UNIT 2 |
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The DASH Diet
What if you are among the seventy eight million Americans who already have high blood pressure? how can you bring it down? The American Heart Association (AHA), the American College of Cardiology (ACC), and the Centers for Disease Control and Prevention (CDC) all recommend that patients first try lifestyle modifications, such as reducing body weight, limiting sodium and alcohol intake, getting more exercise, and eating a healthy diet.
However, if their recommended lifestyle changes don't work, then it's off to the pharmacy. High blood pressure patients commonly end up on three different antihypertensive drugs at a time, yet only about half tend to stick to even the first-line drugs. At the end of all of this, the drugs still haven't gotten to the root cause of the problem. The cause of high blood pressure isn't medication deficiency.
The underlying cause is what you eatand how you live. As we discussed earlier, the ideal blood pressure, defined as the level at which lowering it further yields no additional benefit, is probably around 110/70.90 Can you really get it that low without medication? Remember, this was the blood pressure of men more than sixty years old in rural Africa on no treatment other than their traditional, plant-based diets and lifestyles.97 In rural China, we find similar results: 110/70 throughout life without any increase with age. The reason we suspect that the plant-based nature of their diets is responsible is because, in the Western world, the only group able to routinely achieve these blood pressure readings is vegetarians.
So do the AHA/ACC/CDC guidelines recommend that people with high blood pressure eat a meat-free diet? No. They recommend the DASH diet, which stands for Dietary Approaches to Stop Hypertension, an eating plan specifically designed to lower blood pressure.
So do the AHA/ACC/CDC guidelines recommend that people with high blood pressure eat a meat-free diet? No. They recommend the DASH diet, which stands for Dietary Approaches to Stop Hypertension, an eating plan specifically designed to lower blood pressure.
Although it's been described as a lactovegetarian diet (dairy, but no meat or eggs), that isn't accurate. The DASH diet emphasizes fruits, vegetables, and low-fat dairy, but meat is still present-you're just supposed to eat less of it.102 Why not recommend an even more plant-based diet? We've known for decades that "food of animal origin was highly significantly associated with systolic and diastolic B[lood] P[ressure] after the age and weight effects were removed. That's a quote from a series of studies performed by renowned physician Frank Sacks and colleagues back in the 1970s, but there are studies going all the way back to the 1920s demonstrating that adding meat to a plant-based diet can significantly elevate blood pressure in a matter of days.
Why isn't the DASH diet meatless?
Based on the work of Dr. Sacks at Harvard University, the American Heart Association acknowledged that "[s]ome of the lowest B[lood |P[ ressureJs observed in industrialized countries have been documented in strict vegetarians..105 Were the designers of the DASH diet just not aware of Dr. Sacks's work? No, the chair of the committee that designed the diet was Dr. Sacks. 106
The reason that the DASH diet was modeled explicitly after vegetarian diets but was not meat-free itself might surprise you. The primary design goal of the DASH diet was to explicitly create eating patterns "that would have the blood pressure lowering benefits of a vegetarian diet yet contain enough animal products to make them palatable to nonvegetarians... Dr. Sacks had even shown that the more dairy vegetarians consumed, the higher their blood pressure appeared to rise.108 But he figured there was no point in calling for a diet he believed few would follow. This is a recurring theme in official dietary recommendations. Instead of simply telling you what the science shows and then letting you make up your own mind, experts patronize the population by advocating what they think is practical rather than ideal.
Why isn't the DASH diet meatless?
Based on the work of Dr. Sacks at Harvard University, the American Heart Association acknowledged that "[s]ome of the lowest B[lood |P[ ressureJs observed in industrialized countries have been documented in strict vegetarians..105 Were the designers of the DASH diet just not aware of Dr. Sacks's work? No, the chair of the committee that designed the diet was Dr. Sacks. 106
The reason that the DASH diet was modeled explicitly after vegetarian diets but was not meat-free itself might surprise you. The primary design goal of the DASH diet was to explicitly create eating patterns "that would have the blood pressure lowering benefits of a vegetarian diet yet contain enough animal products to make them palatable to nonvegetarians... Dr. Sacks had even shown that the more dairy vegetarians consumed, the higher their blood pressure appeared to rise.108 But he figured there was no point in calling for a diet he believed few would follow. This is a recurring theme in official dietary recommendations. Instead of simply telling you what the science shows and then letting you make up your own mind, experts patronize the population by advocating what they think is practical rather than ideal.
By making the decision for you, they undermine those willing to make even greater changes for optimal health. The DASH diet does help to bring down blood pressure, but the primary effect seems to arise not from the switch to low-fat dairy and white meat or the reduction in sweets and added fats but from the added fruits and vegetables."
If the benefits are due to the added plant foods, why not strive to center people's diets more around these healthiest of foods in the first place? This question is even more pointed given a 2014 meta-analysis (a compilation of many similar studies) showing that vegetarian diets may be particularly good at lowering blood pressure. And the more plants, perhaps, the better. Meat free diets in general "confer protection against cardiovascular diseases. Some cancers and total mortality," but completely plant-based diets "seem to offer additional protection for obesity, hypertension, type-2 diabetes, and cardiovascular mortality.
There apPpears to be a stepwise drop in hypertension rates the more plant-based foods you eat. Based on the same study of eighty-nine thousand Californians featured in chapter 6, compared with people who eat meat more than once a week, flexitarians (those who eat less meat, perhaps a few times a month) had 23 percent lower rates of high blood pressure. Those who cut out all meat except for fish had a 38 percent lower risk of high blood pressure, and those who cut out all meat had a 55 percent lower rate. People who cut out all meat, eggs, and dairy did the best, with a 75 percent reduced risk of high blood pressure. Those eating completely plant-based diets appeared to have thrown three-quarters of their risk for developing this major killer out the window.
When scientists looked at diabetes and body weight, they found the same apparent progressive improvements as consumption of animal products decreased and plant foods increased. Those eating plant-based diets had just a fraction of the diabetes risk even after factoring out the weight benefits, but what about hypertension? On average, those who eat completely plant-based foods are about thirty pounds lighter than those eating conventional diets.
If the benefits are due to the added plant foods, why not strive to center people's diets more around these healthiest of foods in the first place? This question is even more pointed given a 2014 meta-analysis (a compilation of many similar studies) showing that vegetarian diets may be particularly good at lowering blood pressure. And the more plants, perhaps, the better. Meat free diets in general "confer protection against cardiovascular diseases. Some cancers and total mortality," but completely plant-based diets "seem to offer additional protection for obesity, hypertension, type-2 diabetes, and cardiovascular mortality.
There apPpears to be a stepwise drop in hypertension rates the more plant-based foods you eat. Based on the same study of eighty-nine thousand Californians featured in chapter 6, compared with people who eat meat more than once a week, flexitarians (those who eat less meat, perhaps a few times a month) had 23 percent lower rates of high blood pressure. Those who cut out all meat except for fish had a 38 percent lower risk of high blood pressure, and those who cut out all meat had a 55 percent lower rate. People who cut out all meat, eggs, and dairy did the best, with a 75 percent reduced risk of high blood pressure. Those eating completely plant-based diets appeared to have thrown three-quarters of their risk for developing this major killer out the window.
When scientists looked at diabetes and body weight, they found the same apparent progressive improvements as consumption of animal products decreased and plant foods increased. Those eating plant-based diets had just a fraction of the diabetes risk even after factoring out the weight benefits, but what about hypertension? On average, those who eat completely plant-based foods are about thirty pounds lighter than those eating conventional diets.
Maybe they have such great blood pressure just because they're so much thinner? In other words, do omnivores who are as slim as vegans enjoy the same blood pressure? To answer this question, researchers would have to find a group of individuals who eat the standard American diet but are also as thin as people eating plant-based diets. To find an omnivorous group that fit and trim, researchers recruited long-distance endurance athletes who had run, on average, forty-eight miles per week for twenty-one years. Running almost two marathons a week for twenty years, pretty much anyone can become as slim as a plant eater no matter what they eat! The researchers then compared these hard-core athletes to two groups: sedentary meat eaters who exercised less than an hour per week and sedentary vegans who ate mostly unprocessed, uncooked plant foods. How did the numbers come out? Not surprisingly, the endurance runners on a
standard American diet had a better blood pressure average than their sedentary, meat-eating counterparts: 122/72 compared with 132/79, which fits the definition of prehypertensive. But the sedentary vegans? They averaged an extra ordinary 104/62.5. Apparently, eating standard American fare even when running two thousand miles a year may not bring down your blood pressure as low as a being a couch-potato vegan.
standard American diet had a better blood pressure average than their sedentary, meat-eating counterparts: 122/72 compared with 132/79, which fits the definition of prehypertensive. But the sedentary vegans? They averaged an extra ordinary 104/62.5. Apparently, eating standard American fare even when running two thousand miles a year may not bring down your blood pressure as low as a being a couch-potato vegan.
Foods for Additional Hypertension Protection
A low-sodium diet centered around whole plant foods appears to be the best way to bring down high blood pressure. What if you're already eating this way but that 110/70 still eludes you? There are a few foods in particular you can try that may offer additional protection. I've already touched on whole grains and will go into detail about flaxseeds, hibiscus tea, and nitrate-rich vegetables. Ground flaxseeds alone "induced one of the most potent blood-pressure-lowering effects ever achieved by a dietary intervention. Eating just a few tablespoons a day appears to be two to three times more powerful than adopting an aerobic endurance exercise program"" (not that you shouldn't do both-incorporate flaxseeds into your diet and exercise).
Consumption of both raw and cooked vegetables is associated with lower blood pressure, but raw veggies may be slightly more protective. Studies have also found that loading up on beans, split peas, chickpeas, and lentils may help a little, so add those to your shopping list. Red wine may help, but only nonalcoholic brands. Only wine that has had the alcohol removed appears to lower blood pressure. Watermelon appears to offer protection, which is great (and delicious) news, but you may have to eat about two pounds of it per day to achieve an effect. Kiwifruits flopped, though. In a study funded by a kiwifruit company, kiwi failed to offer any protection. Perhaps the kiwi industry should take a cue from the California Raisin Marketing Board, which funded a study designed to show that raisins can reduce blood pressure.
A low-sodium diet centered around whole plant foods appears to be the best way to bring down high blood pressure. What if you're already eating this way but that 110/70 still eludes you? There are a few foods in particular you can try that may offer additional protection. I've already touched on whole grains and will go into detail about flaxseeds, hibiscus tea, and nitrate-rich vegetables. Ground flaxseeds alone "induced one of the most potent blood-pressure-lowering effects ever achieved by a dietary intervention. Eating just a few tablespoons a day appears to be two to three times more powerful than adopting an aerobic endurance exercise program"" (not that you shouldn't do both-incorporate flaxseeds into your diet and exercise).
Consumption of both raw and cooked vegetables is associated with lower blood pressure, but raw veggies may be slightly more protective. Studies have also found that loading up on beans, split peas, chickpeas, and lentils may help a little, so add those to your shopping list. Red wine may help, but only nonalcoholic brands. Only wine that has had the alcohol removed appears to lower blood pressure. Watermelon appears to offer protection, which is great (and delicious) news, but you may have to eat about two pounds of it per day to achieve an effect. Kiwifruits flopped, though. In a study funded by a kiwifruit company, kiwi failed to offer any protection. Perhaps the kiwi industry should take a cue from the California Raisin Marketing Board, which funded a study designed to show that raisins can reduce blood pressure.
To inflate the benefits of raisins, they used junk food as the control group. So the study found raisins may lower blood pressure, but only, apparently, compared to fudge cookies, Cheez-Its, and Chips Ahoy!
Flaxseed
A remarkable intervention trial published in the journal Hypertension suggests that in this case, the term "miraculous" may not be too far off. Rarely does one see a dietary study of this caliber: It was a prospective, double- blind, placebo-controlled, randomized trial. That's hard to pull off with food. With a drug trial, a blinded study is easy: Researchers give someone a sugar pill that looks identical to the drug, so that neither the study subject nor the person giving the pill knows which one is which (hence, double-blind). But how do you do that with food? People tend to notice if you try to sneak a quarter cup of ground flaxseed into their lunch.
The researchers tried a clever tactic to overcome this problem. They created a number of recipes for common foods including muffins and pasta in which they could disguise placebo ingredients like bran and molasses to match the texture and color of the flax-laden foods. Thisway, they could randomize people into two groups and secretly introduce tablespoons of daily ground flaxseeds into the diets of half the participants to see if it made any difference.
After six months, those who ate the placebo foods started out hypertensive and stayed hypertensive, despite the fact that many of them were on a variety of blood pressure pills. On average, they started the study at 155/81 and ended it at 158/81. What about the hypertensives who were unknowingly eating flaxseeds every day? Their blood pressure dropped from 158/82 down to 143/75. A seven-point drop in diastolic blood pressure may not sound like a lot, but that would be expected to result in 46 percent fewer strokes and 29 percent less heart disease over time.
How does that result compare with taking drugs? The flaxseeds managed to drop subjects' systolic and diastolic blood pressure by up to fifteen and seven points, respectively.
Flaxseed
A remarkable intervention trial published in the journal Hypertension suggests that in this case, the term "miraculous" may not be too far off. Rarely does one see a dietary study of this caliber: It was a prospective, double- blind, placebo-controlled, randomized trial. That's hard to pull off with food. With a drug trial, a blinded study is easy: Researchers give someone a sugar pill that looks identical to the drug, so that neither the study subject nor the person giving the pill knows which one is which (hence, double-blind). But how do you do that with food? People tend to notice if you try to sneak a quarter cup of ground flaxseed into their lunch.
The researchers tried a clever tactic to overcome this problem. They created a number of recipes for common foods including muffins and pasta in which they could disguise placebo ingredients like bran and molasses to match the texture and color of the flax-laden foods. Thisway, they could randomize people into two groups and secretly introduce tablespoons of daily ground flaxseeds into the diets of half the participants to see if it made any difference.
After six months, those who ate the placebo foods started out hypertensive and stayed hypertensive, despite the fact that many of them were on a variety of blood pressure pills. On average, they started the study at 155/81 and ended it at 158/81. What about the hypertensives who were unknowingly eating flaxseeds every day? Their blood pressure dropped from 158/82 down to 143/75. A seven-point drop in diastolic blood pressure may not sound like a lot, but that would be expected to result in 46 percent fewer strokes and 29 percent less heart disease over time.
How does that result compare with taking drugs? The flaxseeds managed to drop subjects' systolic and diastolic blood pressure by up to fifteen and seven points, respectively.
Compare that result to the effect of powerful antihypertensive drugs, such as calcium-channel blockers (for example, Norvasc, Cardizem, Procardia), which have been found to reduce blood pressure by only eight and three points, respectively, or to ACE inhibitors (such as Vasotec, Lotensin, Zestril, Altace), which drop patients' blood pressure by only five and two points, respectively. Ground flaxseeds may work two to three times better than these medicines, and they have only good side effects. In addition to their anticancer properties, flaxseeds have been demonstrated in clinical studies to help control cholesterol, triglyceride, and blood sugar levels; reduce inflammation, and successfully treat constipation.
Hibiscus Tea for Hypertension
Hibiscus tea, derived from the flower of the same name, is also known as roselle, sorrel, jamaica, or sour tea. With a distinct tart, cranberry-like flavor and bright red color, this herbal tea is served and enjoyed both hot and cold around the world. In a comparison of the antioxidant content of 280 common beverages, hibiscus ranked number-one, beating out other heavyweights, including the oft-lauded green tea.
Hibiscus Tea for Hypertension
Hibiscus tea, derived from the flower of the same name, is also known as roselle, sorrel, jamaica, or sour tea. With a distinct tart, cranberry-like flavor and bright red color, this herbal tea is served and enjoyed both hot and cold around the world. In a comparison of the antioxidant content of 280 common beverages, hibiscus ranked number-one, beating out other heavyweights, including the oft-lauded green tea.
Within an hour of consumption, the antioxidant power of your bloodstream shoots up, demonstrating that the antioxidant phytonutrients in the tea are absorbed into your system.129 What effects might this infusion have on your health Unfortunately, efficacy against obesity has been disappointing. After giving hibiscus tea to overweight individuals for months, researchers have only been able to show about an extra half pound of weight loss per month over a placebo.
Early studies on cholesterol-lowering effects looked promising, suggesting that drinking two cups of hibiscus tea a day for a month may provide as much as an 8 percent drop in cholesterol, but when all such studies were put together, the results were pretty much a wash. This may be because, for some reason, hibiscus tea only seemed to have an effect on about half the study subjects. If you're in the lucky half, you may be able to get as much as a 12 percent drop in cholesterol.
But high blood pressure is where hibiscus really shines.134 A double-blind, placebo-controlled study out of Tufts University that compared hibiscus tea with an artificially colored and flavored lookalike showed that three cups of hibiscus tea a day significantly lowered blood pressure in prehypertensive adults better than the placebo beverage. But by how much? How does drinking hibiscus tea compare with other interventions.
The PREMIER Clinical Trial randomized hundreds of men and women with elevated blood pressure into an "advice only" control group or an active lifestyle intervention group. The control group was given a brochure and told to lose weight, reduce their salt intake, get more exercise, and eat healthier (i.e., to go on the DASH diet). The behavioral intervention group received the same instruction but also got face-to-face sessions, attended group meetings, kept food diaries,
Early studies on cholesterol-lowering effects looked promising, suggesting that drinking two cups of hibiscus tea a day for a month may provide as much as an 8 percent drop in cholesterol, but when all such studies were put together, the results were pretty much a wash. This may be because, for some reason, hibiscus tea only seemed to have an effect on about half the study subjects. If you're in the lucky half, you may be able to get as much as a 12 percent drop in cholesterol.
But high blood pressure is where hibiscus really shines.134 A double-blind, placebo-controlled study out of Tufts University that compared hibiscus tea with an artificially colored and flavored lookalike showed that three cups of hibiscus tea a day significantly lowered blood pressure in prehypertensive adults better than the placebo beverage. But by how much? How does drinking hibiscus tea compare with other interventions.
The PREMIER Clinical Trial randomized hundreds of men and women with elevated blood pressure into an "advice only" control group or an active lifestyle intervention group. The control group was given a brochure and told to lose weight, reduce their salt intake, get more exercise, and eat healthier (i.e., to go on the DASH diet). The behavioral intervention group received the same instruction but also got face-to-face sessions, attended group meetings, kept food diaries,
and monitored their physical activity, calories, and sodium intake. Within six months, the intervention group achieved a four-point drop in systolic blood pressure compared with the advice-only group. That may not seem like a lot, but on a population scale, a five-point drop may lead to 14 percent fewer stroke deaths, 9 percent fewer fatal heart attacks, and 7 percent fewer deaths overall each year. Meanwhile, in the Tufts study, a cup of hibiscus tea with each meal managed to lower subjects' systolic blood pressure by six points over the control group.
To lower blood pressure, you should still lose weight, reduce your salt intake, get more exercise, and eat healthier, but the evidence shows that adding hibiscus tea to your daily routine may offer an additional benefit, comparable even to that provided by antihypertensive drugs. Tested head-to-head against a leading blood pressure drug, two cups of strong hibiscus tea every morning (using a total of five tea bags) was as effective in lowering subjects blood pressure as a starting dose of the drug Captopril taken twice a day.
To lower blood pressure, you should still lose weight, reduce your salt intake, get more exercise, and eat healthier, but the evidence shows that adding hibiscus tea to your daily routine may offer an additional benefit, comparable even to that provided by antihypertensive drugs. Tested head-to-head against a leading blood pressure drug, two cups of strong hibiscus tea every morning (using a total of five tea bags) was as effective in lowering subjects blood pressure as a starting dose of the drug Captopril taken twice a day.
However, there are differences: Captopril can have side effects, most commonly rash, cough, and taste impairment, and it can even, though extremely rarely, cause fatal swelling of the thro- at. No side effects were reported for hibiscus tea, though it isn't called sour tea for nothing. If you drink it, make sure to rinse your mouth with water afterward to keep the natural acids in the tea from softening the enamel on your teeth.
And given the extraordinary manganese content in hibiscus tea,4 to be on the safe side, I wouldn't recommend drinking more than a quart of it a day.
The Power of NO
Nitric oxide (NO) is a key biological messenger within the body, and its message is: "Open Sesame!" When released by your endothelium (the cells lining your arteries), it signals the muscle fibers within the walls of your arteries to relax, allowing them to open up and for more blood to flow. That's how nitroglycerin pills work: The nitroglycerin people take them eat even fewer antioxidants, their artery dilation only gets a little bit worse.
And given the extraordinary manganese content in hibiscus tea,4 to be on the safe side, I wouldn't recommend drinking more than a quart of it a day.
The Power of NO
Nitric oxide (NO) is a key biological messenger within the body, and its message is: "Open Sesame!" When released by your endothelium (the cells lining your arteries), it signals the muscle fibers within the walls of your arteries to relax, allowing them to open up and for more blood to flow. That's how nitroglycerin pills work: The nitroglycerin people take them eat even fewer antioxidants, their artery dilation only gets a little bit worse.
It seems we're already near the bottom
of the barrel arterial-function-wise, so
there's not much room for further decli-
ne. But put people on a high-antioxidant
diet by, among many other things, swit-
ching their bananas for berries and their
white chocolate for dark, and within just
two weelks, they experience a significant
boost in their arteries ability to relax
and dilate normally.143
In addition to eating antioxidant-rich
foods that can boost your body's ability
to produce NO, you can also eat certain
vegetables, such as beets and greens,
that are rich in natural nitrates, which
your body can convert into nitric oxide.
(For the difference between nitrates and
nitrites, see chapter 10.) This process ex-
plains why researchers have been able to
show a ten-point systolic blood pressure
drop in volunteers within hours of their
consuming beet juice-an effect that las-
ted throughout the day. 144
That study was performed on a group
of healthy subjects, though. Obviously,
we need to test the power of beets where
it counts most-in people with high blo-
od pressure. If nitrate-rich vegetables
of the barrel arterial-function-wise, so
there's not much room for further decli-
ne. But put people on a high-antioxidant
diet by, among many other things, swit-
ching their bananas for berries and their
white chocolate for dark, and within just
two weelks, they experience a significant
boost in their arteries ability to relax
and dilate normally.143
In addition to eating antioxidant-rich
foods that can boost your body's ability
to produce NO, you can also eat certain
vegetables, such as beets and greens,
that are rich in natural nitrates, which
your body can convert into nitric oxide.
(For the difference between nitrates and
nitrites, see chapter 10.) This process ex-
plains why researchers have been able to
show a ten-point systolic blood pressure
drop in volunteers within hours of their
consuming beet juice-an effect that las-
ted throughout the day. 144
That study was performed on a group
of healthy subjects, though. Obviously,
we need to test the power of beets where
it counts most-in people with high blo-
od pressure. If nitrate-rich vegetables