Tag: red meat

Categories : Metabolic DisordersTags :

Strong Link Between Haem Iron in Red Meat and Type 2 Diabetes Risk

On By ModernMedia
Photo by Jose Ignacio Pompe on Unsplash

Higher intake of haem iron, the type found in red meat and other animal products – as opposed to non-haem iron, found mostly in plant-based foods – was associated with a higher risk of developing type 2 diabetes (T2D) in a new study published in Nature Metabolism. While the link between haem iron and T2D has been reported previously, the findings from this study, which was led by Harvard T.H. Chan School of Public Health, more clearly establish and explain the link.

“Compared to prior studies that relied solely on epidemiological data, we integrated multiple layers of information, including epidemiological data, conventional metabolic biomarkers, and cutting-edge metabolomics,” said lead author Fenglei Wang, research associate in the Department of Nutrition. “This allowed us to achieve a more comprehensive understanding of the association between iron intake and T2D risk, as well as potential metabolic pathways underlying this association.”

The researchers assessed the link between iron and T2D using 36 years of dietary reports from 206 615 adults (79% female) enrolled in the Nurses’ Health Studies I and II and the Health Professionals Follow-up Study. They examined participants’ intake of various forms of iron – total, haem, non-haem, dietary (from foods), and supplemental (from supplements) – and their T2D status, controlling for other health and lifestyle factors.

The researchers also analysed the biological mechanisms underpinning haem iron’s relationship to T2D among smaller subsets of the participants. They looked at 37 544 participants’ plasma metabolic biomarkers, including those related to insulin levels, blood sugar, blood lipids, inflammation, and two biomarkers of iron metabolism. They then looked at 9024 participants’ metabolomic profiles – plasma levels of small-molecule metabolites.

The study found a significant association between higher haem iron intake and T2D risk. Participants in the highest intake group had a 26% higher risk of developing T2D than those in the lowest intake group. In addition, the researchers found that haem iron accounted for more than half of the T2D risk associated with unprocessed red meat and a moderate proportion of the risk for several T2D-related dietary patterns. In line with previous studies, the researchers found no significant associations between intakes of non-haem iron from diet or supplements and risk of T2D.

The study also found that higher haem iron intake was associated with blood metabolic biomarkers associated with T2D. A higher haem iron intake was associated with higher levels of biomarkers such as C-peptide, triglycerides, C-reactive protein, leptin, and markers of iron overload, as well as lower levels of beneficial biomarkers like HDL cholesterol and adiponectin.

The researchers also identified a dozen blood metabolites – including L-valine, L-lysine, uric acid, and several lipid metabolites – that may play a role in the link between haem iron intake and TD2 risk. These metabolites have been previously associated with risk of T2D.

On a population level, the study findings carry important implications for dietary guidelines and public health strategies to reduce rates of diabetes, according to the researchers. In particular, the findings raise concerns about the addition of heme to plant-based meat alternatives to enhance their meaty flavor and appearance. These products are gaining in popularity, but health effects warrant further investigation.

“This study underscores the importance of healthy dietary choices in diabetes prevention,” said corresponding author Frank Hu, Fredrick J. Stare Professor of Nutrition and Epidemiology. “Reducing haem iron intake, particularly from red meat, and adopting a more plant-based diet can be effective strategies in lowering diabetes risk.”

The researchers noted that the study had several limitations, including the potential for incomplete accounting for confounders and measurement errors in the epidemiological data. In addition, the findings – based on a study population that was mostly white – need to be replicated in other racial and ethnic groups.

Source: Harvard T.H. Chan School of Public Health

Categories : Diet and Nutrition Metabolic DisordersTags :

Red Meat Consumption Linked to Increased Type 2 Diabetes Risk

On By ModernMedia

“Meat’s back off the menu, boys”

Photo by Jose Ignacio Pompe on Unsplash

People who eat just two servings of red meat per week may have an increased risk of developing type 2 diabetes compared to people who eat fewer servings, and the risk increases with greater consumption, according to a new study in The American Journal of Clinical Nutrition. However, substituting plant or diary protein for red meat was associated with reduced risk of type 2 diabetes.

“Our findings strongly support dietary guidelines that recommend limiting the consumption of red meat, and this applies to both processed and unprocessed red meat,” said first author Xiao Gu, postdoctoral research fellow in the Department of Nutrition at Harvard T.H. Chan School of Public Health.

While previous studies have found a link between red meat consumption and type 2 diabetes risk, this study, which analysed a large number of type 2 diabetes cases among participants being followed for an extended period of years, adds a greater level of certainty about the association.

Type 2 diabetes rates are increasing rapidly in the US and worldwide. This is concerning not only because the disease is a serious burden, but it also is a major risk factor for cardiovascular and kidney disease, cancer, and dementia.

For this study, the researchers analysed health data from 216 695 participants from the Nurses’ Health Study (NHS), NHS II, and Health Professionals Follow-up Study (HPFS). Diet was assessed with food frequency questionnaires every two to four years, for up to 36 years. During this time, more than 22 000 participants developed type 2 diabetes.

The researchers found that consumption of red meat, including processed and unprocessed red meat, was strongly associated with increased risk of type 2 diabetes. Participants who ate the most red meat had a 62% higher risk of developing type 2 diabetes compared to those who ate the least. Every additional daily serving of processed red meat was associated with a 46% greater risk of developing type 2 diabetes and every additional daily serving of unprocessed red meat was associated with a 24% greater risk.

The researchers also estimated the potential effects of substituting one daily serving of red meat for another protein source. They found that substituting a serving of nuts and legumes was associated with a 30% lower risk of type 2 diabetes, and substituting a serving of dairy products was associated with a 22% lower risk.

“Given our findings and previous work by others, a limit of about one serving per week of red meat would be reasonable for people wishing to optimise their health and wellbeing,” said senior author Walter Willett, professor of epidemiology and nutrition.

In addition to health benefits, swapping red meat for healthy plant protein sources would help reduce greenhouse gas emissions and climate change, and provide other environmental benefits, according to the researchers.

Source: Harvard T.H. Chan School of Public Health

Categories : Cardiovascular Disease Diet and NutritionTags :

Steaks are OK? Global Study Challenges Current Advice on High-fat Diets

On By ModernMedia
Photo by Jose Ignacio Pompe on Unsplash

In a study conducted across 80 countries, researchers found that unprocessed red meat and whole grains can be included or left out of a healthy diet. Published in the European Heart Journal, the findings showed that diets emphasising fruit, vegetables, dairy (mainly whole-fat), nuts, legumes and fish were linked with a lower risk of cardiovascular disease (CVD) and premature death in all world regions. The addition of unprocessed red meat or whole grains had little impact on outcomes.

“Low-fat foods have taken centre stage with the public, food industry and policymakers, with nutrition labels focused on reducing fat and saturated fat,” said study author Dr Andrew Mente of the Population Health Research Institute, McMaster University, Hamilton, Canada. “Our findings suggest that the priority should be increasing protective foods such as nuts (often avoided as too energy dense), fish and dairy, rather than restricting dairy (especially whole-fat) to very low amounts. Our results show that up to two servings a day of dairy, mainly whole-fat, can be included in a healthy diet. This is in keeping with modern nutrition science showing that dairy, particularly whole-fat, may protect against high blood pressure and metabolic syndrome.”

The study examined the relationships between a new diet score and health outcomes in a global population. A healthy diet score was created based on six foods that have each been linked with longevity. The PURE diet included 2-3 servings of fruit per day, 2-3 servings of vegetables per day, 3-4 servings of legumes per week, 7 servings of nuts per week, 2-3 servings of fish per week, and 14 servings of dairy products (mainly whole fat but not including butter or whipped cream) per week. A score of 1 (healthy) was assigned for intake above the median in the group and a score of 0 (unhealthy) for intake at or below the median, for a total of 0 to 6. Dr Mente explained: “Participants in the top 50% of the population – an achievable level – on each of the six food components attained the maximum diet score of six.”

Associations of the score with mortality, myocardial infarction, stroke and total CVD (including fatal CVD and non-fatal myocardial infarction, stroke and heart failure) were tested in the PURE study which included 147 642 people from the general population in 21 countries. The analyses were adjusted for factors that could influence the relationships such as age, sex, waist-to-hip ratio, education level, income, urban or rural location, physical activity, smoking status, diabetes, use of statins or high blood pressure medications, and total energy intake.

The average diet score was 2.95. During a median follow-up of 9.3 years, there were 15 707 deaths and 40 764 cardiovascular events. Compared with the least healthy diet (score of 1 or less), the healthiest diet (score of 5 or more) was linked with a 30% lower risk of death, 18% lower likelihood of CVD, 14% lower risk of myocardial infarction and 19% lower risk of stroke. Associations between the healthy diet score and outcomes were confirmed in five independent studies including a total of 96 955 patients with CVD in 70 countries.

Dr Mente said: “This was by far the most diverse study of nutrition and health outcomes in the world and the only one with sufficient representation from high-, middle- and low-income countries. The connection between the PURE diet and health outcomes was found in generally healthy people, patients with CVD, patients with diabetes, and across economies.”

“The associations were strongest in areas with the poorest quality diet, including South Asia, China and Africa, where calorie intake was low and dominated by refined carbohydrates. This suggests that a large proportion of deaths and CVD in adults around the world may be due to undernutrition, that is, low intakes of energy and protective foods, rather than overnutrition. This challenges current beliefs,” said Professor Salim Yusuf, senior author and principal investigator of PURE.

In an accompanying editorial, Dr Dariush Mozaffarian of the Friedman School of Nutrition Science and Policy, Tufts University, USA, stated: “The new results in PURE, in combination with prior reports, call for a re-evaluation of unrelenting guidelines to avoid whole-fat dairy products. Investigations such as the one by Mente and colleagues remind us of the continuing and devastating rise in diet-related chronic diseases globally, and of the power of protective foods to help address these burdens. It is time for national nutrition guidelines, private sector innovations, government tax policy and agricultural incentives, food procurement policies, labelling and other regulatory priorities, and food-based healthcare interventions to catch up to the science. Millions of lives depend on it.”

Source: European Society of Cardiology

Categories : Cardiovascular DiseaseTags :

Gut Microbes Could Explain Some of Red Meat’s Added Cardiovascular Risk

On By ModernMedia
Photo by José Ignacio Pompé on Unsplash

Part of the higher risk of cardiovascular disease associated with red meat consumption could be from metabolites produced by gut microbes, suggests new research published in Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB).

“Most of the focus on red meat intake and health has been around dietary saturated fat and blood cholesterol levels,” said co-lead author of the study Meng Wang, PhD. “Based on our findings, novel interventions may be helpful to target the interactions between red meat and the gut microbiome to help us find ways to reduce cardiovascular risk.”

Previous research has found that certain metabolites are associated with a greater risk of cardiovascular disease. One of these is trimethylamine N-oxide (TMAO), which is produced by gut bacteria to digest red meat that contains high amounts of the chemical L-carnitine.

High blood levels of TMAO in humans may be linked to increased risks of CVD, chronic kidney disease and Type 2 diabetes. However, whether TMAO and L-carnitine-derived metabolites was linked to cardiovascular disease and to what extent, are still unknown.

To find out, the study researchers measured levels of the metabolites in blood samples. They also examined whether blood sugar, inflammation, blood pressure and blood cholesterol may account for the elevated cardiovascular risk associated with red meat consumption.

Study participants included nearly 4000 of the 5888 adults initially recruited from 1989 to 1990 for the Cardiovascular Health Study (CHS). The participants selected for the current study were free of clinical cardiovascular disease at time of enrolment in the CHS, an observational study of risk factors for cardiovascular disease in adults aged 65 or older. The CHS follows 5 888 participants, whose average age at enrolment was 73; nearly two-thirds were female and 88% of participants self-identified as white. The median follow-up time for participants was 12.5 years, and up to 26 years in some cases.  At follow-up appointment, participants’ medical history, lifestyle, health conditions and sociodemographic characteristics were assessed.

Several blood biomarkers were measured at the start of the study and again in 1996–1997. The fasting blood samples stored frozen at -80°C were tested for levels of several gut-microbiome linked to red meat consumption including TMAO, gamma-butyrobetaine and crotonobetaine.

Additionally, all study participants answered two validated food-frequency questionnaires about their usual dietary habits, including intake of red meat, processed meat, fish, poultry and eggs, at the start of the study and again from 1995 to 1996. For the first questionnaire, participants indicated how often, on average in the previous 12 months, they had eaten given amounts of various foods, ranging from “never” to “almost every day or at least five times per week,” based on medium portion sizes, which varied based on the food source. The second questionnaire used a ten-category frequency of average intake over the past 12 months, ranging from “never or less than once per month” to “six+ servings per day,” with defined standard portion sizes.

For the current analyses, the researchers compared the risk of cardiovascular disease among participants who ate different amounts of animal source foods (ie, red meat, processed meat, fish, chicken and eggs). They found that eating more meat, especially red meat and processed meat, was linked to a higher risk of atherosclerotic cardiovascular disease, an increased risk of 22% for 1.1 serving per day.

The increase in TMAO and related metabolites explained roughly one-tenth of this elevated risk, the authors said. They also noted that blood sugar and general inflammation pathways may help explain the links between red meat intake and cardiovascular disease. Blood sugar and inflammation also appear to be more important in linking red meat intake and cardiovascular disease than pathways related to blood cholesterol or blood pressure. Intake of fish, poultry and eggs were not significantly linked to higher risk of cardiovascular disease.

“Research efforts are needed to better understand the potential health effects of L-carnitine and other substances in red meat such as heme iron, which has been associated with Type 2 diabetes, rather than just focusing on saturated fat,” Dr Wang said. 

Source: American Heart Association