Grilled or well-done beef, chicken or fish may raise the risk of developing high blood pressure among people who regularly eat those foods, according to preliminary research presented at the American Heart Association's Epidemiology and Prevention/Lifestyle and Cardiometabolic Health Scientific Sessions 2018, a premier global exchange of the latest advances in population based cardiovascular science for researchers and clinicians.
Researchers analysed cooking methods and the development of high blood pressure in people who regularly ate beef, poultry or fish: 32,925 women taking part in the Nurses' Health Study; 53,852 women participating in the Nurses' Health Study II; and 17,104 men in the Health Professionals Follow-Up Study. Detailed cooking information was collected in each of these long-term studies. None of the participants had high blood pressure, diabetes, heart disease, or cancer when they enrolled, but 37,123 people developed high blood pressure during an average follow-up of 12-16 years.
Among participants who reported eating at least two servings of red meat, chicken or fish a week, the analysis revealed that the risk of developing high blood pressure was: 17% higher in those who grilled, broiled, or roasted beef, chicken or and fish more than 15 times/month, compared with less than 4 times a month; 15% higher in those who prefer their food well done, compared with those who prefer rarer meats; and 17% higher in those estimated to have consumed the highest levels of heterocyclic aromatic amines (HAAs) – chemicals formed when meat protein is charred or exposed to high temperatures – compared to those with the lowest intake.
Researchers noted the relationship between cooking temperature, method, doneness and high blood pressure was independent of the amount or type of food consumed. "The chemicals produced by cooking meats at high temperatures induce oxidative stress, inflammation and insulin resistance in animal studies, and these pathways may also lead to an elevated risk of developing high blood pressure," said Dr Gang Liu, lead author of the study and a post-doctoral research fellow in the department of nutrition at the Harvard TH Chan School of Public Health in Boston.
Oxidative stress, inflammation and insulin resistance affect the inner linings of blood vessels, and are associated with the development of atherosclerosis, the disease process that underlies heart disease and causes the arteries to become narrowed.
It is important to note that this study identifies a trend but does not prove cause and effect. The findings are limited because data came from questionnaires that did not include certain types of meats (such as pork and lamb) and certain cooking methods (such as stewing and stir-frying). Because the participants were all health professionals and mostly Caucasian, the results may not generalise to other groups.
"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/barbequing and broiling," Liu said.
The study was funded by the National Heart, Lung and Blood Institute.
Background: The role of open-flame and/or high-temperature cooking (grilling/barbequing, broiling, or roasting) and doneness preferences (rare, medium, or well-done) in the association between meat consumption and risk of hypertension remains unknown. This study aimed to examine cooking methods for meats (red meats, chicken, or fish) in relation to hypertension risk among men and women who consumed meat regularly (≥2 servings/week).
Methods: Study population consisted of 32,925 women from the Nurses’ Health Study (NHS 1996-2012), 53,852 women from the NHSII (2001-2013), and 17,104 men from the Health Professionals Follow-Up Study (HPFS 1996-2012), who were free of hypertension, diabetes, cardiovascular disease, and cancer at baseline.
Results: We documented 37,123 incident hypertension cases during 1.06 million person-years of follow-up. After multivariate adjustments of covariates including total consumption of red meats, chicken, and fish, a higher frequency of open-flame and/or high-temperature cooking and a preference for higher meat doneness level were both independently associated with an increased hypertension risk. When comparing open-flame and/or high-temperature cooking >15 times/month with <4 times/month, the pooled hazard ratio (HR) and 95% confidence interval (CI) of hypertension was 1.17 (1.12, 1.21; P trend <0.001). When comparing the extreme quartiles of meat doneness level score, the pooled HR (95% CI) of hypertension was 1.15 (1.12, 1.19; P trend <0.001). The associations persisted when data were analyzed by individual meat groups: comparing extreme groups, for red meats, the pooled HR (95% CI) of hypertension was 1.18 (1.13, 1.23; P trend <0.001) for open-flame and/or high-temperature cooking and 1.15 (1.12, 1.19; P trend <0.001) for high meat doneness level; for white meats (chicken and fish), the pooled HR (95% CI) of hypertension was 1.12 (1.08, 1.16; P trend <0.001) for open-flame and/or high-temperature cooking and 1.10 (1.07, 1.14; P trend <0.001) for high meat doneness level. Moreover, levels of estimated intake of heterocyclic aromatic amines (HAAs) were also independently associated with an increased risk of hypertension. Comparing extreme quintiles of HAAs, the pooled HR (95% CI) of hypertension was 1.16 (1.13, 1.21; P trend <0.001). These associations were attenuated but remained significant when further adjusting for baseline body mass index.
Conclusions: Our results suggest that, independent of the amount of meat consumption, open-flame and/or high-temperature cooking and high doneness level for both red meats and white meats are associated with an increased risk of hypertension.
[link url="https://www.sciencedaily.com/releases/2018/03/180321162250.htm"]American Heart Association material[/link]
[link url="http://circ.ahajournals.org/content/137/Suppl_1/AP184"]AHA Scientific Sessions abstract[/link]