Vegan for Life (23 page)
Total cholesterol in vegans tends to be well below the upper limit of 200 milligrams, and vegans also have low LDL-cholesterol levels. Although they have lower levels of protective HDL-cholesterol, their ratio of total to HDL-cholesterol is better than that of lacto-ovo vegetarians, fish eaters, and meat-eaters. Vegans also have lower triglycerides, a type of fat that is linked to higher risk for heart disease.
HYPERTENSIONInterest in the blood pressure–lowering effect of a vegetarian diet dates back to the early part of the twentieth century. In 1926, one researcher reported that the blood pressure of vegetarian college students increased within two weeks of adding meat to their diets.
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More recent studies of Seventh-day Adventists show that vegetarians have lower blood pressures and also lower rates of hypertension than omnivores.
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Some data indicate that vegans have lower blood pressures than lacto-ovo vegetarians. In one British study, meat-eaters were 2½ times as likely as vegans to suffer from hypertension.
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More recent studies of Seventh-day Adventists show that vegetarians have lower blood pressures and also lower rates of hypertension than omnivores.
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Some data indicate that vegans have lower blood pressures than lacto-ovo vegetarians. In one British study, meat-eaters were 2½ times as likely as vegans to suffer from hypertension.
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The reasons why vegan diets could help lower blood pressure aren’t completely understood. Lower body weight and sodium intake account for some but not all of the difference. Diets high in fruits and vegetables are associated with lower blood pressures, and that may be part of the explanation for the protective effects of plant-based diets. Most experts believe that it is a combination of multiple factors that explains the protective effects of plant-based diets.
BODY WEIGHTScientists assess body weight by looking at the body mass index (BMI), which is a measure of weight based on height. It’s not a perfect assessment, however, because it doesn’t account for muscle mass (which weighs more than fat), but it is a helpful tool for comparing populations.
A BMI of 20 to 25 is considered healthy. Above 25 is overweight and over 30 is considered obese. The two tables below display findings from Seventh-day Adventists and British vegetarians. You can see that in both groups, vegans have lower BMIs than people following either lacto-ovo or semi-vegetarian diets.
BODY MASS INDEXES OF SEVENTH-DAY ADVENTISTS
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BODY MASS INDEXES OF BRITISH VEGETARIANS (FROM THE EPIC-OXFORD STUDY)
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The preliminary data from the newest study of Adventists shows that vegans were less than half as likely to have diabetes when compared with meat-eaters. While being overweight raises the risk for diabetes, the lower BMI of vegans in this study was determined not to be the only reason for their lower diabetes risk.
Research suggests that vegetarians are less likely to form either renal stones or gallstones, and as we would expect from their higher fiber intake, vegetarians are only about half as likely as omnivores to develop intestinal problems like diverticular disease. Among Seventh-day Adventists, vegetarians are also less likely to develop dementia. So far, we don’t have any information about the effects of a vegan diet on these conditions.
VEGETARIAN DIETS AND CANCERThe relationship of diet to cancer has proven to be extremely difficult to study. It’s a complex disease and there aren’t many markers for cancer risk. That is, we can measure the effects of diet on blood-cholesterol levels and make predictions about how that will affect heart disease risk. But we don’t have many blood parameters related to cancer risk that are as straightforward.
There is evidence that how people eat in childhood is linked to their risk later on for developing cancer, which means that it is hard to uncover the links between diet and cancer risk without studying lifelong eating habits And because cancer is such a complex disease, it’s possible that the disease process is affected by interactions among different food components and by food components that aren’t well-understood. As a result, we have a very poor grasp of what type of diet protects against cancer. A few studies have found that vegetarians have lower cancer rates compared to omnivores, but most haven’t shown any difference between the two groups.
The environment of the colon in vegetarians—including the levels of different bacteria and enzymes—differs from meat-eaters in ways that appear to be protective against colon cancer. This is due in part to a higher intake of fiber, which is linked to a lower risk for cancer. Vegetarians and vegans also eat more fruits and vegetables and have a higher intake of antioxidants than omnivores. But while it’s generally believed that this lowers cancer risk, the evidence has weakened over the past few years as some recent studies haven’t supported a link between fruit
and vegetable intake and cancer. Soyfoods are linked to reduced risk for both breast and prostate cancer although this, too, is an area that needs more study.
and vegetable intake and cancer. Soyfoods are linked to reduced risk for both breast and prostate cancer although this, too, is an area that needs more study.
In contrast to the possible protective effects of plant foods, certain animal foods may raise cancer risk. Red and processed meats are linked to a higher risk for colon, stomach, and possibly bladder cancer. Some researchers believe that eliminating meat from the diet is more beneficial for reducing colon cancer than eating more fiber. Others suggest that eating meat in adolescence raises the risk for breast cancer later in life. There is also evidence to suggest that high dairy consumption raises the risk for prostate cancer.
Based on these findings, it would seem that vegans should have a lower risk for cancer, but we don’t have enough research to draw any conclusions. And because of conflicting findings, we haven’t yet been able to define the diet that protects against cancer. Cancer experts advise eating a diet rich in fruits and vegetables, fiber, and phytochemicals from plant foods, while minimizing fat from animal foods. Consequently, it seems like vegans have advantages that may lower their cancer risk.
What about the China Study?
Some readers may wonder why we didn’t cite findings from the China Study in this chapter. The China Study compared the types of food consumed and average disease rates in different counties in China, mostly during the 1980s. The results showed that the more plant products and less animal products consumed in a given county, the lower the rates of most chronic diseases, such as heart disease and many cancers. The China Study was an ecological study, which you may recall from Chapter 2 is a study that compares population groups rather than individuals. Ecological studies can add to our understanding about diet and health, and often give rise to hypotheses that stimulate further research, but they carry less weight than other types of epidemiologic studies.
Additionally, most of the participants in the China Study were neither vegetarian nor vegan, making it difficult to draw specific conclusions about the health benefits of these diets. This is not a criticism of the China Study. It is just to say that it doesn’t provide information for our purpose in this chapter, which is to describe research on the health of vegans.
Because vegans make up such a small percentage of the population, findings about their disease rates are few. What little data we have suggests that vegans have a lower body weight, lower blood-cholesterol levels, and lower blood pressures, all of which may offer significant protection against chronic disease. But one study also suggested that vegans have a higher rate of bone fracture than meat-eaters, although this occurred only when their calcium intake is low.
These findings may not be very exciting and they may surprise you. But while they aren’t necessarily what we want to see—it’s
all the research there is
! What we know about typical vegan diets and vegan health parameters tells us that vegans should have a lower risk for many chronic diseases. And that may very well be the case, but we simply don’t have the studies yet to prove it.
all the research there is
! What we know about typical vegan diets and vegan health parameters tells us that vegans should have a lower risk for many chronic diseases. And that may very well be the case, but we simply don’t have the studies yet to prove it.
However, we do know that choosing more plant foods and fewer animal foods is important for overall health and disease prevention. For those who are making lifestyle changes to manage chronic disease, a vegan diet can be helpful, as we’ll see in the next chapter.
CHAPTER 13
MANAGING WEIGHT, HEART DISEASE, AND DIABETES
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e’ve seen that vegans have lower cholesterol levels, less hypertension and diabetes, and a lower rate of obesity than meat-eaters. So it seems logical that a vegan diet is good therapy for the chronic conditions that are all too common among Americans today. And the research suggests that this may very well be the case—that going vegan can be a smart approach to managing high cholesterol, diabetes, and high blood pressure. To put these benefits to work for you and your family, it helps to know just which aspects of a vegan diet are most beneficial.
BENEFITS OF VEGAN DIETS FOR MANAGING CARDIOVASCULAR DISEASEe’ve seen that vegans have lower cholesterol levels, less hypertension and diabetes, and a lower rate of obesity than meat-eaters. So it seems logical that a vegan diet is good therapy for the chronic conditions that are all too common among Americans today. And the research suggests that this may very well be the case—that going vegan can be a smart approach to managing high cholesterol, diabetes, and high blood pressure. To put these benefits to work for you and your family, it helps to know just which aspects of a vegan diet are most beneficial.
Cardiovascular disease (CVD) refers to conditions that involve narrowed or blocked blood vessels, raising risk for heart attack and stroke. CVD is sometimes used interchangeably with the term “heart disease.”
There has been much discussion of late in the media and among research experts challenging the long-held belief that saturated fats raise the risk for heart disease.
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Extensive analyses have shown that replacing saturated fat in the diet with refined carbohydrates doesn’t lower heart disease risk; it increases it. This has led to the suggestion that the real problem is refined carbohydrates, not saturated fat.
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Extensive analyses have shown that replacing saturated fat in the diet with refined carbohydrates doesn’t lower heart disease risk; it increases it. This has led to the suggestion that the real problem is refined carbohydrates, not saturated fat.
Actually, the problem is probably both refined carbohydrates and saturated fat. We know from a large body of research that replacing saturated fat with healthier fats—poly- and monounsaturated ones—reduces blood-cholesterol levels and is associated with a lower risk for heart disease.
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Similar benefits occur when saturated fat is replaced with carbohydrates from whole, unrefined plant foods. It’s not a matter of giving up carbs or fats; it’s a matter of choosing the right ones.
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Similar benefits occur when saturated fat is replaced with carbohydrates from whole, unrefined plant foods. It’s not a matter of giving up carbs or fats; it’s a matter of choosing the right ones.
In theory, you could eat a high saturated fat diet by loading up on coconut and palm oil, but the reality is that switching to a diet based on plant foods is pretty much guaranteed to substantially lower your saturated fat intake. Vegans eat much less saturated fat than meat-eaters and, as we saw in Chapter 12, they have lower levels of total blood cholesterol and, more importantly, of LDL-cholesterol. This is the “bad” cholesterol that is responsible for increased deposits of plaque in the arteries, which causes them to narrow and even become blocked. Narrowed arteries also cause an increase in blood pressure, and high blood pressure in turn can damage arteries—a vicious and potentially life-threatening cycle.
In addition to their lower saturated fat intake, vegans enjoy other advantages thanks to their diet:
BENEFITS OF VEGAN DIETS FOR CONTROLLING TYPE-2 DIABETES• Plant foods are high in antioxidants, which may prevent cholesterol deposits from forming in the arteries, although not all research supports this theory.
• Vegans tend to have lower blood pressure, putting them at a reduced risk for a heart attack or stroke.
• Vegans are likely to eat more soyfoods than omnivores, and there is evidence suggesting that compounds in soy help make blood vessels more elastic—a factor that reduces the risk for atherosclerosis. Soy protein may also lower blood-cholesterol levels. (More on this in Chapter 15.)
• Nuts, which often play an important role in vegan diets, are linked to a reduced risk for heart disease.
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Type-1 diabetes is an autoimmune disorder in which the pancreas doesn’t produce enough (or any) insulin. Without insulin, blood glucose can’t get into cells, and the cells starve. People with this disease require lifelong insulin therapy. But by far the more prevalent type of diabetes is type 2, in which enough insulin is produced, but the cells become resistant to it.
Being overweight and inactive raises the risk for type-2 diabetes. The disease is on the rise not only among Americans but also among people in developing countries because they are adopting American-style eating habits, including more fatty animal foods and refined carbohydrates.
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