Question

please describe how dietary choices can specifically contribute to cardiovascular disease, type 2 diabetes, and cancer. In addition, describe what dietary interventions can be used to help prevent these chronic diseases and control their complications.

Answer 1

patients with type 2 diabetes have a higher risk of developing cardiovascular disease (CVD). But did you know that heart disease can be associated with an increased risk of type 2 diabetes and that diabetes can raise the risk of various cancers?

Research has shown there are interrelationships among type 2 diabetes, heart disease, and cancer. These interrelationships may seem coincidental and based only on the fact these conditions share common risk factors. However, research suggests these diseases may relate to one another in multiple ways and that nutrition and lifestyle strategies used to prevent and manage these diseases overlap considerably.

This continuing education activity will evaluate the current research showing how cancer, type 2 diabetes, and CVD interrelate with one another, and examine how nutrition and physical activity recommendations developed to reduce cancer risk intersect and can be used to care for patients who have or are at risk for diabetes and heart disease.

Dietary Recommendations
Because of the cancer-fighting compounds found in fruits, vegetables, and whole grains, the AICR recommends at least two-thirds of the food individuals eat come from plants.

The 2010 Dietary Guidelines for Americans say at least one-half of grain products should be whole grain, and people should aim for at least three servings per day. Yet recent reviews that focus on decreasing insulin resistance and ACS recommendations concur with the AICR’s advice to eat more than three servings per day of whole grains if possible and “minimize consumption of refined grains.”

For greater health benefits, clients can use dried beans and peas in place of all or part of the meat in some dishes. When it comes to fruits and vegetables, research shows individuals can eat smaller amounts than what’s recommended to reduce heart disease and still lower cancer risk. ACS recommendations call for a total of at least 21/2 cups of vegetables and fruits daily. The AICR recommends at least five standard-size servings daily of nonstarchy vegetables and fruits, which means potatoes and legumes don’t count toward the total.

Fruit and vegetable targets should focus not only on the amount but also on a variety of choices. To help control or decrease hypertension risk, dietitians can suggest clients include choices rich in potassium. To reduce cancer risk, variety also refers to selections rich in carotenoids and vitamin C as well as cruciferous vegetables, garlic-onion family vegetables, and berries, among other foods.

Limiting Red Meat
In addition to eating more plant foods, limiting red meat consumption also is important. Heart-health messages usually focus on saturated fat and group together poultry, seafood, and lean cuts of red meat as recommended choices. However, research on cancer suggests these foods aren’t all the same.

A meta-analysis conducted as part of the AICR/WCRF continuous update project shows a 17% increased risk of colorectal cancer per 100 g of red meat eaten daily.76 Its higher heme iron content may increase risk by promoting nitrosamine formation within the gut as well as through the generation of DNA-damaging free radicals.

Processed meats—those preserved by smoking, curing, salting, or preservatives—are linked to increased colorectal cancer risk, showing an 18% higher risk for each 50 g consumed per day.76 Most processed meats are high in sodium, so limiting them already is a boon for heart health. A meta-analysis links about 2 oz of daily processed meat consumption with a 42% rise in CHD and also a 19% increase in diabetes risk.77

Clients can reduce their meat consumption through several different approaches, all of which fit well with other prevention-focused goals, such as the following:

• The AICR recommends individuals eat no more than 18 oz (cooked weight) of red meat per week, which includes beef, lamb, and pork.

• Substitute vegetables and beans for some or all of the red and processed meat in dishes, which supports the goals of increasing plant foods and decreasing calorie density.

• The American Heart Association (AHA) recommends eating at least 8 oz, or two servings, of fish each week.46

Curb High-Sodium Foods
Sodium intake is another concern. The 2010 Dietary Guidelines call for keeping daily sodium consumption below 2,300 mg. However, about one-half of the US population falls into groups whose blood pressure tends to be especially sodium sensitive and are therefore advised to reduce sodium to 1,500 mg per day.78 This includes people aged 51 and older, and those of any age who are African American or have hypertension, diabetes, or chronic kidney disease.

Although sodium targets for cardiovascular health are lower than needed to decrease cancer risk, consumption of salt and salt-preserved foods is linked to an increased risk of stomach cancer.

Limiting sodium may make dietary strategies seem more complex, but it can support a healthful eating pattern if the medical community does the following:

• Pairs messages about limiting salt with suggestions for using herbs, spices, garlic, and other flavorings. People will be able to enjoy flavorful food and get health-protective phytochemicals into their diets.

• Teaches people how to replace high-sodium convenience foods with whole foods, which often are lower in saturated and trans fats and added sugar.

Alcohol Consumption
Alcohol in moderation is strongly linked to a decreased risk of CHD, possibly related to increased HDL cholesterol, reduced inflammation, and lower fibrinogen, a protein essential for blood clotting that when too high is a marker of increased CVD risk. In moderation, alcohol decreases insulin resistance and type 2 diabetes risk. However, alcohol in excess can raise triglycerides and boost the risk of developing hypertension and diabetes.

Many people are unaware that alcohol is linked to an increased risk of colon cancer in men, pre- and postmenopausal breast cancer, and mouth and throat cancers.
According to the AHA, “Consumption of alcohol cannot be recommended solely for CVD risk reduction.”46

For people who choose to drink alcohol, the unified recommendation from the AICR, the ACS, the AHA, and the ADA is to limit alcoholic drinks to two per day for men and one per day for women. Women need to consume fewer than one drink per day to reduce their breast cancer risk to that of nondrinkers, so they will need help making choices based on their individual health risks and lifestyle preferences.

Due to the trends in increased portion sizes, the healthcare community must clearly define what’s meant by one drink: 5 oz of wine, 12 oz of beer, or 1 1/2 oz of 80-proof liquor.

Weaving Recommendations Into Healthful Eating Patterns
Research increasingly is looking beyond the health impact of individual food choices to how combined choices as part of overall eating patterns impact diabetes, heart disease, and cancer. Sometimes individual studies compare a particular eating pattern to the Western diet and show a reduced risk of one or more of these conditions. Such comparisons don’t show that the particular alternative-eating pattern tested is “the best” choice for everyone.

Research is exploring how genetic polymorphisms may affect response to dietary fat, carbohydrate, and protein intake and certain cancer-protective phytochemicals. Meanwhile, the challenge is to help people follow healthful eating patterns that satisfy their unique food preferences, calorie needs, health issues, and lifestyles.

Healthful food choices can be combined into different predominantly plant-based eating patterns, including a vegetarian diet, Dietary Approaches to Stop Hypertension (DASH), and the Mediterranean diet.

Very low-fat vegetarian eating patterns include the lacto-ovo vegetarian approach Dean Ornish, MD, originally took to help reverse atherosclerotic heart disease.79 He has since shown decreases in inflammation markers and endothelial dysfunction with this approach in a small group of men with CAD or CAD risk factors80 and protective changes in prostate cancer gene expression and decreased prostate-specific antigen among men with low-risk prostate cancer with a very low-fat vegan diet.81,82

These eating patterns keep fat and carbohydrate intake to 10% and 75% of total calories, respectively. Total fat intake is very low, avoiding even fats in nuts and oils often considered healthful. Despite the high carbohydrate content, hemoglobin A1c levels have been reduced.83 However, these diets’ effects as reported in these studies can’t be separated from other components that promote health, such as three hours per week of moderate physical activity, smoking cessation, one hour of stress management daily, and active group support.

The 2010 Dietary Guidelines support following the DASH diet, which was originally developed to prevent or control hypertension. It decreases LDL cholesterol and blood pressure, and some research suggests it can decrease inflammation and hemoglobin A1c levels in people with type 2 diabetes.84 Limited research links scores showing how closely the DASH diet was followed with reduced risk of colorectal and estrogen receptor-negative breast cancer and type 2 diabetes.85-88

An eating pattern such as the DASH diet is low in total and saturated fat but does include limited amounts of oil. It’s high in vegetables, fruits, and grains (with at least three servings of whole grains per day) and includes low- or nonfat dairy daily, beans and nuts often, and substantially limited sweets and sodium. (Details of how the proportions of different food groups are combined in the DASH diet are provided in Appendix 10 of the 2010 Dietary Guidelines report.78) The DASH diet emphasizes vegetables and fruits, so it generally increases an individual’s intake of potassium and dietary fiber, and reduces sodium intake.

Moreover, the DASH diet is relatively high in carbohydrate. Results of the OmniHeart intervention trial suggest that, at least for some people and in the short-term, replacing some carbohydrate with plant proteins or unsaturated fat may produce even greater improvements in blood pressure and atherogenic lipoproteins,89,90 molecules that transport cholesterol in the bloodstream that can cause blood vessel blockages and lead to heart attacks and strokes.

The 2010 Dietary Guidelines advisory panel also highlights the Mediterranean eating pattern as a healthful choice. It’s a plant-based diet that includes an abundance of vegetables, fruits, grains, and beans. The Mediterranean eating pattern isn’t necessarily low in total fat, but most of the fat comes from olive oil and nuts, so saturated fat is below 10% of total calories. Research links this eating pattern with decreases in metabolic syndrome and in cardiovascular and cancer mortality.91-93 Glucose control and insulin resistance also may improve.94

Because many people think of low-fat eating as a key to health, clinical trials comparing the Mediterranean diet with a low-fat diet are of particular interest. In the PREDIMED dietary intervention trial, people assigned to a Mediterranean-type eating pattern were less likely to develop diabetes or metabolic syndrome than those eating a low-fat diet, and showed lower levels of the oxidized form of LDL now considered an essential influence in atherosclerosis.95-97 A meta-analysis that compared the Mediterranean diet with low-fat eating in overweight adults linked this eating pattern with lower levels of metabolic syndrome components, including blood pressure and fasting glucose, and reduced levels of high-sensitivity C-reactive protein, a marker of inflammation.98

Weight management is a major goal for lowering the risk of and controlling type 2 diabetes, heart disease, and cancer. The Mediterranean diet shows how a diet containing plenty of vegetables and a higher percentage of calories from fat still can have moderately low calorie density and support weight goals.99

Paradigm Shift
Research increasingly shows that the risk of and damage from type 2 diabetes, CVD, and cancer is associated with a constellation of insulin resistance, inflammation, cell signaling and epigenetic changes, and hormones. As health professionals specialize and become more problem focused, it can be easy to concentrate on single measures, such as hemoglobin A1c or LDL levels, and miss the big picture. This big picture extends beyond an intersection of heart disease and diabetes, and includes cancer as well.

Avoiding tobacco is vital to reducing the risk of all three diseases and promoting overall health. However, lifestyle matters to nonsmokers, too. Among almost 112,000 nonsmoking men and women in the Cancer Prevention Study-II Nutrition Cohort, all-cause mortality—reflecting fewer deaths because of both heart disease and cancer—was 42% lower with weight control, regular physical activity, limited use of alcohol, and a healthful diet limited in red and processed meats, and focused around whole plant foods.100