Welcome to Paging Dr. Gupta. Thank you so much for tuning in. I've got to say, I've come to think of this podcast as less of a formal program and more like office hours. Office hours where I just get to hear from you and I love it. I get to answer your questions, big and small. And believe me when I say, I really like hearing what's on your mind. It's great feedback for me. Recently, we got a big piece of news about the FDA's banning or plan to ban of certain artificial food dyes, and that has left folks with a lot of questions. Here's my producer, Sofía.

'That's right, Sanjay. Due to health concerns, the FDA announced its plans to phase out the use of petroleum-based dyes in the US food supply. Now, we got a lot of questions about this topic, including from Lisa. She's from Wyoming, and Lisa would like to know what will replace these dyes.

'All right, Sofía and Lisa, thank you for that question. First of all, yes, I think the best language is to say that the FDA has announced plans to phase out the use of petroleum-based dyes in the U.S. Food supply. This is not an outright ban. We will see if this happens. Right now, it's more like a series of discussions with food manufacturers, but I think there's a lot of broad support for slowly getting rid of these dyes. Keep in mind, as I tell you about them, they really have no nutritional value whatsoever. These dyes exist for aesthetic reasons. I'll tell you why. So before we get to the substitutes, I wanna make sure everyone understands what a petroleum-based dye actually is. They are what they sound like. They are synthetic colors that use petroleum to enhance, achieve, and stabilize those really bright colors that you see. Petroleum and petrochemicals are generally stable chemicals. That means if you color something with this type of chemical, it's likely to last a long time. Now these dyes show up almost exclusively in ultra-processed foods. And again, one clue is that these are colors that don't typically occur in nature. So if a company wants to use a fun color that's gonna keep pigment around for a long period of time, it is quite likely they are gonna choose one of these petroleum-based dyes. Red cherries, for example, on the top of your sundae, that's probably red dye number three. Incidentally, red dye three has been around a long time and the previous administration, the Biden administration, started a phase out in January of this year. Cheese puff dust on your fingers. That's probably yellow dye number six. You get the idea. There's about eight or nine of these dyes out there and many of them have been around for a long time, 30 years even. So what's the problem? Well, the concern is that some of the dyes have been shown to raise the risk of cancer in animals even though it's unclear what that risk is in humans. Some of them may contain or be contaminated with carcinogens. Those are cancer-causing agents. There's also concern that they could be neurotoxic, specifically when it comes to neurobehavioral issues in children. Restlessness, trouble learning, attention problems. One thing I want to make clear, there is not a direct cause-and-effect relationship established between these dyes and harm in people. Think about many of the things that I've said like the neurobehavioural problems. What else has been happening in society over the last 30 years that could be causing that? Could it be the ultra-processed foods themselves? Could it be smart phones, social media, other environmental toxins? The point is that it's very hard to show direct cause and effect in humans. But at the same time, animal studies and epidemiological studies have pointed to potential links. One thing we don't know is what the dose of these dyes are that we are ingesting and what dose could potentially cause a problem in humans and if there's a cumulative effect over time. We know that these dye tend to be metabolized very quickly in animals and the same could be said for humans. But again, what is the cumulative effect? I'm in my mid-50s, I did not grow up eating these dyes. My kids who are teenagers, they've had them their entire lives in their environment. So then the question is, what will they be replaced by? Because people do like their brightly colored foods. You can, as it turns out, make similar colors with natural dyes. They may not be as stable, they may not as vibrant. Again, because petroleum-based dyes really does offer those two ingredients. So for example, carrot juice or watermelon juice or blueberry juice, things like that. That's already what's happening in many countries around the world. They are already using natural dyes. Do we know for sure that using natural dyes will make a difference? Do we see lower rates of some of the harms I mentioned in countries that don't use petroleum-based dyes? Truth is, that's not clear. Many of the countries that use these natural-based dyes still have some of same rights of cancer and neurobehavioral disorders that we see in the United States. So the question then becomes why in Canada or Europe do they use natural dyes in place of these additives? And I think part of the reason is because of something known as the precautionary principle, a precautionary approach. The philosophy is, look, I don't know if this is a problem, but it might be. So let's just avoid it. Why take the risk? And again, keep in mind the backdrop, these dyes don't offer any nutritional value. We are just talking about an aesthetic issue here. So, why take the risk is what many countries around the world ask. Here in the United States, we take a much more cause-and-effect evidentiary approach. What's the evidence? The best advice I think is to avoid the food dyes until they are completely phased out of the food system. You can read your food labels, but I think, you know, the best bet, and this advice applies across the board, avoid ultra-processed foods as much as you can because, if not the dye, then the sugar. Then the other ingredients in there. Then the preservatives. There are lots of things in those ultra-processed foods that could be potentially contributing to this problem. Dyes could be one of them, but there are many other chemicals that could doing the same thing. Eat real food. After the break, a burning question from the freezer aisle. Okay, we're back, and those beeps can only mean one thing. It's time for another question.

Okay, Sanjay, this caller didn't leave a name, but he did leave a great question, and it actually reminds me of something my mom often used to tell me.

I am following up on your episode with Dr. Tim Spector and are frozen vegetables just as good as fresh vegetables? I've heard that they're better fresh frozen, hold their nutrients, vitamins, etc. Thank you. I look forward to hearing podcasts answering these questions.

'Alright, thank you for calling, sir, and Sofia, thanks for teeing us up. First of all, I appreciate the follow-up to a past episode, so thank you being an attentive listener to Chasing Life. It sounds like your main question is whether frozen vegetables are as good or even better at holding nutrients than fresh vegetables. So true or false? This one is true -- some of the time. Research published by the National Center for Biotechnology Information revealed that frozen fruits and vegetables can have just as many vitamins and sometimes even more as compared to fresh.

The best thing you can do is eat fruits and vegetables. Absolutely, but a lot of times when you buy them in the clamshells in the grocery store, they've been in a truck for seven days, even coming from California. And so the longer a freshly picked fruit or vegetable is removed from the vine, removed from plant, they slowly start to lose their active compounds. They don't become bad, but slowly they'll lose what they had when they were freshly picked.

'That's Mary Ann Lila, a professor at North Carolina State University's Plants for Human Health Institute. Now according to her, if you're not getting your fruits and veggies right off the vine from your own backyard or at a local farmer's market at their peak, buying frozen foods is a good way to ensure that your food's natural vitamins have been mostly preserved. And that's because most fruits and vegetables intended to be frozen are typically picked at their peak ripeness when they are the most nutrient dense. Produce intended to be sold fresh are picked at a less mature and so less nutrient-dense stage so they can last longer during transport and storage. In other words, soon-to-be-frozen veggies start with a nutritional advantage which helps offset any nutrient loss during the process, and they still rank higher nutritionally compared to some commercially available fresh produce. Commercially frozen foods go through a process called individually quick frozen. And that happens the day they are picked. So again, with the help of Professor Lila, here's the break now.

That frozen bag of fruits or vegetables. It's absolutely the best way to get a fruit or vegetable that has all of the nutrients and all of phytoactive compounds that you are looking for from the fruit or vegetable. You can pick them from your garden or you can get them from the farmer's market and they've just been harvested that day. But other than those two situations, you run a risk of a fruit or vegetable having been in storage or shipping for quite some time.

Bottom line is that frozen foods are a good option, perhaps a great option, maybe even a better option in some cases. And though you did not ask about this, we asked Professor Lila about canned vegetables as well.

'So canned food, a retort, again, still great, still eat the fruits or vegetables, but they do undergo a heating process and every time a bioactive compound encounters heat, 360 degrees or more, which is in a canned process, you'll start to degrade some of the compounds. Not all of them, they're still gonna be good, but you'll, it won't be the same as a fresh or a individually quick-frozen fruit or vegetable.

'So you're definitely going to have a more nutrient-dense product in a frozen food than something that has likely been picked, refrigerated, shipped on a truck for a few days and then stored in a warehouse before arriving at the grocery store and then maybe sitting around in your fridge. But, to be clear, in terms of nutritional hierarchy, fresh-from-the-garden or garden-ripe veggies would be superior to frozen in terms nutritional value but only if they're eaten within a day or so. So let me stress this: If you don't have a garden or can't afford fresh food, which is a lot of people, frozen is a very attractive alternative, especially if you like to meal prep or simply don't think you'll eat your fruits or veggies within a few days. What is the most important, no surprise, just get those fruits and veggies in your diet. Most people simply don't eat enough. And along those lines, here are a few more tips. Keep your freezer door shut. Every time you open your freezer, you're exposing produce to room temperature, and it thaws a little. According to Professor Lila, this can result in a loss of healthy phytoactive compounds. Store your fruits and veggies as much as possible in the back of the freezer so they don't get partially thawed when you do open the door. Save the front for ice cubes, she says. Defrosting fruit on the countertop is the best way to retain the phytonactive compounds in fruit. Lightly steaming is the best way to preserve nutrients in vegetables. Avoid microwaving at least for more than 15 seconds.

So it can absolutely destroy those active compounds as well as vitamins and minerals and enzymes. So it's so easy to overheat. What I do, for example, I have blueberries every morning and I'm in a power walking group. So before I go on the power walking group, I take those berries out of the freezer, pour them in a bowl that I'm gonna use in my breakfast. Then I go for an hour, and I do my walking, and I'll come back and they'll be defrosted. That's the best way to do it, because if I microwave them to get the ice crystals off of them, yeah, I could be losing a lot. So if you have to microwave, 15 seconds and no more. That's important.

'One other great idea, Professor Lila said, another thing you can do easily, squeeze a lemon over frozen veggies after heating them. The vitamin C in lemon juice can help replenish any lost vitamin C, which is particularly heat sensitive. It will also make veggies brighter and fresher tasting. So I guess the adage is when life gives you lemon juice, go ahead and add it to your veggies. That's all we have for today. Thanks for listening. And remember, I love this podcast, I love hearing from you, send in your questions, and hopefully you'll hear the answer right here. Just record a voice memo and email it to asksanjay@cnn.com or give us a call. Leave a message with your health question at 470-396-0832. Chasing Life is a production of CNN Audio. Our podcast is produced by Eryn Mathewson, Jennifer Lai, Grace Walker, Lori Galarreta, Jesse Remedios, Sofía Sánchez, and Kyra Dahring. Andrea Kane is our medical writer. Our senior producer is Dan Bloom. Amanda Sealey is our showrunner. Dan Dzula is our technical director. And the Executive Producer of CNN Audio is Steve Lickteig. With support from Jamus Andrest, Jon Dianora, Haley Thomas, Alex Manasseri, Robert Mathers, Leni Steinhardt, Nichole Pesaru, and Lisa Namerow. Special thanks to Ben Tinker and Nadia Kounang of CNN Health and Wendy Brundige.