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As a follow-up to the cover story about fruit in this month’s UC Berkeley Wellness Letter, we interviewed Ed Blonz about this and related topics. A member of the Wellness Letter editorial board, Ed Blonz holds an M.S. and Ph.D. in nutrition from the University of California at Davis, and has more than 25 years of experience in the fields of nutrition, food and health. He is the author of seven books, and his syndicated column “On Nutrition” appears in newspapers in the U.S. and Canada. The interview was conducted by Jeanine Barone, the nutrition and sports medicine editor of the Wellness Letter.

Jeanine Barone: People tend to think of fruit as a food group where you can't go wrong. Are there health concerns with fruit? Can eating too much fruit be bad for you?

Ed Blonz: The idea of "can't go wrong" is misleading with any food. There are logical constraints with just about anything we do and that's especially the case with our diet. So irrespective of the health attributes of any item or food group, there's always the possibility of eating too much. At which point, the healthful attributes are displaced by the fact that you are not getting enough of the other things your body requires. The key concept is to get the appropriate amount of all the different foods our bodies need for optimal health. Although the concept of balance may be boring, it really does make a lot of sense. Balance doesn't mean eating fruit all day long.

Q Can eating fruit be an issue for those who want to lose weight—as Gary Taubes suggests?

A Well, I don't accept that. It would be very unusual. But, of course, there can be circumstances where adding fruit or fruit juice doesn't help matters. Let's say, for example, you are taking in all the calories you need to maintain your body weight. In such a situation, eating more fruit could possibly lead to weight gain if you just add the fruit to your normal food intake, rather than eating it instead of other foods. In that case, it wouldn’t be the fruit that's creating the problem, but the foods of lesser value that provide the rest of your daily calories.

Actually, fruit can help if you are trying to lose weight because it contains the sugar fructose. There has been a lot of controversy regarding fructose and weight control. But fructose does have the advantage of being sweeter than other simple carbohydrates, so you need fewer calories to achieve a given degree of sweetness. Fruit doesn't have that many calories and it's a great source of nutrients.

Q How big a health concern is fructose in general?

A Fructose has different metabolic effects than other carbohydrates, and it can be a concern if it's consumed in excess—which is true of just about any food. Studies suggesting that fructose has adverse effects have used large amounts of it. For instance, in one recent study, people got 30 percent of their daily calories from fructose—more than anyone normally consumes. Still, in our culture it’s easy to eat lots of fructose, since soda and sugar-sweetened foods are loaded with it.

But, in fact, fruits don’t supply all that much fructose, and their assets outweigh the potential problems. Fruits are generally good sources of vitamins, minerals, fiber and phytochemicals that act as antioxidants; they can improve blood cholesterol levels; they help lower blood pressure; they improve blood sugar control; and over time they can reduce the risk of coronary heart disease. There is so much going on with fruit beyond their fructose.

Q Is the real problem high fructose corn syrup, which is added to sodas and so many commercial sweets?

A There's been a lot written about high fructose corn syrup. It's made from corn starch, which comes from corn, obviously. Corn starch is a long chain of glucose molecules and it doesn't taste very sweet. Corn syrup is made by breaking apart this long chain into the individual glucose molecules. When this happens, it becomes sweeter because glucose is sweet. Food processors convert the glucose into fructose, which is even sweeter. Fructose is about 1.4 times as sweet as glucose. Then they blend this fructose together with the glucose, producing high fructose corn syrup. There are a number of high fructose corn syrup blends, but the common one is about 55 percent fructose, 45 percent glucose. It's quite similar to honey, which is a 50/50 mix of fructose and glucose. Sucrose, that is table sugar, is also 50/50 fructose and glucose, but in this case these two molecules are attached to each other. So high fructose corn syrup is not innately dangerous or toxic. Rather, the problem with it is that Americans tend to eat so much of it and get it from processed foods and drinks that bring little or nothing to the table besides calories.

Q How bad are beverages containing high fructose corn syrup? What if you drink one a day? Or are they a problem only if you consume them several times a day?

A It does depend on how much you drink. Let's be honest: the only benefits from these drinks are for the companies that profit from the sales. The beverages provide nothing more than artificially flavored and colored sugar water. It makes little difference which caloric sweeteners are used. Still, if you’re in good health and have a balanced diet, an occasional glass of one of these beverages won’t hurt you. But if you drink lots of these sugary beverages, and don’t have a healthy diet, there may be health risks over the long term.

Q Is high fructose corn syrup worse than table sugar because it isn’t natural?

A Whether it's natural or not is not the issue here. When we consume table sugar, it's digested and broken down into its fructose and glucose components. So you end up with about as much fructose. Switching from high fructose corn syrup to table sugar makes little or no difference.

Q Do you drink 100% fruit juice?

A I tend to consume fruits rather than fruit juices. I drink orange or tomato juice occasionally, and sometimes pomegranate or Concord grape. I also drink diluted lemon juice when I exercise every other day.

Q We hear about the special properties of honey, but others say it's similar to eating high fructose corn syrup. What do you think?

A Well, honey is not high fructose corn syrup— it is basically a natural source of fructose and glucose. I think honey can bring amazing flavor. There are many different types of honey. But any special properties from honey are just part of the mystique of marketing around it. I don't think, from a health standpoint, that honey provides anything special.

Q We’re supposed to eat at least five fruits and vegetables a day. Do you think we should switch the emphasis and say "vegetables and fruits" instead of "fruits and vegetables"?

A Either works for me. It's more important to be consuming them as whole foods. And we need to think of these types of foods in a large perspective. A plant cannot get up and run away from danger or threats from the oxidizing rays of the sun or insect pests. So whether it's a fruit or a vegetable, it needs to have a complete nutrient package that will allow it to survive all the insults that nature and the environment will throw their way. And they have to have it all together in order to produce that next generation because that's what the food is all about, that's what the seeds are all about. And it's only when we eat the whole food that we get this entire package of nutrients: fiber and phytochemicals and all the components that protect the plant. And only then can these foods provide benefits to our bodies. It doesn’t matter whether it's fruit or vegetables.

Q How many fruits do you eat a day?

A I have dried fruits with my cereal most mornings. Then during the day I'll usually have a piece of fruit depending on what's in season. It could be an orange, tangerine, an apple. I like berries and occasionally I have a banana.

Q I know someone who only eats fresh fruit salad for breakfast. Is this a good idea?

A It's a personal decision. It's not something I would do, but I see nothing wrong with that. We all have to develop our own ways to get the healthful foods we need to nourish our body.

Q What do you think about people who eat lots of veggies but no fruit, and those who eat lots of fruits but no veggies?

A There are always going to be twists on a theme. So I tend to encourage the consumption of all types of foods. But we're always going to find people who are the outliers, who are doing it in a strange way. In some cases these people are very healthy. There's no one diet that works for everyone.

Q What do you think about the new Weight Watcher's move to assign zero points to fruit?

A I think it's fine. Weight Watchers has proven to be an excellent system for many people, and it's lasted for many years. I think it's a positive step and it encourages the consumption of whole foods.

Q Fruit smoothies are all the rage. What do you think about that?

A I'm not a big smoothie person. I prefer to eat whole fruits instead. On occasion, it’s fine, but there's always the temptation to overload it with extra ingredients. A smoothie is not a good way to replenish fluids, since you're usually getting a big concentration of calories and sugar. Water is the best way to replenish fluids.

Q Marketers make lots of claims for certain juices, such as pomegranate or acai, claiming they are “super foods.” Is there any one juice that provides the most health benefits?

A I wouldn't point to any one juice as being that special or having that many assets. None stands head and shoulders above the rest. But that's not really the point. Eating should not be thought of as a prescription. You need to enjoy what you eat, and just temper your habits with a little guidance and common sense. So I don't like the idea of promoting any one juice, or one fruit. Choose those that really satisfy your taste buds.

UC Berkeley Wellness Letter, July 2011