Facts About Nutrition, Diets, and Psoriatic Disease

Psound Bytes Transcript: Episode 196

Release date: Tuesday, June 6, 2022

“Welcome to this episode of Psound Bytes, a podcast series produced by the National Psoriasis Foundation, the nation’s leading organization for individuals living with psoriasis and psoriatic arthritis. In each episode someone who lives with psoriatic disease, a loved one or an expert will share insights with you on living well. If you like what you hear today, please subscribe to our podcast and join us every month at Psound Bytes for more insights on understanding, managing, and thriving with psoriasis and psoriatic arthritis.”

Shiva: My name is Shiva Mozaffarian and joining me today to discuss myths and facts associated with dietary plans in psoriasis and psoriatic arthritis is renowned dermatologist Dr. Ronald Prussick, Medical Director of the Washington Dermatology Center in Rockville, and Frederick, MD, which specializes in the treatment of psoriasis along with other diseases of the skin, hair and nails. Dr. Prussick is also an Associate Clinical Professor at George Washington University in Washington, DC, and a member of the National Psoriasis Foundation's Medical Board.  Dr. Prussick participated in the development of the 2018 Dietary Recommendations for Adults with Psoriasis or Psoriatic Arthritis from the Medical Board of the NPF, which offered a review of studies addressing the impact of dietary interventions in people with psoriasis and psoriatic arthritis. Dr. Prussick has a special interest in how nutrition choices impact psoriasis and overall health, which he briefly addressed in episode 12 “If I'm clear, why do I need to continue my psoriasis treatment?”

Welcome Dr. Prussick! It’s so great to have you back on Psound Bytes™ today. As you know nutrition and dietary plans remain a hot topic of discussion in the psoriasis and psoriatic arthritis community. How integral is nutrition in the development of psoriasis or psoriatic arthritis?

Dr. Prussick: I just want to thank you for inviting me to do this podcast. I'm really excited to be here and to share some of the latest information we have. I think nutrition does play a role in the development of psoriatic disease in genetically susceptible people and I believe that nutrition does affect your immune system. Remember the expression you are what you eat. So I kind of live by that and I just wanna give you some examples. If people eat foods that have a high glycemic index, that means that they're gonna produce a lot of insulin and insulin causes fat storage and fat storage in the center of the body is called central obesity. Now that fat is very different from the fat in the arms and the legs, that fat cells in the center are like an endocrine organ, they actually produce inflammation. They produce the inflammatory cytokines that cause inflammation, like TNF alpha and other interleukins and they cause metabolic syndrome. So the diet that you have, if you're eating foods that give you a lot more of those bad fat cells, which is gonna cause more inflammation. If you eat foods like processed foods or simple carbohydrates, or drink a lot of alcohol, that can affect your gut microbiome. That just means the normal flora in your gut can change. If it changes, then you can induce inflammation inside the gut wall, and that inflammation can enter your body and cause psoriatic disease. So certain foods like red meat or processed foods can cause oxidative damage and that can damage your immune system by depleting antioxidants like glutathione. So those are all important things that you need to know about in terms of how the diet can affect inflammation. There's also, we call it omega-6 and omega-3, those are different polyunsaturated fatty acids. So there's a ratio of them that's in the diet. So if the omega-6 is too high compared to the omega-3, we see that in a Western diet and that causes inflammation. So normalizing that by reducing the omega-6 in your diet and increasing the omega-3 in your diet will all improve your immune inflammation.

Shiva: So Dr. Prussick given the impact on development of disease, is it possible nutrition or diet can play a role in the management of psoriatic disease?

Dr. Prussick: Yes, I really do believe that nutrition or diet can play a role based upon what I just told you and how certain foods can cause inflammation. But keep in mind that nutrition plays a complementary role in the management of psoriasis. For most people, they still will need medical treatments and this is gonna be used together with their medical treatments. So for example, we know from the Nurses Health Study that nurses with the largest body mass indexes had the highest risk of eventually developing psoriasis because they had the central obesity fat cells that produce a lot of inflammation. So it's important that people know that their nutrition will affect this amount of central obesity, which will increase their risk of having psoriasis. The bigger the person is, the more overweight they are, the higher the risk that their psoriasis will be more severe. The more obese a person is, the more likely they won't respond as well to the treatments we give them. And also if patients have a higher body mass index, they have a higher risk of developing psoriatic arthritis if they already have psoriasis. So using all this information, it's important to have a healthy diet to try to reduce obesity as much as possible. Another thing that's important and we published this in our article in 2018 on Diet in Psoriasis is that patients who have celiac disease or if they have symptoms of gluten allergy and they have antibodies, if we give them a gluten free diet for about six months, most of the patients their skin gets much improved and one paper showed (it was only a small study of seven patients with gluten sensitivity), they all completely had clear skin after a gluten free diet. Another one had 39 patients, 33 had gluten sensitivity and six didn't. 73% of those patients with gluten sensitivity had less psoriasis after a gluten free diet, so in those patients, diet was very important in controlling their disease.

Shiva: So Dr. Prussick, earlier you mentioned the two way relationship between psoriasis and obesity, can you elaborate more about the cyclic nature and impact of that relationship?

Dr. Prussick: Yes as I mentioned that central obesity can trigger psoriasis because of the inflammation that the fat cells are causing. And so patients get metabolic syndrome and they have a higher risk of severe psoriasis because those cells produce inflammatory cytokines like TNF alpha, leptin, interleukin-6 and there's a decrease in anti-inflammatory cytokines like adipokines and Interleukin-10. This causes systemic inflammation. So patients with psoriasis have comorbidities. They have an increased risk of having depression, anxiety and of course they have a risk of about 30% of patients with psoriasis get psoriatic arthritis and these can all impact the ability to develop obesity because if patients have depression or anxiety, they might be eating comfort foods and they might be eating to make them feel better, which will cause weight gain. If they abuse alcohol, that can cause weight gain because for example, beer has a lot of calories, it has gluten in it, and also if they have psoriatic arthritis, if they have pain in their joints or in their tendons or ligaments, they may not be able to exercise or walk as much as they would like, and that will all contribute to obesity.

Shiva: So Dr. Prussick, in the “2018 Dietary Recommendations for Adults with Psoriasis or Psoriatic Arthritis” which you helped develop, one of the recommendations was use of a hypocaloric or low energy diet of 800 to 1400 calories per day. What is the reason for this recommendation? 

Dr. Prussick: Well the reason for this recommendation is we just talked about how those fat cells in the center of the body are a source of inflammation. So if we can get people to lose weight, lose those fat cells, lose that source of inflammation, can their psoriasis improve? And that is the reason for the recommendation. So there was a paper published in Europe looking at this, there were sixty obese adult patients with psoriasis, 30 received a low energy diet, 800 to 1000 kilocalories a day for eight weeks, and then after 8 weeks the calorie increased to 1200 kilocalories per day for another 8 weeks. And they compared that to 30 patients who are on a regular diet. And they found that there was an improvement in their skin and their quality of life index improved as well.

Shiva: Since the publication of these recommendations, have here been any new developments or updates that augment or support the recommendations? 

Dr. Prussick: Yes, there actually have been papers to support our recommendations. There have been some observational studies that show that weight loss can decrease psoriasis scores. The extent of psoriasis versus weight gain can make psoriasis worse over time. So patients with the larger BMI’s have harder to treat psoriasis and were more likely to fail some of the treatments we use, and weight loss made some of the psoriasis treatments more effective. There was a paper looking at a low calorie diet versus a normal diet in 16 weeks. There was an improvement in the psoriasis and at 24 week 66% of patients had a 75% decrease in their psoriasis versus only 21% in the non-diet group. Another trial showed 5% weight loss can result in less psoriasis. There was another pretty important paper that was published in 2020 and they looked at a large database in the United Kingdom. Patients who had psoriasis and they looked at their BMI’s and they wanted to know if the BMI changed. (So BMI is the body mass index.) If the BMI changes over time, will that increase or decrease their risk of eventually developing psoriatic arthritis? For most patients’ psoriatic arthritis comes about 10 years after the psoriasis appears, so it's really useful to know what we can do or what advice we can give people to prevent psoriatic arthritis. So what they found was that it does make a difference. So if patients’ gained weight, so if they went from a BMI of 25 to 30 over a ten year period, the risk of developing psoriatic arthritis went up by 13%. The opposite happened if they're BMI dropped from 30 to 25, the risk of developing psoriatic arthritis decreased by 13%. They had dramatic weight loss, if their BMI changed from 36 to 23, the risk of developing psoriatic arthritis decreased by 30% versus patients who maintain their BMI over the 10 year period. So it is important for patients to know that gaining weight over time is a risk factor for them to develop psoriatic arthritis. There was a paper looking at intermittent fasting in Europe, 12 patients went on a regular diet, versus 12 had a modified intermittent fasting. Five days a week they had their normal diet, and on 2 nonconsecutive days, they only had 500 kilocalories of energy, twice a week, and there was a reduction in their psoriasis. It was not statistically significant, but there was an improvement. There was also an improvement in itching and scaling at 6 and 12 weeks. Our paper that we published showed that fish oil in itself did not improve psoriasis signs and symptoms, but there was a recent paper that showed that if you use fish oil in combination with conventional treatments, there is an improvement in psoriasis. And there were three separate publications that recently confirmed the inverse relationship between the use of a Mediterranean diet and the severity of psoriasis and psoriatic arthritis, which proves that the Mediterranean diet is very helpful in psoriatic disease. 

Shiva: So we hear a lot about use of anti-inflammatory diets and you have also done some research in this area. What are the facts about using an anti-inflammatory diet? And are there any benefits to following this type of diet? 

Dr. Prussick: Well, the goal really is if patients have too much inflammation in their body, can a diet reduce that inflammation? So that is what we're trying to do. Now we talked about reduction of the central fat cells through diet by reducing high glycemic index foods, losing weight, and losing that central obesity should theoretically reduce a source of inflammation. We also talked about omega-6 and omega-3. There are studies, not with psoriasis, but with asthma and with Crohn's disease, that by decreasing omega-6 foods and increasing omega-3 foods and by reducing that ratio, you can improve those particular inflammatory conditions. So those are all important. Also high glycemic index foods cause AGE’s. So there are “advanced glycation end” products and a common one is your doctor will measure that in the blood if you're diabetic, it's called hemoglobin A1C. So by reducing the sugar in your diet, you reduce the AGE’s and those cause inflammation and so that's very helpful as well. One can also reduce AGE’s by not cooking with very high temperature foods. Grilling and frying all cause AGE’s as well. If you cook on low temperature or by poaching foods or broiling foods, that's all better, it reduces AGE’s. If you eat foods that have lemon in them, that will reduce or cooking with vinegar that will also reduce AGE formation by about 50%. So those are all things that we know can help in terms of an anti-inflammatory diet. The most important diet that we know that's helpful in psoriasis is the Mediterranean diet. As I said before there's a correlation between the Mediterranean diet and having a reduction in psoriasis and psoriatic arthritis. 

Shiva: And is there any one diet that is better than another for psoriasis? For example, you mentioned the Mediterranean diet which is high in antioxidants and healthy fats, or Dr. Pagano’s diet, Paleo or the Vegan diet, and will any additional nutritional supplements be needed like omega-3’s or vitamin D?

Dr. Prussick: We have the most information, as I said on the before Mediterranean diet, and this was published in our paper and I talked about these three studies that confirmed the inverse correlation. So I think that focusing on a Mediterranean diet is the best information we can give patients right now. Dr. Pagano is a chiropractor that believes that psoriatic disease is a manifestation of the leaky gut syndrome, and the goal is to increase alkaline and decrease acidic foods by 75 to 25% ratio. At this point we really don't have any strong information that changing the alkalinity or acidity of the food is really gonna impact psoriasis, and leaky gut syndrome is still controversial. In terms of a Paleo diet, really it's based on foods eating during the Paleolithic era before farming when humans were hunting and foraging. The goal there is to eat lean meat, fish, eggs, vegetables, fruits, nuts and seeds, spices, healthy fats, and oils and avoiding grains, most dairies, legumes, starchy vegetables. The problem with this diet is you can have low vitamin D or calcium from the lack of dairy, so you might need supplementation. Too much saturated fats or red meats and proteins can increase the risk of kidney or heart disease so we have to be careful with that. In terms of a vegan diet, it's based on plant foods and avoiding all animal foods. It improves your blood sugar and heart health and helps you lose weight. But you can get nutritional deficiencies so you really have to be under medical supervision during a vegan diet because there's risk of low vitamin D, low vitamin B12, omega-3 deficiency, calcium, zinc, iron, magnesium deficiencies and you have a lack of high quality protein which can cause also other problems as well. So I think those are the important things in terms of supplementations. In our paper we talked about omega-3 and vitamin D. In itself omega-3 and vitamin D don't treat psoriasis according to the data that we have available. But there are many patients with psoriasis especially who are overweight that have vitamin D deficiency so it needs to be corrected. And like I said in the normal Western diet, the Omega-6 to three ratio is very high. So some patients need to improve that ratio by focusing on eating omega-3 foods or taking high quality fish oil. 

Shiva: And how about the use of pro or prebiotics? Will use benefit someone with psoriasis or psoriatic arthritis? 

Dr. Prussick: Let's just talk about some definitions first before I talk about that. So the microbiome just refers to the normal healthy microorganisms that are in the gut and the skin. It's mostly bacteria, but it also can include viruses, fungi, and protozoa. Probiotics are the living bacteria that are beneficial to the body. They colonize the gut and the skin. And prebiotics are the food for the good microbiome that's in your diet. So it's thought that a change in the gut microbiome could trigger inflammation. So in the pathway that we know of psoriasis, the TH17 cells produce Interleukin-17 which can trigger psoriasis and the TH17 cells are activated by Interleukin-23, which can be triggered by a change in the gut microbiome which can start the whole process over. So there have been studies that show that patients with psoriasis have an abnormal microbiome compared to normal non-psoriasis patients. So they have less diversity and they have less good bacteria. Another study showed patients with psoriatic arthritis, two-thirds of them had gut inflammation associated with an abnormal gut microbiome. And there was one study that showed that the patients that took oral Bifidobacterium infantis for 6 to 8 weeks, it reduced serum inflammation cytokines like CRP, TNF-alpha, and Interleukin-6, all improved with taking probiotics. So it just shows you that a change in your gut microbiome can change your blood inflammation levels that we can measure in the blood. There was a randomized controlled trial in 2019 showed a mixture of three probiotics improved psoriasis. So 67% of patients achieved the PASI 75 with the probiotics versus 42% in the placebo group. So there was some modest improvement there, but it was statistically significant. We don't have any data that prebiotics will treat or help psoriasis, but having a good healthy diet with a lot of good fruits and vegetables should benefit your gut microbiome. So things like chicory root, Jerusalem artichoke, garlic, onions, leeks, asparagus, bananas, cocoa, flaxseed, and seaweed are all known prebiotics that will help your gut microbiome. So the chicory root has something called inulin in it, and this is also found in some of the other prebiotics, which is beneficial for your gut bacteria.

Shiva: So Dr. Prussick, I wanted to see if you could squash this once and for all on Psound Bytes, fact or fiction - will increasing use of caffeine help psoriasis?

Dr. Prussick: Well, that's a really great question. And you know, caffeine and coffee is the #3 consumed drink worldwide after water and tea. So it's certainly very prevalent. And I think of it as what do you put in your coffee? So the health effects are impacted by how much sugar you put in and how much milk are you putting in it. So, think of it that way as well. But coffee in itself has not only caffeine it, but it does have other antioxidants, minerals, vitamins, carbohydrates, lipids. So there are some health benefits. In vitro, which means that in laboratory studies, caffeine inhibits inflammation cytokines interleukin-6, TNF alpha and increase anti-inflammatory cytokines like IL-10 and adiponectin. It also works like some of the medications we use by blocking cyclic AMP phosphodiesterase by increasing the cyclic AMP inside immune cells it benefits the amount of proinflammatory and anti-inflammatory cytokines and rebalances and makes it better. There was a recent paper that showed the effect of coffee’s dose-dependent, which means that they found that if you have three cups or less a day that alleviate the symptoms of psoriasis, but four or more cups a day made the psoriasis symptoms worse. So the bottom line there is what you put in your coffee matters, and also how much you drink matters. So you can have some but limit it to three cups or less.

Shiva: And do you feel a personalized approach to nutrition tailored to what therapy someone may be on is the right approach to management of diet, psoriasis, and psoriatic arthritis?

Dr. Prussick: Well, as we discussed, it's very important for a personalized approach to nutrition. I think that nutrition is important and I think that patients should look to talk to a certified dietitian or their physician as opposed to just reading things online. The idea really is to get proper nutrition in a sustainable way. These fad diets or these very drastic diets where people lose a lot of weight quickly, they're not sustainable, and they're probably not healthy for most patients. So the health professional has to look at your comorbidities. Do you have kidney problems? Do you have liver problems? Do you have Vitamin D deficiencies? Do you have other mineral deficiencies, when they come to your personalized approach to nutrition. Like I said before, the goal is to reduce the systemic inflammation by reducing the glycemic index foods, by increasing omega-3 in your diet, and if you have celiac disease or gluten sensitivity by avoiding gluten. So those are all kind of personalized things that you need to work with a professional. 

Shiva: And what are some of the latest areas of research about the relationship between nutrition and psoriasis?

Dr. Prussick: I think there's some really exciting things in terms of looking at how diet and nutrition affects your immune system. And they've been doing this focus mainly with it's called epigenetics. So basically, it's looking at how environments such as pollution or diet can change gene expression rather than actually alternating or mutating the genetic code itself. These things are reversible, they're not changing your DNA sequences, but sometimes they can be heritable as well. So these epigenetic changes are things like histone acetylation to the DNA, DNA methylation, small interferon, mRNA’s and micro mRNA’s. So one of the interesting studies that came out is they looked at various antioxidants in the diet to look whether it would have an effect on these micro RNA's that cause inflammation, and they found that resveratrol quercetin which is a flavonoid, vitamin D, and curcumin. Curcumin is the active ingredient in turmeric, Indian spice. They were all found to reduce inflammation by affecting the epigenetics and reducing inflammation that way. So I think that's really an exciting topic that we're getting more information on. Another exciting topic is looking at sugar alcohols and how they affect the immune system. They're called D-pinitol, D-chiro-inositol, and myo-inositol. And the idea there is these can normalize the balance between the helper T cells and the helper T cells are the source of the inflammatory cytokines. So when they're out of balance, you make abnormal inflammatory cytokines and they've been looking at whether these sugar alcohols can reduce  TNF alpha, reduce oxidative stress and angiogenesis and it's looks very promising. We don't have enough data to recommend anything yet for psoriatic disease, but these are things that we're studying that hopefully in the future we’ll be able to give you more information on these topics.

Shiva: Dr. Prussick, thank you so much for being here with us today and for such an interesting look at the facts versus fiction around diet and psoriatic disease. Do you have any final comments you'd like to share with our listeners today?

Dr. Prussick: I just want to thank you for being interested in this topic. I would say that just think about what you're eating. Is it nutritional? Do you think that it's got a low glycemic index? Try to focus on that, try to eat healthy vegetables, focus on a Mediterranean diet. If you have symptoms of gluten sensitivity or if you have a family history of celiac disease, make sure you get tested. Make sure your vitamin D levels get tested as well. And find someone who's very knowledgeable on this topic that can give you good advice. The goal really is to go on a sustainable, healthy program that you can use your whole life. It's not helpful if you go on a diet and lose a lot of weight in three months, but then gain it all back three months after that. So I think that it's really important to find people that can help you with sort of think of this as a lifelong goal to try to have good nutrition as part of your food is your medicine type of mentality. Thank you.

Shiva: Thank you Dr. Prussick for providing such helpful tips for our listeners today. It's always a pleasure having you on Psound Bytes™. For our listeners, if you'd like to receive additional nutrition tips, contact our Patient Navigation Center for a free healthy eating guide by calling 800-723-9166 or by emailing education@psoriasis.org. And finally, thank you to our sponsors who provided support on behalf of this program activity through unrestricted educational grants Bristol Myers Squibb, Janssen, and UCB.

We hope you enjoyed this episode of Psound Bytes for people with psoriasis and psoriatic arthritis. If you or someone you love has ever struggled with psoriatic disease, our hope is that through this series you’ll gain information to help you lead a healthier life and inspire you to look to the future. Please join us for another inspiring podcast. You can find this or all future episodes of Psound Bytes on Apple Podcasts, Spotify, iHeart Radio, Google Play, Gaana, and the National Psoriasis Foundation web page. To learn more about this topic or others please visit psoriasis.org or contact us with your questions or comments by email at podcast@psoriasis.org.  

This transcript has been created by a computer and edited by an NPF Volunteer.

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• Ford AR, Siegel M, Bagel J, et al. Dietary Recommendations for Adults With Psoriasis or Psoriatic Arthritis From the Medical Board of the National Psoriasis Foundation: A Systematic Review. JAMA Dermatol. 2018;154(8):934-950. https://pubmed.ncbi.nlm.nih.gov/29926091/

• Prussick, R. Diet and Inflammation in Dermatology. Practical Dermatology. May 2019. 38-40.

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