'Small steps' toward a plant-based diet confer enormous benefit
CHICAGO — Food choices are some of the most important choices a person can make for their health, Michelle McMacken, MD, FACP, DipABLM, said during a presentation at the ACP Internal Medicine Meeting.
However, many Americans make food choices that may predispose them for various health conditions. In fact, the top source of calories for Americans aged 2 years and older is grain-based desserts, according to McMacken, who is the executive director of nutrition and lifestyle medicine at NYC Health + Hospitals and an associate professor at NYU Langone Health and the NYU Grossman School of Medicine.
Patients believe that physicians are the most credible source of information for nutritional guidance. Yet, many physicians do not receive adequate nutrition training in medical school or residency, McMacken told Healio.
“It’s important for physicians to recognize that eating patterns have a critical impact on the risk for chronic disease and premature mortality,” she said.
Consumption of red and processed meats is linked to an increased cardiovascular risk, including diabetes, stroke, coronary heart disease and heart failure.
McMacken referenced the Nurses Health Study and Health Professionals Follow-up Study during her presentation. The study revealed that among individuals with one or more mortality risk factor, replacing just 3% of calories with plant protein instead of animal protein was linked to mortality reductions of 34% for processed red meat and 12% for unprocessed red meat.
In addition to meat, sugar intake has been linked to cardiovascular health.
The average consumption of sugar in the U.S. is about double the recommended daily value. The American Heart Association advises a maximum of 6 teaspoons of added sugars per day for women and 9 teaspoons for men. However, the average American consumes about 17 teaspoons of sugars daily.
McMacken emphasized that risk is linked to consumption of added sugars, not natural sugars. Two and a half servings of fruits and vegetables per day can significantly decrease cardiovascular risk, including an 8% decrease for coronary heart disease, 16% decrease for stroke and 10% decrease for all-cause mortality, according to McMacken.
Processed and red meat and added sugars have also been linked to insulin resistance and diabetes, McMacken said during her presentation.
In fact, a daily serving of bacon (or other processed meat) was associated with a greater risk for diabetes (37%) than red meat (17%) and sugar-added beverages (21%).
Substituting just 5% of animal protein calories with plant protein can decrease one’s risk for type 2 diabetes by 23%, research has shown. Moreover, replacing about 35% of an individual’s total animal protein consumption with plant protein significantly lowered HbA1c, fasting glucose and fasting insulin.
Regular consumption of excess calories, saturated fats, and isolated forms of fructose, such as high-fructose corn syrup, can lead to buildup of certain lipid subtypes in the skeletal muscle and liver. This phenomenon, known as lipotoxicity, is a primary cause of insulin resistance and can ultimately lead to type 2 diabetes.
In addition to risk for cardiovascular conditions and diabetes, consumption of red and processed meats also increase the risk for cancer.
WHO’s International Agency for Research on Cancer has labeled processed meats, including sausages, hot dogs, bacon and salami, as Group 1 carcinogens, meaning they have been proven to cause cancer. Other red meats, including beef, pork and lamb, are labeled as Group 2A carcinogens, meaning they probably cause cancer.
The risk for colorectal cancer increases by 17% for each 100 g per day of red meat consumed, and by 18% for each 50 g per day of processed meat consumed, according to McMacken.
However, healthful plant-based foods can have a protective and healing effect on cancer risk.
Increasing consumption of whole grain fiber has been linked to a survival benefit, even in individuals who already have colon cancer, McMacken said. Specifically, every increase of 5 g per day of whole grain fiber is a 33% decrease in colorectal cancer mortality among patients with stages I to III colon cancer.
Moreover, every three servings per day of whole grains consumed is associated with a 17% decrease in colorectal cancer risk and total cancer mortality.
Practical nutrition counseling
Considering the amount of research linking food choice to health risks and benefits, McMacken advocated for a plant-based diet in her presentation.
“A plant-based eating pattern is really just an eating pattern around which [plant-based foods] are really the foundation,” she said. “It doesn't mean you have to be 100% plant based. It just means that you're focusing a lot of your calories on those most healthy foods.”
A healthful plant-based diet, low in unhealthy plant-based foods like fruit juices, white flour, desserts and sugar-sweetened drinks, has been shown to reduce BP, promote a healthier body weight, enhance glycemic control, improve vascular health, decrease inflammation and decrease lipids.
McMacken advised eating mostly vegetables, beans, lentils, peas, fruits and whole grains, and to avoid or work to limit red and processed meats, sugary beverages and highly processed foods. A 20% improvement in diet quality has been linked to an 8% to 17% decrease in mortality, she said.
However, getting patients to adopt and sustain diet improvements can be challenging.
“Small steps work best for many people,” McMacken said. “Ultimately, it is about progress, not perfection!”
When implementing nutrition counseling in practice, McMacken recommended to:
- start the conversation and assess the patient’s level of interest;
- assess current dietary pattern with a 24-hour recall, broad questions or a 3-day food record;
- advise and review the big picture;
- agree on the intensity of your approach based on the patient’s readiness and ability to make changes;
- assist the patient in making a specific, measurable, attainable, realistic and timebound goal (recommend specific food swaps or additions similar to a prescription); and
- arrange follow ups.
“One strategy I’ve found effective is to focus on healthy foods that the patient already likes, has access to and finds culturally relevant,” McMacken said. “These foods can be used to gradually ‘crowd out’ less healthy foods on the plate.”