Increasing red meat consumption linked with higher risk of premature death

People who increased their daily servings of red meat over an eight-year period were more likely to die during the subsequent eight years compared to people who did not increase their red meat consumption, according to a new study led by researchers from Harvard T.H. Chan School of Public Health.

The study also found that decreasing red meat and simultaneously increasing healthy alternative food choices over time was associated with lower mortality.

The study was published online June 12, 2019 in BMJ.

A large body of evidence has shown that higher consumption of red meat, especially processed red meat, is associated with higher risk of type 2 diabetes, cardiovascular disease, certain types of cancers including those of the colon and rectum, and premature death. This is the first longitudinal study to examine how changes in red meat consumption over time may influence risk of early death.

For this study, researchers used health data from 53,553 women in The Nurses’ Health Study and 27,916 men in the Health Professionals Follow-up Study who were free of cardiovascular disease and cancer at baseline. They looked at whether changes in red meat consumption from 1986–1994 predicted mortality in 1994–2002, and whether changes from 1994–2002 predicted mortality in 2002–2010.

Increasing total processed meat intake by half a daily serving or more was associated with a 13% higher risk of mortality from all causes. The same amount of unprocessed meat increased mortality risk by 9%. The researchers also found significant associations between increased red meat consumption and increased deaths due to cardiovascular disease, respiratory disease, and neurodegenerative disease.

The association of increases in red meat consumption with increased relative risk of premature mortality was consistent across participants irrespective of age, physical activity level, dietary quality, smoking status, or alcohol consumption, according to the researchers.

Study results also showed that, overall, a decrease in red meat together with an increase in nuts, fish, poultry without skin, dairy, eggs, whole grains, or vegetables over eight years was associated with a lower risk of death in the subsequent eight years.

The researchers suggest that the association between red meat consumption and increased risk of death may be due to a combination of components that promote cardiometabolic disturbances, including saturated fat, cholesterol, heme iron, preservatives, and carcinogenic compounds produced by high temperature cooking. Red meat consumption has also recently been linked to gut microbiota-derived metabolite trimethylamine N-oxide (TMAO) that might promote atherosclerosis.

“This long-term study provides further evidence that reducing red meat intake while eating other protein foods or more whole grains and vegetables may reduce risk of premature death. To improve both human health and environmental sustainability, it is important to adopt a Mediterranean-style or other diet that emphasizes healthy plant foods,” said senior author Frank Hu, Fredrick J. Stare Professor of Nutrition and Epidemiology and chair, Department of Nutrition.

The first author of the study is Yan Zheng, a former postdoctoral associate in the Department of Nutrition at Harvard Chan School and now a professor at Fudan University, Shanghai, China. Other Harvard Chan School authors include Yanping Li, Ambika Satija, Mercedes Sotos-Prieto, Eric Rimm, and Walter Willett.

The study cohorts were supported by grants of UM1 CA186107 and UM1 CA167552 from the National Institutes of Health. The current study was supported by grants from the National Heart, Lung, and Blood Institute (HL071981, HL034594, HL60712, HL126024), the National Institute of Diabetes and Digestive and Kidney Diseases (DK091718, DK100383, DK112940, DK078616), and the Boston Obesity Nutrition Research Center (DK46200).

“Association of Changes in Red Meat Consumption with Total and Cause-Specific Mortality Among U.S. Women and Men: Two Prospective Cohort Studies,” Yan Zheng, Yanping Li, Ambika Satija, An Pan, Mercedes Sotos-Prieto, Eric Rimm, Walter C. Willett, Frank B. Hu, BMJ, online June 12, 2019, doi: 10.1136/bmj.l2110.

To grow up healthy, children need to sit less and play more

Children under five must spend less time sitting watching screens, or restrained in prams and seats, get better quality sleep and have more time for active play if they are to grow up healthy, according to new guidelines issued by the World Health Organization (WHO).

“Achieving health for all means doing what is best for health right from the beginning of people’s lives,” says WHO Director-General Dr Tedros Adhanom Ghebreyesus. “Early childhood is a period of rapid development and a time when family lifestyle patterns can be adapted to boost health gains.”

The new guidelines on physical activity, sedentary behaviour and sleep for children under 5 years of age were developed by a WHO panel of experts. They assessed the effects on young children of inadequate sleep, and time spent sitting watching screens or restrained in chairs and prams. They also reviewed evidence around the benefits of increased activity levels.

Children playing at Boboh Beach in Sierra Leone. Photo credit: ABC

“Improving physical activity, reducing sedentary time and ensuring quality sleep in young children will improve their physical, mental health and wellbeing, and help prevent childhood obesity and associated diseases later in life,” says Dr Fiona Bull, programme manager for surveillance and population-based prevention of noncommunicable diseases, at WHO.

Failure to meet current physical activity recommendations is responsible for more than 5 million deaths globally each year across all age groups.  Currently, over 23% of adults and 80% of adolescents are not sufficiently physically active. If healthy physical activity, sedentary behaviour and sleep habits are established early in life, this helps shape habits through childhood, adolescence and into adulthood.

“What we really need to do is bring back play for children,” says Dr Juana Willumsen, WHO focal point for childhood obesity and physical activity. “This is about making the shift from sedentary time to playtime, while protecting sleep. “

The pattern of overall 24-hour activity is key: replacing prolonged restrained or sedentary screen time with more active play, while making sure young children get enough good-quality sleep. Quality sedentary time spent in interactive non-screen-based activities with a caregiver, such as reading, storytelling, singing and puzzles, is very important for child development.

The important interactions between physical activity, sedentary behaviour and adequate sleep time, and their impact on physical and mental health and wellbeing, were recognized by the Commission on Ending Childhood Obesity, which called for clear guidance on physical activity, sedentary behaviour and sleep in young children.

Applying the recommendations in these guidelines during the first five years of life will contribute to children’s motor and cognitive development and lifelong health

Study links frequent red meat consumption to high levels of chemical associated with heart disease

Findings reveal tripling of blood levels of TMAO from red meat diet, but dietary effects can be reversed

Researchers have identified another reason to limit red meat consumption: high levels of a gut-generated chemical called trimethylamine N-oxide (TMAO), that also is linked to heart disease. Scientists found that people who eat a diet rich in red meat have triple the TMAO levels of those who eat a diet rich in either white meat or mostly plant-based proteins, but discontinuation of red meat eventually lowers those TMAO levels.

TMAO is a dietary byproduct that is formed by gut bacteria during digestion and is derived in part from nutrients that are abundant in red meat. While high saturated fat levels in red meat have long been known to contribute to heart disease—the leading cause of death in the United States—a growing number of studies have identified TMAO as another culprit. Until now, researchers knew little about how typical dietary patterns influence TMAO production or elimination.

The findings suggest that measuring and targeting TMAO levels—something doctors can do with a simple blood test—may be a promising new strategy for individualizing diets and helping to prevent heart disease. The study was funded largely by the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health. It will be published Dec. 10 in the European Heart Journal, a publication of the European Society of Cardiology.

“These findings reinforce current dietary recommendations that encourage all ages to follow a heart-healthy eating plan that limits red meat,” said Charlotte Pratt, Ph.D., the NHLBI project officer for the study and a nutrition researcher and Deputy Chief of the Clinical Applications & Prevention Branch, Division of Cardiovascular Sciences, NHLBI. “This means eating a variety of foods, including more vegetables, fruits, whole grains, low-fat dairy foods, and plant-based protein sources such as beans and peas.”

“This study shows for the first time what a dramatic effect changing your diet has on levels of TMAO, which is increasingly linked to heart disease,” said Stanley L. Hazen, M.D., Ph.D., senior author of the study and section head of Preventive Cardiology & Rehabilitation at the Cleveland Clinic. “It suggests that you can lower your heart disease risk by lowering TMAO.”

Hazen estimated that as many as a quarter of middle-aged Americans have naturally elevated TMAO levels, which are made worse by chronic red meat consumption. However, every person’s TMAO profile appears to be different, so tracking this chemical marker, Hazen suggested, could be an important step in using personalized medicine to fight heart disease.

For the study, researchers enrolled 113 healthy men and women in a clinical trial to examine the effects of dietary protein—in the form of red meat, white meat, or non-meat sources—on TMAO production. All subjects were placed on each diet for a month in random order. When on the red meat diet, the participants consumed roughly the equivalent of about 8 ounces of steak daily, or two quarter-pound beef patties. After one month, researchers found that, on average, blood levels of TMAO in these participants tripled, compared to when they were on the diets high in either white meat or non-meat protein sources.

While all diets contained equal amounts of calories, half of the participants were also placed on high-fat versions of the three diets, and the researchers observed similar results. Thus, the effects of the protein source on TMAO levels were independent of dietary fat intake.

Importantly, the researchers discovered that the TMAO increases were reversible. When the subjects discontinued their red meat diet and moved to either a white meat or non-meat diet for another month, their TMAO levels decreased significantly.

The exact mechanisms by which TMAO affects heart disease is complex. Prior research has shown TMAO enhances cholesterol deposits into cells of the artery wall. Studies by the researchers also suggest that the chemical interacts with platelets—blood cells that are responsible for normal clotting responses—in a way that increases the risk for clot-related events such as heart attack and stroke.

TMAO measurement is currently available as a quick, simple blood test first developed by Hazen’s laboratory. In recent published studies, he and his colleagues reported development of a new class of drugs that are capable of lowering TMAO levels in the blood and reducing atherosclerosis and clotting risks in animal models, but those drugs are still experimental and not yet available to the public.

The study was supported by grants from the NHLBI and the Office of Dietary Supplements (HL103866, HL126827, HL106003, HL130819) and the National Institute of Diabetes and Digestive and Kidney Diseases (DK106000). The study was also supported by UCSF Clinical and Translational Science Unit.

Part of the National Institutes of Health, the National Heart, Lung, and Blood Institute (NHLBI) plans, conducts, and supports research related to the causes, prevention, diagnosis, and treatment of heart, blood vessel, lung, and blood diseases; and sleep disorders. The Institute also administers national health education campaigns on women and heart disease, healthy weight for children, and other topics. 

 The National Institutes of Health (NIH): NIH, the nation’s medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. 

Cardiovascular diseases (CVDs) number 1 cause of death globally

CVDs are the number 1 cause of death globally: more people die annually from CVDs than from any other cause, according to the World Health Organization.

An estimated 17.7 million people died from CVDs in 2015, representing 31% of all global deaths. Of these deaths, an estimated 7.4 million were due to coronary heart disease and 6.7 million were due to stroke .

Over three quarters of CVD deaths take place in low- and middle-income countries.

Out of the 17 million premature deaths (under the age of 70) due to noncommunicable diseases in 2015, 82% are in low- and middle-income countries, and 37% are caused by CVDs.

Most cardiovascular diseases can be prevented by addressing behavioural risk factors such as tobacco use, unhealthy diet and obesity, physical inactivity and harmful use of alcohol using population-wide strategies.

People with cardiovascular disease or who are at high cardiovascular risk (due to the presence of one or more risk factors such as hypertension, diabetes, hyperlipidaemia or already established disease) need early detection and management using counselling and medicines, as appropriate.

What are cardiovascular diseases?

Cardiovascular diseases (CVDs) are a group of disorders of the heart and blood vessels and they include:

• coronary heart disease – disease of the blood vessels supplying the heart muscle;
• cerebrovascular disease – disease of the blood vessels supplying the brain;
• peripheral arterial disease – disease of blood vessels supplying the arms and legs;
• rheumatic heart disease – damage to the heart muscle and heart valves from rheumatic fever, caused by streptococcal bacteria;
• congenital heart disease – malformations of heart structure existing at birth;
• deep vein thrombosis and pulmonary embolism – blood clots in the leg veins, which can dislodge and move to the heart and lungs.

Heart attacks and strokes are usually acute events and are mainly caused by a blockage that prevents blood from flowing to the heart or brain. The most common reason for this is a build-up of fatty deposits on the inner walls of the blood vessels that supply the heart or brain. Strokes can also be caused by bleeding from a blood vessel in the brain or from blood clots. The cause of heart attacks and strokes are usually the presence of a combination of risk factors, such as tobacco use, unhealthy diet and obesity, physical inactivity and harmful use of alcohol, hypertension, diabetes and hyperlipidaemia.

What are the risk factors for cardiovascular disease?

The most important behavioural risk factors of heart disease and stroke are unhealthy diet, physical inactivity, tobacco use and harmful use of alcohol. The effects of behavioural risk factors may show up in individuals as raised blood pressure, raised blood glucose, raised blood lipids, and overweight and obesity. These “intermediate risks factors” can be measured in primary care facilities and indicate an increased risk of developing a heart attack, stroke, heart failure and other complications.

Cessation of tobacco use, reduction of salt in the diet, consuming fruits and vegetables, regular physical activity and avoiding harmful use of alcohol have been shown to reduce the risk of cardiovascular disease. In addition, drug treatment of diabetes, hypertension and high blood lipids may be necessary to reduce cardiovascular risk and prevent heart attacks and strokes. Health policies that create conducive environments for making healthy choices affordable and available are essential for motivating people to adopt and sustain healthy behaviour.

There are also a number of underlying determinants of CVDs or “the causes of the causes”. These are a reflection of the major forces driving social, economic and cultural change – globalization, urbanization and population ageing. Other determinants of CVDs include poverty, stress and hereditary factors.

What are common symptoms of cardiovascular diseases?

Symptoms of heart attacks and strokes

Often, there are no symptoms of the underlying disease of the blood vessels. A heart attack or stroke may be the first warning of underlying disease. Symptoms of a heart attack include:

• pain or discomfort in the centre of the chest;
• pain or discomfort in the arms, the left shoulder, elbows, jaw, or back.

In addition the person may experience difficulty in breathing or shortness of breath; feeling sick or vomiting; feeling light-headed or faint; breaking into a cold sweat; and becoming pale. Women are more likely to have shortness of breath, nausea, vomiting, and back or jaw pain.

The most common symptom of a stroke is sudden weakness of the face, arm, or leg, most often on one side of the body. Other symptoms include sudden onset of:

• numbness of the face, arm, or leg, especially on one side of the body;
• confusion, difficulty speaking or understanding speech;
• difficulty seeing with one or both eyes;
• difficulty walking, dizziness, loss of balance or coordination;
• severe headache with no known cause; and
• fainting or unconsciousness.

People experiencing these symptoms should seek medical care immediately.

What is rheumatic heart disease?

Rheumatic heart disease is caused by damage to the heart valves and heart muscle from the inflammation and scarring caused by rheumatic fever. Rheumatic fever is caused by an abnormal response of the body to infection with streptococcal bacteria, which usually begins as a sore throat or tonsillitis in children.

Rheumatic fever mostly affects children in developing countries, especially where poverty is widespread. Globally, about 2% of deaths from cardiovascular diseases is related to rheumatic heart disease.

Symptoms of rheumatic heart disease

• Symptoms of rheumatic heart disease include: shortness of breath, fatigue, irregular heart beats, chest pain and fainting.
• Symptoms of rheumatic fever include: fever, pain and swelling of the joints, nausea, stomach cramps and vomiting.

Published courtesy of WHO