Welcome to Straight Talk on Health. I’m your host Dr. Chet Zelasko. Together with WGVU in Grand Rapids MI, I examine the world of health and health research. Whether it’s research that makes the news, another miracle diet, or a new food fad, I look at the science behind them, and let you know whether it’s real or not. You can check out other things that I do on my website Drchet.com and sign up for my free emails.
One of the changes I’ve made in selecting topics to talk about is to read the table of contents of the scientific journals to which I subscribe, especially the nutrition journals. It’s easier to see what’s controversial by looking at news feeds, but they miss a lot of positive nutrition science. One question that’s ever-present is this: when it comes to nutrients, is getting nutrients from supplements as good as getting nutrients from food?
In this case, the research effort coincides with a major marketing effort by a company that’s related to products containing dehydrated fruits and dehydrated vegetables. It raises a question: would it be better to just eat the fruit and vegetables? I'm going to give you that answer right now and it's a resounding yes. But could there be some benefits from taking a supplement that has dehydrated and ground up fruits and vegetables in it? That's what a group of researchers decided to examine in a study titled Efficacy of Dietary Polyphenols from Whole Foods and Purified Food Polyphenol Extracts in Optimizing Cardiometabolic Health: A Meta-Analysis of Randomized Controlled Trials recently published in the journal Advances in Nutrition in early 2023.
Here's what they did. Researchers searched four databases of scientific journals to find randomized-controlled trials that examined the effect of either polyphenol-rich foods or polyphenol extracts on risk factors for cardiovascular disease (CVD). It’s estimated that there are more than 8,000 types of polyphenols, including flavonoids, polyphenolic amides, phenolic acids, resveratrol, and ellagic acid. You’ll find polyphenols in fruits, vegetables, spices, herbs, teas, nuts, and seeds.
They found over 1,100 studies that fit the profile. Using subject, statistical, and nutrient criteria, they whittled the number of studies down to 46. Why so few? The reason is that there may have been duplicate studies where parts of a large study were published in different journals based on the same data. Or more than likely, they were not studies that were well constructed nor well executed. Not everything can be a randomized control trial where the researchers nor the subjects know who is getting the experimental design substance. It's easier to do with supplements than it is with food because even if you grind up the food and put it in a liquid form, it's still going to have a taste and flavor that people may recognize. So when you consider all the things that they had to consider in those 1100 original studies, it's really not surprising that they only ended up with 46. Then, they conducted a meta-analysis of the impact of food and supplements on the following CVD risk-factors: systolic BP, diastolic BP, endothelial function, fasting blood glucose, total-, LDL-, and HDL-cholesterol, C-reactive protein, Il-6, and waist circumference. For those of you who have listened to the podcast before, you know I'm not a fan of meta-analysis. There are too many that are done by companies that specialize in statistics. They get the parameters from the researchers, do the heavy lifting in terms of finding all the studies, whittling them down, and giving what they find to the actual researchers to decide what should and should not be included. Believe it or not, there are some meta-analyses where the researchers get the finished product with the statistics already completed. Not all but that seems to be commonplace today as it doesn't require any work on the part of the researchers and yeah they can get credit for having a publication. That helps with either getting tenure or fulfilling a research requirement as a physician. I'm not saying it's all bad because to be honest, the statistics used in studies in the last five years can be very difficult to understand and even more challenging to interpret.
On top of that, nutrition studies are usually messy, and this one was no exception. I spot-checked the 46 studies and found different foods for the polyphenol sources and different extracts for the supplements. Still, it was as well-done as such a study could be. The results of the polyphenol study examining the impact on cardiovascular (CVD) risk factors were mixed. Here’s what the researchers found:
Neither the polyphenol-rich foods which include berries, spices, herbs, teas, nuts, seeds, etc. nor the extracts had a significant effect on LDL- or HDL-cholesterol, fasting blood glucose, IL-6, and C-reactive protein.
When looking at the studies using polyphenol-rich food, there was a significant decrease in systolic and diastolic BP.
The polyphenol extracts had a significant effect on total cholesterol and triglycerides and had a greater reduction of waist circumference.
However, when both whole-food polyphenols and polyphenol extracts were used together, there was a significant reduction in systolic BP, diastolic BP, endothelial function, triglycerides, and total cholesterol.
Before we jump out of our skin and start taking all kinds of fruit and vegetable extracts from supplements, let's look at the upside and downside of the study. The Upside was that polyphenols in foods and supplements were effective in reducing risk factors for CVD, both independently and when combined. This wasn’t a seminal paper that changes approaches to nutrition forever, but there were benefits. I think that’s something that was needed. It supports what my approach has always been: eat as healthy a diet as you can, and fill in the nutritional gaps with supplements.
As for the downsides of the study, there were several issues. The studies included in the meta-analysis had little cohesiveness as to subjects used, sources of the foods, or the type of supplements; some used capsules while others used juices or drinks.
The issue with foods, among many, is the digestion and absorption of the active polyphenols. There’s competition with other nutrients and then the issue of the microbiome—is it functioning properly in every subject? That could have a major impact on what is absorbed and what is not.
The issue with supplements, besides the delivery system, is whether the dose is appropriate or therapeutic. Would the amount of quercetin found in apples be the correct dose, or would you need to eat 10 apples? Would it respond the same way in the body isolated from the other polyphenols, or would another factor come into play? That would be an issue when taking specific plant based material as whole, ground up, fruits and vegetables.
Wrapping up our look at this particular study, in spite of its flaws, I think this study was fantastic. It demonstrated that nutrients extracted from foods can be effective in reducing CVD risk. It demonstrated that foods alone aren’t the answer and neither are supplements; it’s their use in a complementary fashion where the benefits may be found. The researchers set the stage for putting more effort into nutrition research, because there’s so much we don’t know. Yet.
Let's go back and take a look at this popular dietary supplement that contains the powders of dehydrated fruits and vegetables. When you look at the label, it has two products. One is a fruit blend of 16 fruits and it's subdivided into categories that are supposed to address specific aspects of your health. And a second supplement that contains a blend of 15 vegetables, again dehydrated and ground up. In fact, if you dig into the details about the product, it's ultra-fine ground so that there is better absorption. They did not provide references that support that statement.
I decided to look at how much plant material is left after taking out all the water of a serving of spinach. Going to the USDA FoodData central, a serving of spinach is supposed to be 1 cup or 30 grams. If you take away the water, you would be left with roughly 2 grams of plant material including the fiber. That translates to 2000 milligrams per serving. If you look at the supplement, the vegetable supplement has a total of 2000 grams of the plant dehydrates from 15 vegetables. That works out to roughly 130 mgs per vegetable if it were evenly distributed. That would include the spinach. If they are included in equal amounts, that would be about 10% of what would be found in a serving of spinach. Would that be enough spinach to provide enough of the phytonutrients they claim are in the product or not? We don't know because there is no research to support this blend of vegetables.
That raises another potential problem. Having all the vegetables in one supplement and all the fruit in another supplement means that you're going to have hundreds of phytonutrients competing for absorption. Will all of them be absorbed? Which ones will compete with each other? And when we throw in the fruit blend with 16 different fruit dehydrates, what impact will that have? We don't know because they didn't do any research or at least use the research of others to support their position that you're going to get benefit from taking the supplement. All they really have are a variety of testimonials about the efficacy for people. I'm not suggesting it's bad and I'm not suggesting it's good. What I am saying is that even if they use non-GMO, fruits and vegetables, grown under ideal organic conditions as the source of their plant material, we don't know how beneficial it can be because there's no research to support it. Except the study I reviewed in this podcast, the meta-analysis of 46 studies.
The way that I see it, your mother was right: eat your fruits and vegetables. That's the best way to make sure you get all the nutrition that you can. But it wouldn't hurt if you have the ability, to compliment your diet with quality nutritional supplements that contain plant concentrates and dehydrates. That way you get the best of both worlds.
