Plum is a common name for certain members of the genus Prunus domestica, which belongs to the rose family. It produces a smooth-skinned, elliptical, heart-shaped, oblong, ovate or round fruit with a flat seed. They are typically yellow, red or blue in colour.
Plums have been native to North America for a long time.
Native, wild North American plums were gathered and eaten by aboriginal peoples and European colonists alike. Today, however, European and Japanese plums are the more common variety that is grown for food.
European plums were first brought to the Maritimes by French colonists. Later, Japanese plums were introduced to North America around 1870 and domestication of native species began around 1850.
Plums are a very nutritious fruit. You can get them fresh, or dried. You likely know dried plums better as prunes.
Both yellow and red are descended from Japanese plums. Blue plums and their dried version of blue prunes are forms of European plums.
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Prune and plum nutrition
The difference in plum and prune nutrition is only because of the serving sizes.
Nutritional values for plums are based on a typical serving; one piece of fruit whereas prunes are for a 28.5 g (1 oz) serving or 3 prunes (1). The information below is based on those respective servings.
Both are relatively low in calories. Plums have 30 calories and prunes have about 60.
One plum as 1 g of fiber and prunes 2 g; not a big difference.
Carbohydrate & sugar
Both contain carbohydrates. A plum has 8 g and prunes 18 g. Because there are about 3 prunes (dried plum) per serving, the amount of carbohydrate will be higher for prunes.
Both contain naturally-occurring sugars with one plum providing 7 grams worth and prunes 11 grams.
Both contain potassium, one plum has about 105 mg whereas prunes have 210 mg per serving.
Prunes are a very underappreciated source of much-needed iodine. Iodine is needed for healthy thyroid function and its hormones, which is why iodine is needed for good mental health. Many are not aware of the signs and symptoms of an iodine deficiency.
Both plums and prunes contain small amounts of other essential nutrients such as folate, vitamin C, calcium, magnesium, phosphorus, and vitamin K1 (prunes).
Health benefits of plums and prunes
Several different health benefits have been researched and documented for these humble fruits. They contain several vitamins and minerals, in addition to fiber and antioxidants, that may help reduce your risk of several chronic diseases.
Plant foods all contain plant (phyto) nutrients. Phytonutrients aren’t classic nutrients like vitamins and minerals are but rather compounds that help humans thrive. Plums and prunes are rich in one category of these called polyphenols.
Plums and prunes contain more phytonutrients than other more common fruit such as peaches and nectarines (2, 3).
Anthocyanins, a specific type of polyphenol, appear to be the most active phytonutrient found in plums and prunes (3, 4, 5, 6). They may even play a role in cancer prevention and heart disease prevention (6, 7).
There’s no, “may prevent or treat” constipation when it comes to prunes. They’re a go-to for constipation management and with great reason:
But it’s not just the fruit. Prune juice for constipation treatment is standard. It’s a standing treatment in all the hospitals I’ve worked in including my current place of employment, especially in the geriatric population.
Prunes do have fiber which helps support bowel health and bowel function. The fiber in prunes is mostly insoluble which helps to bulk your stool and increase transit time (the rate at which digestive foods moves through your digestive tract) (8, 9, 10).
But fiber isn’t prunes only weapon against constipation. Both prunes and prune juice contain sorbitol; a sugar alcohol, or polyol, that has a laxative effect (9, 11).
Prunes and their sorbitol content are arguably better than fiber for preventing constipation. A common fiber type, psyllium, which is used to make many over-the-counter fiber supplements appears to be less effective as prunes (12).
In one study, people who consumed 2 ounces/50 g of prunes every day for three weeks reported better stool consistency and frequency compared to a group that consumed psyllium (13).
Of note, both interventions contained 6 g of added fiber but prune’s sorbitol content proved more effective.
Blood sugar control
You’re probably thinking how could a fruit, with its natural sugars, help to lower blood sugar?
But plums and prunes do have properties that help them do just that – believe it or not. Plums and prunes don’t seem to cause a significant rise in blood sugar making them less of a concern compared to other carbohydrate-rich foods like rice or potatoes (14, 15).
It’s thought that the polyphenols influence how sugars are digested and absorbed by the intestines (16). Also, plums and prunes increase a hormone called adiponectin that regulates blood sugar (15).
And yes, to a small degree, their fiber content will blunt the rise in blood sugar; fiber slows the rate of which your body absorbs sugar. In this way, plums and pears can help to keep after meal (post-prandial) blood sugar more balanced (15, 17).
Bone health? But isn’t bone health all about consuming heaps of calcium? 🙂
Studies have shown a link between prune consumption and reduced risk of bone diseases and conditions such as osteoporosis and osteopenia; the hallmark of both being low bone density (18, 19).
Amazingly, prunes have not only been shown to prevent bone loss, but they may also be able to reverse bone loss that has already occurred (18, 19, 20).
We don’t know for sure why, but we think prunes are beneficial because of their phytonutrient content. Prune’s polyphenols and other antioxidants seem to lower inflammation and protect bones against bone resorption (the process where bone is broken down and releases its minerals) (20, 21, 22).
A study comparing the consumption of two different amounts of prunes in 48 osteopenic women (65-79 years old), found that compared to 10-12 prunes per day, 5-6 were just as effective at preventing bone loss (23).
Additionally, research suggests prune consumption may increase levels of certain hormones that are involved in bone formation (18).
A 3-month study looked at the effect of a placebo (dried apple) compared to 100 g of prunes (10-12) on bone-friendly hormones. After 12 weeks, the prune group saw an increase in insulin-like growth factor 1 (IGF-1) and bone-specific alkaline phosphatase (BSAP). Both hormones are involved in bone formation (24).
Human research on prune intake and bone health has produced promising results. Compared to other fruits, prunes appear to be the most effective at preventing and reversing bone loss (18).
The cardiovascular system includes your heart, the blood vessels (arteries and veins) and your blood. Anything that affects the health of those, affects the cardiovascular system.
With that, eating plums and prunes by have a beneficial effect on cardiovascular health. The main proxies include blood pressure, blood sugar, and lipid ratios (the balance of blood fats like cholesterol and triglycerides).
One study showed that consuming prune juice and eating prunes (a mere 3 to 6) each morning on an empty stomach, for eight weeks resulted in lower blood pressure compared to those who didn’t. Total and LDL cholesterol were also lowered (25).
Another study found that eating 12 prunes daily for eight weeks resulted in lower LDL cholesterol in a group of men with hypercholesterolemia (elevated cholesterol) (26).
Some of the cardiovascular benefits (total & LDL cholesterol) are attributed to the fiber content, and potassium where blood pressure is concerned (27), most is likely due to the numerous phytonutrients (6).
Plum and prune phytonutrients (polyphenols) positively impact cardiovascular health in ways that go beyond traditional nutrition (vitamins and minerals) (28, 29).
Digestive health is a popular focus of health these days. The ‘gut’ is seen as an important organ when it comes to overall health.
Prunes contribute to digestive health in many ways: dietary fiber, phytonutrients/polyphenols and sorbitol (which isn’t necessarily ‘evil’ as many have it made out to be).
Prunes have been shown to improve stool output, gut transit time (improve frequency of bowel movements) and positively impact the gut bacteria, specifically the Bifidobacteria type (30).
A study comparing 50 to 100 g of prunes per day found another benefit with respect to bowel movements; both doses appear to decrease any discomfort associated with “going number 2” (31).
An exciting way in which plums and prunes benefit the gut is their impact on the microbiota. Why it’s not entirely understood, the sugar alcohols in this fruit (mannitol and sorbitol) are metabolized by gut bacteria. These metabolites positively change the gastrointestinal environment and animal studies have shown a decrease in precancerous lesions (32).
Cancer risk reduction
Plums and prunes are rich in a class of polyphenols/phytonutrients called anthocyanins. They give certain fruits (like plums & prunes) and vegetables their distinct bright red, blue and purple colours (33).
Anthocyanins have been shown to exhibit anti-cancer activity against multiple cancer cell types in vitro (test tubes) and tumor types in vivo (organism studies) (5).
In rat studies, prunes have been shown to reduce precancerous lesions in intestinal tract cancer models (34). Benefits are likely due to their ability to reduce inflammation, likely some modification of genes and their prebiotic fiber content which positively impacts the gut environment (34).
Sugar alcohols have been used for decades as an alternative to regular sugar (sucrose or table sugar).
They are similar to regular sugars, but as the name implies, have an alcohol molecule attached to the sugar molecule BUT they don’t have a mood-altering effect like regular alcohol (ethanol).
These sugar alcohols, also called polyols, are naturally occurring in fruits and vegetables or they can be added to foods as a low calories alternative to other refined sugars.
Sugar alcohols, when consumed in large enough amounts, can have a laxative effect…for anyone. A common side effect of eating too many candies etc sweetened with them, is gastrointestinal upset and at worse, diarrhea (35).
Sugar alcohols, or polyols, are a type of FODMAP. In fact, the “P” in FODMAP stands for polyols. Those following a low FODMAP diet need to be on the lookout for polyols. Sorbitol, which is found in plums, prunes and prune juice, is one such sugar alcohol.
For the average person, sorbitol is easily tolerated and it’s the main reason prunes and prune juice are so effective at preventing and treating constipation.
Ten to twelve prunes have about 15 g of sorbitol; eating 5-6 prunes, twice a day is one of the best ways to prevent constipation, especially traveller’s constipation. 🙂
Buying and storing
Shop for plums with good colour and a full, smooth, relatively heavy feel. They should yield to gentle pressure, especially at the end opposite the stem. Good quality ripe plums should have a distinctively “plumy,” sweet fragrance.
Skip shrivelled skin, bruises or brown spots unless maybe you want to make a compote, jam or even to cut up and freeze for smoothies.
On the other end, leave any plum that feels hard (but not firm); they’ve been picked too soon and won’t ripen nicely. Also, best to avoid excessively soft fruit or any sign of leakage or decay; no luck really salvaging them
Ripen plums at room temperature out of direct sunlight or in a loosely closed brown paper bag. Ripe plums should be refrigerated and eaten as soon as possible.
Most prunes are packed in cellophane bags or canisters with a resealable lid.
They do not require refrigeration as long as they’re covered to keep safe and sound. They should be stored in dry, cool conditions. Keeping them airtight and even out of the fridge will help keep them moist.
Possible effects of prunes and prune juice
Even though they’re tasty and have many health benefits, prunes and prune juice can also have a few negative effects.
Gas and bloating.
- Prunes contain concentrated sorbitol, a sugar alcohol that can cause gas and bloating. Fiber, also contained in prunes, can also cause gas and bloating.
- Some are more sensitive to sugar alcohols and those with digestive issues may need to avoid prunes and prune juice.
- Prunes contain insoluble fiber, which can worsen diarrhea. Best to avoid until bowel movements return to normal.
- When you increase your intake of fiber, it’s important to drink enough fluids. If you don’t, you could get constipated. So be sure to drink plenty of water when adding prunes to your diet.
To avoid these problems, introduce prunes and/or prune juice into your diet slowly. This will give your digestive system time to adjust to them, and symptoms of gastrointestinal upset should be reduced.
Most will benefit from limiting prunes to a serving of about 1/4 to 1/2 cup per day.
Because prunes are dehydrated, it’s easier to overeat them compared to a fresh prune, and like any juice, prune juice is a concentrated source of calories. Mindfulness is needed.
A serving size of six uncooked prunes (or 57 g) has 137 calories and 21.7 g of sugar. A 1-cup serving of prune juice has about 182 calories.
So you should be mindful of the calories and sugar in these food items, which can add up if you find yourself consuming them often throughout the day.
Other potential side effects and a caution
Prunes do contain trace amounts of histamine, so it’s possible (though uncommon) to develop a reaction to them if you have a histamine sensitivity.
You shouldn’t drink prune juice if you’re already experiencing diarrhea.
Adding plums and prunes to your diet
Plums and prunes are delicious and nutritious and while adding whole plums to your diet is pretty straightforward. When in season, eating fresh fruit is easy. But for some, including prunes into their diet is more challenging.
Here are some easy ways to add plums and prunes to your diet:
- Eat them alone as a snack.
- Slice plums or prunes and add them to yogurt
- Add prunes to your breakfast oatmeal.
- Mix prunes with nuts, other dried fruits such as apricots, and dark chocolate chips for a healthy trail mix.
- Add prunes to baked goods.
- Blend them (or use a small amount of prune juice) in your protein shakes or smoothies.
- Puree prunes and eat them as “prune butter” or jam.
- Add prunes to a savory stew.
A stated, make sure that you increase your prune intake gradually to avoid any unwanted digestive effects.
Plums are very nutritious.
Both plums and prunes are an excellent source of vitamins, minerals, fiber, and phytonutrients.
The abundance of potassium and phytonutrients such as polyphenols, flavonoids, and organic acids are responsible for their numerous health benefits.
These include reducing the risk for many chronic diseases, such as osteoporosis, low bone density, cancer, cardiovascular disease, and poor digestive health.
Best of all, you get all of those health benefits in tasty and delicious food that requires little preparation, and easy to incorporate into your diet. Enjoy!
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Doug Cook RDN is a Toronto based integrative and functional nutritionist and dietitian with a focus on digestive, gut, mental health. Follow me on Facebook, Instagram and Twitter.