Nutrition and health benefits of guava

Introduction

Guava is a tropical tree or shrub of myrtle family (myrtaceae), with a botanical name; Psidium guajava, native of Mexico, Central America and the Northern South America. Although related species may be called “guavas”, they actually belong to other genera, such as the “strawberry guava” Acea sellowiana (Gutierrez, Mitchell & Solis, 2008).

It is a yellowish tropical fruit, 1 ¼ to 2 inches, globular or pear shaped with thin yellow, green or brown skin, the flowers are white, with five petals and numerous stamens.

It is an important food crop and medicinal to humans and animals; is widely used as food and in folk medicine around the world. In many parts of Africa, the leaf, stem, bark and roots of guavas are used traditionally for the management, control and/or treatment of an array of human disorders. It is often made into jams, jellies and also added in the preparation of tooth-pastes.

It is a fruit rich in high-profile nutrients. With its unique flavour, taste, and health-promoting qualities, the fruit easily fits in the new functional foods category, often called “super-fruits.”

It is an evergreen, tropical shrub or low-growing small tree probably originated in the central Americas. Guavas actually thrive in both humid and dry climates and can tolerate brief periods of cold spells, but can survive only a few degrees of frost. Adaptability makes it a favorite commercial crop in some tropical areas (Ramat, Abubakar, Faezah & Hambali, 2004).

History of guava

According to Olajide, Awe and Makinde (1999), the young leaves of the plant have been used as a tonic to treat digestive conditions such as dysentery and diarrhea in the indigenous medical systems of Brazil and Mexico. Mexican medicinal data document the treatment of acute diarrhea, flatulence, and gastric pain by using a guava leaf water decoction for oral administration 3 times daily. A decoction of young leaves and shoots has been prescribed as a febrifuge and a spasmolytic. In Bolivia and Egypt, guava leaves have been used to treat cough and pulmonary diseases; they have also been used to treat cough in India and as an anti-inflammatory and haemostatic agent in China.

Guava bark has been used medically as an astringent and to treat diarrhoea in children, while the flowers have been used to treat bronchitis and eye sores and to cool the body. The fruit has been used as a tonic and laxative and for treatment of bleeding gums. The plant has been used in Africa and Asia to prevent and treat scurvy and to treat hypertension in western Africa. Ethnomedicinal reports document use of the plant in treating malaria. Scientific investigations of the medicinal properties of guava leaf products date back to the 1940s.

Pakistan, India, Brazil, and Mexico are the major commercial producers of guava fruit. Hawaii is the largest producer in the United States. Processed guava products include beverages, cheese, ice cream, jams, jellies, juice, syrup, toffee, wine, and dehydrated and canned products (Gutierrez, Mitchell & Solis, 2008).

Types of guavas

According to Ojewole, Awe and Chiwororo (2008), there are three types of guavas, namely:

Tropical guavas

These are known scientifically as Psidium guajava they are the best tasting with the largest fruit with the most juice. These are the most frost tender Guavas. Tropical Guavas grow up to 10 to 15 feet high and wide.

Strawberry guavas

Psidium lucidum are shrubby trees with tart but very flavourful fruit that is smaller than a Tropical Guava. Strawberry Guavas are very productive and grown 12 feet high and wide.

Pineapple guavas

Feijoa sellowiana is a South American plant which is related to other Guavas. Their fruit is tangy with a citrus flavour. This is the most frost tolerant variety. Pineapple guavas grow to 15 feet high and wide and have wonderful gnarled trunks and make good substitutes for olive trees.

Chemical analysis of guava

Analyses have shown that almost all the parts of the plant contain tannins as the main active ingredient and also constituents like volatile and fixed oils, saponins, malic acid, phenolic acid, etc.

Phytochemical analyses of guava leaf reveal alkaloids, anthocyanins, carotenoids, essential oils, fatty acids, flavonoids (especially quercetin), lectins, phenols, saponins, tannins, triterpenes, and vitamin C (80 mg per 100 g of guava) (Gutierrez, Mitchell & Solis, 2008).

The essential oil contains alpha pinene, caryophyllene, cineol, D-limonene, eugenol, and myrcene. The major constituents of the volatile acids include (E)-cinnamic acid and (Z)-3-hexenoic acid.  The guava fruit has a high water content with lesser amounts of carbohydrates, proteins, and fats. The fruit also contains iron, vitamins A and C, thiamine, riboflavin, niacin, and manganese. The characteristic fruit odor is attributed to carbonyl compounds. Unripe fruits are high in tannins. The major constituent of the fruit skin is ascorbic acid, largely destroyed by canning and processing.

The bark of the plant contains tannins (12% to 30%) and calcium oxalate crystals, while the seeds contain glycine-rich proteins, starch, and phenolic and flavonoid compounds (Latza, Ganber & Berger, 2006)

Guava fruit and its nutritive value

Guava fruits, usually 4 to 12 centimetres (1.6 to 4.7 in) long, are round or oval depending on the species. They have a pronounced and typical fragrance, similar to lemon rind but less sharp. The outer skin may be rough, often with a bitter taste, or soft and sweet. Varying between species, the skin can be any thickness, is usually green before maturity, but becomes yellow, maroon, or green when ripe. The pulp inside may be white, pink, yellow or red. The seeds in the central pulp vary in number and hardness, with numerous tiny, semi-hard edible seeds. The ripe fruit also has sweet, musky aroma, creamy in texture and rich flavour with sweet-tart taste (Ramat, Abubakar, Faezah & Hambali, 2004).

Nutritive value

Guavas nutritional value per 100g

Source: Ramat, Abubakar, Faezah and Hambali (2004).

Culinary uses

In many countries, guava is eaten raw, typically cut into quarters or eaten like an apple, whereas in other countries it is eaten with a pinch of salt and pepper, cayenne powder or a mix of spices (masala). It is known as the winter national fruit of Pakistan. In the Philippines, ripe guava is used in cooking sinigang. Guava is a popular snack in Taiwan, sold on many street corners and night markets during hot weather, accompanied by packets of dried plum powder mixed with sugar and salt for dipping. In East Asia, guava is commonly eaten with sweet and sour dried plum powder mixtures. Guava juice is popular in many countries. The fruit is also often prepared in fruit salads.

Because of its high level of pectin, guavas are extensively used to make candies, preserves, and also for juices and aguas frescas or may be used in a marmalade jam on toast. Red guavas can be used as the base of salted products such as sauces, substituting for tomatoes, especially to minimize acidity. A drink may be made from an infusion of guava fruits and leaves, which in Brazil is called chá-de-goiabeira, i.e., “tea” of guava tree leaves, considered medicinal (Adeyemi & Akanji, 2011).

Preventive uses of guava

Depending on the species, a guava’s flesh and seeds can be white, orange, pink or red. The skin is green before maturity and becomes yellow, maroon or remains green when ripe.  They are best eaten when semi-ripe because they are crunchy.

Guavas are a treasure-trove of nutrients. Their being high in antioxidants has made them known as one of the “superfoods.” They are also known for their high pectin content.

The following are some of the major preventive uses of guava as stated by Singh (2009):

1. Lower cancer risk (vitamin C – 27.5%)

Guava contains one of the highest vitamin C content among produce at four times more than oranges. Vitamin C is known as one of the potent antioxidants which help protects cells from free radical damage. High levels of oxidants in the body can damage cell membranes and may contribute to the development of heart disease and cancer.

2. Reduce risk of diabetes (fibre – 5.4%)

Looking for other sources of fibre? Grab a delicious guava. It is rich in fibre, one of the most talked about nutrients today as it has found to be beneficial in a wide range of disease prevention including diabetes by slowing down the absorption of sugar in the body and thus very beneficial for diabetic individuals. A high fiber diet has also been linked to a lowered risk of developing type-2 diabetes.

3. Promotes good eyesight (vitamin A – 4%)

Guavas are very good sources of vitamin A, the nutrient best known for preserving and improving eyesight. Therefore it is advisable to take guavas in its season because it is a seasonal food.

4. Supports fertility (folate – 12%)

Munching on guava also supplies a good amount of folate in the body. Folate is a must-have nutrient for a healthy pregnancy. Guava leaf tea also has been proven to be effective in increasing sperm production, thus helping with conception.

5. Stabilizes blood pressure levels (potassium – 9%)

One cup of guava leaves concoction (i.e. the liquid or water from boiled guava leaves) or a handful of fresh guava leaves and even guava fruits itself is packed with almost the same potassium as bananas. Potassium works as an important factor in regulating blood pressure by reversing the role of sodium in unbalancing normal blood pressure.

6. Maintains thyroid health (copper – 3%)

Guavas are good sources of copper, a trace mineral which plays a role in thyroid metabolism especially in hormone production and absorption.

7. Helps the body make use of key nutrients (manganese -7%)
   One of the key functions of manganese in the body is being an enzyme activator including the enzymes responsible for the utilization of some key nutrients such as biotin, thiamine and ascorbic acid; and one guava contain 7% (0.15mg) of manganese which makes it a good source of it.
8. Relaxes nerves and muscles (magnesium – 6%)

Magnesium is one of the essential minerals which needs to be obtained from food as the body cannot make them. Eating guavas can help relax the nerves and muscles through its good amount of magnesium content thus acts as a natural pain reliever.

9. Keeps brain healthy (vitamin B6 – 8%)

The B group of vitamins plays a vital role in brain function. Guavas are rich in vitamin B3 and B6. Vitamin B3 stimulates brain function and promotes blood flow and vitamin B6 is an important nutrient for brain and nerve function.

10. Good for the skin (vitamin E – 5%)

Regular guava consumption can also do the skin good through its vitamin E content. Vitamin E helps maintain healthy skin through its antioxidant properties.

Health benefits of guava

Since the 1950s, guavas – particularly the leaves – have been studied for their constituents, potential biological properties and history in folk medicine. In Trinidad and Brazil, a tea made from young leaves is thought to be useful for diarrhoea, dysentery or fever and diabetes.

According to Bakr (2007), the following are the health benefit of guava;

1. Diarrhoea & dysentery: Guava is very rich in astringents (compounds those make your gums feel tighter and fresh after you chew guava leaves or eat a raw guava or use some toothpaste) which binds up loose bowels in diarrhoea. These astringents are alkaline in nature and have disinfectant and anti-bacterial properties, thus help cure dysentery by inhibiting microbial growth and removing extra mucus from the intestines. Further, other nutrients in guava, such as vitamin-C, Carotenoids and potassium strengthens and tones up the digestive system and disinfect it. Guava is also beneficial in gastroenteritis due to reasons stated above.
2. Constipation: Guava is one of the riches sources of dietary fiber. Its seeds, if ingested whole or chewed, serve as excellent laxatives. These two properties of guava help forming bowels, retaining water and clean your intestines and excretory system thoroughly. It is said that single constipation can lead to seventy two types of ailments. It is absolutely true. Every way to your total health goes through proper digestion and more importantly, proper excretion. Guava ensures both of these.
3. Cough & cold: Juice of raw and immature guavas or decoction of guava-leaves is very helpful in giving relief in cough and cold by loosening cough, reducing mucus, disinfecting the respiratory tract, throat and lungs and inhibiting microbial activity due to its astringent properties. Guava is one of richest in vitamin-C and iron which are proven to be preventive against cold and viral infections. In some areas in India, roasted ripe guava is used as a remedy against extreme cases of cough and cold and congestion.
4. Skin care: Guavas can help improve your skin texture and avoid skin problems more than the best of beauty creams or skin toner gels can do. This is chiefly due to the abundance of astringents in its fruits (more in immature ones) and in leaves. You can benefit from it either by eating the fruits (this help tighten your muscles apart from your skin) or by washing your skin with the decoction of its immature fruits and leaves. It will tone up and tighten the loosened skin. In addition to the astringents, guava is very-very rich in vitamin-A, B, C and potassium which are very good anti oxidants and detoxifiers and keep your skin glowing and free from aging, wrinkles and other disorders.
5. Scurvy & toothache, sore throat and gun diseases: Guava can outdo many other fruits, including orange and other citrus fruits, when it comes to concentration of vitamin-C, whose deficiency causes scurvy and which is the only remedy to it. It contains five times the vitamin-C in oranges. Due to their anti-inflammatory qualities, fresh guava leaves can relieve tooth ache, heal gum and mouth sores and treat sore throats when used for gargling. The antibacterial agent in these leaves protect the teeth and gums and therefore, guava leaves are used as an ingredient in toothpastes and mouth fresheners. Guava leaves can even be made into a natural paste at home for brushing the teeth and gums.
6. Reduction of allergies: Guava leaves prevent the release of histamine. Moreover, the compounds found in guava leaves are effective in blocking all allergic reactions.
7. Weight loss: Guava is very helpful for those who want to lose weight without compromising with their intake of proteins, vitamins and fiber. Guava, being very high in roughage and very rich in vitamins, proteins and minerals, but with no cholesterol and less digestible carbohydrates. Guava leaves aid in weight loss by preventing the complex starches from being converted into sugars. For this purpose, the carbohydrates must be broken down in the liver for use by the body and guava leaves prevent the transition of carbohydrates to usable compounds. But ironically, it helps gaining weight in lean and thin people. This is probably due to its richness in nutrients, which keeps your metabolism right helping proper absorption of food take place.
8. Lower/stabilize blood pressure and cholesterol: Research has proved that drinking guava leaf tea for 3 months can lead to reduction in LDL or bad cholesterol and triglycerides without any adverse effect on good cholesterol. Besides, the guava leaves are a great liver tonic. Because of the reduction of cholesterol in blood and prevents it from thickening, thereby maintaining fluidity of blood and reducing blood pressure. Studies have shown that food stuffs which lack fibre (such a refined flour) add to blood pressure, due to quick conversion to sugar. Guava, being very rich in fibre and hypoglycemic in nature, helps reduce blood pressure.

Conclusion

The health benefits of guavas are enormous. There is no reason not to eat guava and drink it decoction since it is rich in minerals and vitamins. Ignorance or lack of awareness on the intake of guava considering its nutritive value can predispose an individual to certain deficiencies that can lead to scurvy, cancer, constipation, etc.

The importance and awareness of the benefits of guava is a public health issue and as such more effort should be made by health authorities to create more awareness.

References

Adeyemi, O. & Akanji, M. (2011). Biochemical changes in the kidney and liver of rats following administration of ethanolic extract of Psidium guajava leaves. Hum Exp Toxicol. 30(9):1266-1274.

Bakr, A.A. (2011). Application potential for some sugar substitutes in some low energy and diabetic foods . Nahrung. 41(3):170-175.

Gutierrez, R.M.; Mitchell, S. & Solis, R.V. (2008). Psidium guajava : a review of its traditional uses, phytochemistry and pharmacology. J Ethnopharmacol. 117(1):1-27.

Latza, S.; Ganber, D. & Berger, R.G. (2006). Carbohydrate esters of cinnamic acid from fruits of Physalis peruviana , Psidium guajava and Vaccinium vitis-idaea . Phytochemistry. 43:481-485.

Ojewole, J.A.; Awe, E.O. & Chiwororo, W.D. (2008). Antidiarrhoeal activity of Psidium guajava Linn. (Myrtaceae) leaf aqueous extract in rodents. J Smooth Muscle Res. 44(6):195-207.

Olajide, O.A.; Awe, S.O. & Makinde, J.M. (1999). Pharmacological studies on the leaf of Psidium guajava . Fitoterapia,70:25-31.

Rahmat, A.; Abubakar, M.F.; Faezah, N. & Hambali, Z. (2004). The effects of consumption of guava (Psidium guajava ) or papaya ( Carica papaya ) on total antioxidant and lipid profile in normal male youth . Asia Pac J Clin Nutr 13(suppl):S106.

Singh, R.B. (2009). Effects of guava intake on serum total and high-density lipoprotein cholesterol levels and on systemic blood pressure . Am J Cardiol. 70(15):1287-1291.