Researchers tested whether swapping red and processed meat for beans and legumes could improve health in men. Over 6 weeks, 102 healthy men either ate their normal amount of red meat or switched to mostly beans while cutting back on meat. The men who ate more beans had better cholesterol levels, weighed less, and had healthier heart markers. However, they needed to be careful about getting enough vitamin B12 and iodine, which are naturally found in meat. This study suggests that eating more plant-based proteins like beans can be a healthy choice, as long as people pay attention to getting all their nutrients.

The Quick Take

  • What they studied: Does replacing red and processed meat with beans and legumes improve heart health and weight in healthy adult men?
  • Who participated: 102 healthy working men with an average age of 38 years (ranging from 21 to 61 years old) with no serious health conditions
  • Key finding: Men who ate mostly beans instead of red meat for 6 weeks had lower cholesterol levels, weighed less, and showed better heart health markers compared to men who kept eating red meat regularly.
  • What it means for you: Swapping some red meat for beans may help improve your heart health and weight. However, if you make this switch, you should ensure you’re getting enough vitamin B12 and iodine from other sources like dairy, eggs, or supplements, since these nutrients are less abundant in plant-based foods.

The Research Details

This was a randomized controlled trial, which is considered one of the strongest types of scientific studies. Researchers divided 102 healthy men into two groups randomly. One group (called the MEAT group) continued eating about 760 grams of red and processed meat per week, which is what many people typically eat. The other group (called the LEGUME group) cut their red meat down to just 200 grams per week and replaced the missing protein with beans, lentils, and other legumes. Both groups aimed to get the same total amount of protein from their food.

The study lasted 6 weeks, which is a relatively short time period. At the beginning and end of the study, researchers collected detailed food records from the men, took blood samples, and collected 24-hour urine samples to measure various nutrients and health markers. This allowed them to see exactly what nutrients each group was eating and how their bodies responded.

This research design is important because it randomly assigns people to different groups, which helps eliminate bias and makes it easier to prove that the diet change—not something else—caused the health improvements. By measuring actual food intake and collecting biological samples, the researchers could see real changes in nutrients and health markers rather than just relying on what people remember eating.

This study has several strengths: it’s a randomized controlled trial (the gold standard for nutrition research), it included a reasonable number of participants, and it measured multiple health markers. However, the study only lasted 6 weeks, which is relatively short for seeing long-term health effects. The study also only included healthy men, so the results may not apply to women, older adults, or people with existing health conditions. Additionally, the study didn’t track whether men actually stuck to the diet plan perfectly.

What the Results Show

Men in the LEGUME group who ate mostly beans instead of red meat showed significant improvements in several important health markers. Their total cholesterol and LDL cholesterol (the “bad” cholesterol) both decreased noticeably compared to the MEAT group. They also weighed less and had lower BMI (body mass index, a measure of healthy weight), even though both groups ate the same total amount of calories and protein.

The LEGUME group also ate more fiber, healthier types of fat (polyunsaturated fats), and iron compared to the MEAT group. They ate less saturated fat, which is the type of fat linked to heart disease. These dietary changes happened naturally because beans contain more fiber and healthier fats than red meat.

However, the LEGUME group had some nutritional challenges. They had lower levels of vitamin B12 in their blood, which is important for nerve function and energy. They also had lower iodine levels, which is crucial for thyroid health. These differences occurred because red and processed meat contain more of these nutrients than beans do.

Beyond the main findings, the study showed that the LEGUME group maintained adequate nutrition in most areas despite eating less meat. Their iron intake was actually higher, which is important because many people worry about getting enough iron on a plant-based diet. The study also showed that the dietary shift was sustainable for 6 weeks, suggesting that people could realistically make this change in their eating habits.

This study supports previous research suggesting that eating more plant-based proteins and less red meat is associated with better heart health. The findings align with major health organizations’ recommendations to reduce red and processed meat consumption. However, this study adds important new information by showing that even a moderate reduction in meat (not complete elimination) combined with legume consumption can produce measurable health benefits in just 6 weeks. The vitamin B12 and iodine findings confirm what other research has shown: people who reduce meat intake need to be intentional about getting these nutrients from other sources.

This study has several important limitations to consider. First, 6 weeks is a short time period, so we don’t know if these benefits would continue or increase over months or years. Second, the study only included healthy men between ages 21-61, so the results may not apply to women, children, older adults, or people with existing health conditions like diabetes or heart disease. Third, the study relied on men to accurately report what they ate, which can be unreliable. Fourth, we don’t know if the men actually followed the diet plan perfectly or if some cheated. Finally, the study didn’t measure other important factors like exercise or stress, which could have affected the results.

The Bottom Line

Based on this research, eating more beans and legumes while reducing red and processed meat appears to be a healthy dietary choice for adult men. The evidence is moderately strong for improving cholesterol levels and weight management. However, if you make this dietary change, you should: (1) ensure you’re getting enough vitamin B12 from sources like dairy products, eggs, fortified plant-based milks, or supplements; (2) include iodine-containing foods like seaweed, dairy, or eggs; and (3) consider consulting with a healthcare provider or registered dietitian to ensure you’re meeting all your nutritional needs. Confidence level: Moderate (based on a single 6-week study in healthy men).

This research is most relevant to healthy adult men looking to improve their heart health and manage their weight. It may also apply to women and younger adults, though the study didn’t specifically test these groups. People with existing heart disease, diabetes, or nutritional deficiencies should talk to their doctor before making major dietary changes. Vegetarians and vegans may find this research less relevant since they’ve already eliminated or reduced meat. Older adults and people with certain health conditions should consult healthcare providers before changing their diet significantly.

Based on this study, you might see improvements in cholesterol levels and weight within 6 weeks of making this dietary change. However, these are relatively short-term results. For long-term benefits and to ensure the changes stick, you’d want to maintain this eating pattern for several months or longer. Don’t expect dramatic weight loss—the study showed modest but meaningful improvements. It typically takes 2-4 weeks to adjust to eating more beans and fewer meat products.

Want to Apply This Research?

  • Track your weekly red and processed meat consumption in grams, aiming to reduce from 760g to 200g per week while replacing it with legumes (beans, lentils, chickpeas). Also track your vitamin B12 and iodine intake through food sources or supplements.
  • Start by replacing one or two red meat meals per week with legume-based meals (bean chili, lentil soup, chickpea curry). Gradually increase to replacing 3-4 meals per week. Use the app to log these meals and track your progress toward the target of 200g red meat per week.
  • Weekly tracking of meat consumption and legume intake; monthly check-ins on energy levels and digestion; quarterly assessment of weight and how clothes fit; annual blood work to monitor cholesterol, B12, and iodine levels with your healthcare provider.

This research describes findings from a 6-week study in healthy adult men and should not be considered medical advice. Before making significant dietary changes, especially if you have existing health conditions, take medications, or have nutritional concerns, consult with your healthcare provider or a registered dietitian. This study does not replace professional medical guidance. If you experience any adverse health effects after changing your diet, contact your healthcare provider immediately. Vitamin B12 and iodine deficiencies can have serious health consequences, so supplementation or medical monitoring may be necessary when reducing meat intake.