How red and processed meat affect heart disease risk

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Red meat is commonly red when raw and has a dark color after it is cooked, in contrast to white meat, which is pale in color before and after cooking.

Common red meat includes beef, lamb and mutton, pork, veal, venison, and goat.

Processed meats are meats that have been preserved by smoking or salting, curing, or adding chemical preservatives. They include deli meats, bacon, and hot dogs.

Recent studies have found that red and processed meat could harm heart health and increase heart disease risk.

In a study from the University of Oxford, researchers showed that red and processed meat is linked to a higher risk of heart disease.

They conducted the largest systematic review of the prospective evidence to date, including thirteen cohort studies involving over 1.4 million people.

The participants completed detailed dietary assessments, and their health was tracked for up to 30 years.

Overall, the evidence from the analysis indicated that: each 50 g/day higher intake of processed meat (e.g. bacon, ham, and sausages) increased the risk of coronary heart disease by 18%.

Each 50 g/day higher intake of unprocessed red meat (such as beef, lamb, and pork) increased the risk of coronary heart disease by 9%.

There was no clear link between eating poultry (such as chicken and turkey) and an increased risk of coronary heart disease.

The team says the high content of saturated fat in red meat, and sodium (salt) in processed meat may be harmful to heart health.

High intakes of saturated fat increase levels of harmful low-density lipoprotein (LDL) cholesterol, whilst excess salt consumption raises blood pressure.

Both LDL cholesterol and high blood pressure are well-established risk factors for coronary heart disease.

The team says red and processed meat has been consistently linked with bowel cancer and their findings suggest an additional role in heart disease.

The study was published in Critical Reviews in Food Science and Nutrition and conducted by Dr. Keren Papier et al.

In another study at Cornell University and elsewhere, researchers found that eating two servings of unprocessed red meat, processed meat, or poultry a week has been linked to an increased risk of heart disease.

They found that eating two servings of red meat, unprocessed meat, or poultry – but not fish – per week was linked to a 3 to 7% higher risk of cardiovascular disease.

Additionally, eating two servings of unprocessed red meat or processed meat – but not poultry or fish – was associated with a 3% higher risk of all causes of death.

The team says modifying the intake of these animal protein foods may be an important dietary strategy to help reduce the risk of cardiovascular disease and premature death at the population level.

They also found a 4% higher risk of heart disease for people who ate two servings per week of poultry, but the evidence so far is not sufficient to make a clear recommendation about poultry intake.

The researchers suggest dietary alternatives, such as fish, seafood, and plant-based sources of protein, to lessen one’s risk of heart disease and premature death.

The findings support current dietary guidelines that recommend limiting processed meat and unprocessed red meat intake.

The study was published in JAMA Internal Medicine and conducted by Victor Zhong et al.

High heat may be a factor

One study by the University of South Australia also found that high-heat caramelization could be bad for health.

They found that consuming red and processed meat increased a protein compound that may increase the risk of heart disease, stroke, and complications in diabetes.

The finding provides important dietary insights for people at risk of such diseases.

The study tested the impacts of two diets—one high in red meat and processed grains and the other high in whole grains dairy, nuts, legumes, and white meat using steaming boiling, stewing, and poaching cooking methods.

It found that a diet high in red meat significantly increased AGE levels in blood suggesting it may contribute to disease progression

The team says when red meat is seared at high temperatures, such as grilling, roasting, or frying, it creates compounds called advanced glycation end products—or AGEs—which when consumed, can accumulate in the body and interfere with normal cell functions.

Consumption of high-AGE foods can increase the total daily AGE intake by 25%, with higher levels contributing to vascular and myocardial stiffening, inflammation, and oxidative stress—all signs of degenerative disease.

While there are still questions about how dietary AGEs are linked to chronic disease, this research shows that eating red meat will alter AGE levels.

Frying, grilling, and searing may be the preferred cooking methods of top chefs, but this might not be the best choice for people looking to cut their risk of disease.

The study was published in Nutrients and conducted by Dr. Permal Deo et al.

Sulfur amino acids may play a role

One study from Penn State University found that eating too much food containing sulfur amino acids – primarily found in proteins such as beef, chicken, and dairy – may increase a person’s risk of heart disease and death.

Sulfur amino acids are essential for metabolism and overall health, but the average person in the United States consumes far more than is needed.

In the study, the team analyzed data from 120,699 people in two long-term national studies.

Participants completed detailed health questionnaires, including questions about their diets, every two to four years.

The team found on average, participants ate more than twice the recommended daily amount of sulfur amino acids, mostly from beef, chicken, and milk.

Compared to those who ate the least, those who consumed the most sulfur amino acids had a 12% increased annual risk of developing heart disease and a 28% increased risk of dying from the condition over the 32-year study period.

Several animal studies in the past have shown that restricting these types of amino acids – notably methionine and cysteine – delayed the aging process and helped animals live longer, but translating those benefits to people has proven to be difficult.

The team says people can get their estimated average requirement of sulfur amino acids – 15 milligrams per kilogram of body weight per day – through plant-based sources or fish.

Since red meat has been found to be associated with worse health outcomes, it would be better to focus on healthier sources of proteins for meeting the average requirement of sulfur amino acids.

The research was presented at Epidemiology and Prevention, Lifestyle and Cardiometabolic Health conference and conducted by Laila Al-Shaar et al.

Plant protein foods may reduce heart disease risk

In a recent study from Harvard University, scientists found that replacing red meat with high-quality plant foods such as beans, nuts, or soy may be associated with a modestly reduced risk of heart disease.

They found Substituting whole grains and dairy products for total red meat, and eggs for processed red meat might also reduce this risk.

In the study, researchers examined the relationship between total, processed, and unprocessed red meat and the risk of heart disease and estimate the effects of substituting other protein sources for red meat on heart disease risk.

They used data from 43,272 US men (average age 53) from the Health Professionals Follow-Up Study who were free from cardiovascular disease and cancer when they enrolled.

Medical records were used to track heart disease events over this 30-year period. During this time, 4,456 heart disease events were documented of which 1,860 were fatal.

The researchers found that for each one serving per day, total red meat was associated with a modest (12%) higher risk of heart disease.

Similar associations were seen for unprocessed (11% higher risk) and processed red meat (15% higher risk).

However, compared with red meat, intake of one serving per day of combined plant protein sources, including nuts, legumes (such as peas, beans, and lentils), and soy was associated with a 14% lower risk of heart disease.

This risk was lower still (18%) among men over the age of 65, and when compared with processed red meat (17%).

Substituting whole grains and dairy products (such as milk, cheese, and yogurt) for total red meat and eggs for processed red meat was also associated with lower heart disease risk.

This association was particularly strong among younger men, in whom the replacement of red meat with egg was linked to a 20% lower risk of heart disease.

Replacing red meat with total fish was not linked to heart disease risk. But the researchers say this could be due to the cooking methods (ie. deep frying) and the fact that this food group also included processed fish products.

The study shows that greater intakes of total, unprocessed, and processed red meat were associated with a higher risk of heart disease, independent of other dietary and non-dietary heart disease risk factors.

The study was conducted by Laila Al-Shaar et al and published in The BMJ.

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