Raisin (Vitis vinifera L.) comes from a process of drying the grapes.
The addition of grape or grape derivatives to the diet may exert a certain benefit for the anti-inflammatory action carried out by the polyphenols contained in the berries and seeds of the grape, especially against colon cancer.
Raisin has 330 calories, contains fiber, sugar, magnesium, potassium and traces of iron. It also contains flavonoids (catechins, quercetins, kaempferol and rutin), traces of epicatechins and resveratrol (1).
However, the beneficial effects of the raisin are rather discordant.
This study (in vitro) attributes antioxidant and anti-inflammatory activity to the methanolic extract of two Greek raisin species (Corinthian e Sultanas) that have demonstrated in vitro preventive efficacy on colon cancer cells (2).
This other 3-month study by researchers at the University of Florida found no significant improvement and concludes that "Future studies need to include well-defined health outcomes to establish if the microbial changes resulting from raisin intake correlate with health benefits." (3).
However, raisin has a moderate glycemic index and a low insulin index so it has the potential to reduce the risk of developing diabetes or cardiovascular risks (4).
During processing, raisins can be treated with sulphites (sulphur dioxide) to extend its shelf life. Some people may be allergic to it, especially asthma sufferers.
Be careful not to let pets swallow it as they could have serious digestive problems (5).
Raisin studies
References_______________________________________________________________________
(1) Fulgoni VL 3rd, Painter J, Carughi A. Association of raisin and raisin-containing food consumption with nutrient intake and diet quality in US children: NHANES 2001-2012. Food Sci Nutr. 2018 Oct 15;6(8):2162-2169. doi: 10.1002/fsn3.780.
(2) Kountouri AM, Gioxari A, Karvela E, Kaliora AC, Karvelas M, Karathanos VT. Chemopreventive properties of raisins originating from Greece in colon cancer cells. Food Funct. 2013 Feb 26;4(3):366-72. doi: 10.1039/c2fo30259d.
Abstract. Colorectal cancer is one of the major causes of cancer-related mortality in humans in both developed and developing countries. Dietary patterns influence the risk of colon cancer development, while plant-derived foods have gained great interest, due to the high content of antioxidants. Corinthian raisins (Currants, CR) and Sultanas (S) (Vitis vinifera L., Vitaceae) are dried vine fruits produced in Greece with many culinary uses in both the Mediterranean and the Western nutrition. In the present study, we investigated the effects of CR and S on human colon cancer cells. Methanol extracts of CR and S were used at different concentrations. The total polyphenol content and anti-radical activity were measured by Folin-Ciocalteu and DPPH, respectively. Antioxidant, anti-inflammatory and anti-proliferative effects on HT29 cell culture were evaluated. All extracts exhibited DPPH˙ scavenging activity in a dose-dependent manner. Both products suppressed cell proliferation, while the levels of glutathione and cyclooxygenase 2 were significantly decreased. A significant reduction in IL-8 levels and NF-kappaB p65 activation was also observed. Both antioxidant and anti-inflammatory effects were dependent on the duration of exposure. Results indicate that the methanol extracts of CR and S exhibit anti-radical activity in vitro, as well as cancer preventive efficacy on colon cancer cells, with S having slightly higher activity. The beneficial properties of these unique dried grapes are attributed to their high content of phenolic compounds.
(3) Wijayabahu AT, Waugh SG, Ukhanova M, Mai V. Dietary raisin intake has limited effect on gut microbiota composition in adult volunteers. Nutr J. 2019 Mar 7;18(1):14. doi: 10.1186/s12937-019-0439-1.
Abstract. Background: Dried fruits, such as raisins, contain phytochemicals and dietary fibers that contribute to maintaining health, potentially at least partially through modification in gut microbiota composition and activities. However, the effects of raisin consumption on gut microbiota have not previously been thoroughly investigated in humans. Therefore, the objective of this study was to determine how adding three servings of sun dried raisin/day to the diet of healthy volunteers affects gut microbiota composition....Conclusion: Our findings suggest that adding raisins to the diet can affect the prevalence of specific bacterial taxa. Potential health benefits of the observed microbiota changes should be determined in future studies in populations for which specific health outcomes can be targeted.
(4) Anderson JW, Waters AR. Raisin consumption by humans: effects on glycemia and insulinemia and cardiovascular risk factors. J Food Sci. 2013 Jun;78 Suppl 1:A11-7. doi: 10.1111/1750-3841.12071.
(5) Stanley SW, Langston CE. Hemodialysis in a dog with acute renal failure from currant toxicity.
Can Vet J. 2008 Jan;49(1):63-6.
Elwood S, Whatling C. Grape toxicity in dogs. Vet Rec. 2006 Apr 8;158(14):492.
Raisin 
Catechins
