The role of plant foods during the fluted-point period (FPP) of North America is contested. Central to this debate is whether the scarcity of FPP macrobotanical materials stems from poor preservation of archaeological features and the macrobotanical remains they might contain or from the limited use of plants during the FPP. Employing summed probability distributions of radiocarbon date frequencies in northeastern North America, we find that FPP hearths are as common as expected, given the small number of well-dated FPP sites in the region. A second comparison shows that northeastern FPP hearths contain macrobotanical remains at a higher frequency than hearths from a region with better preservation and where small seeds formed a part of the diet. The macrobotanical materials so far recovered from FPP hearths in the Northeast show that plant foods contributed to diets during the FPP but that the plant diet breadth was relatively narrow, consistent with a specialized caribou hunting lifeway.

Food phytochemicals are increasingly considered to play a key role in the cardiometabolic health effects of plant foods. However, the heterogeneity in responsiveness to their intake frequently observed in clinical trials can hinder the beneficial effects of these compounds in specific subpopulations. A range of factors, including genetic background, gut microbiota, age, sex and health status, could be involved in these interindividual variations; however, the current knowledge is limited and fragmented. The European network, European Cooperation in Science and Technology (COST)-POSITIVe, has analysed, in a systematic way, existing knowledge with the aim to better understand the factors responsible for the interindividual variation in response to the consumption of the major families of plant food bioactives, regarding their bioavailability and bioefficacy. If differences in bioavailability, likely reflecting differences in human subjects’ genetics or in gut microbiota composition and functionality, are believed to underpin much of the interindividual variability, the key molecular determinants or microbial species remain to be identified. The systematic analysis of published studies conducted to assess the interindividual variation in biomarkers of cardiometabolic risk suggested some factors (such as adiposity and health status) as involved in between-subject variation. However, the contribution of these factors is not demonstrated consistently across the different compounds and biological outcomes and would deserve further investigations. The findings of the network clearly highlight that the human subjects’ intervention studies published so far are not adequate to investigate the relevant determinants of the absorption/metabolism and biological responsiveness. They also emphasise the need for a new generation of intervention studies designed to capture this interindividual variation.

The classic image of Upper Palaeolithic hunter-gatherers in Europe envisages them hunting large mammals in largely treeless landscapes. That is partly due to the nature of the surviving archaeological evidence, and the poor preservation of plant remains at such ancient sites. As this study illustrates, however, the potential of Upper Palaeolithic sites to yield macrofossil remains of plants gathered and processed by human groups has been underestimated. Large scale flotation of charred deposits from hearths such as that reported here at Dolní Vӗstonice II not only provides insight into the variety of flora that may have been locally available, but also suggests that some of it was being processed and consumed as food. The ability to exploit plant foods may have been a vital component in the successful colonisation of these cold European habitats.

Non-enzymatic antioxidant capacity (NEAC) represents a sensitive biomarker measuring the in vivo antioxidant potential of vegetable foods. To evaluate the effectiveness of plant-derived foods and beverages on the plasma non-enzymatic antioxidant system, we analysed all literature published upto May 2010. Data were extracted by two authors independently, and the effect size was summarised using standardised mean differences by a random-effects model. For the analysis, eighty-eight studies were included, reporting a total number of 122 interventions and involving 2890 subjects. There was overall evidence of the effectiveness of fruit, vegetables, dietary patterns based on plant foods, red wine and tea in increasing plasma NEAC. No changes were found for chocolate and fruit juices. We observed an overall effect size three times higher in subjects with risk factors when compared with healthy subjects. Total radical-trapping antioxidant parameter, oxygen radical absorbance capacity and ferric-reducing antioxidant power methods showed a similar increase in plasma NEAC following dietary supplementation, whereas Trolox equivalent antioxidant capacity did not respond to dietary supplementation. Data from the present meta-analysis show that plant-derived foods represent an effective strategy to enhance an endogenous antioxidant network in humans. This is particularly evident in the presence of oxidative stress-related risk factors.

Epidemiological evidence suggests that a high intake of plant foods is associated with lower risk of chronic diseases. However, the mechanism of action and the components involved in this effect have not been identified clearly. In recent years, the scientific community has agreed to focus its attention on a class of secondary metabolites extensively present in a wide range of plant foods: the flavonoids, suggested as having different biological roles. The anti-inflammatory actions of flavonoids in vitro or in cellular models involve the inhibition of the synthesis and activities of different pro-inflammatory mediators such as eicosanoids, cytokines, adhesion molecules and C-reactive protein. Molecular activities of flavonoids include inhibition of transcription factors such as NF-κB and activating protein-1 (AP-1), as well as activation of nuclear factor-erythroid 2-related factor 2 (Nrf2). However, the in vitro evidence might be somehow of limited impact due to the non-physiological concentrations utilized and to the fact that in vivo flavonoids are extensively metabolized to molecules with different chemical structures and activities compared with the ones originally present in the food. Human studies investigating the effect of flavonoids on markers of inflammation are insufficient, and are mainly focused on flavonoid-rich foods but not on pure molecules. Most of the studies lack assessment of flavonoid absorption or fail to associate an effect on inflammation with a change in circulating levels of flavonoids. Human trials with appropriate placebo and pure flavonoid molecules are needed to clarify if flavonoids represent ancillary ingredients or key molecules involved in the anti-inflammatory properties of plant foods.

Studies on the association between plant foods and cerebrovascular diseases have given contradictory results suggesting the existence of some effect-modifying factors. The present study determines whether the consumption of plant foods (i.e. fruits and berries, vegetables, and cereals) predicts a decreased cerebrovascular disease incidence in a population with low fruit and vegetable and high wholegrain intake. This cohort study on 3932 men and women was based on data from the Finnish Mobile Clinic Health Examination Survey, conducted in 1968–72. The participants were 40–74 years of age and free of cardiovascular diseases at baseline. Data on the plant food consumption were derived from a 1-year dietary history interview. During a 24-year follow-up 625 cases of cerebrovascular diseases occurred, leading to either hospitalisation or death. An inverse association was found between fruit consumption and the incidence of cerebrovascular diseases, ischaemic stroke and intracerebral haemorrhage. The adjusted relative risks (RR) between the highest and lowest quartiles of intake of any cerebrovascular disease, ischaemic stroke and intracerebral haemorrhage were 0·75 (95 % CI 0·59, 0·94), 0·73 (95 % CI 0·54, 1·00) and 0·47 (95 % CI 0·24, 0·92), respectively. These associations were primarily due to the consumption of citrus fruits and occurred only in men. Total consumption of vegetables or cereals was not associated with the cerebrovascular disease incidence. The consumption of cruciferous vegetables, however, predicted a reduced risk of cerebrovascular diseases (RR 0·79; 95 % CI 0·63, 0·99), ischaemic stroke (RR 0·67; 95 % CI 0·49, 0·92) and intracerebral haemorrhage (RR 0·49; 95 % CI 0·25, 0·98). In conclusion, the consumption of fruits, especially citrus, and cruciferous vegetables may protect against cerebrovascular diseases.

Plant foods are the major staples of diets in developing countries, in which the consumption of animal-source foods is often low because of economic and/or religious concerns. However, such plant-based diets are often associated with micronutrient deficits, exacerbated in part by poor micronutrient bioavailability. Diet-related factors in plant foods that affect bioavailability include: the chemical form of the nutrient in food and/or nature of the food matrix; interactions between nutrients and other organic components (e.g. phytate, polyphenols, dietary fibre, oxalic acid, protein, fat, ascorbic acid); pretreatment of food as a result of processing and/or preparation practices. Consequently, household strategies that reduce the content or counteract the inhibiting effects of these factors on micronutrient bioavailability are urgently needed in developing-country settings. Examples of such strategies include: germination, microbial fermentation or soaking to reduce the phytate and polyphenol content of unrefined cereal porridges used for young child feeding; addition of ascorbic acid-containing fruits to enhance non-haem-Fe absorption; heating to destroy heat-labile anti-nutritional factors (e.g. goitrogens, thiaminases) or disrupt carotenoid–protein complexes. Such strategies have been employed in both experimental isotope-absorption and community-based studies. Increases in Fe, Zn and Ca absorption have been reported in adults fed dephytinized cereals compared with cereals containing their native phytate. In community-based studies in rural Malawi improvements in dietary quality and arm-muscle area and reductions in the incidence of anaemia and common infections in young children have been observed.

Plants provide the major part of human food intake. Whilst advances in agronomic characteristics (improved yield and better pest and disease resistance) continue to be a very high priority, there is increasing opportunity to enhance the nutritional value of plant based diets by improving the nutritional quality of staple foods. We now have proof of principle that genetic engineering can be used to produce plant-derived human vaccines. In relation to plant foods for human health, the research challenges include understanding: (1) why certain foods cause adverse reactions in some individuals but not in others; (2) the mechanisms of action of apparently ‘protective’ foods such as fruits and vegetables. There is also a need to develop much more informative and robust methods for measuring dietary exposure to specific plant foods or food constituents, including both recent exposure, for which a metabolomics approach may be particularly helpful, and long-term exposure.

There is evidence that a diet rich in fruit and vegetables reduces blood pressure (BP). Characteristically, the Mediterranean diet is rich in plant-derived foods and also in fat, but studies conducted in Mediterranean countries to relate diet to BP are scarce. We studied the association between fruit and vegetable consumption and BP in a cross-sectional analysis of 4393 participants in the Seguimiento Universidad de Navarra (SUN) Study, an ongoing dynamic cohort study in Spain. Diet was measured using a food-frequency questionnaire previously validated in Spain. Fat represented more than 37% total energy intake. Subjects were considered to have undiagnosed hypertension if they reported systolic BP ≥140 mmHg or diastolic BP ≥90 mmHg, and not a medical diagnosis of hypertension. The adjusted prevalence odds ratio of undiagnosed hypertension (upper v. lowest quintile) was 0·58 (95% CI 0·36, 0·91; P for trend 0·01) for vegetable consumption and 0·68 (95% CI 0·43, 1·09; P for trend 0·10) for fruit consumption. Comparing those in the highest quintile of both fruit and vegetable consumption with those in the lowest quintile of both food groups, the prevalence odds ratio was 0·23 (95% CI 0·10, 0·55; P=0·001), after adjusting for risk factors for hypertension and other dietary exposures. In a Mediterranean population with an elevated fat consumption, a high fruit and vegetable intake is inversely associated with BP levels.

The glycaemic index (GI) is an in vivo measurement based on the glycaemicresponse to carbohydrate-containing foods, and allows foods to be ranked on the basis of the rate of digestion and absorption of the carbohydrates that they contain. GI values are normalizedto a reference amount of available carbohydrate and do not reflect the amounts of carbohydrate normally present in foods; for example, a food with a low content of carbohydrates will have a high GI value if that carbohydrate is digested and absorbed rapidly in the human small intestine. This is potentially confusing for a person wishing to control his or her blood glucoselevels by the choice of foods. The rate and extent of starch digestion in vitro has been measured using a technique that classifies starch into three major fractions: rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS). In addition, thistechnique gives a value for rapidly available glucose (RAG), which includes RDS, free glucose and the glucose moiety of sucrose. When the values for thirty-nine foods were expressed on the basis ofthe available carbohydrate content of these foods, highly significant (P<0·001) positive correlations were observed between GI and both RDS and RAG. The measurement of RAGin vitro provides values for direct calculation of the amount of glucose likely to be rapidly absorbed in the human small intestine and,thus, to influence blood glucose and insulin levels. These values can be used to compare foods, as eaten,on an equal-weight basis. Food-table RAG values would allow simple calculation of the total amount of RAG provided by single foods, by whole meals and by whole diets. Studies are planned in which RAG and the glycaemic response in man will be measured for identical food products.