Now there is another thing to worry about, apparently.
While almost everyone knows that what we eat can affect our risk of high blood pressure, a new study out of Harvard suggests that how “cooked through” our food is may also influence the risk.
The researchers analyzed the data of over 100,000 men and women who took part in one of three studies that collected information on how much meat and fish participants consumed each month, how these foods were cooked, and their levels of “doneness.”
At the beginning of their study participation, none of the men or women had high blood pressure. At the end of the follow-up period, which averaged 12 to 16 years, more than a third had developed the condition.
The research team, led by Gang Liu, Ph.D., of the Department of Nutrition at the Harvard T.H. Chan School of Public Health in Boston, found that participants who ate grilled, broiled or roasted beef, chicken or fish at least 15 times each month were 17 percent more likely to develop high blood pressure than those who ate these foods fewer than four times per month.
But the real news out of the study is this: Among participants who reported preferring their meat, poultry and fish well-done, the risk of high blood pressure was increased by an additional 15 percent, compared with those who preferred those foods prepared less well-done. This finding was not affected by the type – or how much – food the participants consumed, only how well-done it was.
Samantha Lynch, MS, RDN, LDN, a registered dietitian and nutritionist with a private practice in Vero Beach, is familiar with the study. She says “it’s important to know the ‘smoke points’ of the oils we cook with. The smoke point is the cooking temperature at which a fat or oil begins to break down and degrade. When we eat food cooked past the smoke point, harmful compounds begin to circulate in our bodies, leading to inflammation and oxidative stress, which reduces the ability of the body to detoxify.”
High blood pressure (hypertension) occurs when the force of blood that pushes against the wall of the arteries becomes too high. In 2017, the American Heart Association and the American College of Cardiology revised the definition of high blood pressure from 140/90 or higher to 130/80 or higher. “Normal” blood pressure is 120/80; a top (systolic) number between 121 and 129 is now considered “elevated.” The new guidelines eliminate the category of “prehypertension.”
Under the new definition, it’s estimated that almost half of adults in the United States have high blood pressure, with the associated increased risk of stroke, heart attack and heart disease. Vero’s Lynch says “under these new guidelines, the prevalence of high blood pressure is expected to triple among men under age 45, and double among women under age 45.”
The link between hypertension and the “doneness” of food may have to do with something called heterocyclic aromatic amines (HAAs), potentially harmful compounds produced when meats, poultry, and fish are cooked at high temperatures. Harvard’s Liu says HAAs and other chemicals produced by high-temperature cooking may lead to oxidative stress, inflammation and insulin resistance, which can raise the risk of high blood pressure.
Lynch says “it’s important to know the smoke points of the oils we cook with. The smoke point is the cooking temperature at which a fat or oil begins to break down and degrade. When we eat food cooked past the smoke point, harmful compounds begin to circulate in our bodies, leading to inflammation and oxidative stress, which reduces the ability of the body to detoxify.”
An oil has reached its smoke point after it starts to smoke and burn when heated. The estimated smoke point of common cooking oils can vary greatly depending on the quality of the oil, but Lynch shared the following guidelines:
- Butter: 350°F
- Extra-virgin olive oil: 325°F
- Sesame oil: 350°F
- Coconut oil: 350°F
- Grapeseed oil: 420°F
- Ghee: 485°F
- Avocado oil: 520°F
A caveat: “It is important to note this study identifies a trend, not a cause and effect,” says Lynch. “I would like to see a study which has controls for variables such as the person’s weight, their fruit and vegetable intake, and overall health.”
While the research team acknowledges their study cannot prove cause and effect, Liu says “our findings suggest that it may help reduce the risk of high blood pressure if you don’t eat these foods cooked well-done and avoid the use of open-flame and/or high-temperature cooking methods, including grilling/barbecuing and broiling.”
Lynch offers this additional advice: “Use unrefined, cold-pressed and/or unfiltered cooking oils, as they are the least processed and have the best nutrient profile. Opt for the lowest heat application possible when cooking to minimize the ingestion of harmful compounds. Olive oil is fine for lower-heat cooking and finishing, but with polyunsaturated fats such as nut and seed oils (like flaxseed oil), it’s best to avoid heating at all; save these for dressings.”
Samantha Lynch’s office is located at 4445 Hwy A1A, Suite 239, in Vero Beach. She can also be reached via her website: www.samanthalynchnutrition.com.
