, low-fat and fat-free cheese Meats, poultry, 2 or less 3 oz cooked meats, poultry, Select only lean; trim away visible Rich sources of protein and fish or fish fat; broil, roast, or boil instead of and magnesium frying; remove skin from poultry

1 Nuts, seeds, and 4–5 per 1.5 oz or ⁄3 cup nuts Almonds, filberts, mixed nuts, Rich sources of dry beans week ½ oz or 2 tbsp seeds peanuts, walnuts, sunflower seeds, energy, magnesium, ½ cup cooked dry beans kidney beans, lentils potassium, protein, and peas and fiber Fats and oils† 2–3 1 tsp soft margarine Soft margarine, low-fat mayonnaise, DASH has 27% of its 1 tbsp low-fat mayonnaise light salad dressing, vegetable calories from fat, 2 tbsp light salad dressing oil (such as olive, corn, canola, or including that in or 1 tsp vegetable oil safflower) added to foods Sweets 5 per week 1 tbsp sugar Maple syrup, sugar, jelly, jam, fruit- Sweets should be low 1 tbsp jelly or jam flavored gelatin, jelly beans, hard in fat ½ oz jelly beans candy, fruit punch, sorbet, ices 8 oz lemonade

*Equals ½–1¼ cup, depending on cereal type. Check the product’s nutrition label.†Fat content changes serving counts for fats and oils. For example, 1 tbsp of regular salad dressing equals one serving; 1 tbsp of a low-fat dressing equals ½ serving; 1 tbsp of a fat-free dressing equals zero servings. From the Dietary Approaches to Stop Hypertension study, as published by the Joint National Committee on Prevention, Detection, Evalu- ation, and Treatment of High Blood Pressure and the National High Blood Pressure Education Program Coordination Committee. The sixth report of the Joint National Committee on prevention, detection, evaluation and treatment of high blood pressure. Arch Intern Med. 1997;157:2413–2446.

total cholesterol, low-density lipoprotein, weight, tri- Proton pump inhibitors reduce enzymes (DDAH, ADMA) that are needed to make nitric oxide. Taking this class of glycerides, and fasting blood glucose concentration, medicines may negate the beneficial influence vegetables while raising high-density lipoprotein. Although the have on blood pressure and may help explain the increased magnitude of the effects varied by sex, they were positive risk for myocardial infarction seen with long-term use of in both groups.8 An investigation of 31 type 2 diabetic this class of medicine. H2 blockers do not inhibit these individuals also found favorable changes in these param- enzymes. eters, including hemoglobin A1c (decrease of 1.7),9 and adherence to this diet may actually have the potential to prevent type 2 diabetes.10 Interestingly, the lipid- and glucose-lowering effects of the DASH diet seem to be BESIDES LOWERING BLOOD PRESSURE, independent of sodium intake, which again supports the notion that this eating plan works through several nutri- HOW ELSE DOES THIS DIET AFFECT tional mechanisms.9 CARDIOVASCULAR HEALTH? In a retrospective analysis using data from the Nurses’ Health Study, a DASH score was composed A study of 116 men and women with metabolic syndrome on the basis of foods that individuals had consumed. In showed that consuming a DASH diet versus a control comparing the top and bottom 20% on the basis of this diet can reduce most of the metabolic risks, including score, the investigators found a nearly 50% decrease in

O HOW DOES THIS DIET AFFECT BONE HEALTH? ON

O Investigators at Duke University found that those who Nitrates ate a DASH diet had evidence of less bone turnover that (vegetables) over time resulted in a stronger bone structure. This effect was enhanced when the DASH diet group further reduced their intake of sodium.18 Gut salivary glands bacteria CAN THE DASH DIET SLOW COGNITIVE DECLINE? O In a sample of 826 older adults with an average age of 81 Nitrites N years, participants filled out a food frequency question- naire related to both the DASH diet and the Mediter- O ranean diet. Those who ate the most foods in both these dietary plans had the slowest rate of cognitive decline. Endothelium The DASH diet was rated on a scale of 1–10. For a one- DDAH and ADMA unit higher DASH score, rates of cognitive decline were enzymes 0.007 standard units slower, which was equivalent to adults aged at least 4.4 years younger.19 O

Nitric-oxide N WHAT FOODS ARE EMPHASIZED IN THIS DIET, AND HOW DO THEY INFLUENCE ONE’S HEALTH?

↓ Blood pressure To summarize, the diet is: ↓ Arterial stiffness • High in fruits and vegetables. These are rich in an- ↑ Endothelial function tioxidants (especially those with vibrant colors), are FIG. 89.1 □ Nitrites are further reduced in the endothelium to relatively low in calories, and contain significantfiber. nitric oxide (NO). ADMA, asymmetric dimethylarginine; DDAH, • Low in dairy, animal meat, and saturated fat. These dimethylarginine dimethylaminohydrolase. fats increase the risk for atherosclerosis. • High in nuts, seeds, and beans. These are high in pro- kidney stones, even in participants with lower calcium tein and in monounsaturated and polyunsaturated fats, intake.11 which can decrease inflammation and cardiovascular Regarding cardiovascular disease–oriented outcomes, disease. the DASH eating plan has been shown to lower the rates • Low in snacks and sweets. Many of these foods con- of stroke,12 heart failure events (including mortality),13 tain partially hydrogenated fats that act to preserve and coronary artery disease.14 shelf life. These types of fats are sources of trans– fatty acids that play a significant role in increasing the risk for heart disease. Many common snacks are DOES THIS DIET REDUCE THE RISK FOR also composed of simple carbohydrates, which cause CANCER? a rapid rise in insulin after they are consumed. Over time, elevations in insulin result in the body becom- A prospective study assigning a DASH score to more ing less responsive to its effect. In turn, the body will than 100,000 participants showed an 80% reduction in start to produce excessive amounts of insulin, result- colorectal cancer between the top and bottom 20% of ing in more inflammation and elevated risk for car- scores during a 26-year period. Those following a Medi- diovascular disease. terranean diet had no such decrease in their risk.15 This • The diet is based on 2000 calories a day. Large portion study was supported by a Canadian study also showing a sizes are a major contributor to rising obesity rates reduction in colorectal cancer.16 A review of the available worldwide. Combining this diet with a regular exer- research suggests an overall reduction in the incidence of cise routine can lead to even more dramatic decreases cancer among those who eat a DASH diet.17 in blood pressure and other chronic diseases.

Key Web Resources

The National Heart, Lung, and Blood Institute (NHLBI). A http://www.nhlbi.nih.gov/health/health-topics/topics/dash summary of the DASH diet and its benefits The National Heart, Lung, and Blood Institute (NHLBI). http://www.nhlbi.nih.gov/files/docs/public/heart/dash_brief.pdf A PDF patient handout explaining the how to use the DASH diet to lower blood pressure

REFERENCES References are available online at ExpertConsult.com.

Downloaded for Aman Shah ([email protected]) at Elsevier - Demonstration Account from ClinicalKey.com by Elsevier on December 21, 2017. For personal use only. No other uses without permission. Copyright ©2017. Elsevier Inc. All rights reserved. REFERENCES 11. Taylor EN, Fung TT, Curhan GC: DASH-style diet associates with reduced risk for kidney stones, J Am Soc Nephrol 20:2253– 1. Appel LJ, Moore TJ, Obarzanek E: A clinical trial of the effects of 2259, 2009. dietary patterns on blood pressure. DASH Collaborative Research 12. Chen ST, Maruthur NM, Appel LJ: The effect of dietary patterns Group, N Engl J Med 336:1117–1124, 1997. on estimated coronary heart disease risk: results from the Dietary 2. Young CM, Batch BC, Svetkey LP: Effect of socioeconomic sta- Approaches to Stop Hypertension (DASH) trial, Circ Cardiovasc tus on food availability and cost of the Dietary Approaches to Stop Qual Outcomes 3:484–489, 2010. Hypertension (DASH) dietary pattern, J Clin Hypertens (Greenwich) 13. Levitan EB, Wolk A, Mittleman MA: Relation of consistency with 10:603–611, 2008. the dietary approaches to stop hypertension diet and incidence of 3. Sacks FM, Svetkey LP, Vollmer WM: Effects on blood pressure heart failure in men aged 45 to 79 years, Am J Cardiol 15:1416– of reduced dietary sodium and the Dietary Approaches to Stop 1420, 2009. Hypertension (DASH) diet, N Engl J Med 344:3–10, 2001. 14. Fung TT, Chiuve SE, McCullough ML, et al.: Adherence to a 4. Lopes HF, Martin KL, Nashar K: DASH diet lowers blood pres- DASH-style diet and risk of coronary heart disease and stroke in sure and lipid-induced oxidative stress in obesity, Hypertension women, Arch Intern Med 168:713–720, 2008. 41:422–430, 2003. 15. Fung TT, Hu FB, Wu K, et al.: The Mediterranean and Dietary 5. Harsha DW, Sacks FM, Obarzanek E: Effects of dietary sodium Approaches to Stop Hypertension (DASH) diets and colorectal intake on blood lipids: results from the DASH-sodium trial, Hyper- cancer, Am J Clin Nutr 92:1429–1435, 2010. tension 43:393–398, 2004. 16. Jones-McLean E, Hu J, Greene-Finestone LS, de Groh M: A 6. Al-Solaiman Y, Jesri A, Mountford WK, et al.: DASH lowers blood DASH dietary pattern and the risk of colorectal cancer in Canadian pressure in obese hypertensives beyond potassium, magnesium, adults, Health Promot Chronic Dis Prev Can 35:12–20, 2015. and fiber,J Hum Hypertens 24:237–246, 2010. 17. Onvani S, Haghighatdoost F, Azadbakht L: Dietary approach 7. Kapil V, Khambata RS, Robertson A, et al.: Dietary nitrate pro- to stop hypertension (DASH): diet components may be related vides sustained blood pressure lowering in hypertensive patients: to lower prevalence of different kinds of cancer: a review on the a randomized, phase 2, double-blind, placebo-controlled study, related documents, J Res Med Sci 20:707–713, 2015. Hypertension 65:320–327, 2015. 18. Lin PH, Ginty F, Appel LJ: The DASH diet and sodium reduc- 8. Azadbakht L, Mirmiran P, Esmaillzadeh A, et al.: Beneficial effects of tion improve markers of bone turnover and calcium metabolism in a Dietary Approaches to Stop Hypertension eating plan on features adults, J Nutr 133:3130–3136, 2003. of the metabolic syndrome, Diabetes Care 28:2823–2831, 2005. 19. Tangney CC, Li H, Wang Y, et al.: Relation of DASH- and Med- 9. Azadbakht L, Fard NR, Karimi M: Effects of the Dietary iterranean-like dietary patterns to cognitive decline in older per- Approaches to Stop Hypertension (DASH) eating plan on cardio- sons, Neurology 83:1410–1416, 2014. vascular risks among type 2 diabetic patients: a randomized crossover clinical trial, Diabetes Care 34:55–57, 2011. 10. Liese AD, Nichols M, Sun X, et al.: Adherence to the DASH diet is inversely associated with incidence of type 2 diabetes; the insulin resistance atherosclerosis study, Diabetes Care 32:1434–1436, 2009.

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