A Nutritionist Clarifies Some Common Health Claims

KATHLEEN DAVIS: This is Science Friday. I’m Kathleen Davis. We recently asked you, our listeners, which dubious health claims you’ve been seeing in your social media feeds or being circulated by friends and family. Unsurprisingly, we received a ton of questions about nutrition. So today we’re going to answer some of your nutrition questions with the help of an expert, Jessica Clifford, registered dietitian and nutrition specialist at the Department of Food Science and Human Nutrition at Colorado State University based in Fort Collins. Jessica, welcome to Science Friday.

JESSICA CLIFFORD: Hi. Thank you so much for having me.

KATHLEEN DAVIS: We’re so glad to have you. So let’s get right in to our listener questions. The first one that we have is from Lynne S. She’s based in Syracuse, New York. She asks why are internet comment sections freaking out about seed oils? OK, Jessica, first of all, what is a seed oil?

JESSICA CLIFFORD: Well, seed oils are those oils that are extracted from the seed of a plant, and generally they contain unsaturated fats. Seed oils include oils like canola oil or corn oil, cottonseed oil, soybean oil, sunflower oil, and safflower oil among a few others. That is what a seed oil is.

KATHLEEN DAVIS: And so why are people concerned about these?

JESSICA CLIFFORD: Well, I think the biggest thing that we see across media platforms is that there is some concern about the way that these seed oils are processed, and that is often through the form of heat and the use of a solvent, which is commonly hexane. Now hexane is a toxic compound, but research shows that really there’s a very, very tiny amount in the oils that we’re actually consuming. And so really there’s very little reason for concern with that level of the oil that we’re eating.

When you hear of a compound like hexane, you automatically might think, oh my gosh, this is horrible. Of course, we shouldn’t be consuming it. But it’s really not showing that it’s harmful to our health and the amount that we’re consuming. And, in fact, the benefits that we see from some of the oils because they’re made up of these unsaturated fats can outweigh the risks that come with them as it relates to that hexane compound.

And then another thing I think that draws concern for some people and maybe leads to some of this misinformation related to seed oils is the fact that they contain omega 6 fatty acids, so that might come up in discussions around seed oils. I was just going to say omega 6 fatty acids are known to be– they’re pro-inflammatory. And so these oils do contain these omega 6 fatty acids, but it doesn’t necessarily make them inherently bad.

KATHLEEN DAVIS: OK. So how does canola oil compare to an olive oil, for example, nutritionally.

JESSICA CLIFFORD: So canola oil has unsaturated fats, so monounsaturated fatty acids as well as polyunsaturated fatty acids, which are heart healthy unsaturated fats, and so does olive oil. But the thing that differs with olive oil is that it also contains these other bioactive compounds like phenolic compounds which have anti-inflammatory and antioxidant properties. So there may be some advantage that olive oil has over canola oil or maybe other seed oils, but the seed oils do also have heart healthy fats.

KATHLEEN DAVIS: So, Jessica, give us a verdict. Overall, is seed oil bad for you?

JESSICA CLIFFORD: I would say no. It’s definitely not bad for you. Again, everything should be consumed in moderation. So it’s not like you want to rely solely only on one type of seed oil, but it definitely can be consumed as part of a healthy diet.

KATHLEEN DAVIS: OK. So this next question that we have comes from David K. in West Richland, Washington. He asks I am skeptical about the way all processed foods have been lumped into a single category from cooked mashed potatoes to hyper-processed hot dogs laced with preservative chemicals that I can’t even pronounce. Are all processed foods supposed to be bad for my health?

OK, Jessica, let’s talk about this question. What does it actually mean for a food to be processed versus ultra-processed?

JESSICA CLIFFORD: Yeah, so a processed food– so the definition of just processed food in general is any raw agricultural commodity or food that has been altered from its original state or it’s whole food form. But there are, as you said, these various levels of processing. So you really can’t lump them all together. Even slicing an apple is a form of processing, but we all know that just cutting an apple makes it no less healthy. That’s not going to change the nutrition of an apple.

A food becomes ultra-processed when there are things added like preservatives, flavorings, colors, and other food additives such as added salt, sugars, and fats, particularly for flavor and shelf life. So really you can think of it like a spectrum of processing. So on the left side, you might have that sliced apple and then all the way to the right might be that hot dog or that cellophane packaged cupcake.

KATHLEEN DAVIS: There has been a lot of research into, quote unquote, ultra-processed foods recently. What do we know about their effect on our health?

JESSICA CLIFFORD: Well, research shows that people who eat more processed foods gain weight, maybe more weight and more quickly, and it’s interesting because it’s not just because they’re eating more energy dense foods that are higher in calories but lower in nutrients but also because the way the foods are engineered is actually making people eat more of them. It’s that perfect concoction of sugar, salt, and fat that really makes people want more, and it’s actually triggering something in our brain to making us want to eat more of them. And then research also shows that greater exposure of those ultra-processed foods is associated with increased risk of heart disease related death as well as diabetes among other things.

We want to have a healthy relationship with food, and really all foods can fit into a healthy diet. And so we don’t want to make it about demonizing certain foods and saying you can never eat this food or this is horrible and you should never have this. Because really I think having even some of these ultra processed foods that some people might enjoy once in a while can be OK and can fit as part of a healthy lifestyle and a healthy diet. But I do think from a public health sense that I really do think our food industry could use a little work in terms of providing or making less ultra-processed foods for sure.

KATHLEEN DAVIS: So once in a while, my McDonald’s quarter pounder is OK to eat but in moderation.

JESSICA CLIFFORD: Absolutely. Yeah.

KATHLEEN DAVIS: OK so let’s move on to something that I’ve heard about for quite some time and that is the health benefits of apple cider vinegar. People have attributed this to weight loss, lowering blood sugar, lowering cholesterol. Is there evidence to support these claims?

JESSICA CLIFFORD: Yeah. So this sort of information has been out for such a long time in the media and even in research around this. There is some evidence. I think apple cider vinegar has been touted to have so many benefits, and while I think some are true to some degree, they may not be to the degree that some media or people are saying.

I think first and foremost that the one thing where there’s the most research or the strongest research to support is that apple cider vinegar can help to lower blood glucose levels or A-1C levels, but the effect is minimal. So it’s nothing huge. It’s nothing Earth shattering. If someone has pre-diabetes or diabetes, this should definitely not replace any medications they’re on or other lifestyle changes that would be recommended, but it could be used in addition or in an adjunct to medication and/or healthy eating or exercise.

And then you mentioned weight loss. So there is some research showing that it can help possibly with weight loss as well, but the research doesn’t seem to be as strong as that with its effects on blood glucose. And really with weight loss, it’s so complicated. So it– it’s not necessarily a sustainable solution I think to weight loss, and it definitely wouldn’t be a silver bullet here. It could maybe help a little bit, but it’s not to the degree that’s being presented in the media.

And I do want to say one more thing related to that if that’s OK. With that said, even despite some of these minor benefits, apple cider vinegar is very acidic. So it can cause damage to tooth enamel and your esophagus, so people might experience some sort of upset, stomach upset or acid reflux. So if people do choose to consume this, it should be diluted, or I would recommend that it be diluted with water or added to a tea or maybe a salad dressing as opposed to consuming it directly.

But, again, this should be in conjunction with a healthy diet. You can’t just drink apple cider vinegar and expect to lose weight or reduce your blood glucose.

KATHLEEN DAVIS: But why does it seem that apple cider vinegar specifically has these modest health benefits?

JESSICA CLIFFORD: So apple cider vinegar is made by fermenting apple juice with yeast and bacteria, in particular bacteria– class of bacteria called acetic acid bacteria– to make the vinegar, and so a lot of it from what we can tell in the research is due– I think is due to the effects of that fermentation and how that is impacting– at least related to the blood glucose decrease, it’s affecting the absorption of carbohydrates into the blood or the slowed breakdown of the carbohydrates into sugars in our body. And so I really think a lot of it is attributed to the effects of the fermentation.

KATHLEEN DAVIS: So is it possible that other fermented foods have similar benefits?

JESSICA CLIFFORD: Maybe, yes. I think it really depends on the bacteria present in the fermentation process and the impacts that those specific bacteria or their byproducts have. So it can really vary from product to product depending on what the food is and what the bacteria are that are doing the fermenting and the impacts that those bacteria or their byproducts would have. But, yeah, there could be some of those benefits seen, yes, from other fermented foods.

KATHLEEN DAVIS: Got it. So let’s move on to our next topic. There is a group of fruits and vegetables that people are sometimes suspicious of, and these are nightshades. So these are potatoes, tomatoes, eggplants, and some people incorrectly argue that they cause inflammation. But it’s my understanding that the opposite is actually true. Right?

JESSICA CLIFFORD: Yes. Yeah, that is true. I think, like you said, people believe or claiming that these cause inflammation, and maybe even other health issues have been mentioned as well. Some people may associate this with alkaloids, which is a compound found in these plant foods but in very small amounts though there really is not a large amount of evidence demonstrating that association.

So those experiences are what people are saying that it’s happening here are generally individual experiences and they’re not generalizable, and it’s not based on research that has been seen. There’s really no conclusive scientific evidence to support those claims. And like you said, yep, it’s quite the opposite that these foods can actually– most of them if not all of them– can help fight inflammation and have very many positive health benefits.

KATHLEEN DAVIS: So it’s possible that some people– some individuals are experiencing inflammation when it’s really– that’s their body and that’s their gut versus the entire population?

JESSICA CLIFFORD: Yes, exactly. And so some people do have an intolerance for certain foods that they might relate to something that in truth is really something else. And so in those cases, I would really suggest they meet with a registered dietitian to maybe do an elimination diet or something like that to figure out exactly what it is because it may not be a whole category of foods or the whole family of nightshade plants.

KATHLEEN DAVIS: Right. So every few years, it seems like there’s a whole new fad diet. So first it was low fat back in the ’90s, and more recently we’ve seen Keto and low carb diets. Why does it often feel like what is healthy is constantly changing?

JESSICA CLIFFORD: I really think this has to do with– we always hear this. We’re always like nutrition is so hard to understand because, like you said, it’s always changing. But I think it’s hard for folks to navigate because research is constantly underway, and there are people out there who might hear something about one small research study that was done on one small thing and really blow that out of proportion or misrepresent what is actually being said. And then they may make it seem like things are changing or there are new recommendations when there are, in fact, not.

True recommendations are ones that we as registered dietitians and maybe some other physicians and other health care practitioners might recommend are usually– true recommendations anyway– are usually based on years and years of research that has shown repeated results over time. So I think this idea that it’s constantly changing is really just due to some of this spreading of misinformation because research is constantly underway even though it’s not ready to make a recommendation yet if that makes sense.

KATHLEEN DAVIS: So what is your advice to listeners who come across nutrition information online and they maybe have a gut feeling that it’s not correct and they want to vet it? What do you recommend that people do?

JESSICA CLIFFORD: If you’re looking to make a decision on your own, if you come across some information online, well, I’ve got about five tips that I might recommend. And I think first people should consider who’s offering the information. Who is this coming from, what are their credentials, and what’s their purpose. And even if someone has credentials, I think folks should consider if those individuals or that individual represents a for-profit or if they’re an influencer trying to make money or garner a following. Really think critically about who that is.

Number two, I think folks should think critically about the recommendations that promise a quick fix or provide any dramatic advice. If the claim sounds too good to be true or maybe a little crazy, they probably are.

Number three, think about if this suggestion or this advice is providing lists of black and white lists like good or bad foods or maybe they use the word toxic or they talk about removing foods or even whole food groups from the diet. That’s another red flag for sure.

And number four, folks should determine if their recommendation is based on solid research. And the word solid here is key because if it’s not solid, if it’s based on, for example, a personal or a non-science based testimonial, that can be concerning because that’s not science.

And even if it is based on research, people should be cautious if those recommendations are based on just one single study or research where they’re stating research is currently underway, which really indicates that there’s no current completed research. Any sort of worthy nutrition recommendation should be based on robust and repeated research. And then I just want to say related to that, despite some of this guidance, people may find it hard nonetheless despite these recommendations to wade through and navigate all that information, and in those cases I recommend they meet with a registered dietitian who can help talk through some of the issues or concerns that they have related to any nutrition issue.

KATHLEEN DAVIS: Well, that’s all the time that we have for now. Jessica, thanks so much for taking the time to be on the show.

JESSICA CLIFFORD: Yeah, thank you so much for having me. It’s been a pleasure.

KATHLEEN DAVIS: Jessica Clifford, registered dietitian and nutrition specialist at the Department of Food Science and Human Nutrition at Colorado State University based in Fort Collins.

And we want to hear from you. Is there a piece of health information that you’ve seen recently that makes you skeptical about its accuracy? You can email us or send a voice memo to scifri@sciencefriday.com. You can also leave us a voicemail at 646-767-6532, or you can go to sciencefriday.com/HealthInfo to submit a topic. In the coming weeks, we’ll bring on another expert to help answer your questions.

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