Does red meat increase the risk for heart disease, stroke, or diabetes?

In a nutshell: It depends on the type of red meat.

The Evidence

Micha, R., Wallace, S. K., & Mozaffarian, D. (2010). Red and processed meat consumption and risk of incident coronary heart disease, stroke, and diabetes mellitus: A systematic review and meta-analysis. Circulation, 121, 2271- 2283. DOI: 10.1161/CIRCULATIONAHA.109.924977

What did the meta-analysis look into?

This meta-analysis investigated whether eating red meat (e.g., beef, lamb, pork, game), processed red meat (meat that is smoked, salted, cured and/or added chemical preservatives, such as bacon, salami, hams, sausages), and total red meat (all red and processed meats) increases the risk of Coronary Heart Disease (CHD), stroke, and type 2 diabetes. The meta-analysis synthesized evidence from 20 studies, including a total of 1 218 380 people from the United States, Europe, Asia, and Australia. Of these, 23 889 had CHD, 2280 had had experienced at least one stroke, and 10 797 had type 2 diabetes.

The meta-analysis also investigated whether several factors affected the relationship between the meat consumption and risk of disease, including:

1. Number of meat servings per week (serving sizes were defined as 100 grams for red meat and 50 grams for processed meat)

2. Location of participants (USA, Europe, Asia, Australia)

3. Socio-demographic characteristics of participants (e.g., education, income)

4. Other participant risk-factors for disease or special diets (e.g., current smoking, being overweight, family history of chronic disease, higher calorie intake)

What did the evidence suggest for CHD?

Red meat consumption was not associated with CHD, but each daily serving of processed meat was associated with 42% higher risk of CHD. Consumption of ‘total meat’ was associated with a trend towards higher CHD risk. None of the additional 4 factors played a role for CHD.

What did the evidence suggest for type 2 diabetes?

Red meat consumption was not associated with type 2 diabetes. However, each serving of daily processed meat was associated with 19% higher risk of type 2 diabetes, and the risk was even higher for US participants. Each daily serving of total meat was associated with 12% higher risk of type 2 diabetes.

What did the evidence suggest for stroke?

Red or processed meat consumption was not associated with higher risk for stroke, but each daily serving of ‘total meat’ was associated with 24% higher risk.

The take-home message

Unprocessed red meat consumption does not appear to be associated with higher risk for CHD, stroke, or type 2 diabetes, but processed and ‘total’ meat consumption appears to be associated, especially if the consumption is on a daily basis. The meta-analysis proposed that the high amounts of salt and nitrate (and other chemical) preservatives in processed meats could be the culprits behind the higher risk of CHD, stroke, and type 2 diabetes. Broadly speaking, consumption of red meat appears to be safe, as long as it is not processed and not consumed daily.

Which popular diet is best for weight loss?

In a nutshell: The one you will maintain.

The Evidence

Johnston, B. C., Kanters, S., Bandayrel, K., Wu, P., Naji, F., Siemieniuk, R. A., ... & Jansen, J. P. (2014). Comparison of weight loss among named diet programs in overweight and obese adults: A meta-analysis. JAMA, 312, 923-933. doi:10.1001/jama.2014.10397

What did the meta-analysis look into?

This meta-analysis investigated weight loss on people who followed 3 known (named/ branded) dietary programs, for up to a year. The meta-analysis synthesized evidence from 59 studies, including 7286 overweight and obese adults.

The diets were:

(1) Low carbohydrate diets (Atkins, South Beach, and Zone)

(2) Low in fat diets (Ornish and Rosemary Conley)

(3) Eating “in moderation” (Biggest Loser, Jenny Craig, Nutrisystem, Volumetrics, and Weight Watchers).

Weight loss was measured at 6 months and 12 months of following the diet. The meta-analysis also investigated if the following 3 factors affected the weight-loss, in addition to the diets:

(1) Calorie restriction (<1800 calories per day)

(2) Following a specific exercise programme

(3) Receiving support during the course of the diet (attending group or individual support sessions with health professionals)

The dieters’ weight-loss was compared to that of people who followed no named diet or had received the usual weight-loss advice (“engage in physical activity, keep records of food and calories consumed, eat ‘healthily’, set specific plans, and exercise self-control”).

What did the evidence suggest?

At 6 months, people who followed all 3 known diets lost more weight than those who had followed no known diet, or had followed the ‘usual advice’. Low carbohydrate diets resulted in more weight loss (minus 8.73 kilos), as compared to all other diet programmes, but weight loss from low-fat diets was similar (minus 7.99 kilos).

At 12 months, weight-loss slowed down for all dieters. Both low fat and low carbohydrate diets were superior to “eating in moderation”, to following “usual advice”, or to adhering to a no-known diet. Low carbohydrate eaters lost 7.25 kilos, while low fat eaters lost 7.27 kilos. In addition, exercising was associated with more (but small) weight loss for all dieters throughout the 12 months, while receiving expert support was associated with more weight loss during the first 6 months only. Dieters who also restricted their calorie intake did not lose more weight at any time.

The take-home message

Low carbohydrate and low fat diets appear to be superior to other diets, and equally successful in losing weight over a period of 12 months. Engaging in exercise and receiving support may offer additional (albeit small) weight loss benefits. Therefore, both diets will result in noteworthy weight loss, as long as they are maintained for a minimum of 6 months. Broadly speaking, several diets will result in weight loss, for as long as they are maintained.