Can Diet Protect Against Age-Related Macular Degeneration (AMD)?
Allen Taylor, PhD
Allen Taylor, PhD directs the Laboratory for Nutrition and Vision Research at Tufts (a part of the USDA Human Nutrition Research Center on Aging), and also holds faculty positions in nutrition, ophthalmology, molecular & chemical biology, and development at the Tufts University School of Medicine. He talks about how age-related macular degeneration (AMD) develops, the nutritional component, and what new research shows about ways to delay onset or progress.
Can Diet Protect Against AMD?
November 29, 2017
Transcript of Teleconference with Dr. Allen Taylor
1:00–2:00 pm EDT
The information provided in this transcription is a public service of BrightFocus Foundation and is not intended to constitute medical advice. Please consult your physician for personalized medical, dietary, and/or exercise advice. Any medications or supplements should be taken only under medical supervision. BrightFocus Foundation does not endorse any medical products or therapies.
Please note: This Chat has been edited for clarity and brevity.
MICHAEL BUCKLEY: Hello, I am Michael Buckley from BrightFocus Foundation. Welcome to today’s BrightFocus Chat. If this is your first time on a BrightFocus Chat, let me take a moment to tell you about BrightFocus and what we will do today.
BrightFocus Foundation is a nonprofit, and we fund some of the top researchers in the world. We support researchers who are trying to find cures for macular degeneration, glaucoma, and Alzheimer’s disease. We make sure that we are sharing the latest research and news from these scientists with families who are impacted by these diseases. We do that through our website, www.BrightFocus.org, we do it through a number of free print publications for families, and we also do it through what we are doing today—a BrightFocus Chat. This is an opportunity to spend some time with an expert in the field of macular degeneration and learn what is new.
I would like to tell you about today’s guest. Dr. Allen Taylor from Tufts University in Boston, Massachusetts. Dr. Taylor directs a lab on nutrition and vision research. He is a professor of nutrition, development, molecular and chemical biology, and ophthalmology at the Tufts University School of Medicine. Dr. Taylor, I’d like to thank you for joining us today.
DR. TAYLOR: My pleasure.
MICHAEL BUCKLEY: I know that today we will discuss some of your research into the dietary factors that may affect macular degeneration. I want to start with a very basic question—how did you get into this line of work? What was your motivation to become a scientist?
DR. TAYLOR: My motivation to become a scientist is, I guess I was a Sputnik baby. This was the thing to do for young boys. I’ve always been intrigued by the basic principles of science and loved doing science at home. My parents always encouraged me to do that even though they themselves were never educated. Maybe they saw me as a way to fulfill some of their dreams. And then, to make a long story short, after I was in college and graduate school, where I did my degree in basic chemistry, I went to University of California, Berkeley, where I was isolating an enzyme. At that time, isolating and characterizing enzymes was quite exciting. In order for me to isolate the enzyme I was interested in, I literally had to cut 20,000 cow eyes apart to get the enzyme. The tissue I was after was the lens. So, I got deep into the eye and I became curious as to why, and how, does nature make this beautiful tissue that becomes clear and stays clear for virtually all the life of the animal. That began many years of experimentation and inquiry into trying to understand why lenses remain clear, and then why the retina—which is tissue right next to it—functions as a much more complicated organ, and how the two tissues work together to create vision.
MICHAEL BUCKLEY: It is amazing. I know you are leading some studies that look at how individual foods and dietary patterns that vary around the world, how those affect macular degeneration. I was wondering if you could characterize some of your research and what you’ve found in that area.
DR. TAYLOR: Sure. First, it is important to appreciate that we ask the question about macular degeneration in a few ways. That is—do you get it or don’t you get it? Do you have it or don’t you have it? Or if you have it, how advanced is it? The reason we ask the question about how advanced it is, is because if we can delay the progress of macular degeneration from very early stages to middle or late stages where it compromises vision, we virtually have developed a cure without any drugs.
To backtrack about the nutritional information we ask—we ask about whether people who eat diets that are what we call a prudent diet, rich in fruits, vegetables, and fish—as compared to people who eat a diet that is laden with oils, fats, and sugars. How does their risk for macular degeneration compare? We found that people who consume what we call a typical American diet, which is high fat and high sugar, have much greater risk for macular degeneration than people who consume the prudent diet. More importantly, or equally importantly, the more you subscribe to one of those diets the greater the correlation with risk for macular degeneration.
In other words, the more careful you are with your diet, the less chance you have of getting macular degeneration, both the advanced form and the early form. The more you consume diets that are rich in refined sugars and fats, the more chances you have of developing advanced macular degeneration.
We were very excited to find that these relationships all helped with early macular degeneration because, as I said, to the extent that you can arrest or delay the progress of the early disease, you preserve vision for that many more years.
MICHAEL BUCKLEY: Wow. That is an amazingly powerful correlation there. So, when you look around the world, are rates of macular degeneration connected with those types of diets? Diets that are more prevalent in different regions of the globe?
DR. TAYLOR: That is a very important question. At the moment, we’ve used diet with cohorts in the United States and in Australia. I think those diets are somewhat comparable. We really don’t have as much data as we would like to have, say from countries where people consume much more vegetable-rich diets, or vegetable- and fish-rich diets—some places like Israel, where people consume a lot of vegetables, or what we used to call the Mediterranean diet. I think in some of the Mediterranean countries where people consume a high amount of fruits and vegetables, more fish, less beef, and less sweets, we would anticipate that they would be better protected. We don’t have a lot of data, but the data that we have around does support the idea that consuming diets rich in fruits, vegetables, and fish, and less rich in sweets and high fats, is better for your eyes.
MICHAEL BUCKLEY: That is interesting. I’ve heard a lot of people in the science and medical world talk about a glycemic index. Is that another way of talking about the points you’ve made?
DR. TAYLOR: When you talk about the glycemic index, you are really zeroing in on specific aspects of the diet. What I mean by that is specifically the dietary glycemia. Glycemia refers to the amount of sugar that your blood sees when you consume a food item that contains carbohydrates—carbohydrates being the same thing as sugar. What we found is that people who consumed diets that deliver sugar rapidly to the bloodstream, which we call a high glycemic index diet, those diets are clearly associated with a greater risk for macular degeneration of all stages—be it advanced or early macular degeneration—when compared to people who consume lower glycemic index diets. You might sort of generalize that to say “glycemia”—that is, diets that deliver sugar fast versus diets that deliver sugar slowly. High glycemic versus low glycemic diets. The reason I make that distinction is because some people argue about, what is the glycemic index, per se? Is it a very precise measure? It’s not, but on the other hand, accounting for the glycemia—however it comes through the blood—is a better physiological measure. I hope I’m not confusing you.
MICHAEL BUCKLEY: No. Just to double check, are foods that are high glycemic the ones you mentioned that have a lot of fats and oils? Would high glycemic raise your risk?
DR. TAYLOR: I need to make a correction. “High glycemic” refers to diets that liberate a lot of glucose, a lot of sugar in your blood. Now, I’m specifically making a distinction between that and fat. Fat actually has zero glycemic index. It isn’t good for you, but it has zero glycemic index. That is a way that food manufacturers sometimes alter foods to make them low glycemic index, but they could put fat in there. We don’t want to talk about fat when we are speaking about glycemic index. Glycemic index specifically measures carbohydrates and sugars.
MICHAEL BUCKLEY: I appreciate the distinction. Why do you think, if I am hearing correctly, sugar can be bad for the eyes?
DR. TAYLOR: Correct. So if you drink a lot of soda that is considerably damaging to the eyes. I was shocked to find out that, not too long ago, they estimated that the average American can drink 50 gallons of soda per year. In my mind, that is absolutely mind boggling.
MICHAEL BUCKLEY: Doesn’t sound good when you phrase it that way. In terms of changes that people could make, would a relatively modest change—like switching from white bread to whole grain—are there more nuanced changes that bring about significant benefits? Or is it more of a wider change in diet that would make a difference?
DR. TAYLOR: We calculated that if you consider all of your carbohydrates in your diet to come from bread, which it doesn’t, but make a guess or estimate that all of your carbohydrates came from bread. If you converted just five or six slices of white bread to five or six slices of whole grain bread per day, you could go from a high glycemic index to a low glycemic index and capture or explore the benefits of that low glycemic index diet with regards to macular degeneration. This is a change that is very easily done. This is not like stopping smoking, or changing your diet in a drastic way. We are not asking people to not eat bread, or not eat pasta, or not eat potatoes or corn, but rather to replace a little bit of that with something that is more whole grain or something that liberates the sugar more slowly.
MICHAEL BUCKLEY: That is great. That is very helpful and encouraging.
DR. TAYLOR: By the way, we also did a calculation so that if people just change their diet with these, from five slices of white bread to whole grain bread, you could save 100,000 people from macular degeneration over several years. That is profound.
MICHAEL BUCKLEY: Wow, that is, like, two or three lunches. That is really impressive. Now, does it make a difference if foods are cooked versus raw? Particularly, the ideal foods you are mentioning—does that have an impact? Like cooked carrots versus raw carrots or any type of food.
DR. TAYLOR: The extent to which the particle size of food changes will also change the rate at which the carbohydrates in our food are liberated. The smaller and smaller you make the particle size, the more and more there is a chance that the sugar will be liberated quickly. In other words, steel cut oats, which are relatively large particle sizes, probably liberate sugar less rapidly than a more refined oat product,
MICHAEL BUCKLEY: That is good to know. One more question along those lines. Do these diet changes—are these preventive from someone getting AMD? Or is it more reducing their AMD from getting worse? Am I conflating those two? Where is the nutritional impact?
DR. TAYLOR: You’re asking a very important question. The answer is that we don’t exactly know. Our data suggests that people who consume low glycemic index diets will get, or have the onset of, macular degeneration later. I can tell you that we modeled this whole situation in mice. In mice, I can speak much more definitively, because it is very clear. The mice to which we feed a low glycemic index diet, comparable to the diets that people consume, actually do have delayed onset of any damage of their retina. Mice don’t have a macula, so we have to talk about their retina. Those animals don’t get damage to the retina. Not only that, but if we switch them, from a high glycemic index to a low glycemic index diet, we seem to arrest the damage at very early stages. If that same information plays out in humans, then I think the answer to your question would be yes. We can delay the onset of age-related macular degeneration.
MICHAEL BUCKLEY: That would change quality of life for millions of people. We have a number of callers who actually have very similar questions. It is about AREDS, A-R-E-D-S. I was wondering, in terms of supplements to diets, if you could speak a little bit about AREDS and how it is relevant here.
DR. TAYLOR: So, about 20 or 30 years ago people were concerned with this phenomenon called oxidative stress. Oxidative stress results in damage to a lot of the molecules in various tissues of your body. What AREDS came up with was a formulation of nutrients which they thought were antioxidants—Vitamin C, Vitamin E, beta-carotene—now replaced with lutein and zinc. They found over several studies that people who used these supplements have delayed progress of macular degeneration, going from say medium-stage macular degeneration, to more advanced stages of macular degeneration. There is some delay for the people who use that kind of a supplement.
By the way, I would like to back up one minute in terms of the glycemic index work we did—or the glycemia work we did—that has already demonstrated that people who consume lower glycemic diets are protected against cardiovascular disease and getting type 2 diabetes. It isn’t just protecting your eye; you’re really protecting your whole body.
MICHAEL BUCKLEY: Well, that is great. We have a questions from a caller who wants to get back to the whole grain bread and the examples we talked about. Are there other ways, besides the bread we mentioned, to change from a high-glycemic diet to a low-glycemic diet?
DR. TAYLOR: Yeah, absolutely. In fact I just used the bread as an example. I think the diminishing or eliminating very sweet drinks is one way to do it. Many foods that you find in your food shelves in supermarkets, in fact I was told that something well above 50 percent of foods are sweetened, so it probably is good to eliminate some of those. I’m not suggesting any extreme diets. I just think that if your diet is carbohydrate heavy, do diminish that level of carbohydrate somewhat such that it is a little less heavy, without starting to increase the fat intake.
MICHAEL BUCKLEY: Yeah. That is great. You talked about some of the studies that you’ve done in mice. I was wondering, what are some of the challenges or hurdles that happen when studying nutrition in humans?
DR. TAYLOR: In terms of studying the eye specifically, there are a lot of hurdles. First of all, change happens slowly, and it is very difficult to measure. Even measuring the change in a retina is not easily done; it requires a lot of technology. It is hard for people to come into the office, especially people who may have some retina problems. So, getting people into studies and actually doing the real measurement requires a lot of training. To do the measurements requires specific technology, and there is not a lot of noninvasive machinery that can evaluate the retina so easily. We certainly could use better tools
If you’re talking about cataracts, for instance, and remembering that cataracts are still one of the major blinding diseases, even measuring something as simple as the density of the lens is not all that easily done. It takes a lot of labor to interpret the images that you get from retinas or lenses. Each step of these kinds of investigations is very time-consuming. Also, because the change is gradual, these studies can go on for a prolonged period of time and require a large investment. But if you think about the quantity of money invested, albeit large, it is trivial compared to many of the other things we spend money on. The return on that investment is enormous because remediating or taking care of the medical problems associated with compromised vision is a very large proportion of the Medicaid budget at this time. These investments are very worthwhile, but, at the moment, when you invest in them they seem to be a high-cost item.
MICHAEL BUCKLEY: That is interesting. You’re right. Certainly the long-term costs to families and society from vision loss is just staggering. We have a question from Janet from California wondering, is there any benefit in going to a vegan or vegetarian diet?
DR. TAYLOR: I have not heard that vegetarians are better protected in terms of their eyesight, as compared with people who consume what we call the prudent diet—high fruits and vegetables, fish, and things like that.
MICHAEL BUCKLEY: We also have a question from Seattle. The caller wants to know about Stargardt’s disease and if some of your findings are the same. As part of that, could you also briefly explain what Stargardt’s is and if there are similarities or not in your research between macular and Stargardt’s?
DR. TAYLOR: You know, I better not answer that question because I don’t know enough about Stargardt’s disease. It also has to do with some of the similar compromises of the retina, but I don’t think, as far as I know, there hasn’t been a nutritional study done that has addressed Stargardt’s specifically.
MICHAEL BUCKLEY: For folks who follow health and science news, and read the newspaper or other sources, they’ve been hearing a lot about gut bacteria lately or the microbiome. Would you mind explaining a little bit about that? Is there a connection between microbiome, the gut bacteria, and vision health?
DR. TAYLOR: Yes. What we found recently in our mouse studies—and this is supported by two very preliminary human studies—but we did a lot of work in mice, and we found that the diet affects the microbiota. That is the bacteria in your gut.
You might think that there is no connection between your gut and the eye because, after all, in physical distance you couldn’t get a much larger distance in your body, and even biologically they seem to be unrelated. It turns out that the gut does make some compounds that are absorbed into your bloodstream. Those compounds may affect the vitality and the function of your eyes. It turns out that there really is some kind of a relationship, maybe—I don’t know how intimate to describe it at this point—but there is certainly a functional relationship between the diet, the microbiome with the gut bacteria, and your eyes.
We found, in fact, that when we put mice on low-glycemic-index diets, they had a different microbiome and different gut bacteria from the mice on high-glycemic-index diets. Certain products of that microbiome were related to retinal health. The important thing about our work was that when we took animals that were on the high-glycemic-index diet and switched them back to the low-glycemic-index diet, their microbiome switched back. It switched to a microbiome that resembles the low-glycemic-index group and, as I mentioned before, their retinal disease was arrested. So, we think that this forms an ecology in which you have diet, you have microbiome, you have the body, and all of these are working together to affect your vision. I hope I’m being clear.
MICHAEL BUCKLEY: That is fascinating. I think you’re right; I think most people wouldn’t think there is a connection between their GI region in their body and vision. In terms of keeping your gut bacteria happy and healthy, is that the same thing as the prudent diet?
DR. TAYLOR: Well, the prudent diet is associated with what we consider a healthier gut microbiome. In order to do the proper experiments to answer questions definitively, what one should do is change the microbiome and see if it effects your eyes. Right? In other words, not just change the diet but change the microbiome per se, and see if it affects your eyes. We are just beginning that work now.
MICHAEL BUCKLEY: That is really interesting. It is definitely on the cutting edge. We have some callers who asked if AMD is hereditary. They are wondering [about] the influence of genetics versus the lifestyle issues that you mention. Is one more of an indicator or a factor than the other? In terms of genetics and hereditary versus diet?
DR. TAYLOR: There have been a variety of genetic alterations that are associated with increased risk for AMD. There is no doubt that there is a genetic component to the disease. But does that genetic component have to drive the fact of whether you’ll get the disease or not?
The answer is that it seems to be affected by environmental influences as well. Whether or not you have the genes that may make you more susceptible to AMD, to the extent to which you can, protect yourself by consuming a healthier diet. And I would say starting early in life. Depending on how old people are, they might be talking to themselves, or their children, or their children’s children, in terms of developing healthier eating lifestyles. I think one can begin to enjoy that protection very early on. As I mentioned to you before, it is also associated with protection of cardiovascular disease or heart disease, and diabetes. Why not do it?
MICHAEL BUCKLEY: I’m glad you mentioned that. Here at BrightFocus, we hear from a lot of people who are of the age where they have children and grandchildren and really want to pass on a healthy lifestyle and best practices. Your suggestions today seem like they would work well for people of all ages.
Dr. Taylor, you’ve mentioned a few times the different nutrition studies. How does someone become involved in a nutrition study? Is that something they can sign up for in some fashion? How does that work?
DR. TAYLOR: It is a very good question. We usually work from cohorts that have been previously organized. In other words, there is a large cohort of nurses going across the country. There are 150,000 or so nurses for whom there is an enormous body of data collected. If someone was a nurse and wanted to volunteer for that study or the next phase of that, that would be the right thing to do.
There are also studies going on in communities like Beaver Dam in Wisconsin, or various cohorts that are being organized. People could inquire, say, through their academic ophthalmology department—because it’s usually through academic ophthalmology departments that studies are organized. I would suggest that they speak to their ophthalmologist and ask if they know of any studies that are recruiting subjects and join through their ophthalmologist. Specifically, I think most importantly, having an academically based ophthalmologist.
MICHAEL BUCKLEY: If I were in a nutritional study, what are some of the things that I would do or be asked about to help advance the field of research?
DR. TAYLOR: Well, there are several things. One is that people might ask you to fill out a health questionnaire to tell them what your health is like, and they will ask you for permission to contact your doctor to validate some of the information that you put down or to get more detail. They might, for an ophthalmology study—which we’ve done here when I’ve directed them myself—ask people to come in for an ophthalmological exam. Sit in the chair and let the ophthalmologist give you a full eye exam. That might involve looking at your retina or asking you to do a dilated exam, where they put some drops in your eye and wait for your iris to open up a bit so they can look more clearly at the back of your eye, and maybe your lens as well.
They might ask questions about glaucoma pressure in the eye. That exam might take a couple of hours. I think that those are probably the major hurdles. Maybe, sometimes, they will take a blood sample to corroborate what you have in your blood with what you may have mentioned. If they give you a dietary history questionnaire to fill out, that kind of information is enormously useful for ophthalmologists as we try to do these kind of things. But we need blood from very large numbers of people, so it is crucial that people do participate. And maybe the earlier in your life you get started, the better. That way you have a track record of your disease and when disease develops. Remember, what we want to do is delay the onset of disease.
MICHAEL BUCKLEY: In these situations, are studies sometimes slowed down by a lack of participation? Is it hard to get folks to join studies like this?
DR. TAYLOR: The studies are costly. The hardest thing is to get the money to do the studies. Then, recruiting cohorts is extremely difficult. I think that most academic institutions try to focus on a specific cohort and keep studying them because they can’t recruit more and more cohorts. It certainly is crucial that we have people from every walk of life—be it rich, poor, different background, cultural backgrounds—to participate. We really need to have information that is applicable to black, white, yellow, red…people from all different backgrounds, because we don’t know the effects of genetics on the risk for disease in many cases. So it is critical that we have the nutritional correlation of different cultures as well.
MICHAEL BUCKLEY: That is great to know. Just two more quick questions, and then we will wrap up for today. We have Mary from Illinois with a question about probiotics. I think that is something you hear a lot about and you hear about people taking them, but I’m not quite sure everybody knows what they are and what they do. Is there any impact for vision health with probiotics?
DR. TAYLOR: Well, our data would suggest that—so, the probiotics first of all impact your gut microbiota. They are a way to alter the bacteria in your gut. The extent to which that is really a long-lasting effect—and I’m not sure it’s a long-lasting effect if your diet is highly variable—but that may in fact influence, either positively or negatively, the extent to which you get eye disease. But, those are the kinds of experiments we are trying to do in a very rigorous way in our labs now, specifically with mice where we can actually sterilize them with no microbiota, put in different types of microbiota, and then ask if those different microbiota really affect the risk for disease. At the moment, there really isn’t good information about that for humans. It is very limited.
MICHAEL BUCKLEY: One other quick question from a listener and then we will conclude. Olga from Texas is wondering, are whole grains like whole grain bread versus a wheat bread, are those similar in terms of a prudent diet? Is there a difference? Is one better than the other?
DR. TAYLOR: Yes. That is exactly the conclusion of one of our studies is that people who use whole grain bread—rather than typical white bread, for instance—do enjoy a lower glycemic index diet, assuming they are eating the same amount of bread. It isn’t like one can consume a tremendous amount and the other a little. For the same amounts of bread, those who consume whole grain bread will have a lower glycemic diet than those who consume the white bread, so their glycemic index—or the burden of sugar in their body—will be lower. They will be protected against those diseases where higher risk is associated with higher glycemic diets, like cardiovascular disease, diabetes, and macular degeneration.
MICHAEL BUCKLEY: That’s great. Dr. Taylor, just to conclude, I really appreciate your insights on the impact of diet and AMD. I was wondering, from your perspective as a researcher, do you have some faith or optimism about the future of vision science? How would you assess the future in terms of the research that you and your colleagues are doing and how that will affect AMD and related diseases?
DR. TAYLOR: Well I think—because of the research that has been done over the last 50 years, and it is coming on faster and faster—we can all look forward to preserved vision, and it is really just due to that kind of research, whether it is research to enhance surgical techniques, how to modify the biochemistry within the eye, or even simple things with nutrition that can have the most profound effects in terms of delaying diseases. I think we can look forward to what I call “optimal aging”—that is, to live longer and healthier, or to live healthier longer, with the goal of getting through the older years without as many debilitating disabilities as our parents had.
MICHAEL BUCKLEY: That is a great point. I really appreciate your helping the BrightFocus audience today to understand the impact of lifestyle on healthy aging and offering some great advice that people can share with their children and grandchildren. Thank you Dr. Taylor and thank you to our audience for your time today. I think this has been very helpful. Dr. Taylor, I really appreciate all that you are doing.
DR. TAYLOR: Thank you very much for the crucial support that you’ve given us, and thank you to the patients and people out there for their curiosity. It is wonderful to have people engaged.
MICHAEL BUCKLEY: It’s a pleasure being a partner with you. Thank you very much and this concludes today’s BrightFocus Chat. Thank you.
BrightFocus Foundation: (800) 437-2423 or visit us at www.BrightFocus.org. Available resources include—
- Information on research funded by BrightFocus Foundation
- Update on Clinical Trials for Macular Degeneration (Article)
- Clinical Trials: Your Questions Answered (Publication)
- Healthy Livingand Macular Degeneration:Tips to Protect Your Sight (Publication)
- Macular Degeneration: Essential Facts (Publication)
- The Top Five Questions to Ask Your Eye Doctor (Publication)
- Treatments for Age-Related Macular Degeneration (Fact Sheet)