What's the most important thing people should know about this study as it relates to their health?
If the goal is to lower levels of low density lipoprotein (LDL) cholesterol, the "bad" cholesterol associated with heart disease, the saturated fat content of the food appears to be more important than whether the meat is primarily white or red.
However, eating a plant-based protein diet (primarily beans, nuts, grains, and soy products) with no meat appears to be better for cholesterol levels.
This study does not apply to all the health effects of red and white meat, which are more complicated than just the effect on cholesterol levels.
What was this study seeking to determine? Has this been done before?
The essential question was whether the saturated fat content of the diet is more important than the color of the meat in determining blood cholesterol levels.
The goal was to see if cholesterol levels would change significantly when comparing diets using red meat, white meat, or no meat (plant-based protein) sources. LDL cholesterol and a fat-carrying protein called apolipoprotein B (apoB) were the most important lab measures used in this study.
There have been studied comparing red meat, white meat, and plant-based proteins in the past, but they have been primarily long-term studies observing people and what they eat, then following up for many years to see what happens to them. These uncontrolled studies can be helpful but are not always accurate when trying to sort out true connections of eating habits and health outcomes.
This new study was a controlled, short-term experiment in which most food was provided to participants, preventing undesirable variables from interfering as much with the results. It should be noted that lean meats and dairy products were used in this study.
What were the results?
The trial revealed that LDL cholesterol and apoB were higher with white and red meat protein than with plant-based protein. This was true both when saturated fat intake was high and when it was low.
In both meat groups, the saturated fat level was more important than the color of the meat, with a high saturated fat diet causing greater increases of LDL cholesterol than a low saturated fat diet.
High saturated fat intakes increased LDL cholesterol and apoB compared with low saturated fat intakes, and this was true with red meat, white meat, and plant-based protein diets.
Did the study reveal any differences concerning subgroups? Did they examine sex as a biological variable?
Women were well represented in this study – there were actually more women than men. No subgroup differences were reported here, but may be reported in future studies.
What were the strengths and shortcomings of this study's design and execution?
Strengths include that this was a randomized controlled trial, where there is more precision and control of what participants are actually eating and doing. Here the primary food was provided to participants.
Shortcomings include that the trial was relatively short, that the saturated fat content of the food came primarily from lean meats and dairy products, and that the study didn't include very high fat meats or fish.
In general, nutrition studies are very difficult to conduct because it is challenging to control all variables related to eating, exercise, and other medical problems and medications in the usual lives of participants.
What, if anything, should people and health care professionals do differently in the face of these findings? What are the challenges to addressing this issue?
This study supports the current American Heart Association and U.S. Department of Agriculture recommendations that emphasize increasing plant food consumption and reducing meat intake.
The saturated fat content of the diet appears to be more important than whether meat is red or white, and some attention to that is recommended. When cutting back on higher saturated fat foods, like meat and butter, it is recommended to replace them with fish, beans, nuts, plants, and plant oils instead of refined carbohydrates, such as white bread, white rice, pizza dough, and pastries.
There are lower saturated fat red meats available that might be better choices, especially in reasonable portions, such as sirloin versus ribeye steak.
The current recommendation to keep saturated fat intake at around 5-6% of total calorie intake is still reasonable for many people. This would be around 120 calories of a 2,000 calorie daily diet, which would be around 13 grams of saturated fat.
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Answers to your questions on timely topics in cardiac care to help make sense of research reports in the media. The series includes questions on your heart and the effect of medications, exercise, diet, and hormones.
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The information provided here may help you make more informed choices. However, it is not a substitute for an individualized medical opinion or diagnosis, and everyone should always consult with their personal physicians to make decisions about their condition or treatment.