In the last 50 years science has provided new perspectives on the ancient art of herbal medicine. The present article discusses ways in which the evidence base for the professional use of 'Western' herbal medicine, as therapy to treat disease, known as phytotherapy, can be strengthened and developed. The evidence base for phytotherapy is small and lags behind that for the nutritional sciences, mainly because phytochemicals are ingested as complex mixtures that are incompletely characterised and have only relatively recently been subject to scientific scrutiny. While some methodologies developed for the nutritional sciences can inform phytotherapy research, opportunities for observational studies are more limited, although greater use could be made of patient case notes. Randomised clinical trials of single-herb interventions are relatively easy to undertake and increasing numbers of such studies are being published. Indeed, enough data are available on three herbs (ginkgo (Ginkgo biloba), St John's wort (Hypericum perforatum) and saw palmetto (Serenoa repens)) for meta-analyses to have been undertaken. However, phytotherapy is holistic therapy, using lifestyle advice, nutrition and individually-prescribed mixtures of herbs aimed at reinstating homeostasis. While clinical experience shows that this approach is applicable to a wide range of conditions, including chronic disease, evidence of its efficacy is scarce. Strategies for investigating the full holistic approach of phytotherapy and its main elements are discussed and illustrated through the author's studies at the University of Reading.

Plant biotechnology can make important contributions to food security and nutritional improvement. For example, the development of ‘Golden Rice’ by Professor Ingo Potrykus was a milestone in the application of gene technology to deliver both increased nutritional qualities and health improvement to wide sections of the human population. Mineral nutrient and protein deficiency as well as food security remain the most important challenges for developing countries. Current projects are addressing these issues in two major staple crops, cassava (Manihot esculenta Crantz) and rice. The tropical root crop cassava is a major source of food for approximately 600 million of the population worldwide. In sub-Saharan Africa >200 million of the population rely on cassava as their major source of dietary energy. The nutritional quality of the cassava root is not sufficient to meet all dietary needs. Rice is the staple food for half the world population, providing approximately 20% of the per capita energy and 13% of the protein for human consumption worldwide. In many developing countries the dietary contributions of rice are substantially greater (29·3% dietary energy and 29·1% dietary protein). The current six most popular ‘mega’ rice varieties (in terms of popularity and acreage), including Chinese hybrid rice, have an incomplete amino acid profile and contain limited amounts of essential micronutrients. Rice lines with improved Fe contents have been developed using genes that have functions in Fe absorption, translocation and accumulation in the plant, as well as improved Fe bioavailability in the human intestine. Current developments in biotechnology-assisted plant improvement are reviewed and the potential of the technology in addressing human nutrition and health are discussed.

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.

Se is an essential element for animals. In man low dietary Se intakes are associated with health disorders including oxidative stress-related conditions, reduced fertility and immune functions and an increased risk of cancers. Although the reference nutrient intakes for adult females and males in the UK are 60 and 75 μg Se/d respectively, dietary Se intakes in the UK have declined from >60 μg Se/d in the 1970s to 35 μg Se/d in the 1990s, with a concomitant decline in human Se status. This decline in Se intake and status has been attributed primarily to the replacement of milling wheat having high levels of grain Se and grown on high-Se soils in North America with UK-sourced wheat having low levels of grain Se and grown on low-Se soils. An immediate solution to low dietary Se intake and status is to enrich UK-grown food crops using Se fertilisers (agronomic biofortification). Such a strategy has been adopted with success in Finland. It may also be possible to enrich food crops in the longer term by selecting or breeding crop varieties with enhanced Se-accumulation characteristics (genetic biofortification). The present paper will review the potential for biofortification of UK food crops with Se.

Simplification of human diets associated with increased accessibility of inexpensive agricultural commodities and erosion of agrobiodiversity leads to nutrient deficiencies and excess energy consumption. Non-communicable diseases are growing causes of death and disability worldwide. Successful food systems in transition effectively draw on locally-available foods, food variety and traditional food cultures. In practice this process involves empirical research, public policy, promotion and applied action in support of multi-sectoral, community-based strategies linking rural producers and urban consumers, subsistence and market economies, and traditional and modern food systems. Implementation of the International Plant Genetic Resources Institute's Global Nutrition Strategy in Sub-Saharan Africa offers a useful case study. Relevant policy platforms, in which biodiversity conservation and nutrition are and should be linked, include the Millennium Development Goals, Millennium Ecosystem Assessment, Convention on Biological Diversity, Global Strategy on Diet, Physical Activity and Health, Food-Based Dietary Guidelines, Right to Adequate Food and UN Human Rights Commission's Permanent Forum on Indigenous Issues. The largely unexplored health benefits of cultivated and wild plants include micronutrient intake and functions related to energy density, glycaemic control, oxidative stress and immuno-stimulation. Research on the properties of neglected and underutilized species and local varieties deserves higher priority. In tests of the hypothesis that biodiversity is essential for dietary diversity and health, quantitative indicators of dietary and biological diversity can be combined with nutrition and health outcomes at the population level. That traditional systems once lost are hard to recreate underlines the imperative for timely documentation, compilation and dissemination of eroding knowledge of biodiversity and the use of food culture for promoting positive behaviours.

Fungi are a good source of digestible proteins and fibre, are low in fat and energy and make a useful contribution to vitamin and mineral intake. In terms of current dietary advice, 80 g fungi represent one portion of vegetables. Dried fungi and concentrated extracts are also used as medicines and dietary supplements. Some species show strong anti-tumour and antioxidant activity by enhancing various immune system functions and lowering cholesterol levels. Nevertheless, there are also some safety concerns. Edible species might be mistaken for poisonous ones, high heavy-metal concentrations in wild edible fungi (WEF) are a known source of chronic poisoning and the consumption of WEF can contribute markedly to the radiocaesium intake of human subjects. Some regions of Europe have a strong WEF tradition, especially eastern Europe. In the UK the consumption of wild fungi is considered of minor importance. Only one-third of adults consume fungi (cultivated species and WEF) throughout the UK; the average intake of fungi in the UK is estimated to be 0.12 kg fresh weight per capita per year. At least eighty-two species of wild fungi are recorded as being consumed in the UK, although certain species (e.g. chanterelle (Cantharellus cibarius), cep (Boletus edulis), oyster mushroom (Pleurotus ostreatus)) are favoured over others. Although WEF are not essential components in the daily diet, they are a nutritionally-valuable addition to the range of vegetables consumed, and their role in helping to avert food shortages in less-favoured areas should be definitely considered.

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.

Neural-tube defects (NTD) are common congenital malformations that can lead to severe disability or even death. Periconceptional supplementation with the B-vitamin folic acid has been demonstrated to prevent 50–70% of NTD cases. Since the identification of the first genetic risk factor of NTD, the C677T single-nucleotide polymorphism (SNP) in the methylenetetrahydrofolate reductase (MTHFR) gene, and the observation that elevated plasma homocysteine levels are associated with NTD, research has focused on genetic variation in genes encoding for enzymes of folate metabolism and the closely-related homocysteine metabolism. In the present review relevant SNP in genes that code for enzymes involved in folate transport and uptake, the folate cycles and homocysteine metabolism are summarised and the importance of these SNP discussed in relation to NTD risk.