Background

In Trinidad and Tobago the incidence of cancer and mortality rates are amongst the highest in the develo** world [1]. The major ethnic groups on the islands are African and Asian Indian descendants with disproportionately higher incidences of prostate and breast cancers among African-Trinidadians [2], with poorer prognosis compared with their Asian Indian counterparts [3, 4]. It has also been shown that African-Caribbean men with prostate cancer living in the Caribbean had a 3.7-fold increased risk of death compared with their African-Caribbean born counterpart living the United States [5]. Similarly, African-Caribbean women with breast cancer had poorer prognosis than their African-American counterparts [6]. It has been suggested that poor survival rates may be due to diagnosis at advanced stages and failure to use multimodality as the first course of treatment [7, 8].

Although conventional interventions, including surgery, chemotherapy and radiation, are available, surveys elsewhere have shown that many cancer patients use various forms of complementary and alternative medicine [9, 26].

Oxidative stress is known to induce cancer and a recent study in overweight breast cancer survivors showed that the daily consumption of carrot juice increased plasma carotenoid levels, this would subsequently reduce oxidative stress and it has been postulated that this would reduce the risk of recurrence of cancer [27]. Studies in human colon and breast cancer cell lines demonstrated anti-proliferative effects of extract of carrot oil by modulating various mediators of apoptosis and cell cycle arrest [28, 29].

Wheatgrass (Triticum aestivum L.) was another popular remedy used mostly by breast and colorectal cancer patients in our study. Although there were no clinical studies to support its use, there are a few in vitro studies using breast and colorectal cancer cell lines. Wheatgrass is fermented by gut microflora to secondary products, and it has been proposed that these compounds possess significant antineoplastic activity. Non-fermented and fermented wheatgrass extract significantly decreased growth in a colon cancer cell line [30]. These results were corroborated in another laboratory study which showed that fermented wheatgrass extract inhibited growth and increased apoptosis in two different colon cancer cell lines [31]. More recently, it was shown that the combination of cisplatin and wheatgrass extract had a synergistic effect to inhibit growth in a breast cancer cell line and modulate apoptosis and proliferation-associated genes [32].

The use of papaya (Carica papaya L.) was also common among our patients with leaves being used to make a tea and the fruit being juiced or blended. The aqueous extract of fresh papaya leaves was tested against various cancer cell lines and human peripheral blood mononuclear cells to determine whether it exhibited cytotoxic activity and inhibitory effects on various biomarkers of inflammation and apoptosis [33]. The results showed that papaya extract significantly inhibited growth of cancer cells and down-regulated the expression of pro-inflammatory cytokines IL-2 and IL-4. Although the use of papaya in cancer treatment is commonly practiced, a review of the literature did not unearth any observational or interventional clinical studies which supported the use of papaya in cancer treatment.

Although the Indian spice saffron (Crocus sativus L.) was also popular among our patients, we suspect that the spice used may in fact be mixed with other spices such as turmeric, which is a known cultural culinary/traditional medicine practice among East Indians in Trinidad. Crocin, the major constituent of saffron, was shown to have a dose-dependent anti-proliferative effect against three colorectal cancer cell lines and a non-small cell lung cancer cell line whilst not having any effect on normal cells [34]. In another in vitro experiment crocetin, the main metabolite of crocin, was anti-proliferative and prevented the migration of a highly invasive breast cancer cell line by down-regulating the expression of matrix metalloproteinases [35]. Extracts have also been shown to have anti-proliferative effects against aggressive prostate cancer cell lines by mechanisms which include down-regulation of metalloproteinases, DNA fragmentation and induction of mediators of apoptosis [36, 37].

This study was limited due to its cross-sectional nature and the short time frame and we were not able to follow-up patients to determine the impact of supplementation on clinical outcomes. Our access was limited to patients attending public healthcare facilities who generally were at the lower economic strata with less disposable income to make “out-of-pocket” purchases for commercial products. We also limited our target population to breast, prostate and colorectal cancer patients and there may be differences in the pattern of herbal remedy and functional food use in patients with other types of cancers. However, despite these limitations the study highlighted the most common herbal remedies and functional foods used in the most common cancers in patients accessing public healthcare in Trinidad.

Conclusions

This study unearthed the herbal remedies and functional foods used by patients with the most prevalent cancers in Trinidad. It was not surprising that soursop (Annona muricata L.) was the most common herbal remedy, as the herb has strong traditional use on the island. We also found high use of juices made from vegetables, which were used on a daily basis by most patients. As in our previous surveys in Trinidad [11–13] women used more of herbal remedies/functional foods than men, especially beetroot and carrots. Most of the scientific evidence of antineoplastic activity of these plants and functional foods comes from in vivo and ex vivo studies. However, despite the lack of clinical evidence most patients felt or believed that these remedies are equally or more efficacious than conventional treatments.