Since the origins of human existence, people have looked to their natural surroundings for sources of nutrition and health remedies. One of the authors (SJ), after traveling in many parts of sub-Saharan Africa and talking to traditional healers in rural communities, has found that the plants in one’s immediate vicinity often will contain a surprising amount of constituents with nutritional and medicinal benefits. One example is the baobab tree (Adansonia digitata, Malvaceae), one of the largest sub-Saharan botanicals, which the author has termed a “Cinderella species” — one that is often overlooked, but once properly researched and examined, is shown to be a novel foodstuff with significant health benefits. This article addresses some of the traditional nutritional and medicinal uses, the chemical and pharmacological profile, and scientific facts and myths of the iconic baobab tree.
With its distinctive silhouette, broad trunk, unusual root-like branches, and large, velvety fruit, baobab is the best known of all African trees. The tree is steeped in legend, and due to the many different uses of its various parts, it is known by the local people as the “tree of life.” A large tree can hold up to 4,500 liters of water; its fibrous bark can be used for rope and cloth; its edible leaves and fruit can provide relief from sickness; and its hollow trunk can provide shelter for as many as 40 people.1 So, it is easy to see why it has earned this name.
There has been a renaissance of ethnobotanical surveys of medicinal plants, especially in the cosmetics and nutrition sectors where industry chemists and product formulators are constantly looking for new and natural healthy ingredients.2,3 Since its approval as a novel food ingredient by European Union (EU) food regulators in 2008,4 the native African baobab tree has gained increasing market and media exposure. This paper presents a study of the ethnopharmacological uses of the tree in southern Africa and its significant array of ethnobotanical and potential commercial uses.
The baobab tree is also known as the upside-down tree, boab, boaboa, bottle tree, kremetart tree, cream of tartar (not to be confused with the multipurpose ingredient potassium bitartrate, which is made from fermented grapes [Vitis vinifera, Vitaceae]) tree, or monkey bread tree. The word “baobab”is derived from the Arabic bu hobab, meaning “fruit with many seeds.” There are eight species of baobab: six are indigenous to Madagascar, one to Australia, and one to mainland Africa (A. digitata). Adansonia digitata grows in most countries south of the Sahara, although in South Africa it is restricted to the Limpopo and Mpumalanga provinces.5
A massive deciduous tree with a round or spreading crown, it can grow to heights of 20 m (approximately 65 ft). The trunk is stout, tapering, and abruptly bottle-shaped, and it can be up to 12 m (39 ft) in diameter. The bark is smooth, grayish-brown, and has heavy folds. The bark on the lower part of the trunk often bears scars from local people who harvest it to retrieve the strong fibers, and from elephants that try to obtain water from the trees. However, even with trunk damage, baobab can continue to grow and regenerate new layers of bark. The leaves are alternate and palmately compound in mature plants. The flowers are waxy, white, crinkly, and mostly solitary, growing up to 20 cm in diameter. The ovoid-shaped fruits are roughly 15 cm long with a hard, woody shell covered by velvety hairs, and they contain kidney-shaped seeds that are embedded in a powdery pulp. In sub-Saharan Africa, baobab is harvested in April and May, and flowers are harvested from November to December. The tree favors a dry, woodland habitat with rocky, well-drained soil.
Baobab is a slow-growing tree and, as such, there has been much speculation about the age of large trees and their growth rate. Carbon-dating techniques and analyses of core samples suggest that baobab trees with 10 m diameters may be around 2,000 years old.5
TRADITIONAL MEDICINAL USES
Baobab leaves, bark, and fruit are used for food and medicinal purposes in southern Africa. The bark has astringent properties and has been used traditionally to alleviate colds, fevers, and influenza (a decoction made from the fresh bark is taken as a beverage for one week to treat the flu).6 The wood, bark, and seeds of the tree are known to have anti-inflammatory properties.7 The leaves may be used as an antiperspirant, and they also have been used to treat fever, kidney and bladder diseases, as well as asthma and diarrhea.8-14 In African traditional medicine, baobab fruit pulp is used to treat fever, diarrhea, dysentery, smallpox, measles, hemoptysis (the coughing up of blood), and as a painkiller. For the treatment of infant diarrhea, a mixture made from the floury pulp mixed with millet flour and water is given to the child until cured.8 For dysentery, baobab leaves are administered orally or crushed into a drink. Leaves can also be used in hip-baths to treat parasitic skin infections. The seed can be pulped and applied externally or added to water as a drink to treat gastric, kidney, and joint diseases.15
During the rainy season when the trees are in leaf, baobab is a good fodder tree, especially for game such as elephants, kudus, nyalas, and impalas. At the end of the season, cattle eat the fallen leaves, and various game species relish the fallen flowers. As far as humans are concerned, the roots can be tapped for water, and the young roots are cooked and eaten. Young leaves can be cooked and eaten like spinach or dried and powdered to be used later. The leaves are rich in ascorbic acid (vitamin C), sugars, and potassium tartrate.16 The acid pith of the fruit is rich in vitamin C and can be used to make a refreshing drink. Baobab seeds, the oil of which is high in calories, can be eaten fresh, dried, or roasted as a substitute for coffee (Coffea spp., Rubiaceae). The pulp and seeds have high nutritional value in the form of iron, calcium, and vitamin C, and they can be fed to livestock toward the end of the dry season when grazing is poor.
The citric and tartaric acids found in the pulp inspired one of baobab’s popular names, “cream of tartar tree.” Baobab pulp is often used in baking as a milk-curdling agent, as a flavoring for yogurt and ice cream, and as a source of calcium for pregnant and lactating women. Due to its high pectin content, the pulp also has been used traditionally as a thickening agent for sauces and jams. In some African cultures, the pulp has been used as an ingredient in cosmetics.17
Baobab has a long history of use as a medicinal product. The botanist and physician Prospero Alpini (1553-1617) wrote in his book De plantis Aegypti liber that fresh baobab fruit had a very pleasing taste, and that the Ethiopians used it on burns and rashes and to cool the effects of serious fevers. For these afflictions, they either chewed the flesh of the fruit or pressed it into a juice with added sugar. Alpini also wrote that in Cairo, Egypt, where fresh baobab fruit was unobtainable, Egyptians made preparations from its powder to treat fevers, dysentery, and bloody wounds — an indication that this plant has been used medicinally for centuries.18
Local medicinal uses for baobab are richly varied.15 The bark, along with dried leaves, is made into a preparation called lalo that is used to induce sweating and reduce fever. The bark contains a quantity of edible, insoluble, acidic, tragacanth-like gum, which is used to disinfect skin ulcers and wounds. Mucilages made from baobab phloem sap in the bark are used as a remedy for gastrointestinal inflammation.15,19 The bark also is popular as a cardiotonic; this traditional use has been confirmed experimentally by researchers who demonstrated the positive inotropic effect of an ethanolic bark extract on isolated atrial muscles of rats.20
In Sierra Leone specifically, the leaves and bark are used as a prophylactic against malaria. In the Congo, a bark decoction is used to bathe children with rickets, and in Tanzania, as a mouthwash to treat toothache. In Ghana, the bark is used as a substitute for quinine in cases of fever. In southern Zimbabwe, the leaf is eaten as a vegetable, while in central Africa it is used as a diaphoretic (perspirant) against fevers, and the seeds as a remedy for dysentery. In Messina, South Africa, the powdered seed is given to relieve hiccups in children.1
In Nigeria and Senegal, baobab fruits are reputed to be effective against microbial diseases. This has been confirmed in tests against certain bacteria and fungi, although the active constituents responsible for these effects have yet to be isolated.21 A prepared root infusion is used as a bath for babies to maintain soft skin.20 Conditions including asthma, sedation, colic, fever, inflammation, diseases of the urinary tract, ear trouble, backache, wounds, tumors, and respiratory difficulty are treated orally. The leaves are considered an emollient and diuretic, and leaf decoctions are used for earache and otitis (inflammation of the outer ear, middle ear, or ear canal).15 In general, leaf preparations are used for the control of kidney and bladder diseases, asthma, fatigue, and as a tonic, blood cleanser, prophylactic, and febrifuge (a medication that reduces fever). They have also been used for diarrhea, inflammation, insect bites, the expulsion of guinea worms, internal pain, and other afflictions.
The pulp of baobab fruit contains astringent compounds (e.g., tannins and cellulose), which exert an antidysenteric action due to an osmotic effect and an inhibitory interaction with acetylcholine, the neurotransmitter that is responsible for gut spasms. The fruit has anti-inflammatory, febrifuge, and analgesic properties due to the presence of saponins and sterols; experimental data have also shown the fruit to have hepatoprotective effects.20 The leaves have both antihypotensive and antihistaminic properties, and the leaf powder, due to its antihistaminic properties, has been suggested as an anti-asthmatic.22
Anticancer activity is virtually unheard of in plants in the family Malvaceae, yet research suggests that A. digitata may have antitumor properties.1 In Senegal and Guinea, both a decoction and a poultice made from baobab fruit extract were shown to have antitumor activities.23,24 The specific bioactive constituents responsible for these actions have not yet been identified.
Sickle-cell anemia is a problem that has affected Africans for centuries. One Nigerian remedy is derived from a concoction of an aqueous extract of the bark of A. digitata, which is used locally for its antisickling activity. However, after testing various concentrations on washed sickle-cell blood samples, researchers in Nigeria found that the results did not support the anecdotal reports.25
In vitro studies in Saudi Arabia have shown that aqueous extracts of A. digitata pulp demonstrate hepatoprotective activity against carbon tetrachloride administered in rats. Consumption of certain Adansonia fruits may play an important role in human resistance to liver damage. The mechanism of action for liver protection is unknown, but it may be due to the triterpenoids, beta-sitosterol, beta-amyrin palmitate, alpha-amyrin, and/or ursolic acid in the fruit.26
Antiviral, Antibiotic, Anti-inflammatory, Antipyretic, and Analgesic Effects
Researchers in Togo, western Africa, and Canada studied 19 medicinal plants of Togo and analyzed them for antiviral and antibiotic activity. Of the 19 species studied, 10 demonstrated significant antiviral activity, and all but two showed antibiotic activity. A. digitata was the most potent, exhibiting activity against each of the three tested viruses (herpes simplex, Sindbis, and polio).27 Further antimicrobial tests undertaken in Nigeria confirmed the aforementioned results.21
Aqueous extracts of baobab fruit have exhibited marked anti-inflammatory, antipyretic (in rats given 400 and 800 mg/kg dosages), and analgesic (in mice two hours after administration) effects.28,29 Phytochemical examination has revealed the presence of sterols, triterpenes, saponins, tannins, and glycosides, which may play a role in these actions.
Other studies support baobab’s anti-inflammatory and antiviral activities as well. In one experiment, baobab leaves, fruit pulp, and seeds were extracted with three different solvents: water, methanol, and dimethyl sulfoxide (DMSO).7 Researchers compared the three extracts to determine the minimum concentration required to inhibit 100% of three viruses (herpes simplex, influenza, and respiratory syncytial virus), and assessed their effects on cytokine secretion (interleukin [IL]-6 and IL-8) in human cell cultures. Cytokines are cell-signaling proteins that play an important role in the immune system. The leaf extracts exhibited the most potent antiviral properties, particularly the DMSO extracts, and the influenza virus was the most susceptible virus. Pulp and seed extracts were less active but still showed significant results. Cytotoxic activities of the extracts were evident only at much higher concentrations. Additionally, the researchers found that the extracts — particularly the leaf extracts — acted as cytokine modulators, meaning that they possessed anti-inflammatory activity. Overall, the results indicate the presence of multiple bioactive compounds in different parts of the plant, which may explain some of the medical benefits attributed to traditional leaf and pulp preparations. These promising results highlight the urgent need for more scientific research to be conducted on the baobab tree.
Epidemiological evidence has linked intake of vitamin C and other antioxidant micronutrients to health benefits, by virtue of their capacity to trap reactive oxygen species (ROS) that are associated with degenerative diseases and damage to biological systems.30 Current scientific evidence has helped boost consumer interest in supplementing the diet with antioxidants, especially those derived from natural sources. Baobab fruit pulp is a valuable source of vitamin C, while baobab leaves contain provitamin A.13 The red funicles (threadlike stalks that connect seeds to the ovary wall) present in the fruit have an impressive antioxidant capacity, higher than in other parts of baobab and in many other fruits as well (Table 1).12,31 However, the exact antioxidant composition in baobab has not yet been determined.
The method most widely used to measure antioxidant activity involves generating radical species and analyzing the antioxidants that cause the disappearance of these radicals. The scavenging activity of antioxidants is measured against a reference compound, such as Trolox, a water-soluble equivalent of vitamin E. Most published antioxidant activity investigations conducted on baobab have focused on fresh leaves only.12
Vertuani et al. investigated the fresh fruit pulp, fruit shell, and dry leaves of baobab and compared the antioxidant values to those of other commonly consumed fresh fruits with high levels of vitamin C, including orange (Citrus sinensis, Rutaceae), kiwi (Actinidia chinensis, Actinidiaceae), apple (Malus domestica, Rosaceae), and strawberry (Fragaria × ananassa, Rosaceae).12 In this study, antioxidant activity was measured with a photochemiluminescence method of aqueous/methanol extracts from baobab products. This method allows for the measurement of the antioxidant capacities of both water- and lipid-soluble components. In water-soluble fractions, antioxidants such as flavonoids and vitamin C can be detected, while in lipid-soluble fractions, tocopherols and carotenoids can be measured.32,33 Baobab products displayed the highest capacity. Notably, dry leaves exhibited an antioxidant capacity of approximately 6.4 mmol (millimoles) of Trolox equivalents per gram of tested product (Table 1). In comparison to the baobab fruit pulp, kiwi, orange, strawberry, and apple all showed a much lower antioxidant capacity.12 However, comparing fresh fruit to dry fruit is misleading since baobab fruit is naturally dry, but these figures represent the best data available, and are a fairly good indication of baobab’s antioxidant capacity.
With regard to the lipid-soluble antioxidant component, baobab fruit pulp also showed the highest antioxidant capacity (4.15 mmol/g), followed by the dry leaves (2.35 mmol/g). The other fruit pulps had very limited capacity, which may be due to their low levels of lipid-soluble antioxidants.12
To account for the potential effects of secondary antioxidant products, and to avoid underestimation of antioxidant activity, the oxygen radical absorbance capacity (ORAC) assay can be used to follow reactions for extended periods of time. With this method, values are also reported as Trolox equivalents. Seasonal variation in fruit products, different methods of extraction, and treatment of samples can lead to differences in the outcome values. Absolute ORAC values are more significant when the test materials are in the same condition.31
In a study using ORAC values to compare the antioxidant capacities of baobab and so-called “superfruits” (Baobab Foods, unpublished data, 2011), the baobab red funicle was found to contain the highest level of antioxidants compared to goji berry (Lycium barbarum, Solanaceae), pomegranate (Punica granatum, Lythraceae), and cranberry (Vaccinium macrocarpon, Ericaceae), with the exception of the açaí berry (Euterpe oleracea, Arecaceae). Baobab fruit pulp has an ORAC value twice as high as those of cranberry and pomegranate. These data suggest potential antioxidant benefits from the consumption of baobab-containing products, although these results have been difficult to replicate and validate.
In a separate study of African fruits and culinary spices, A. digitata fruit once again showed high antioxidant capacity along with the highest amount of total phenolics (237.68 mg gallic acid equivalents/g) and total flavonoids (16.14 mg vitamin E/g) of the botanicals tested.34 Researchers reported IC50 (the half maximal inhibitory concentration) values of 8.15 µg/mL and 9.16 µg/mL using the DPPH (a standard antioxidant assay using 2,2-diphenyl-1-picrylhydrazyl) and ABTS (an enzyme assay using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) assays, respectively. The FRAP (ferric reducing ability of plasma) assay determined a Trolox equivalent antioxidant capacity of 0.75 mmol/g.
Acids, terpenoids, and flavonoids
Adansonia digitata fruit contains organic acids such as citric, tartaric, malic, and succinic acids, and its seeds yield oil that contains oleic, linoleic, and linolenic acids, as well as cyclopropenic fatty acids.8,16 Baobab also contains terpenoids, such as α- and β-amyrin palmitate, β-sitosterol, and ursolic acid.
In the 1980s, researchers in India identified two new flavonol glycosides from the roots of A. digitata, namely 3,7-dihydroxy flavan-4-one-5-O-β-D-galactopyranosyl (1→4)-β-D-glucopyranoside from the benzene extract of the water-insoluble fraction of the ethanolic root extract, and quercetin–7-O-β–D-xylopyranoside from spectral data and chemical studies of an ethyl acetate stem extract.35,36 Further investigation has identified another flavanone glycoside, fisetin-7-O-α-L-rhamnopyranoside, in the roots of baobab.37
Published research has shown that baobab fruit pulp contains sugars but no starch and is an excellent source of vitamin C, calcium, and pectin. The fruit pulp is composed of carbohydrates (75%), proteins (2.5%), and a limited amount of lipids.20 It also contains fibers (50%), both soluble and insoluble, which are composed mainly of pectin. Pectin levels range from 23.4-33.8 mg/100 g depending on varieties and geographical location.38,39
Recently, researchers have focused on the potential gut health benefits associated with pectin, which exhibits health-promoting properties in the gastrointestinal tract. This polysaccharide has shown potential as a prebiotic, as it enhances the growth of probiotic bacteria in the large intestine. Studies have shown that pectin prevents pathogenic bacteria from binding to the intestinal wall, and that it chelates heavy metals, which are then excreted through urine.40-42
Adansonia digitata’s leaves and bark have been reported to contain an alkaloid called adansonin, which is used as an antidote to strophanthin, a poisonous cardiac glycoside alkaloid that is present in vines of the genus Strophanthus (Apocynaceae). This is important to locals since strophanthin is used as an arrow poison in Africa. Previously, adansonin was sold as a substitute for quinine due to its febrifuge properties.43,44 However, it is not clear whether adansonin is a pure compound or if it is indeed an alkaloid. It is possible that the substance is a mixture of compounds, but more structural research is needed. Baobab leaves are also rich in mucilage that contains uronic acids, rhamnose, and other sugars.
Minerals and trace elements
Calcium, potassium, magnesium, and iron are abundant in baobab.38 In general, it is rare for calcium to be found in large quantities in fruits and vegetables, but baobab dried fruit pulp contains large amounts of this micronutrient, ranging from 257-370 mg/100 g. The leaves contain even greater amounts (307-2640 mg/100 g dry weight).45 These quantities rival those of other good dietary sources of calcium — for example, dried skim milk (960-1890 mg/100 g) — but it is much higher than levels present in other fruits and vegetables.16 Baobab contains four times the amount of calcium found in dehydrated apricots (Prunus spp., Rosaceae), and 13 times that in dehydrated apples.46 Whether or not the calcium is in a form suitable for absorption via oral administration is currently under review.
Baobab dried fruit pulp also has the highest concentration of potassium, magnesium, copper, and manganese among popular dehydrated fruits, and the second-highest concentration of zinc. The magnesium content of baobab is similar to that of dehydrated bananas (Musa acuminata, Musaceae), whereas iron levels are comparable to those found in dehydrated apricots and peaches (Prunus persica, Rosaceae).38 Based on the European Recommended Daily Allowances (RDAs) for calcium, iron, and magnesium of 800 mg, 14 mg, and 375 mg, respectively, baobab powder could prove to be a useful dietary source of these minerals, provided that sufficient amounts could be added to a product to enable a label claim. In order to make an on-label claim in Europe, the product must contain 15% of the RDA of the vitamin or mineral per 100 g, or per single-serving package.16,46
The main vitamins found in baobab include vitamin C and various B vitamins. On average, baobab ripe pulp has a vitamin C content of approximately 107 mg/100 g, which will remain stable for months if protected from moisture. Even if no precautions are taken, appreciable quantities of the vitamin will endure in the pulp for many years. One study found that baobab ripe pulp stored in a glass bottle showed no signs of bacterial or fungal decomposition after two years.47
Baobab dried fruit pulp contains significantly higher levels of vitamin C than other commonly consumed dried fruits16 (Table 2). Obtaining the dried pulp traditionally involves minimal processing, which helps preserve heat- and moisture-sensitive vitamins. Vitamin C is present in an amount of about 300 mg/100 g of dried fruit pulp15 — six and a half times higher than that of oranges (46 mg/100 g), five times higher than that of strawberries (61 mg/100 g), and 10 times higher than that of dried peaches and apricots.9,38 Baobab fruit pulp, naturally in powdered form, contains levels of vitamin C ranging from 34-499 mg/100 g. (According to the unofficial African Herbal Pharmacopoeia, such levels depend on the source, with pharmacopeial-grade material containing the largest amounts.48) Based on the European RDA of 80 mg of vitamin C, baobab fruit pulp powder added to an ingestible product could provide an adequate daily source of vitamin C.
In a study that assessed the vitamin B1 (thiamine) and B2 (riboflavin) contents in A. digitata, the leaves were found to contain higher levels of vitamin B2 than vitamin B1, with the most vitamin B2 (1.04 ± 0.05 mg/100 g dry matter) found in baobab leaves from Senegal. The highest iron content (26.39 mg/100 g) was found in leaves from Mali.45
In terms of macronutrients, baobab dried fruit pulp is low in fat and consists of approximately 50% fiber. It is relatively low in protein but contains numerous amino acids.16 Baobab dried fruit pulp therefore would be ideal as a fiber-supplementing ingredient in foods, raising the overall nutritional profile. According to the EU Nutrition and Health Claims Directive (No. 1924/2006), a claim that a food is a source of fiber may be made only if the product contains a minimum of 3 g/100 g, or at least 1.5 g/100 kcal.50 A claim that a food is high in fiber may be made only if the product contains a minimum of 6 g/100 g, or at least 3 g/100 kcal. No specific information is available on the glycemic index (GI) or satiating effects of baobab, but its profile, compared to other foods, would indicate that it may have the potential to be a low-GI and satiating ingredient due to its low sugar and high soluble fiber content.43,51
Baobab vs. Superfruits: Comparing Nutritional Content
To date, the oft-used marketing term “superfruit” does not have an official regulatory definition, but products marketed as superfruits are generally high in a variety of nutrients and thus are associated with health benefits. Fruits currently marketed as superfruits include açaí berry, blueberry (Vaccinium spp.), cranberry, goji berry, mangosteen (Garcinia mangostana, Clusiaceae), and pomegranate, and some have suggested adding baobab to the list as well.
When comparing the micronutrients found in baobab to those found in superfruits, one must take into account that values for baobab are for the dried fruit pulp, whereas the data for superfruits are for raw foods. The vitamin C content of baobab dried fruit pulp is up to five times higher than that of raw blueberries and 15 times higher than that of pomegranates. It has much higher levels of niacin (vitamin B3), slightly higher levels of vitamin B1, and about the same amount of vitamin B2 as the selected superfruits. Baobab dried fruit pulp has also been found to contain greater quantities of calcium, magnesium, and iron. It is worth noting that removing water from fresh fruit concentrates the nutrients, so it may be an unfair comparison. However, as baobab is naturally dry, the situation is unavoidable.
In summary, baobab fruit pulp has the following:
Vitamins B1 and B2, and a high natural vitamin C content (at least 100 mg/100 g);
Strong antioxidant properties with an Integral Antioxidant Capacity of 11.1 mmol/g, which is significantly higher than that of orange pulp (10.2 mmol/g) and grape seed oligomers (10.25 mmol/g);
Minerals, including calcium (293 mg/100 g), phosphorus (96-118 mg/100 g), iron (7-8.6 mg/100 g), and potassium (2.31 mg/100 g);
Low amounts of fat and high levels of soluble fiber;
High levels of pectin, making it a useful binding and thickening agent;
Organic acids such as ascorbic, citric, malic, and succinic acids, which contribute to baobab’s bitter taste.
Since baobab obtained approval from EU regulators in 2008 as a novel food ingredient, the United Kingdom has been increasing imports of powdered baobab fruit for use as a healthy additive to snack foods and beverages. In the UK, the amount of baobab dried pulp that can be added to foods, such as cereal bars and smoothies, ranges from 10-20% (typically 5-10 g).16 This should be kept in mind when assessing baobab’s contribution to the product’s overall nutritional intake.
A 2008 report by the UK-based Natural Resources Institute estimated that trade in baobab fruit could be worth up to $961 million per year for African producers — it is currently valued at $11 million.13 African producers export approximately 20 tons of baobab each year, and the growing industry is crucial in bringing money to local people who harvest and process the fruit.
Baobab fruit pulp is currently available as a milled and sifted, free-flowing, light-colored powder, as well as a de-pectinized extract, and in the form of leaf extracts, fruit fiber (funicles), or fruit seed oil. The powder can be taken in its pure form as is done traditionally, but it can also be stirred into porridge, yogurt, or smoothies to appeal to a Western diet. Companies in Europe and North America offer baobab food products in a variety of forms, including sauces, jams, bars, and fruit chews, among others.
Skin and Cosmetic Benefits
In addition to its nutritional value, baobab has been shown to be beneficial for skin care. Studies suggest that baobab preparations can promote skin cell regeneration and tone, tighten, and moisturize the skin.17,20,52 These effects may be due, in part, to baobab’s vitamin A, D, and E content. The fruit pulp provides a complex of vitamins that exerts a variety of positive, synergistic actions, including the following: emollient effects (vitamin A), the control of sebaceous gland excretion (vitamin B6), the induction of melanin synthesis (vitamin B1/B2 complex), antioxidant defense and collagen synthesis stimulation (vitamin C), improvement of cutaneous circulation (vitamin B4), action against lipid peroxidation (vitamin E), and defense from tissue matrix degradation (triterpenic compounds).20
Fiber contained in the pulp also promotes anti-aging and antioxidant effects on the skin. Leaf extracts have antioxidant, emollient, and soothing properties, keeping skin soft and elastic while also exerting antibacterial activity. The fatty oil from the seeds improves the firmness, hydration, and lightness of the skin. It also has soothing and anti-inflammatory effects due to essential oils, hydrocarbons, and sterols, making it an ideal treatment for dry skin and the prevention of wrinkles. Baobab seed oil can heal abrasions, sunburns, and hematomas, and promote tissue regeneration.17
CONTAMINANTS & ADULTERANTS IN BAOBAB DRIED FRUIT PULP
Foreign Matter and Silicon
Baobab fruit is sustainably wild-harvested and the fruit pulp is separated from the other unwanted parts of the fruit. This process can potentially introduce contaminants into the baobab dried fruit pulp from two sources: extraneous matter, such as soil, and endogenous matter, such as seed and plant fiber.
To quantify these potential sources of contamination, one of the authors (SJ) of this article analyzed samples of baobab dried fruit pulp to determine levels of both foreign matter and silicon (Jackson et al., unpublished data, 2013). The analysis found less than 0.026% of extraneous and endogenous matter (by weight) in tested samples of dried fruit pulp, which suggests that the producers used proper collection and handling practices. An acid-insoluble ash test (a method used to gauge the purity of a substance53) found silicon levels of 0.1 g/100 g baobab dried fruit pulp. This result suggests that there were no significant problems with soil, sand, or diatomaceous earth contamination during or after harvest.
Suppliers can address potential contamination issues (e.g., excess levels of foreign matter, pesticide residues, heavy metals, microbes, or mycotoxins) by adhering to the US Food and Drug Administration’s (FDA’s) current Good Manufacturing Practices (cGMPs). The baobab fruit pulp samples tested by the author were screened for each of these contaminants using the methods published in the African Herbal Pharmacopoeia.48
Botanical adulteration may be the result of accidental or intentional contamination. Microscopic analyses can help identify foreign matter in samples. For example, researchers can learn more about the quality of a sample by simple microscopic observation using a polarizing filter and chloral hydrate, or iodine, which reveals any added starch grains.
Intentional adulterants (e.g., ascorbic acid) are sometimes added to fortify samples or make the raw material or extract appear more valuable. If ascorbic acid were added to a sample, for example, analyses would show abnormally high values of vitamin C (more than 500 mg/100 g). The authors and their colleagues have tested at least three different samples from various suppliers in different countries, and are confident in the results shown (Jackson et al., unpublished data, 2013).
In order to assess potential microbial contamination, the author tested baobab dried fruit pulp (in duplicate) for several microbial organisms, including E. coli, fecal Streptococci, and Salmonella (Jackson et al., unpublished data, 2013). The results were within the range that is generally accepted in cGMP guidelines for limits of microbial contamination (i.e., less than 1,000 colony-forming units [cfu]/g). E. coli, Staphylococcus aureus, fecal Streptococci, and yeasts were below the limit at which the numbers of the colonies are counted; Salmonella was not detected in the samples. Finally, both the total viable count and mold-produced colony counts ranged between 2,600 and 7,800 cfu/g. These counts are not unduly high or unexpected in a fruit that is wild-harvested and processed by a simple mechanical separation.
The data in Table 3 show the results of a multi-residue pesticide analysis on the baobab dried fruit pulp. The results are presented in terms of the pesticide class rather than the individual pesticide, and the data clearly show that pesticide residues are below the limits of detection. These results are to be expected, as pesticides are not used at any stage during the growing or harvesting of wild-harvested baobab fruit.
The author (SJ) also analyzed three samples of baobab dried fruit pulp in duplicate for the presence of four heavy metals: arsenic, cadmium, lead, and mercury (Jackson et al., unpublished data, 2013). The levels of arsenic, cadmium, and mercury in the baobab dried fruit pulp samples were all below the detection limits (Table 4). Only lead was detected (at levels much lower than acceptable limits established by European food guidelines).54
Mycotoxins and Related Substances
The baobab dried fruit pulp samples were also analyzed in duplicate for mycotoxins, and the results are shown in Table 5. In each of the samples, the amount of total aflatoxins was below the limit of detection.
Summary: Contaminants & Adulterants
In all of these categories, the levels of potential food contaminants were found to be acceptable and unlikely to cause harm to consumers. According to the analyses performed by the author, the levels of pesticide residues and mycotoxins were below the limits of detection. Three out of four of the heavy metals analyzed were also below the limits of detection, and the content of lead was well below permitted safety limits. Additionally, the foreign matter content of the baobab dried fruit pulp was found to be less than 0.026% by weight, the microbial contamination level was in the acceptable range, and the total viable count and mold levels were low. It warrants mention that only a small number of samples were tested, and testing for possible contamination and/or adulteration of material from other commercial sources was not performed.
The fruit of A. digitata is nutritious and could have significant value as an ingredient in functional foods, dietary supplements, and skincare products, and as a novel source of anti-inflammatory and antiviral compounds. In addition, the vitamins and oils derived from baobab can be highly beneficial for skincare products due to their moisturizing, healing, and skin-regenerating effects.
Baobab is rich in vitamins and minerals, containing more than 100 mg vitamin C per 100 g of dried fruit pulp — higher than many other fruits. If added to a product in sufficient quantities, baobab could satisfy label claims as a source of vitamin C (12 mg or 15% of the RDA) in the UK market. The presence of vitamin C combined with its iron content may make baobab an effective optimizer of iron uptake. The African botanical is also a good source of calcium (317 g/100 g), iron (5.94 g/100 g), and magnesium (148 g/100 g) compared to other fruits. While the amount of baobab in consumer products (typically up to 20%) may be insufficient to claim it as a source of these minerals, baobab still can contribute to a product’s total mineral content.
Based on its ORAC values, baobab fruit pulp has a higher antioxidant capacity than many berries — twice as high as those of pomegranate and cranberry. This is an added selling point for baobab, as consumers are increasingly interested in products high in antioxidants, and manufacturers have developed a variety of antioxidant superfood products, such as drinks and foods containing goji berry, pomegranate, or açaí.
Finally, since the potential contaminants of baobab are classified as avoidable contaminants, they should either not be present or be present at such low levels as to pose no health risk to consumers.
Simon Jackson, PhD, graduated from the King’s College Department of Pharmacognosy with a doctorate in bioactive natural products of sub-Saharan African origin. He has spent subsequent years studying uses of African medicinal plant species. Dr. Jackson has since set up the Natural Products Community (NPC) Research Foundation to promote the study and commercialization of African indigenous plant extracts.
Anabel Maldonadoreceived her BSc at York University in Canada and is a London-based editorial and copywriting consultant who works across lifestyle and health topics. Her interests span beauty, nutrition, skin care, natural products, mental health, and the biological basis of behavior.
Dr. Jackson is the founder and CEO of Dr. Jackson’s Natural Products, which specializes in African-based cosmetic and herbal preparations. Some of these products contain baobab.
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