Black Jamun [Part I]: Nutrition, Anti-Diabetic Effect and More…

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Diabetic Food Series # 1: Java plum (Syzygium cumini)


Jambun preparations are employed by natural health practitioners for treatment of diabetes and related complications, antioxidant, anti-inflammatory, and anti-fertility agents as active treatment and a natural fruit sweetener. It is an evergreen tree but bears ripen fruits post-summer (June-July), marking the beginning of rains. In this part of the blog, we will see the nutrition constituents and pigments in the fruit. We will also discover how the fruit, as well as other parts of the plant, are traditionally known to have anti-diabetic properties, and now are  backed by scientific evidence.

This well-known traditional fruit has less sugars and its seeds have shown potential reducing effect on the blood sugars. Although it’s an expensive fruit, it is a nutritious-seasonal powerhouse of antioxidants, so grab it while it’s in season!

Jamun, the fruit

The fruit is oblong/ovoid and resembles large berries. The fruits develop by May or June, starts from green and turns pink,as it matures, to shining crimson black. A variant of the tree produces white colored fruit. The unripe Jamun are greenish/reddish-white because of phytopigment (phyto -plant, pigment-color) called chlorophyll (green) and carotenoid (red). As it ripens the starches convert to natural fruit sugars and also proteins break to form free amino acids. The ripened fruit is bluish black due to another plant pigment/antioxidant called antho-cyanin (blue). It takes usually a raw Jamun a day or two to ripen and become consumable. It tends to color the tongue purple and has a combination of sweet, mildly sour and astringent flavor.

Nutrition content and constituents


The 100 grams of the fruit contain nutrients: calories (62 k cal), carbohydrate (14 gm), protein (0.995 gm), fat (0.23 gm),  water (84.75 gm). Calcium (15 mg), iron (1.41 mg), magnesium (35 mg), phosphorous (15 mg), sodium (26.2 mg), Potassium (55.00 mg), Carotene: 48.00 mg, Vitamin C (18 mg), thiamine (0.019 mg), riboflavin (0.009 mg), niacin (0.245 mg), vitamin B6 (0.038 mg), folic acid (3 mg), fiber (0.6 gm)

Jamun has significant antioxidant activity because of the pigment anthocyanin as compared to non-anthocyanin fruits such as sapota, papaya, banana, and guava. The phytochemical screening of extracts revealed the presence of phytoconstituents like alkaloids, tannins, saponins, flavonoids, phenols, terpenoids and amino acids and absence of anthraquinone glycosides (compounds accelerate defecation). The fruit pulp accumulated  amount of soluble sugars (6.51–17.6 mg/g), anthocyanins (29.7−47.7 mg%) and free amino acids (7.54–18.9 mg%) while that of seeds exhibited higher amount of crude fibre (6017–10.5 g%), ascorbic acid (90–137 mg%), starch (22.8–29.4 g%), total protein (4.72–7.17 mg%), phenols (45–56.7 mg/g). The entire plant parts can be used as a natural antioxidant source to prevent diseases associated with free radicals.


The Anti-diabetic effect of plant

Different Parts of Jamun Plant Used for Medicinal Properties!

Both with fruit as well as the seed powder benefit at the stage of IFG (Impaired fasting glucose level). It is a symptom of a pre-diabetics hence regulation of IFG prevents the early onset of diabetes and further conditions. Jamun seeds contain substances alkaloid, jambosine, and glycoside jambolin or antimellin, which halts the diastatic conversion of starch into sugar (diastase enzyme converts starch-sugar). Both these are believed to slow down the process of converting starch into sugar. Only 2 g of Jamun seed can reduce 20-30% of fasting glucose due to the “Jamboline” in a period of just 2 months in early diabetics/prediabetics. Jamun seeds ensure a greater availability of insulin by either increasing its secretion or preventing it from degrading fast.

The consumption of Jamun juice can facilitate the usage of sugar by the cells, thereby causing the levels of sugar in the blood to be normalized. Jamun extracts used in conjunction of Gymnema (Gurmar), bitter melon (karela), Salacia (saptrangi), cinnamon, fenugreek makes an excellent product. Especially if combined with cinnamon, can be excellent for controlling surging blood sugar levels. Using Jamun extract reported an increase in cathepsin B activity, which assisted in proteolytic (protein breakdown) conversion of proinsulin to insulin.

The bark extract of Jamun, inhibited an enzyme called α-glucosidase which breaks down stored energy in the liver called glycogen to release glucose into the blood. Leaves are also used in combination with other anti-diabetic leaves as a diabetes antidote.

An active compound named ‘Mycaminose present in Jamun stimulates the secretion of insulin from pancreatic beta-cells and works similar to an anti-diabetic drug called ‘Glibenclamide’

Traditional medicine soaks pieces of jamun wood overnight in water and recommends to drink early morning for diabetes

How much is usually recommended?

Jamun: 10 – 12 jamuns giving 50 gram of fruit intake per serving.

Jamun juice:

Around 0.5-2 tsp (2.5-10 ml) at least three times of ripe fruit juice, daily (depending upon the individual) has been recommended for the treatment of diabetes.

Dried seed powder:

It reduces insulin dosage and around 2 g daily can reduce excessive urine of any cause.

Jamun leaves:

A leaf decoction is seen helpful in pre-diabetics. 60 grams of Jamun leaves paste made by mixing them with water for diabetes, dividing the dose for 3 times a day for 10 days to diabetics. Check if you got your results and repeat after two months.


  1. Milk shouldn’t be taken before/after eating jamun. A gap of > 1-hour should be kept for both.
  2. It’s not recommended to have it before or after surgery.
  3. Too much jamun is known to cause cough and accumulation of sputum in lungs.


So that was all about therapeutic uses of Jamun. Next Up in the series is

Black Jamun [Part II]: Health Benefits & Recipes Takeaway…

Poorvi Anandan, Nutritionist

Poorvi Anandan, Nutritionist

A Nutrition and Food Science grad, Poorvi is currently pursuing her Master's Degree in the same. She believes that a way to a better health both is through one's stomach :) She is on a quest to find out the innate wisdom of Intuitive Eating and also propagates it. She strongly believes, health is a holistic concept than just changes made in a Diet plan. Although she is not into cooking, she enjoys developing recipes and enjoys experimenting. But, mostly likes to be fed :P

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