The alkaline pH food tables in two of the papers cited below, Remer and Manz’s and Scialla and Anderson’s, give their scores per 100 grams. That sounds neutral, but as the figures below show, it favours fruit that has had its water taken out. Dried fruit looks far stronger per 100g than the fresh fruit it came from, and dates sit with the dried fruit. This article puts fresh and dried fruit side by side, using the same formula and the same database, to see how much of that strength is real and how much is just weight.
The score behind the lists
Gerry Schwalfenberg’s 2012 review (PubMed 22013455) says foods can be categorized by their potential renal acid load, or PRAL. He groups fruits, vegetables, fruit juices and potatoes among the foods with a negative acid load, and lists grain products, meats, dairy products and fish as having relatively high acid loads. In their 1995 paper (PubMed 7797810), Remer and Manz worked out PRAL values per 100g, from an average of 23.6 mEq for certain hard cheeses, through 0 for fats and oils, to about −3 for fruits, fruit juices and vegetables.
Scialla and Anderson’s 2013 review (PubMed 23439373) prints the equation, adapted from Remer and applied per 100g serving: 0.49 × protein (g) + 0.037 × phosphorus (mg) − 0.021 × potassium (mg) − 0.026 × magnesium (mg) − 0.013 × calcium (mg). The same review notes that this kind of estimate is dependent on accurate nutrient composition databases. So every figure below uses one source, USDA FoodData Central (FDC).
Grapes and raisins on the same scale
FDC lists 100g of raw grapes (FDC 174683) at 80.5g water, 69 kcal and 191mg potassium. The same weight of dark seedless raisins (FDC 168165) has 15.5g water, 299 kcal and 744mg potassium. Run both through the equation and grapes come to about −3.2 per 100g, raisins to about −12.1.
On a per-100g list, the raisin looks almost four times as alkaline. Now divide each score by the calories. Grapes give about −4.7 per 100 kcal and raisins about −4.1. Per unit of energy, the fresh fruit is slightly ahead.
Plums, prunes and apricots
The pattern holds for the other pairs in FDC. Raw plums (FDC 169949) score about −2.6 per 100g and prunes (FDC 168162) about −13.4. Per 100 kcal, both sit near −5.6 to −5.7. Raw apricots (FDC 171697) score about −4.3 per 100g and dried sulfured apricots (FDC 173941) about −21.6, yet per 100 kcal both land at about −9.0.
In each pair the dried version looks several times stronger per 100g, while the score per calorie barely moves. On these figures, most of what drying adds is concentration.
Where dates fit
FDC lists Deglet Noor dates (FDC 171726) at 20.5g water and 282 kcal per 100g, and Medjool dates (FDC 168191) at 21.3g water and 277 kcal. In water and energy they sit next to raisins and prunes, far from grapes or plums. Their PRAL works out at about −11.9 per 100g for Deglet Noor and −13.7 for Medjool. Per 100 kcal that is about −4.2 and −4.9, close to grapes and raisins and below plums or apricots.
Among these fruits, then, a date is not unusually alkaline for its calories. With about a fifth of its weight as water, it packs a lot of potassium and a lot of energy into a small piece: FDC puts one pitted Deglet Noor date at 7.1g.
Comparing by portion instead
The NHS uses a different yardstick. It counts 80g of fresh fruit as one of your 5 A Day, and says 30g of dried fruit is equivalent to around 80g of fresh fruit. It names dates in that list, with currants, sultanas and figs, and says dried fruit should be eaten at mealtimes, not as a snack between meals, to reduce the impact on teeth.
By portion, 30g of Deglet Noor scores about −3.6 and brings about 85 kcal. An 80g portion of grapes scores about −2.6 with about 55 kcal. The date portion is a little more alkaline and carries about half as much energy again.
What “required” can and cannot mean
Schwalfenberg describes a tightly controlled serum pH of about 7.4 (7.35 to 7.45), while urine may vary from acid to alkaline depending on the need for balancing the internal environment. Remer and Manz found a correlation of r = .83 between net acid excretion and urine pH. So a diet’s acid load is read in the urine, while the serum, on Schwalfenberg’s account, stays in its narrow range. What the per-100g lists add is a ranking, and as the fruit pairs show, part of that ranking is water content rather than anything special in the food.
About this site and how to get in touch
The about page describes the site as a date supplier serving retail and wholesale buyers, with delivery across Malaysia and customer service on WhatsApp. Questions on quotes, stock availability or delivery can go through the form or WhatsApp on the contact page, and more date articles are on the blog. A link kept from the earlier version of this post points to Kurma Mazafati Malaysia.
The video below is from the YouTube channel AbuAyyash Farms, titled as a look at Medjool date farming and a date processing factory.
This article is general information about food composition, not personal advice. If you have a health condition or take regular medication, speak to your doctor before making big changes to what you eat.