Guava goodness

LOOKING for a fruit high in vitamin C? Guava may well be your answer.

It has been reported that one large guava (820g) contains 1,221mg of vitamin C. The vitamin C is found in the whole fruit, not just in the skin. Researchers have found comparatively higher levels of vitamin C in the skin than in the flesh and the lowest amount was found in the central pulp of the seeded varieties. Vitamin C content declines if the fruit is overripe.

Vitamin C is one of the important nutrients in fruits. We are encouraged to include at least 200g of fresh fruit in our diet every day. Vitamin C functions as an antioxidant in the body. It is critical for good immune functions and maintaining good health.

In view of changing lifestyles, the amount of vitamin C included in our diet has been revised to higher levels. Depending on age group, the US National Academy of Sciences recommends daily adequate intake levels of vitamin C to be around 100mg and sets a tolerable upper intake level of 2,000mg (2g) for adults 19 years and above.

The Nutrient Composition of Malaysian Foods showed that 100g of guava provide 152mg of vitamin C; papaya gives 71mg and pear, 6.1mg. A 100g slice of guava has sufficient vitamin C to meet our daily needs.

For the heart, colon and more

Quercetin is another highly sought after nutrient in guava. Many medicinal plants owe much of their activities to their high quercetin content.

Quercetin is also the flavonoid that is responsible for the strong antioxidant activities in fruits and vegetables, especially apple, red grape and onion.

The powerful antioxidant activities of quercitin act by mopping up oxygen free radicals that can damage DNA. Together with the high vitamin C in guava, they help to bolster the body’s immune system and lower the risk of health problems, including cancer and heart disease. The quercetin anti-inflammatory activity also supports the immune system to protect against allergies.

Guava’s dietary fibre does more than prevent constipation. It lowers cholesterol levels and binds toxic residues and cancer-causing chemicals in the colon. In this way, guava may help us to maintain a healthy colon.

Guava contains pectin that aids in setting in jam-making. Enjoy a serving of guava if you do not have appetite for food. The pectin promotes digestion and improves appetite. Pectin is also an ingredient in throat lozenges. A drink of cool guava juice is an enjoyable way to combat sore throat.

Astringent: pros and cons

Guava contains a different profile of acids as found in other fruits. It is sweet with an astringent taste. It contains oxalic, malic and phosphoric acids as well as tannin. The amounts are higher in unripe fruits which are more astringent and sour than mature fruits.

Chewing the crunchy fruit is good exercise for the jaws and believed to be beneficial to brain functions.

The various components of acids clean the teeth and gums, thus freshening the mouth and healing mouth ulcers. Chewing the young leaves also aids healing.

The astringent taste is due to the polyphenol tannin, which is the same as in tea. The healthful benefits of the antioxidant tannins are touted to be good for the heart.

In traditional practice, the low amount of tannin in guava makes it a fruit taken to combat diarrhoea. On the other hand, excessive consumption of guava may affect bowel regularity, resulting in constipation in some people.

Tannins are metal ion chelators. They bind minerals, especially iron, and make it unavailable for absorption. People with anaemia or expectant mothers who need more iron in their diet should avoid excessive consumption of guava daily. Iron plays an important role in bodily functions. On the other hand, if a person’s daily diet consists mainly of red meat that supplies good amount of iron and he is also taking a supplement that is high in iron, guava is a good choice. Excessive iron intake has been implicated as a cause of heart disease and some types of cancer.

Guava contains oxalic acid but the amount is lower than what is found in star fruit. People with kidney problems should avoid excessive consumption of guava. The oxalic acid can interfere with calcium absorption. Individuals who are taking calcium supplements would be better off eating the fruit one to two hours before or after taking the calcium supplement.

Added value

Guava or jambu batu as is known locally belongs to the Psidium guajava L. of the family Myrtaceae. There are many clones and varieties. The fruits can be round, ovoid or pear-shaped with hard seeds, ranging from hundreds to a few or even seedless.

Seedless guavas are not bred through genetic modified techniques. Due to selection of better varieties for commercial planting, the small seeded and hard guava varieties are disappearing from the market.

Guava has a delicious sandy granular pulp and was once known as sand plum. The fruit has a distinctive aromatic flavour and may emit a strong musky smell when overripe. The thin edible skin turns a pale yellow-green when mature, while the flesh can be white, yellowish, pink or red, depending upon the variety.

All parts of the guava plants are useful. The fruit, leaves, bark, wood and root are used in making products ranging from food, medicine, cosmetics, dyes and many others.