“Eat food. Not too much. Mostly plants.” - Michael Pollan
In 1999, food psychologist Dr. Paul Rozin at the University of Pennsylvania conducted a study on cultural attitudes related to food-pleasure and health attitudes. He sought to assess the way food functions in the minds and lives of people in different countries—Japan, Belgium, France, and the United States—to see if there were cross-cultural differences related to whether food was a stressor or a source of pleasure. Of the four countries he studied, the French reported the highest levels of pleasure in eating and the lowest concern about the health of their food choices. Americans landed at the opposite end of the spectrum. They did the most work to make their diets healthy, but reported the least pleasure in eating, and they expressed the highest levels of anxiety about their food choices. From his data, Rozin concluded that Americans found food to be a significant stressor, whereas the French found it to be a significant source of pleasure.
Rozin’s research added to data from decades of research that reported what came to be known as the French Paradox. Starting in the 1980’s, numerous studies revealed that, although the French had one of the highest levels of per-capita consumption of dietary fat, with diets rich in cream, butter, and cheese, they had much lower rates of heart disease than people from other areas, especially Americans. They also had longer life expectancies and took fewer medications. These findings flew in the face of what was widely understood as the bedrock of a “heart healthy” diet, which was one low in fat and high in fiber. How could the French be so much healthier even though they ate foods that were known to cause heart disease?
After studying different cultural attitudes, Rozin concluded that perhaps stress was the answer to the puzzle of the French’s immunity to heart disease. He concluded that the French’s pleasure-oriented approach to eating provided immunity against food related stress. The constant worry and fretting about food choices experienced by Americans triggered inflammation which then contributed to their higher rates of heart disease. But while Rozin looked to psychosocial factors to explain the French Paradox, other research was following the trail of the French’s fondness for red wine to explain their longer life expectancies, better health, and lower incidence of heart disease. Compared to other cultures, the French drank significantly more red wine. Could that be the missing link?
Following the lead of a red wine connection, further research led to the discovery of polyphenols, the plant compounds found in red and purple grape skins that were found to protect against heart disease. The polyphenols in red wine became the widely accepted explanation for the French’s good health, which led to the popularization of red wine as being good for your heart. You may remember the buzz this news generated about a decade ago and the related explosion in sales of red wine, as people topped off their glass of pinot noir while making a toast to heart health and, perhaps, the French.
Anything that seems too good to be true most likely is, and so it goes with the story of red wine and heart health. Since the wine soaked bliss of the 2010’s, research methods in nutritional science have improved significantly. Up until quite recently, the connection between red wine consumption and heart disease was observational; data collected through self-report methods is not always reliable. Newer research methods track data more directly, providing a much different picture about red wine and heart health. The newer data collection methods found that red wine and, for that matter, any alcohol, does not confer any heart health benefits, even in moderate amounts. In fact, alcohol has a dose dependent impact on heart health. At low levels--roughly seven drinks per week--it is associated with a low level of risk, but as consumption rises above that level, the risk of developing heart disease rises quite rapidly.
Perhaps the French Paradox is not very paradoxical after all. Data from more recent studies have uncovered the missing link that sheds light on the French mystique—flawed research. Data collection has become more robust in the past several years. Using these newer techniques shows that lower levels of drinking are associated with lower rates of heart disease, but not because of any particular property in the alcohol, such as the polyphenols in red wine. The lower levels of heart disease enjoyed by light drinkers tend to reflect common lifestyle patterns of those who imbibe with restraint. People who limit their alcohol consumption also tend to lead healthier lifestyles, such as eating more fruits and vegetables, exercising more, and smoking less than people who drink more heavily. At such low levels of consumption, the polyphenols in red wine are not ingested at levels that would confer benefits that override the French’s high fat diet. The final debunking of the French Paradox came with evidence that physicians in France tend to underreport cardiovascular issues. When adjustments were made for these differences, French rates of heart disease got closer to those of Americans.
The pendulum swing from promoting the regular consumption of wine to counseling restraint with alcohol may seem like just another swing of the nutritional pendulum. Although it may seem that nutritional advice keeps changing, most nutritionists would argue that this is not the case. In the 1950’s, dietary recommendations for heart disease advised minimizing foods high in saturated fat, salt, and sugar. Plenty of recent research over the past 50 years continues to support this basic nutritional guidance but includes a strong emphasis on whole grains, nuts, fruits, and vegetables. We may wish there was some secret to good health to be found in a bottle of red wine and a creamy slab of cheese, but it seems heart health is much more tedious, coming down to what my grandmother would say when she served us bowls of lima beans and corn: Eat your roughage.
Although it is far from glamorous, fiber is key to the health of our heart. Fiber is a type of carbohydrate that the body cannot break down, so it passes through the colon undigested. There are two varieties of fiber, both of which are beneficial but work to protect the heart in different ways. Soluble fiber, such as oatmeal, chia seeds, nuts, beans, apples, and blueberries, dissolve in water. This type of fiber has been found to lower blood cholesterol levels in the small intestine by interfering with bile acid production. Cholesterol is used to make bile in the liver. When soluble fiber binds to bile acids in the gut, they are excreted from the body, thereby reducing the amount of available bile. These lower levels trigger the liver to pull cholesterol from the blood to produce bile, which lowers both total and LDL blood cholesterol levels.
Insoluble fiber, which does not dissolve in water, helps to transport food through the digestive system. It is found in whole wheat products, quinoa, brown rice, legumes, leafy greens, almonds, walnuts, seeds, and fruits with edible skins such as apples, pears, and plums. Research has found that higher intakes of these foods are associated with a reduced risk of heart disease and heart attacks, as well as a lower risk of metabolic syndrome, which is associated with high blood pressure and heart disease.
Although fiber has plenty of benefits, its relationship with our gut microbiome may bestow the greatest benefits to the heart. The gut is home to trillions—yes, trillions--of microbes, which collectively are referred to as the human microbiota. They play an important role in digestion, the production of certain nutrients, and the release of substances that are known to have a significant impact on our health and well-being. We are just starting to understand the complex relationship between these microbes and several of our body systems, many of which are important to cardiovascular health.
What we eat plays an important role in the composition of our microbiome; what we feed these microbes can either help or hurt the cardiovascular system. For example, when gut microbes feed on choline, a nutrient found in red meat, they produce trimethylamine (TMA), which gets converted in the liver to a substance associated with the formation of artery clogging plaque. Other food sources, such as fish, poultry, and eggs, also have choline, but microbes feeding on red meat create two additional byproducts—gamma-butryobetaine and crotonobetaine—which contribute to the development of atherosclerosis. This may explain why, for those 65 and older who eat an average of 1.1 servings of red meat per day, the risk of heart disease is 22% higher compared to those who eat less or none at all.
When fiber gets broken down by microbes in the colon, it is turned into substances known as short-chain fatty acids. These are important regulatory compounds that interact with specific receptors on cells that perform specific functions, such as blood pressure regulation, controlling blood glucose levels, and reducing inflammation. Our gut microbes produce more short-chain fatty acids when we eat a plant-based diet compared to an animal-based diet. Whole grains rather than those ground into flour, as well as a wide variety of fruits and vegetables keep these microbes well fed, leading to better regulation of our metabolism, and helping to reduce inflammation.
Most of us eat only about 15 grams of fiber per day, but nutritional guidelines recommend at least 25 to 35 grams per day. Some people will have a fruit or vegetable with each meal, but we typically overestimate the fiber content in our diets. Considering that one medium apple has 4.4 grams of fiber, a banana only 3 grams, and a cup of broccoli only 2.4 grams, it is easy to see that it takes diligence to reach the recommended levels. Caloric restriction makes it even harder, especially when meat or protein is part of the menu. It is much easier to meet fiber recommendations when we build our meals around plants, whole grains, and nuts, eating meat in significantly smaller portions, if at all. Doing so offers additional benefits to heart health, as animal products can be a significant source of saturated fat, which has long been associated with heart disease.
We may have solved the French Paradox, but perhaps Rozin’s research leaves us with just a small slice of mystery. What can we learn from the French’s love of food and lack of worry about the health of their diet? Can the joy of eating provide some level of immunity from the artery clogging fats found in butter, cream, and cheese? What role does American food-based worry play in inflammation? These are topics that are open to debate and even harder to study. What we should and should not eat to keep our heart healthy is an incredibly complicated topic, one which makes for a lively debate, but, at its foundation, comes back to what my grandmother knew about lima beans and Michael Pollan advised in 2009: Eat food. Not too much. Mostly plants.
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