Introduction

Dates are considered as one of the oldest and most ancient crops in Southwest Asia and Northern Africa. Dates have been cultivated and utilized as an important staple food as far back as 5500-3000 BC [1]. Medjool dates are but one of hundreds of varieties of dates. Besides being sweet and tasty, they contain phytochemicals that many claim to have health benefits, such as the ability to lower cholesterol, treat constipation, treat diabetes, and improve bone health.

Are any of the health statements backed by scientific evidence? Let’s examine the scientific literature.

What’s So Good About Medjool Dates?

Medjool dates are one of the hundreds of species of dates that arise from the date palm tree. The name Phoenix dactylifera originates from its fruit- phoenix from the Greek means purple or red and dactylifera refers to the finger-like appearance of the fruit bunch.

Nearly every part of the date palm tree has been used: the wood and leaves have been used for timber and fabric for houses and fences. Rope and baskets are made from its leaves. The stalk is used as fuel. The date seeds have fed livestock, and of course, the fruit has been eaten as is, or produced into vinegar, flavoring, or bakery items. [2]

The date fruit goes through 5 stages of pre-maturation, maturation, and ripening described as Harbabauk, Kimri, Khalal, Rutab, and Tamr. The fruits are considered edible at three stages of maturity- khala, rutin, or tamr. Tamr- the dehydrated form, is the form most commercially available.

It should be noted that the chemical composition of the date differs, depending on the stage of maturation. For instance, with maturation there is an increase in sugar levels but a decrease in fiber, minerals and vitamins. [3]

Dates consist of 70% carbohydrates. Fructose and glucose are the major sugars found, and as they are considered reducing sugars, they are readily absorbed by the GI tract and lead to a rapid rise in blood sugar levels. Dates are also high in dietary fiber in the forms of cellulose, hemicellulose, pectin and lignin. The content of fiber ranges from 7.5g/100g to 8.0g/100g in fresh to dehydrated dates, respectively. [3]

Dates contain a little protein (1.8 g/100g) and essentially no fat (0.15g/100 g). In terms of minerals, dates are rich sources of selenium, copper, potassium and magnesium and moderate amounts of manganese, iron, phosphorus and calcium (USDA). Dates are a moderately good source of vitamin B6, B9, B2 and B3. However, Vitamins B1, C and A are found in relatively low amounts.

Phytochemicals (any biologically active compounds found in a plant) in dates include carotenoids, phytosterols and polyphenols. Carotenoids are the major class of phytochemicals found in date fruit, with lutein and beta carotene as the predominant carotenoids. It should be noted however, that a 1983 study by Gross et al [4] showed that the total amount of carotenoids decreases rapidly as the fruit ripens.

Phytosterols are found exclusively in plants and are structurally similar to cholesterol. Although the seeds of date palm and the pollen grains are the major reservoirs of phytosterols [5], Kikuchi and Miki [6] isolated a phytosterol mixture of campesterol, stigmasterol, beta-sitosterol, and isofucosterol in the edible flesh of the date fruit.

It is believed that phenolic acids are part of a plant’s defense against pests and other pathogens. In date fruit, the phenolic acids are primarily derivatives of benzoic or cinnamic acid. Vinson et al. compared the amount and quality of phenolic antioxidants among dried and fresh fruit.

They found that “Dates have the highest concentration of polyphenols among the dried fruits. Figs and dried plums have the best nutrient score among the dried fruits, and dates among the fresh fruits. Processing to produce the dried fruit significantly decreases the phenols in the fruits on a dry weight basis.” [7]

Is There Any Research?

A search of PubMed for the term “Phoenix dactylifera” brings up 684 articles. Of these, only 9 are considered clinical trials. There is only one entry in clinicaltrials.gov: The Effect of Date Fruit on Mood and Cognition in Healthy Adults which is currently recruiting volunteers.

In comparison, let’s look at another dried fruit native to the Middle East and western Asia- the fig (Ficus carica). In PubMed, there are 3158 articles for the term “figs,” 313 for the term “Ficus carica.” There are 58 clinical trials in PubMed, and on clinicaltrials.gov, 5 using the term “figs,” 2 using the term “Ficus carica.”

Is It A Healthier Alternative to Table Sugar?

Are dates a healthier alternative to table sugar? The short answer is “Yes… and maybe.” I think a bit more of an explanation is needed. Table sugar is a refined sugar which comes from sugar cane or sugar beets. They are “processed” to extract the sugar, which is primarily sucrose. Sucrose is a disaccharide, which means it is a molecule with two monosaccharides (the most basic form of sugar)- glucose and fructose (see image). It contains 390 calories/100gm serving. There are no significant amounts of micro-nutrients in refined table sugar.

In humans, sucrose is broken down into glucose and fructose by the enzymes sucrase or isomaltase glycoside hydrolases, which are in the membrane of the microvilli (tiny fingerlike projections) which line the first section of the intestines. The resulting glucose and fructose molecules are then rapidly absorbed into the bloodstream.

This provides a quick source of energy and a rapid rise in blood glucose after ingestion. Rapid changes in blood sugar can be a problem in individuals with defective glucose metabolism, such as hypoglycemia (low blood sugar) or diabetes mellitus.

Dates also contain sucrose, especially in their early maturational stages. As the date ripens, the sucrose is converted to fructose and glucose. As just stated, these forms of sugar can be rapidly absorbed, theoretically causing a spike in blood sugar. This wouldn’t necessarily be a problem for healthy people, but is it a problem for those with diabetes?

Glycemic index is a measurement of which compares the effect of a particular food on glucose levels after ingestion. It measures the rate at which glucose enters the blood as well as the time it takes until glucose levels return to normal. It compares the measurements for that food to those which occur when a subject is given a standard amount of pure glucose.

Carbohydrates with a low GI value are more slowly digested, absorbed and metabolized and cause a lower and slower rise in blood glucose and, therefore insulin levels. A glycemic index of ≤55 is considered low, 56-69 is considered medium, and ≥ 70 is considered high. But this is not the whole story when it comes to deciding what effect a food will have on blood glucose.

Glycemic Load (GL) combines both the quantity and quality of carbohydrates, i.e. besides GI, it also considers the amount of glucose in a typical serving size. For example, the mean GI of watermelon is 76, which is the same as the GI of a doughnut. However, one serving of watermelon provides 11 g of available carbohydrate, while a medium doughnut provides 23 g of available carbohydrate. Glycemic load is calculated using the formula:

GLFood = (GIFood x amount (g) of available carbohydrateFood per serving)/100

For a typical serving of a food, GL≥20 is considered high, GL = 11 to 19 is intermediate and GL≤10 is low. In the example above, despite similar GIs, one serving of watermelon has a GL of 8, while a medium-sized doughnut has a GL of 17.

A few studies have looked at the glycemic index (GI) of several varieties of dates. Two studies, by Alkaabi et al [8] and AlGeffari et al [9], calculated the glycemic indices of several date varieties. Alkaabi calculated the GI for the Fara’d, Bo ma’an, Lulu, Dabbas and Khalas varieties of dates (all cultivars of Phoenix dactylifera grown in the United Arab Emirates). The GI was measured in both healthy subjects and in patients with Type 2 diabetes.

The GI’s ranged from 46.3 ± 7.1 to 55.1 ± 7.7, putting them in the low to moderate GI categories. In addition, “there were no statistically significant differences in the GIs between the control and the diabetic groups for the five types of dates, nor were there statistically significant differences among the dates’ GIs.” AlGeffari looked at 17 varieties of dates, including medjool dates.

They found GI’s in a range similar to those calculated by Alkaabi, without any significant differences in GI between the varieties. They also measured the GL of the different varieties and found a large variation ranging from 8.5 to 24. Medjool dates came in at 17.2 (intermediate).

Ahmed et al [10] examined the effect of the date fruit variety Aseel on blood sugar levels in normal and diabetic rats. In healthy rats, administration of dates demonstrated mixed effects on glucose levels compared to controls and rats treated with standard antiglycemic medications. In diabetic rats, administration of one of two doses of date fruit (300 or 600mg/kg) lead to a significant rapid rise in blood sugar, followed by a significant decrease in sugar compared to diabetic controls.

The decrease was not as significant as that found in rats treated with the antiglycemic medication. They postulated that Aseel dates “possess antiglycemic activity because of its phytochemicals, low GI, and high fiber content …[which] makes it an effective medicinal food in the management of diabetes.”

Rock et al [11] looked at the effect of Medjool or Hallawi dates on serum glucose, serum oxidative status and lipid levels (more on this in the next section). Ten healthy human subjects consumed 100g/day of either Medjool or Hallawi dates for 4 weeks. Fasting blood glucose did not change over the test period for either group.

One other factor needs to be considered when deciding whether dates are a healthier alternative to table sugar- what else do you get when you eat a date? As mentioned above, date fruit is high in fiber, has a moderate amount of some vitamins and minerals and has phytochemicals which have potential health values. Sucrose has no significant micronutrients.

Bottom line

Dates are a healthier alternative to table sugar. Some caution might be taken in patients with diabetes, specifically in terms of the amount of date fruit consumed.

Does It Reduce Cholesterol or Triglyceride Levels?

There is growing scientific evidence that hyperlipidemia (high blood fats/cholesterols) and associated complications, such as atherosclerosis, may be modified by changes in nutritional habits. A diet rich in polyphenols, flavonoids, and antioxidants can have anti-atherogenic effects. For this reason, researchers have started to examine whether date fruit can have anti-hyperlipidemic properties.

Borochov-Neori et al [12] did in vitro studies (a process performed in a test tube, culture dish, or elsewhere outside a living organism) of the phenolic composition and anti-atherogenic properties of nine Israeli date varieties (Amari, Barhi, Deglet Noor, Deri, Hadrawi, Hallawi, Hayani, Medjool, and Zahidi).

The highest phenolic concentration was found in the Amari, Deri and Zahidi varieties. They tested the date extracts’ effect on LDL oxidation (a process which occurs when LDL cholesterol particles in your body react with free radicals—unstable molecules that are produced as a result of normal metabolism, a disease, or exposure to toxins). All the date extracts inhibited LDL oxidation, but by how much varied greatly between species.

The most effective were Barhi and Hayani, and the least effective were Hallawi, Medjool and Hadrawi. Lastly, they looked at the effect of date extract on cholesterol accumulation inside of macrophages, which is believed to be one of the earliest factors in the development of atherosclerotic plaques. Enhancement of cholesterol removal from macrophages would be considered anti-atherogenic.

According to the authors: “The varietal order of the ability of date ethanol extracts to increase serum-mediated cholesterol removal was as follows: ‘Hallawi’ > Deri > ‘Medjool’ > ‘Amari’ ≈ ‘Zahidi’ >‘Hadrawi’ > ‘Deglet Noor’. The extracts of ‘Barhi’ and “Hayani’, on the other hand, had no effect.”

In addition to glycemic effects mentioned in the previous section, Rock et al [11] and Ahmed et al [10] studied the effect date fruit on lipid levels. Ahmed used the Pakistani date variety Aseel in his study on albino rats fed either a standard diet (control) or a high fat, high sugar diet (hyperlipidemic group). The hyperlipidemic group were additionally fed distilled water, date fruit suspension (at 300 or 600mg/kg), or atorvastatin (a treatment for high cholesterol) for a two-week period.

The results showed a significant decrease (P≤ 0.05) in cholesterol and a highly significant (P ≤ 0.005) decrease in triglycerides, LDL and VLDL in animals receiving 300mg/kg of date fruit. The results were similar to those obtained with atorvastatin. In animals fed 600mg/kg date fruit, only serum triglycerides and VLDL were significantly decreased.

Rock’s group looked at Medjool and Hallawi dates. The ten patients in their study ate 100g/day of either Hallawi or Medjool dates for 4 weeks. Neither date significantly affected the patients’ BMI (body mass index), total serum cholesterol, or VLDL, LDL or HDL fractions. Serum triglyceride levels significantly (p<0.05) decreased by 8 or 15% after Medjool or Hallawi date consumption, respectively.

They found that Hallawi dates had higher total phenolic concentration by 20-31% compared to Medjool dates, as well as a significant proportion of catechins (a flavan-3-ol, a type of natural phenol and antioxidant). Hallawi dates also had a 24% higher antioxidant power over Medjool dates. These differences may account for the increased ability of Hallawi dates as an anti-atherogenic nutrient.

Bottom Line

Dates contain polyphenols, flavonoids, and antioxidants which may have anti-hyperlipidemic and anti-atherogenic properties. However, date varieties may differ significantly in the concentration of these compounds. Although Medjool dates do contain these helpful substances, other date varieties may be more useful for this purpose. More clinical trials with larger numbers of participants are needed.

Does It Prevent & Relieve Constipation?

As dates are high in fiber, it would not be surprising that dates would be recommended for the treatment or prevention of constipation. But is there more to this than just fiber?

A study by Souli et al [13] looked at the effect of date pulp extract on gastrointestinal mobility in rats. They found that date pulp from Deglet-Nour dates increased, in a dose-dependent fashion, the gastrointestinal mobility. Stool that passes through the intestine in a rapid fashion has less water reabsorbed from it and therefore is softer than slow moving stool.

The microbiome is the collection of all the microorganisms living in association with the human body. Microbiome communities consist of a variety of microorganisms including bacteria, viruses and fungi. Because of their small size, microorganisms make up only about 1 to 3 percent of our body mass (that’s 2 to 6 pounds of bacteria in a 200-pound adult) but bacterial cells outnumber human cells by a factor 10 to 1.

The biggest population of microbes reside in our gastrointestinal tract – our “gut” — mostly in the colon. Abnormalities in the intestinal microbiome can be a factor in constipation. [14]

Two studies by Eid et al. [15, 16] studied the impact of palm date on the microbiome in the human intestine. In the first study, date fruit extract (variety: Ajwa) was incubated in vitro with a fecal slurry (a term I hope never to have to write about again) obtained from three healthy volunteers.

They examined the amount and types of bacteria as well as bacterial metabolites found before and after incubation. They found that date extract was able to significantly increase the growth of beneficial bacteria, such as bifidobacteria, but other bacterial groups, such as lactobacilli and C. histolyticum did not change.

In the second study, Eid recruited 21 health human volunteers randomly assigned to a control group or an intervention group fed 7 dates for 21 days. After a 15-day washout period, the participants crossed over to the alternative intervention. The researchers claim that there was a significant increase in stool frequency with date extract, but how do you define a stool frequency going from 1.21 to 1.4 as an improvement?

There was no significant difference in stool type, abdominal pain, bloating or flatulence.  They also found no significant alterations in the growth of microbiome or of microbiological metabolites except for a significant reduction in fecal ammonia levels.

Bottom Line

Dates can be considered a high fiber fruit that may be useful in the maintenance of bowel regularity or the treatment of mild constipation. There is not enough clinical evidence at this time to support a role in improved GI motility or changes in the intestinal microbiome.

Does It Boost Energy Levels?

A 100 g serving of date fruit (tamr stage) contains nearly 300 calories. As mentioned above, the sugars in date fruit (glucose and fructose) are readily absorbed from the intestine. So yes, it can temporarily boost your energy levels. The key word here is temporary. Many energy bars currently on the market are now including dates as one of their ingredients.

There are no studies in PubMed with clinical trials concerning “dates and energy boost.”

Bottom line

Dates are fine for a quick energy boost before a workout, but the effect is temporary.

Is It Good for Bone Health?

There are no studies in PubMed that look at dates and bone health. The recommended daily intake (RDI) of calcium is 1,000 mg per day for most adults, though women over 50 and everyone over 70 should get 1,200 mg per day. Although dates do have a modest amount of calcium, with 64 mg/ 100g, you’d have to eat a whole lot of dates to make a significant dent in your RDI for calcium.

There are so many other foods that are higher in calcium such as  milk, cheese, yogurt, sardines, canned salmon, beans and lentils, and/or dark leafy greens.

Bottom Line

There is no direct evidence linking dates with bone health.

Is Eating Medjool Dates Safe?

Dates have been a food staple for thousands of years, so overall its safety profile is very good (with the mild caution mentioned above concerning those with issues with sugar metabolism). There are very few studies which examine the safety of eating dates. One, by Lynch et al [17] looked at the safety of a water-soluble extract from date fruit on rats. No observable adverse effects were noted with levels up to 2000 mg/kg of body weight/day.

Another study by Abdallah, Krska and Sulyok [18] looked for the occurrence of fungal and bacterial metabolites in 28 samples of dried date palm fruit collected from shops different shops in Upper Egypt. They found a number of mycotoxins (toxins produced by fungi) in 6 of the samples. Unfortunately, only an abstract is available, so additional details are not known.

Bottom line

Although dates are considered a safe dried food to eat, with a long shelf life, they can occasionally go bad. Signs that this may have happened include:

  1. They are discolored or moldy (This does not include a white film frequently present on the outside- this is just crystallized sugar).
  2. They smell bad.
  3. You find “visitors” in your dates. Organic dates are not treated with pesticides, so they have the potential to attract insects which burrow into the fruit. It’s best to remove the seed from the date before eating it. This will expose any hidden critters. Keeping dates in a closed container will combat against unwanted pests.

Conclusion

Dates have been used for thousands of years as a food staple. They are high in sugar and fiber, and have moderate amounts of minerals, vitamins and phytochemicals. The evidence for additional health benefits is limited, and plagued by the great variation in the composition of date varieties and the use of different varieties of dates in the scientific studies.

There’s no good reason not to eat dates as a part of a healthy balanced diet. Enjoy!