Herbs and spices have been used for both culinary and medicinal purposes for centuries. Over the last decade, research into their role as contributors of dietary polyphenols, known to possess a number of properties associated with reducing the risk of developing chronic non-communicable diseases, has increased. However, bearing in mind how these foods are consumed, normally in small quantities and in combination with other foods, it is unclear what their true benefit is from a health perspective. The aim of this review is to use the literature to discuss how preparative and digestive processes, bioavailability and interactions between foods may influence the bioactive properties of these foods, and whether or not polyphenols are responsible for these properties. Furthermore, this review aims to highlight the challenges that need to be addressed so as to determine the true benefits of these foods and the mechanisms of action that underpin their purported efficacy.

There is little research on how cooking and digestion affect the anti-inflammatory activity of culinary herbs. Thus, the aim of this paper was to investigate this activity following cooking and in vitro digestion of the common culinary herbs, rosemary, sage, and thyme, and the relationship between their anti-inflammatory activity, polyphenol content, and antioxidant capacity. The anti-inflammatory activity of uncooked (U), cooked (C), cooked and in vitro digested (C&D), and standardised (STD, 30 mg/mL) culinary herbs was assessed by measuring their effect on interleukin 8 (IL-8) release from stimulated human peripheral blood lymphocytes (PBLs) and Caco-2 cells. The trolox equivalent capacity (TEAC) and estimated total phenolic content of the herbs were also determined. There was a significant decrease in IL-8 release from PBLs stimulated with H2O2 incubated with (U), (C), (C&D), and (STD) herbs and from Caco-2 cells stimulated with TNFα incubated with (C&D) and (STD) herbs. PBLs pre-incubated with (C&D) herbs prior to stimulation (H2O2 or TNFα) caused a significant inhibition in IL-8 release. The significant correlations between TEAC and estimated phenolic content and the anti-inflammatory activity suggest a possible contributory role of polyphenols to the anti-inflammatory activity of the culinary herbs investigated.

The impact of cooking and digestion on the antioxidant capacity (AC), estimated total phenolic content (TPC) and anti-inflammatory activity (AA) of culinary spices was determined to investigate their significance as dietary contributors to these properties. Extracts of uncooked (U), cooked (C) and cooked and digested, in vitro, (D) cinnamon, clove and nutmeg were prepared and the TPC, AC and AA, specifically the inhibition of cyclo-oxygenase 2 (COX-2) and the amount of prostaglandin (PG) synthesized, were determined. Compared to their uncooked (U) counterparts, the following changes were statistically significant: the AC and TPC for (C) clove, and the TPC for (D) clove decreased, the TPC for (D) clove increased, the TPC for (C) nutmeg increased, and the AC and TPC for (D) nutmeg increased, and the TPC for (C) and (D) nutmeg increased. All the spices achieved near 100 % inhibition of COX-2 which was associated with the inhibition of the amount of PG synthesized. Based on estimated levels of ingestion, cinnamon possesses a much higher AC than clove and nutmeg because it is typically used in larger quantities. For AA, (U, C and D) cinnamon and clove maintain near 100 % inhibition of COX-2 but only the inhibitory potential of (D) nutmeg could be ascertained (70 %). Cooking and digestion alter the TPC and AC of these spices although the changes are not consistent between spices or across treatments. In contrast to AC, significant AA is likely to be present in these spices at amounts used in cooking.

Culinary herbs have the potential to be a significant source of antioxidants in the diet. However, many culinary herbs are cooked or undergo some other form of processing before they are consumed as part of a meal and such factors may affect their significance as a source of dietary antioxidants. Thus, the impact of cooking (simmering, microwaving, stewing, stir frying and grilling) and storage (vinegar maceration, cold maceration and freezing) on the antioxidant capacity of common culinary herbs was investigated. Extracts of cinnamon, cloves, fennel, ginger, lavender, parsley, rose, rosemary, sage and thyme were prepared pre and post cooking or storage and their antioxidant capacities determined using the Trolox equivalent antioxidant capacity assay (TEAC). Simmering, soup making and stewing significantly increased antioxidant capacity, whilst grilling and stir frying decreased it. Both freezing herbs at -20 degrees C and cold maceration had preservative effects on antioxidant capacity. Herbs in cold vinegar macerations for 1 week showed a decrease in antioxidant capacity compared to the control extracts. These results indicate that the potential of culinary herbs to be significant contributors to dietary antioxidant intake is significantly affected by both cooking and storage.

Flaxseed has become the focus of many studies as a functional food due to its potential health benefits, especially in disease prevention.(1) Flaxseed is considered to be one of the richest plant sources of lignin, which can lower the risk of cardiovascular disease as well as inhibit the development of type 2 diabetes.(2) Flaxseed also contains fibre which plays a key role in lowering postprandial blood glucose levels.(3) The aim of this study was to determine the effect of whole and ground flaxseed on glycaemic response (GR), insulinaemic response (IR) and satiety.In a randomized cross-over design, 32 healthy volunteers (21 female, 11 male; age 29 SD 5·8 years) consumed three different muffins (control, whole flaxseed and ground flaxseed) and the effects on GR and IR were measured over 2-hours using capillary blood samples. Participants' subjective feelings of satiety/hunger were also recorded on seven-point hedonic scales.The results for the iAUC for glucose and insulin showed that both the whole and ground flaxseed muffins significantly lowered GR and IR compared to the control muffins at 60, 90 and 120 min (P < 0·001); however, there were no significant differences between the two flaxseed muffins (P < 0·05). The results for the iAUC for satiety showed that at 60, 90 and 120 min post consumption there was not significantly different (P > 0·05) between the types of muffins; however, whole flaxseed muffins had the highest iAUC results compared to the control and ground flaxseed muffins. Overall, the results of this study highlight the importance of investigating the addition of flaxseed in different forms to bakery products, in terms of GR and IR and satiety.In conclusion, there is a limited amount of literature on the effect of flaxseed on GR and IR among healthy individuals. Most flaxseed-based studies have focused on hyperlipidaemic or diabetic patients, but the results of this study suggest there may be benefits to encouraging consumption of flaxseed among healthy individuals. This demonstrates the potential for flaxseed to improve GR and IR control in healthy individuals. a Significant difference between whole flaxseed muffin and control muffin (P < 0·05). b Significant difference between ground flaxseed muffin and control muffin (P < 0·05).