Rajani Katta, MD, Discusses the Science Between the Skin/Diet Link

Rajani Katta, MD, board-certified dermatologist and adjunct clinical faculty at Baylor College of Medicine and the McGovern Medical School at The University of Texas, Houston, joined Dermatology Times^® to discuss the connection between skin and diet. She emphasized the role nutrition plays in many skin diseases, including atopic dermatitis, psoriasis, acne, and aging.

Katta explained the science connecting skin and diet and the thinking behind her mantra to Eat Power. She also discussed sugar spikes and how advanced glycation end products play a role in skin health.

Transcript

Rajani Katta, MD: I'm really excited to be here. I'm Dr. Rajani Katta. I'm a board-certified dermatologist who practices in Houston. I'm also adjunct clinical faculty at both the Baylor College of Medicine and the McGovern Medical School at the University of Texas Health Science Center at Houston.

Dermatology Times: Could you explain the connection between skin and diet?

Katta: Oh, absolutely. This is an area that I find fascinating. And I think within dermatology, we have known really, for many, many decades, that there's a link between skin and diet. If you think about the fact that acanthosis nigricans is related to diabetes or insulin resistance, and it causes skin findings. And then you think about the fact that diabetes causes impaired wound healing. We've known about that link for a long time. But I think what's really new in the last few decades is that we're starting to see a lot more research that's really more clearly delineating this link.

So, we now have research from population health studies, from clinical intervention studies, from laboratory and animal studies that are really fleshing out that link far more clearly. And when I'm looking at the link between skin and diet, I'm looking at what evidence do we have about specific skin conditions, for example. And the framework that I like to use is, whether you're talking about psoriasis, or rosacea, or atopic dermatitis, or aging skin, I really start with, What is the evidence that there may be comorbidities associated with that skin disease? And with those comorbidities, can dietary change make any difference? And then beyond the question of comorbidities, I also like to think about helpers and triggers. And by that what I mean is, are there any specific nutrients or foods or dietary patterns that can act to help in a particular skin condition? And the converse of that is triggers? Are there any specific nutrients or foods or dietary patterns that may act as triggers for that specific skin disease? And if you look over the last few decades, there's really a robust body of literature now that has shown these multiple interactions between skin and diet.

Dermatology Times: What is the science between the skin and diet connection?

Katta: I think if you start with this whole idea of the framework, comorbidities, helpers, and triggers, and I'll just show a few examples. For example, with comorbidities, I think one area that's really exploded in research is the fact that psoriasis has now been linked to multiple systemic comorbidities. So, we know that patients with psoriasis have a higher risk, independent of other risk factors, for conditions such as hypertension, and diabetes, and hypercholesterolemia. And so when you're thinking about those comorbidities, we know that dietary change is really an important facet of reducing the risk of those comorbidities.

And there have been studies showing that psoriasis is an independent risk factor for heart disease, and independent of these other risk factors. And so you think about how do you reduce your risk of heart disease. And this is where you start to think about dietary change. And specifically with psoriasis there's also been some really interesting randomized controlled trials showing that in patients with psoriasis and obesity, that weight loss can actually help improve the efficacy of treatment for psoriasis. So that's one example of the comorbidity aspect of it.

If you think about helpers, so what kind of studies do we have showing that certain dietary changes may help in the treatment of skin disease? Well, I think one really interesting area is that of acne. If you look at patients with acne, there have now been multiple randomized, controlled trials where they're not testing a pill or they're not testing pharmaceutical drugs, what they are testing is a particular dietary intervention. So, for example, in one study, patients who had inflammatory acne were asked to follow a low glycemic load diet for 12 weeks. And they compared that to a different group that did not follow that diet. What they found was at the end of the 12 weeks, the patients following a low glycemic load diet had a greater improvement in their clinical signs of acne. And then they did later studies of that same exact intervention and what they found was that histologically, if you take a skin biopsy, you're starting to see smaller sebaceous glands and you're starting to see less inflammation. So that's another example of how they're approaching this in different ways.

Huge population studies where you're looking at psoriasis and comorbidities, and then small, interventional studies, randomized clinical trials. And then there have certainly been studies of rosacea and a lot of interesting studies with atopic dermatitis, really showing an interesting gut skin connection. And then, I think another area that that I find interesting that we're starting to see more of is with aging skin. And in some of the research there has found that if you look at population health studies, patients who report a healthier eating pattern over their lifetime, have actually been documented to have fewer signs of aging skin. And these studies are all really interesting. And they are starting to point us in certain directions on how can we take all of this science and then direct it towards recommendations for our patients.

Dermatology Times: Could you explain the phrase Eat Power that you talk about in your literature?

Katta: Yes, I thought long and hard about how do you translate the science to the dinner plate? Because it's all wonderful to see all of these different research studies. But at the end of the day, you're the one sitting in front of your dinner plate. And how do I translate this into action? One of my key tenants for eating for healthy skin comes down to Eat Power. And basically what that means is to focus on eating foods that are rich and powerful nutrients.

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So, for example, we have multiple studies showing that patients who eat foods that are rich in antioxidants, and this is over a longer period of time, that they have a lower risk for, let's say nonmelanoma skin cancer. And if you look at their overall dietary pattern, and so when you're talking about Eat Power, one of those keys is to eat foods that are naturally rich in antioxidants. You can also focus on things like prebiotic and probiotic foods. So prebiotic foods are those foods that encourage the growth of good microbes in the gut. Probiotics are foods that naturally contain good beneficial microbes. And if you are able to focus on eating prebiotic and probiotic foods that can have a beneficial effect on the gut microbiome. And that has been linked to improvements in skin barrier function.

So those are some examples of some of the foods that I recommend as part of that Eat Power. I'll also mention that I really focus on high quality carbohydrate sources, or what I call power carbs. So instead of empty carbs, power carbs are those like beans and legumes, or whole grains, for example, that not only do they have carbohydrates, but those carbohydrates are mixed in with fiber, which feeds the gut microbiome, and also vitamins, minerals, as well as phytonutrients. If you just take black beans, for example, they’re a rich source of fiber, of protein, of zinc, of anthocyanins, which are phytonutrients. So those are some of the ways that I'm looking at these foods that are rich and powerful nutrients and how that can translate to skin benefits.

Dermatology Times: Could you talk about sugar spikes and how diet contributes to those?

Katta: Sometimes I find it easier to use the metaphor of a house when I'm talking to patients. So, if you think of your skin like a house, there are a lot of forces every single day that can start to damage the walls of your house. And so I think of the 3 major forces that can damage your skin are oxidation, inflammation, and glycation.

And I think of oxidation as very similar to hail hitting your house and just pounding away. So that's free radicals that develop from oxidation just causing damage over and over again. And that's where antioxidants can protect you. Inflammation is, I think of it as similar as if you had a tiny little leak in your roof and you hired somebody to come in and fix it. And by the time you're done, you just end up with this big giant hole in your roof. That's inflammation because inflammation is your body's repair processes. And that's important. But chronic inflammation is when those repair processes go out of control. So that's where anti-inflammatory foods come into play.

And then glycation. I think of that as if you think about the walls of your house like collagen and holding up the walls of your house and then you start to have termites that are attacking the walls of your house and then you start to get sagging of those walls. We call that sugar sag. And those termites, the way I picture them, advanced glycation end products. And those are known as AGEs for short. And they are created when you have a protein and a sugar combining together in a process called glycation. And that forms a new compound that starts to glob onto your collagen and starts to weaken it. And so one of my key tenants of eating for healthy skin is to stop sugar spikes, because if you are eating foods that increase levels of blood sugar, what that does is that contributes to the new formation of those advanced glycation end products. And if you think of collagen as very similar to a net, it's very strong, it's very flexible. If you start having those advanced glycation end products, you can almost think of it as like caramel. Sugar and butter combining together the sticky compound. Well, those AGEs can be really sticky and damage your net. So that's another way of looking at it. So that's why stopping sugar spikes is so important. And also, one of the reasons that individuals with diabetes can start to have poor wound healing because of the effects on collagen.

Dermatology Times: Is there anything you would like to add?

Katta: I think one of the things that I really want to emphasize as a take home point is that all of the research that's coming out, a lot of it is very actionable. If you start to look at it, you can start to implement these small, tiny changes. And that can add up to some larger changes over the long term. So that's one of the points I like to emphasize to my patients. And then I did want to add one more point and that is that nutrition is not the same as nutritional supplements. We have done some research on some of the skin, hair, and nail supplements out there. And I really want to emphasize to patients that even though they sound all natural, or they call themselves nutritional supplements, those are very different than nutrition and some of them can have serious side effects.

[This transcript has been edited for clarity.]