Recent headlines and a new study seem to suggest that we’ve overturned nutrition science and eating recommendations once again — this time around red and processed meat consumption. If it feels like we can’t make up our minds about how to eat well, it’s because we’ve been here before. There are many examples, but probably few as extreme as butter and eggs, which have been through the same back and forth. But before you reach for the red and processed meat, butter and eggs, let’s take a look at why nutrition science keeps getting turned on its head, and what you need to know about these standard American diet staples.

What’s the deal with red and processed meat?

To meat or not to meat? In a new analysis of previously published research, study authors suggest there’s no need to cut back on red or processed meat. However, this report isn’t based on new science or information. The team of researchers argue that previous research is weak, and that since people enjoy red and processed meat, they’d find it difficult to stop eating it. Therefore, they conclude: Don’t bother trying. Instead, they suggest eating red and processed meat in the amount you’re currently eating.

This conclusion has been massively refuted by other health authorities and organizations, including the Harvard School of Public Health and the American Institute for Cancer Research. In essence, it’s total bologna! Nutrition is an imperfect science because much of what we know comes from a type of study known as an observational study. To help you understand why these (and other diet-related) studies seem so conflicting, I’m going to break down some research basics. Stick with me! We’ll get to the bottom of all of this!

The most well-regarded diet-related observational studies are conducted by following people (often hundreds of thousands of them) over an extended period of time (often decades), collecting dietary recalls every so often, and then determining who develops health problems. From there, researchers can see if there’s a link between a certain dietary pattern (say, high in red meat) and a disease (say, heart disease). But these studies aren’t meant to prove any cause and effect (for example, that red meat causes heart disease). They’re only looking at trends — for instance, that people with diets especially high in red meat are more likely to experience heart disease compared with non-meat eaters. (Note, I’m not citing any study specifics here, but using these examples for illustration purposes.)

Another form of observational study matches people with the disease (let’s stick with heart disease) to a similar set of people who are healthy. They might look back, asking study participants questions about their diet or other lifestyle factors to see if any trends emerge. This type of data points us in the right direction, but there are obvious issues with asking people to recall how often they typically ate something or participated in another behavior in the past. Still, these studies help scientists connect the dots between a potential behavior (let’s go with eating red meat again) and a health phenomenon.

A more rigorous study is called a randomized clinical trial. This type of research design is considered the gold standard because it can prove one thing causes another thing. Though it’s a great way to study certain scientific questions, it’s not necessarily the most practical way to address the link between diet and disease since diseases may take years upon years to surface and these studies involve a more controlled (and therefore, costly) set up. That’s why it’s common — though not perfect—to use observational studies to inform us about diet and health.

So in essence, what this new report says is that observational studies don’t give us strong enough evidence to suggest that people who enjoy eating meat should stop eating it. However, when multiple observational studies make the same links, it strengthens the case. And we do have many studies along these lines suggesting that red and processed meats are associated with health problems. Also, we can’t ignore the science on other dietary patterns, like the Mediterranean Diet, which is limited in red and processed meat in favor of a more plant-based eating pattern with smaller amounts of animal protein. Studies consistently link this eating pattern with health benefits, which are important to consider when assessing the big picture and making health recommendations.

Bottom line: There’s nothing new to report here, other than the fact that this new analysis opened up Pandora’s box (and created a lot of confusion) by interpreting the previously reported and well-established data another way. Experts and health organizations are aligned on this: It’s still a smart idea to reduce your red meat intake and really curtail your processed meat consumption in order to reduce your risk of cancer, heart disease and type 2 diabetes.

What about eggs? Are they good or bad?

Based on what we currently know about eggs, most healthy people can safely consume up to seven eggs per week, be it a three-egg omelet twice a week or a hard boiled egg every day. The concern with eggs stems from the fact that they’re high in cholesterol and there’s a link between high blood cholesterol and heart disease. However, over time, we’ve learned that the cholesterol from food sources doesn’t impact the cholesterol in your blood. So in 2015, the U.S. Dietary Guidelines noted that current evidence doesn’t support concerns with cholesterol coming from dietary sources, such as eggs. At that time, the U.S. Dietary Guidelines stopped recommending cholesterol limits.

A recent study gave rise to questions about this direction. This type of study, known as a meta-analysis, pooled data from previous studies in order to get a potentially broader picture of risk. Pooled data can strengthen our understanding of certain things, but in this case, there were flaws in how egg consumption was assessed. The studies from which the data was pooled used a single food recall to determine egg consumption, which I mentioned earlier is problematic for obvious reasons. Though food recall is an important tool to help scientists on their fact-finding mission, it’s not the most conclusive tool. Plus, while this study looked at other sources of cholesterol and saturated fat in the diet, along with other lifestyle factors (like exercise patterns) that might contribute to someone’s heart disease risk, it didn’t account for these factors in a meaningful way.

Bottom line: How you eat your eggs matters as much as how often and how many you’re eating. To protect your heart and lower the risk of other serious health concerns, rethink common sides, like bacon, sausages and white toast. Instead, focus on heart-healthy accompaniments, like sliced avocado, salsa, black beans, whole grain toast, roasted sweet potatoes and sautéed greens. If you want to bolster egg-based dishes without going over the seven-egg-per-week cutoff, use a mix of egg whites with whole eggs since it’s the yolk that contains all of the cholesterol (though it also contains most of the other nutrients as well).

Is butter back?

Not necessarily, but it’s probably not as harmful as we once thought. The concern with butter comes from the fact that it’s high in saturated fat, which was thought to raise blood cholesterol levels and therefore, increase your risk of cardiovascular disease. But we now know that the story behind saturated fat is more complex. Some sources, like red meat, are still suspect (though health risk may also be related to other compounds in red meat) whereas other sources (like full fat dairy products) are now considered less risky.

That said, while butter may not raise your risk of health problems in and of itself, it doesn’t appear to lower your risk, either. But other fats, like avocado oil and extra virgin olive oil have been found to be health protective so your overall diet should emphasize these types of plant-based fats.

Bottom line: If you want to spread a little butter on your whole grain toast and are otherwise eating wholesome foods and healthy fats, it’s probably fine. But make avocado and extra-virgin olive oil your go-to cooking oils and emphasize other healthier fats (such as nuts and seeds and their butters) in meals and snacks.

The final word

Here’s what we’ve covered: Nutrition is an imperfect science and there’s some discomfort in that. Because of the way we study diet patterns and health phenomena, we might not get the most conclusive info. But we can gather a lot of evidence that points us in a solid direction. Just about all of that evidence tells us that your overall dietary pattern matters more than one thing (like butter or red meat) on your plate. The dietary pattern that’s consistently linked with the best health outcomes — longer, healthier lives with limited pain and illness, and fewer memory problems — is one that’s rich in plant foods. Those are foods, like vegetables, fruits, pulses (the umbrella term for beans, legumes and lentils), whole grains (like oats, bulgur, quinoa and brown rice), and healthy fats from plant sources, like nuts, seeds, avocados and olives (as well as all of their butters and oils).

In addition to what you’re emphasizing, it’s important to think about what foods to limit and what swaps you’re making to replace those gaps in your diet. A healthy eating pattern is low in red meat and very low in processed meat, and it contains few refined grains, heavily processed snack foods, and foods with added sugars. That means swapping your steak for pizza or fried chicken with French fries isn’t a trade up.

However, if your plate contains generous portions of veggies and you’re routinely consuming wholesome plant-based foods and fats, a weekly lean steak dinner along with a baked potato with a pat of butter can be OK.

MORE FROM SAMANTHA CASSETTY, RD

Want more tips like these? NBC News BETTER is obsessed with finding easier, healthier and smarter ways to live. Sign up for our newsletter and follow us on Facebook, Twitter and Instagram.