Nutrition: an evidence-based approach is the key

• A period of change​ ​
• Epigenetics​​
• Analysis of food composition​​
• Media and public interest​​

It was during the first half of the 20th century that nutrition science was shaped and significant improvements in child growth and population health occurred.

Vitamins, minerals and the essential building blocks of protein and fats were identified, and the nutrient composition of everyday foods was established.

The National Food Survey, the world’s longest running dietary survey – now called Family Food –  was established in 1940 by the Ministry of Food.

It provides a fascinating insight into trends in food and nutrient intakes over 75 years and its legacy is one of the topics covered in a special issue of Nutrition Bulletin, produced to celebrate the 50th anniversary of the British Nutrition Foundation (BNF), which was established as a charity in 1967.

The BNF publication​ comprises articles that chart developments over the past half century in various disciplines that together contribute to the nutrition science evidence base: research methodology, epidemiology, biochemistry, behavioural science, epigenetics, biomedical science, and food science and technology.

Accompanying editorials, one by chair of the BNF board of trustees Professor Christine Williams, and a celebratory booklet​, summarise these developments in the context of BNF’s achievements during this period in food and nutrition education in schools, including the now annual BNF Healthy Eating Week, and in nutrition science communication via task force reports, reviews, conferences, training and websites.

These editorials also acknowledge many key figures in the world of food and nutrition who have generously given their time and shared their wisdom and expertise, not least BNF’s royal patron HRH The Princess Royal.

BNF’s second director general was Dorothy Hollingsworth, who had previously worked alongside Sir Jack Drummond at the Ministry of Food in the 1940s and, in 2012 – perhaps by coincidence – BNF took over management of the Drummond Memorial Fund set up following Drummond’s untimely death in the 1950s.

This fund is now devoted to supporting the work and celebrating the achievements of students of food and nutrition and early career nutrition scientists. The fund also supports a BNF internship programme for nutrition graduates.

A period of change (back to top)​​

The past half century has been characterised by major technological discoveries and massive societal change, which have profoundly changed how food is produced, processed, sold and consumed.

The development of epidemiology as a discipline is one of the most important contributors to our understanding of diet-disease relationships during the 20th century, in particular heart disease, stroke, type-2 diabetes and cancer. It has also led to important advances in understanding the effect of early diet on future health.

Epidemiology shifted attention back towards consideration of long-term effects of undernutrition in infancy and childhood and the importance of protein adequacy and micronutrients, such as folate.

It is now recognised that diet and growth during early-life has a significant impact on an individual’s later risk of obesity and ill health – the topic of a recent BNF taskforce. Epidemiology also stimulated interest in biological mechanisms, such as epigenetics, that might underpin this ‘programming’ response to adverse early-life nutrition.

Epigenetics (back to top)​​​

Epigenetics involves small chemical changes in the structure of DNA and there is now plausible evidence that diet can lead to such changes, with associated effects on regulatory genes.

It seems likely that epigenetics is the biological key for the long-term effects of early life nutrition, first proposed by Professor David Barker in 1986, and epigenetic patterns may also have potential as biomarkers of healthy ageing, an increasingly important topic as lifespan increases.

Nevertheless, knowledge remains incomplete and some early hypotheses have not been fully supported by subsequent meta-analyses and mechanistic studies, whereas others have been strengthened, such as the relationships between obesity and cancer risk and between dietary fibre intake and health.

From time to time, established diet-disease associations are challenged and debated in the media, even when they have been confirmed in controlled feeding studies.

This has happened recently with heart disease, the topic of a BNF taskforce report to be launched in 2018.

Professor Williams comments that the debate failed to recognise the major change in population fat intakes over the past 50 years or that earlier studies often relied on a single measurement of diet to classify subjects’ habitual diets, which provided a poor marker of an individual’s overall saturated fat exposure during the subsequent period of follow-up.

Williams notes that a rapid change in population diets over time is a challenge that the design of future epidemiological cohort studies needs to address.

Another aspect often overlooked is the nature of the substitution made when saturated fat is reduced.

Discussed is evidence from a meta-analysis of randomised controlled trials, which shows that replacing saturated fat with polyunsaturated fats reduced cardiovascular death by 27%, with the greatest reduction seen in the sub-group that showed the greatest fall in blood cholesterol. Whereas, when saturated fat is replaced by refined carbohydrates, the beneficial effect is not seen.

Analysis of food composition (back to top)​​​

Advances in the analysis of food composition, extending beyond established nutrients to other bioactive components of plant foods, such as polyphenols, has supported research into the wider role of plant-derived foods in protection against chronic disease, although research is still in its infancy and few health claims have been established.

Understanding factors (physiological and psychological) that affect energy balance, food choice and appetite control, including the role of energy density, portion size and the wider environment, is also fundamental.

Behavioural science has contributed to understanding the complexity but has yet to produce a behavioural solution that accommodates the diversity of eating patterns and high degree of individual variability.

A lot of evidence has come from lab studies but this is now being joined by research, using technologies to collect information in real-life situations, such as eye tracking.

A major review of UK nutrition and human health research, published in July1, reported that the biggest contributor to ill health over the past 25 years is the combination of unhealthy diets, inactivity and overweight, with these lifestyle factors overlapping with metabolic risks such as high blood pressure and blood cholesterol.

The document describes the grand challenges, such as maximising human potential through nutrition and detailing the role of nutrition in healthy ageing.

It emphasises the need to capitalise on existing strengths, through greater co-operation and leadership, and to forge links between the expertise and resources that exist within the public and private sectors in order to maximise value from existing investment, supported by a transparent framework for engagement.

The review’s authors state these actions will facilitate translation of research for the benefit of public health and clinical practice.

They also emphasise the need to consider diet and dietary patterns in a holistic way, and echo the government’s childhood obesity plan in saying that long-term sustainable change needs active engagement of schools, communities, families and individuals.

Media and public interest (back to top)​​​

Media and public interest in food and health in the UK has continued to grow and is arguably at an all-time high.

The plethora of health and nutrition information available these days – through routes as diverse as family, friends, teachers, health professionals, the media, celebrity chefs and the internet, including bloggers and other social media – makes provision of consistent and evidence-based information increasingly difficult.

It is not easy to predict the future in the uncertain times in which we live. But it now seems clear that pressures on the global food supply and the challenges of securing a food supply that is both healthy and sustainable can be expected to escalate as the impact of climate change bites and affects the types of crops we can grow and where they thrive, and as the world’s population continues to increase, live longer and the world’s poorer communities become more prosperous and aspire to a different lifestyle and diet.

The ramifications of this confluence of factors will be considered at a BNF conference on October 12 2017 to celebrate our 50th anniversary, in the context of the technological developments over the past 50 years that have contributed positively to the food system we currently have and the opportunities for technology to support sustainable nutrition over the coming decades.

In such scenarios, evidence-based nutrition science communication becomes ever more important, yet evidently increasingly difficult to achieve with the explosion of communications channels now available.

Although many of these sources offer well-meaning advice, confusion can result from conflicting recommendations and the absence of proper context.

Science communication is an area in which BNF plans to remain actively involved, focusing on our vision of making nutrition science accessible to all.