Scientists studied 102 healthy men for 6 weeks to see what happens when they eat more beans and lentils instead of red meat and processed meats like bacon. The men who ate more legumes (beans, lentils, chickpeas) and less red meat lost weight, had better cholesterol levels, and improved heart health markers. However, they had slightly lower levels of vitamin B12 and iodine. This study suggests that swapping some of your weekly red meat for beans could be good for your heart and waistline, but you might need to pay attention to getting enough B12.

The Quick Take

  • What they studied: Whether replacing some red meat and processed meat with beans, lentils, and chickpeas affects health markers in healthy men
  • Who participated: 102 healthy working men, average age 38, ranging from 21 to 61 years old
  • Key finding: Men who ate more legumes and less red meat lost weight and had better cholesterol levels after 6 weeks
  • What it means for you: Swapping some of your weekly red meat for beans may help your heart health and weight, but monitor your B12 levels

The Research Details

This was a randomized controlled trial, which is considered the gold standard for nutrition research. The scientists randomly divided 102 healthy men into two groups for 6 weeks. One group continued eating their normal amount of red and processed meat (about 760 grams per week, which is like having a burger every day). The other group cut way back on red meat to just 200 grams per week and replaced the rest with legume-based foods like beans, lentils, and chickpeas. The researchers tracked what the men ate using detailed food diaries and measured various health markers through blood and urine tests at the beginning and end of the study.

This type of controlled study design is important because it can show cause and effect, not just associations. By randomly assigning people to different diets and controlling other factors, researchers can be more confident that any changes they see are actually due to the dietary changes, not other lifestyle factors.

This study has several strengths: it’s a randomized controlled trial, it measured objective biomarkers (not just self-reported outcomes), and it was registered in advance. However, 6 weeks is relatively short for seeing long-term health effects, and the study only included healthy men, so results may not apply to women or people with health conditions.

What the Results Show

The men who ate more legumes and less red meat showed several positive changes after 6 weeks. Their total cholesterol dropped significantly, as did their ‘bad’ LDL cholesterol levels. They also lost weight and had a lower BMI compared to the meat-eating group. The legume group ate more fiber, which is good for digestive and heart health, and more healthy polyunsaturated fats. They also consumed less saturated fat, which is linked to heart disease risk. Interestingly, despite eating less meat, their iron intake was actually higher, likely because legumes are rich in iron.

The legume group had some nutritional trade-offs. Their vitamin B12 levels dropped slightly, which makes sense since B12 is mainly found in animal products. Their iodine levels also decreased somewhat. However, both nutrients remained within healthy ranges during the short study period. The researchers noted that all participants maintained adequate nutritional status for these key nutrients.

These findings align with previous research showing that plant-based proteins can improve heart health markers. The cholesterol improvements are consistent with decades of research on legumes and heart health. The weight loss effect has been seen in other studies comparing plant proteins to animal proteins, possibly due to the higher fiber content and different protein structure in legumes.

This study only lasted 6 weeks, so we don’t know about long-term effects. It only included healthy men, so results might be different for women, older adults, or people with health conditions. The study was also conducted in a controlled research setting, so it’s unclear how well these results would translate to real-world eating patterns over longer periods.

The Bottom Line

Based on this research, healthy adults may benefit from replacing some of their weekly red and processed meat with legumes like beans, lentils, and chickpeas. The study suggests aiming for about 3-4 servings of legumes per week while reducing red meat to 1-2 small servings. However, if you make this change long-term, consider monitoring your B12 levels and possibly taking a supplement.

This research is most relevant for healthy adults who currently eat a lot of red and processed meat and want to improve their heart health or lose weight. People with existing heart conditions should consult their doctor before making major dietary changes. Those already following vegetarian or plant-based diets may not see additional benefits.

The positive effects on cholesterol and weight were seen within 6 weeks, suggesting benefits may appear relatively quickly. However, for lasting heart health benefits, this would likely need to be a permanent dietary change rather than a short-term experiment.

Want to Apply This Research?

  • Track weekly servings of red/processed meat (aim for 2-3 servings max) and legume servings (aim for 4-5 servings) to monitor your protein source balance
  • Start by replacing one red meat meal per week with a legume-based meal, such as swapping a beef burger for a black bean burger or having lentil soup instead of a deli sandwich
  • Monitor weight changes, energy levels, and digestive comfort weekly while making this transition, and consider annual B12 level checks if maintaining long-term

This information is for educational purposes only and should not replace professional medical advice. Consult with a healthcare provider before making significant dietary changes, especially if you have existing health conditions or take medications.