What Is Cranberry Good For?

The cranberry, also known as the cranberry, is an evergreen small shrub of the genus Vaccinium (Vacinium macrocarpon) of the Ericaceae family. The plant is 5 to 20 cm high, with spreading vine-like branches about 2 m. It has oval leaves 5–10 mm long and dark pink flowers with curved petals and exposed stamens pointing forwards. The whole plant looks like a crane, and the flowers resemble the head and beak of a crane, which is why cranberries are also called “craneberries”. Its fruit is an oval berry 2–5 cm long, which changes from white to dark red and has a slightly sweet and sour taste.

Cranberries grow in damp bogs and sandy soil. Their branches are rooted in a sandy soil bed made from acidic sand, and they take 3–5 years to mature and bear fruit. Cranberries grow from March to September. In mid-July, the petals fall off and the fruit sprouts. The fruit is harvested from mid-September to mid-October. There are two harvesting methods: wet and dry. The wet method is used most often. The farmer fills the cranberry field with water, so that the water surface is 15–20 cm above the cranberry vines. The cranberries float to the surface, and the farmer collects them in a circle and then transported to the truck on a conveyor belt. Dry harvesting involves a machine with a comb-like conveyor belt that picks the cranberries off the branches and transports them directly into sacks for loading onto trucks[1]. Dry-harvested cranberries account for only 5% to 10% of the total weight of cranberries and are mainly sold as fresh fruit.

1 History of cranberries

Cranberries have a long history of cultivation in North America, and the local Native American tribes were the first to eat them. They made jam, dried fruit and other foods from cranberries; they also used cranberry juice to apply to wounds to heal them; and as a dye to dye fabrics. In the 15th century, when European colonists first set foot on the North American continent, they suffered from various illnesses due to the unfamiliar environment. The Indians introduced cranberries to the settlers, and the health benefits of cranberries played a significant role in the recovery of the European settlers' health. They fell in love with these small red berries and promoted their cultivation. They soon invented new cranberry food recipes, including sauces, pies and juices, and made them a Thanksgiving food.

The settlers exported cranberries to Europe and offered them as tribute to the European aristocracy. In 1677, the colonial government of New England offered the British king three native American products as tribute: Indian corn, codfish and cranberries. However, after the long voyage, the codfish and corn had rotted, and only the cranberries were presented to the king in their original state. Since then, cranberries have become famous for their long shelf life and resistance to decay. 300 years ago, a New Jersey ship captain took a large quantity of dried cranberries with him on a voyage to feed his sailors, and accidentally discovered that cranberries could cure scurvy. Since then, cranberries have been prized as a food that prevents scurvy. During the American War of Independence, a veteran named Henry Hall established a cranberry farm in the town of Dennis, Massachusetts, which is the earliest record of commercial cranberry cultivation [2]. Over the next 200 years, as cultivation techniques improved and the health benefits of cranberries were discovered, more and more people became aware of the health benefits of cranberries, and the scale of cultivation and production continued to increase. By 2008, the world's cranberry cultivation area had reached 41.62×104 hm2, with about 1,200 growers and total sales of over 1.5 billion US dollars [3].

Cranberries mainly grow in the cold northern hemisphere, limited to the northern United States in Massachusetts, Wisconsin, Maine, etc., and Quebec, Columbia, and Chile in South America, as well as a small area in northeastern Europe. The United States accounts for 95% of the world's total production, with Wisconsin ranking first in production and accounting for 50% of the total, and Massachusetts ranking second, accounting for 28% of the total [4]. The growth in production is due to the continued increase in demand for cranberry products. Since cranberry fruits are not resistant to storage and transportation, they are usually sold as frozen fruits or processed into canned, jam and juice products.

As can be seen from Table 1, the demand for cranberries is increasing year by year both worldwide and in China. In 2006, world demand was 3.47 billion US dollars, and in 2010 it exceeded 4.2 billion US dollars.

In China, cranberries are still in the wild, with only some wild species distributed in the northeast and other places. The breeding and cultivation of cranberries has just begun. With the rapid growth of market demand, some domestic research institutes have also begun to select, introduce and breed cranberries[6].

2 Main nutrients in cranberries

Table 2 shows that cranberries are low in calories, high in fiber, and rich in vitamins and minerals. High dietary fiber content can promote intestinal detoxification, prevent constipation, prevent colon cancer, and treat diabetes; VC can prevent scurvy, promote growth and development, enhance physical strength, and relieve fatigue; high potassium and low sodium foods are beneficial for people with hypertension; and VA can maintain normal visual function and enhance immunity. Compared to other fruits, cranberries have a high nutrient content and are healthier for the body.

3 Functional properties of cranberries

3.1 Prevention of urinary tract infections

The most unique effect of cranberries is that they can effectively prevent urinary tract infections (UTIs). Escherichia coli is the cause of 80% to 90% of UTIs. Domestic and foreign scholars have been studying the mechanism of this function for many years. In the early days, it was believed that the various acidic substances in cranberries can increase the acidity of urine in the bladder, creating a strongly acidic environment that kills E. coli in the urethra [8].

In 1998, a study by scientists at New Jersey State University, led by Howell A B, identified for the first time the active substance in cranberries responsible for inhibiting urinary tract infections as concentrated tannic acid or proanthocyanidins (PACs), which had been isolated from cranberries. Proanthocyanidins are concentrated tannins, mainly oligomers or polymers of epicatechin and epigallocatechin. The proanthocyanidin content of cranberries is 34.3 mg/100 g. A large number of studies have shown that it has anti-bacterial adhesion properties, which can prevent pathogenic bacteria such as Escherichia coli from adhering to the epithelial cells of the urethra and the bladder wall. The pathogenic bacteria flow away with the urine, thereby preventing the occurrence of urinary tract infections [9].

Foo LY et al. [10] used 13C nuclear magnetic resonance spectroscopy, electron emission mass spectrometry and other methods to detect the structure of proanthocyanidins in cranberries and found that it is different from the proanthocyanidins in apples, grapes and green tea. The proanthocyanidins in these plants are all B-type linked flavan bonds, while the proanthocyanidins in cranberries contain one or more A-type flavan bonds. This unique A-type structure can compete with the exogenous lectin on the bacterial cilia, preventing the bacteria from binding to the cell receptor. This competitive inhibition is an effective anti-bacterial adhesion property. Currently, only a few plants have this type of structural anthocyanin.

Many researchers have conducted clinical trials and population-based tests on cranberries for their ability to prevent urinary tract infections. David T Bailey et al. [11] selected susceptible women aged 25 to 70 years with a history of urinary tract infections. Before the test, the researchers tested their urine, then had them take capsules containing 200 mg of cranberry concentrate twice a day for 12 weeks. They were then asked about their health every month and their urine was tested for comparison for 2 years. The results showed that during the 12 weeks of taking the capsules and for 2 years after they stopped taking them, these women did not suffer from any further urinary tract infections.

Avorn J et al. [12] conducted a randomized controlled trial with 153 elderly female volunteers and found that women who drank 300 mL of cranberry juice a day had a 27% lower risk of recurrent urinary tract infections than the control group (p=0.0106).

Greenberg J A et al. [13] conducted a small comparative test with five people, who consumed dried cranberries and raisins respectively, and then tested the adhesion of E. coli in their urine. The results showed that the adhesion of E. coli in the urine of the test subjects who consumed dried cranberries was significantly reduced, indicating that dried cranberries are effective in inhibiting the adhesion properties of E. coli.

3.2 Anti-Helicobacter pylori

Cranberries contain proanthocyanidins, ellagic acid, phenolic acids, resveratrol and other substances with antibacterial properties. Many studies have shown that cranberries can inhibit H. pylori infection and are effective in preventing gastric ulcers, gastric cancer and duodenal ulcers. Matsushima M et al. [14] showed that cranberry extract can inhibit the proliferation of H. pylori, and that the polyphenols in the extract play a key role. Cell morphology analysis showed that the substances in cranberries induced H. pylori to develop into spherical shapes, thereby inhibiting H. pylori reproduction.

Ora Burger et al. [15] studied the changes in the adhesion ability of H. pylori to gastric juice and red blood cells in the presence of high concentrations of cranberry extract. The results showed that high concentrations of cranberry extract can effectively inhibit the adhesion ability of H. pylori and prevent diseases caused by H. pylori, such as gastric ulcers.

Zhang et al. [16] conducted a clinical trial on cranberry against H. pylori in Shandong Province. 189 H. pylori-infected people were divided into 2 groups: 97 people drank 250 mL of cranberry juice daily, and 92 people drank an equal dose of a control agent. After 90 days, these infected people were tested for infection using the carbon-13 urea breath test. The results showed that 14 people (14.43%) in the cranberry juice group had negative urea breath tests (elimination of infection), while only 5 people (5.44%) in the control group had negative urea breath tests. There was a significant difference between the two groups. This shows that cranberry juice can inhibit the infection of Helicobacter pylori in the population.

3.3 Antioxidant

In 2007, the US Department of Health compared the antioxidant capacity of commonly consumed fruits, and cranberries came out on top.

Mao Guangming et al. [18] used mice with two models of natural aging and irradiation to feed different doses of cranberries, and after 30 days, the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH2Px) and the content of malondialdehyde (MDA) in the blood and liver tissue of the mice were measured separately. The results showed that cranberries can significantly enhance the activity of SOD and GSH2Px in mouse blood and liver tissue, and reduce the content of MDA in mouse blood and liver tissue. This indicates that cranberries can improve the body's antioxidant capacity in both naturally aging and irradiated mice.

Reed J et al. [19] found that the flavonoids in cranberries have antioxidant properties in both in vivo and in vitro tests, and that flavonols and proanthocyanidins in particular have a preventive effect on atherosclerosis.

3.4 Antitumor

The antioxidant ingredients in cranberries can remove free radicals and mutated cells in the body, which is effective in preventing cancer and killing cancer cells. Catherine Neto et al. [20] extracted proanthocyanidins and other substances from cranberries and then tested their effects on a variety of cancer cells. The results showed that the extract had a toxic effect on lung cancer cells, colon cancer cells, and leukemia cancer cells, significantly inhibiting the growth of these cancer cells, while having no toxic effect on other healthy cells.

Ferguson et al. [21] extracted anthocyanins and other flavonoids from dried cranberries and fed them to mice implanted with breast cancer cells. After a period of feeding, it was found that the spread of cancer cells in the mice was limited and slowed down, and the tumors shrank.

Sun et al. [22] confirmed that cranberry nutritional extracts inhibit the growth of breast cancer cells in two ways: ① inducing cancer cell suicide; and ② preventing the completion of cancer cell reproductive replication, thereby inhibiting their growth.

3.5 Prevention of cardiovascular disease

Cranberries contain a variety of flavonol compounds such as hyperoside, pentahydroxyflavone and myricetin, which, together with anthocyanins, determine the colour of the cranberry fruit. Flavonols have strong antioxidant activity, inhibit the oxidation of low-density lipoprotein cholesterol, lower the level of triglycerides in the blood, and help promote cardiovascular health.

Wilson [23] showed that cranberry juice and extracts can reduce the oxidation of low-density cholesterol.

Reed [24] conducted an animal experiment on pigs, which showed that cranberry juice can reduce the total cholesterol content in pig blood. In particular, the higher the initial total cholesterol level, the greater the decrease in cholesterol levels after consumption, and the better the effect.

Caron [25] conducted a population test, asking the test subjects to compare drinking low-energy cranberry juice with other drinks, and test their cholesterol levels after 28 days. The results showed that the total cholesterol and low-density cholesterol levels in the blood of test subjects who drank cranberry juice decreased significantly, while the triglyceride and high-density cholesterol levels did not change.

Kruse-Elliott et al. [26] showed that cranberries not only increase the level of high-density cholesterol, but also maintain cardiovascular function, which is beneficial for patients with atherosclerosis.

3.6 Protection of the mouth and teeth

Koo et al. [27] found that substances isolated from cranberry juice can break down the flora in the mouth, especially Streptococcus mutans in saliva, which causes tooth decay and plaque, thereby protecting the teeth.

Hyun studied the mechanism of action of cranberries against tooth decay and found that cranberry juice prevents Streptococcus mutans from adhering to the tooth surface, inhibits its reproduction, and thus prevents tooth decay.

Weiss et al. [28] conducted a preliminary clinical study in which participants used mouthwash containing cranberry concentrate (a non-dialyzable polymer) and ordinary mouthwash. The results showed that the participants using cranberry mouthwash had a two-order-of-magnitude reduction in Streptococcus mutans in the mouth, effectively protecting the mouth.

3.7 Lower blood pressure

Cranberries are low in sodium and high in potassium, which makes them effective in lowering blood pressure. Maher et al. [29] conducted an experiment using rats, injecting cranberry juice intravenously and finding that the rats' blood pressure decreased. They also tested the effect of cranberry juice on nitric oxide production in arterial endothelial cells. The study found that cranberry juice can promote the production of nitric oxide in vascular endothelial cells, causing the blood vessels to relax and thus lowering blood pressure. This helps to explain how lingonberries can help promote a healthy blood pressure level.

Apostolidis et al. [30] used water-soluble cranberry extracts combined with oregano, rosemary and rhodiola as raw materials to determine their inhibitory effects on α-glucosidase, pancreatic α-amylase and ACE-1, to evaluate their antioxidant activity, as well as their effects on diabetes and anti-hypertension. The results showed that the ability of different ingredients to inhibit α-glucosidase, pancreatic α-amylase, and ACE-1 was significantly enhanced when combined with cranberry extract, indicating that cranberry extract has antioxidant properties and can lower blood pressure and prevent diabetes.

In addition, cranberries have a variety of other health benefits, such as laxative, lowering cholesterol, preventing heart disease, preventing atherosclerosis, antioxidant, antitumor, antiviral, liver protection, anti-ulcer.

4 Cranberry products

Cranberry products come in a variety of forms and have a wide range of applications, so they have good prospects for promotion. With the rapid development of the cranberry industry and the food and nutrition sector's promotion of its powerful health benefits, cranberries will become better known and more popular to more and more people, and the various products derived from them will also become popular in China. Cranberries will become a rising star in the food industry and contribute to the nutritional health of the Chinese people.

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