Nutrition Diva

Prunes: How many are too many?

Episode Summary

Research shows that eating prunes every day has multiple benefits. But is it too much sugar?

Episode Notes

Don't miss last week's episode where I talk about how you should eat if you are looking to lose fat and gain muscle at the same time. Here's a link: https://nutrition-diva.simplecast.com/episodes/lose-fat-and-gain-muscle-at-the-same-time-update

Nutrition Diva is hosted by Monica Reinagel. A transcript is available at Simplecast.

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Episode Transcription

I got a great email last week from a listener who was confused about prunes. Or more specifically, by information about prunes they were finding online. 

“There are sources that recommend 100 grams of prunes per day for constipation. This works out to 38 grams of sugar. Although it’s naturally occurring sugar (not added), it still seems like a lot for every day. Other sources say that the sorbitol in prunes mitigates the effect on blood sugar–and that the laxative effect of the sorbitol is as useful as the fiber content. Is the sorbitol included in the total sugar or separate? Does it really mitigate blood sugar response? Is eating that many prunes every day a bad idea? Signed: Confused and Constipated”

So many good questions in there!  And with any luck, we can address both the confusion and constipation in this episode.

Let’s start with the nutritional content. 

A serving of pitted prunes (about 3-4 prunes) contains about 100 calories, 16 grams of sugar, 3 grams of fiber, and about 5 grams of sorbitol. The sorbitol is not included in the amount of sugar.

Sorbitol is a type of molecule known as a sugar alcohol. It contains neither sugar nor alcohol. (Hey, don’t shoot the messenger. I don’t name the molecules.) 

Although they taste sweet, sugar alcohols are lower in calories than regular sugar and they don't affect blood sugar levels. You'll often find them in sugar-free products or foods made for diabetics. Other common sugar alcohols include xylitol, maltitol, and erythritol. But unlike most of the sugar alcohols we encounter in the food supply, the sorbitol in prunes is naturally occurring. 

Sugar alcohol, when consumed in sufficient quantities, can have a laxative effect. You’ll sometimes see warnings to this effect on foods sweetened with sugar alcohols. In the case of prunes, however, the laxative effect of the sorbitol is seen as a feature, not a bug.  

Indeed, although the fiber may help a bit, it is probably the sorbitol in prunes that is responsible for their well-deserved reputation as a treatment for constipation. Prune juice, for example, contains much less fiber than whole prunes but is just as effective. 

Unfortunately, sorbitol can also create uncomfortable bloating and gas pains and is a common trigger for those with IBS. For example, prunes would not be allowed on the low FODMAP diet.

On a per-serving basis, the sugar content of prunes is comparable to other fruits. And, like most fruit, prunes have a relatively low glycemic impact–meaning that they don’t have as negative an impact on your blood sugar as sugar in, say, candy or soda. This is due in part to the fiber and water and other constituents that make up the whole-food matrix. (We talked about the food matrix a few episodes ago.) This is why we don’t count the sugar in fruit toward the recommended limit for added sugars, which is about 25 grams per day.  

However, just to make sure we’re not skimping on other healthy foods, I generally recommend keeping fruit to 2-4 servings a day, with no more than one of those servings being in the form of juice. Eating 100 grams of prunes a day would be about 3 servings, and while this would certainly fit into that guideline, it does sort of use up your fruit allowance for the day. And I don’t know about you, but I still want to be able to include peaches, melon, berries, and other fruits in my diet without feeling like I’m overdoing it. 

Fortunately, you can likely get the benefit of prunes at a far lower dosage than 100 grams per day–and it is less likely to cause gas and bloating. Assuming that your gut tolerates prunes, to begin with, I think I’d start with one serving a day and see how it goes. (Pun intended)

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Prunes are, by the way, totally delicious, and quite versatile. 

Again, don’t overdo it (especially if you’re cooking for kids) or you may have some unintended consequences. 

Although prunes and prune juice can be an effective way to treat and prevent constipation, you don’t need to (and probably shouldn’t) put all of your eggs in that one basket. Eating a variety of higher-fiber foods, drinking plenty of water or other fluids, getting regular exercise, and keeping a regular eating, sleeping, and elimination schedule are all good strategies for maintaining good bowel habits.

Prunes are also good for more than constipation. They are high in potassium, vitamin K, boron, and other minerals that support a healthy heart as well as contribute to healthy bones. 

In fact, there has been quite a bit of research done on prunes and their effects on bone health. Some of the results have been quite impressive. One study, for example, found that subjects who had already experienced substantial bone loss were able to completely reverse these losses by eating prunes every day! Others show that eating prunes can help prevent the bone loss from occurring in the first place. 

The only problem is that these studies were all done in mice and involved eating prunes as 25% of the entire diet. I’ll just give you a moment to contemplate the potential impact of that.

There have also been a few trials involving actual humans. One compared the effects of eating 100 grams of prunes with 75 grams of dried apples on bone mass in women who were post- menopausal. The study went on for one year, during which both groups also took calcium and vitamin D supplements. Both groups experienced similar increases in the bone density of their hips and thigh bones; the group eating the prunes had slightly better results in their spines and forearms. While the difference at those two sites was statistically significant, I’m not sure it was all that meaningful.  

Unfortunately, the study did not include a group that just took calcium and vitamin D without eating any dried fruit. That makes it hard to say whether either the prunes or the dried apples offered any substantial benefit above and beyond the supplements. A subsequent study found that eating half that many prunes each day works just about as well as eating a full 100 grams. Again, however, the positive effect—while statistically significant—was modest. Another human study asked whether eating prunes would enhance the positive effect of resistance or weight training on bone mineral density. It didn’t.

Although prunes contain several nutrients known to have a positive influence on bone health, you can get all of these nutrients from other sources, of course. For example, 1/4 cup of broccoli gives you as much vitamin K as you’d get from the same amount of prunes. A quarter of an avocado or six dried apricots has the same amount of boron as 3-4 prunes. And an ounce of almonds or a half cup of kidney beans will give you at least as much potassium as a serving of prunes.

I’m not sure that prunes offer a unique and/or significant advantage in terms of preventing or reversing bone loss–but, hey, they can’t hurt. They are a delicious and nutritious fruit and can be very useful for those who struggle with constipation. But one or two servings a day is probably plenty.  

Thanks again to “Confused and Constipated” for suggesting this great topic. I sincerely hope you are less confused (and less constipated!). 

If you have a question you'd like me to answer, you can email me at nutrition@quickanddirtytips.com. You can also leave me a message at 443-961-6206

I’d also like to invite you to check out my other podcast. It’s called the Change Academy, where Brock Armstrong and I squabble about the art and science of behavior change. You can find it on all the major podcast platforms, so whatever app you’re using right now to listen to me, just head to the search bar and type in “Change Academy.”

Nutrition Diva is a Quick and Dirty Tips podcast. It's audio-engineered by Nathan Semmes with script editing by Adam Cecil. Our Podcast and Advertising Operations Specialist is Morgan Christianson. Our Digital Operations Specialist is Holly Hutchings. Our Marketing and Publicity Assistant is Davina Tomlin, and our intern is Brendan Picha. 

Thanks for listening and remember to eat something good for me!