Food is a mixture of components which possess an important role in healthful life. The phytochemicals (phyto-plant) present in fruits and vegetables may play an important role in decreasing the risk of chronic diseases. Grapes, one of the most popular and widely cultivated and consumed fruits in the world, are rich in phytochemicals. It has been proved by epidemiological evidence that the consumption of grapes reduces the risk of chronic diseases, including certain types of cancer and cardiovascular diseases. In vitro and in vivo studies have shown that grapes have strong antioxidant properties, that helps to inhibit cancer cell proliferation and suppressing platelet aggregation while also lowering cholesterol. Grapes contain a wide variety of phytochemicals, like phenolic acids, stilbenes, anthocyanin, and proanthocyanidin all of which are strong antioxidants. The phytochemical composition, however, varies greatly among different varieties. Grapes come in different colours and types, such as red, green, and purple grapes, or in different forms like seedless grapes or jelly, jam or juice raisins, currents, and sultanas, not to mention wine.
Nutritive value: Indian food composition table, NIN,201o
Grapes are an excellent source of manganese and vitamin K. They also contribute in thiamine (vitamin B1), vitamin B6, potassium, and vitamin C. The plant nutrients within grapes include polyphenols, such as anthocyanins, catechin, epicatechin, and quercetin, which are flavonoids, and potentially resveratrol, which is a stilbene.
‘Phyto’ refers to the Greek word for plant. Plant food contains thousands of naturally occurring chemicals. Together they are called phytonutrients or phytochemicals. These chemicals help protect plants from germs, fungi, bugs and other threats. They are beneficial for human health as well. More than 25000 phytonutrients are found in plant foods.
Polyphenols are secondary metabolites of plant and are generally involved in defence against ultraviolet radiation or aggression by pathogens. Epidemiological studies suggest that long-term consumption of diets rich in plant polyphenols offer protection against the development of cancers, cardiovascular diseases, diabetes, osteoporosis and neurodegenerative diseases (2).
Phenolic acids are found mainly in foods and divided into two classes: derivatives of benzoic acid and derivatives of cinnamic acid. The hydroxybenzoic acid content of edible plants is generally low, with exception of certain red fruits, black radish and onions, But the hydroxycinnamic acids are more common than hydroxybenzoic acids and consist mainly of p-coumaric, caffeic, ferulic and sinapic acids.
Flavonoids are the subclasses of polyphenols which posses the main role as an anti-inflammatory and antioxidant ability. Recent epidemiological studies have shown that flavonoids may enhance bone formation and inhibit bone reabsorption through different cell-signalling pathways that may help with the bone cells called osteoblasts and osteoclast differentiation. This is likely due to the anti-inflammatory mechanism of chemicals. Bone health benefits of the flavonoids can be seen most readily in older adults consuming mostly animal protein because people who regularly consume a high animal protein diet have an increased loss of calcium through their urine and a significant amount of bone loss over time, which eventually leads to osteoporosis. Other than that diets high in animal protein generate a large amount of acid, but a plant-based diet has the opposite effect. Eating in this pattern supplies the body with bicarbonate or potassium-rich combination that counteracts acidity and protects and preserves the bone mass, promoting long-term skeletal health. Furthermore, flavonoid-rich fruits and vegetables are rich in the mineral potassium, which plays an exceptionally huge role in keeping the blood pressure under control.
Research investigating flavonoid’s potential for preventing cancer or at least reducing the risk of developing it is still under process. There are some evidential data suggesting that flavonoid consumption may be tied to cancer prevention. Researches showed that flavonoids may have a protective effect on a number of cancers, including oropharyngeal cancer, gastric cancer, possibly pancreatic cancer, as well as colorectal cancer.
More than 4,000 varieties of flavonoids have been identified, many of which are responsible for the attractive colours of the flowers, fruits and leaves. Based on the variation in the type of heterocycle involved, flavonoids may be divided into six subclasses: flavonols, flavones, flavanones, flavanols, anthocyanins and isoflavones.
Stilbenes compounds are part of a vast group of natural defence polyphenols occurring in many plant species. Resveratrol is a well-known polyphenol phytoalexin which is found mainly in the skin of grapes, it has potential health benefits related to its cardiovascular, chemopreventive, anti-obesity, anti-diabetic, and neuroprotective properties. However, recent data has highlighted that other stilbene compounds such as pterostilbene may have higher bioavailability and possess better neuroprotective ability against Alzheimer disease than resveratrol itself.
GRAPES & PREVENTION OF DISEASES:
A diet rich in fruits and veggies is beneficial in reducing the risk of various terminal diseases like diabetes, cancer, cardiovascular diseases, obesity, etc. Grapes also contain a good amount of dietary fibre and water. There are some ways in which the above-discussed nutrients boost our health, such as:
Above discussed polyphenols present in grapes possess anti-inflammatory and antioxidant properties. One of this is Resveratrol, which is present in the skin of red grapes. Laboratory researches suggested that this nutrient is able to slow or prevent the growth of tumours in lymph, liver, stomach, breast, colon, skin cancer and leukaemia. Another natural anti-inflammatory present in grapes is the flavonoid quercetin. Studies suggested that this, too, may help prevent or slow cancer growth.
Animal studies have shown quercetin and resveratrol may reduce the risk of atherosclerosis and protect against the damage caused by low-density lipoprotein (LDL), the so-called bad cholesterol. Resveratrol, which has a strong anti-oxidant property that helps to reduce the cholesterol and shows anti-inflammatory actions which in turn reduce the risk of CVDs. They may accomplish this by preventing platelet build-up and reducing blood pressure and the risk of irregular heart rhythms.
Dietary fibre present in grapes helps to improve the cardiac health
High potassium content helps reduce the negative effect of too much sodium in the diet which automatically normalises the blood pressure.
Clinical trial suggested that whole grapefruit (not juices) may reduce the risk of type 2 diabetes in adults.
Because of the anti-inflammatory effects of quercetin, some suggest that consuming grapes may help to alleviate symptoms of allergies, including a runny nose, watery eyes, and hives, but it is not proven by human studies.
Other than the above-mentioned conditions grapes are also beneficial in a few more conditions for its phytochemical contents, such as Alzheimer disease, osteoarthritis, acne, immunity boosting, etc.
- T.Longvah et al. (2017), Indian Food Composition Tables, NIN, ICMR, India
- K.B.Pandey et al. Plant polyphenols as dietary antioxidants in human health and disease, Oxidative Medicine and Cellular Longevity, 2009 Nov-Dec; 2(5): 270–278. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2835915/
- J. Chang, A. Rimando, M. Pallas et al., “Low-dose pterostilbene, but not resveratrol, is a potent neuromodulator in aging and Alzheimer's disease,” Neurobiology of Aging, vol. 33, no. 9, pp. 2062–2071, 2012.