Opinion: Healthy diets for a growing world population

Tuesday 5th March 2019

New Zealand is a nation of food and beverage producers with our primary industries producing enough food and beverage annually to feed over five to ten times our population. Yet with the world population set to increase to 9.7 billion by 2050, only 31 years away, global food systems will be seriously challenged to nutritiously and sustainably feed everyone.

Primary industries worldwide are facing growing environmental and social challenges and emerging disruptive food technologies. We see frequent media stories about the environmental cost of our agriculture: water quality, greenhouse gas emissions, climate change and degradation, animal welfare. Consequently, we also see frequent stories about the rise in emerging and disruptive technologies supposedly free of some of these very real concerns, or in the case of recent media reports a suggestion of a new diet (EAT-Lancet) that can feed the growing planetary population sustainably.

The Riddet Institute conducts a wide-ranging research programme to examine these issues to support and challenge changing current opinion, with innovative scientific research. Our current opinion is that a well-balanced diet containing good quality nutrients including proteins, including animal-sourced and dairy foods, alongside vegetables, fruits, legumes and nuts, provides the best overall nutrition for the general population, and more specifically groups of consumers such as children, seniors and pregnant females. While 821 million people worldwide are hungry, over 2 billion suffer from single or multiple micronutrient deficiencies and more than 70 % of global deaths are attributed to non-communicable diseases (NCDs). Therefore, while ensuring access to sufficient food; it is also particularly important to improve the quality of nutrients that global diets currently provide.

The Riddet Institute supports dietary guidelines that have the potential to help global efforts to counter the epidemic of malnutrition and non-communicable diseases in a sustainable way. However, we do recognise personal choice in planning our chosen diets within traditional, sustainable food patterns worldwide, and recognise nutritional and economic constraints of populations under poverty thresholds, that can also be living in difficult and challenging political and environmental situations.

The Riddet Institute is investigating the uncertainty around the supply and value chains for our food and nutrition, including alternative protein sources and the impact of food biodiversity on the nutrient composition of foods, including their true environmental and social costs, the production costs and scalability of their supply chains, food safety concerns and likely consumer acceptance. Moreover, the positive environmental, nutritional and health impacts attributed to alternative proteins has yet to be scientifically substantiated. Research is urgently required to ensure the validity of the inevitable comparisons between existing animal-based protein sources and their alternatives.

The Riddet Institute-led “Proteos” project is evaluating the quality of protein and nutritional supply of amino acids from human foods. It is a research collaboration between Massey University, Wageningen University and Research (WUR), University of Illinois and AgroParisTech, France; and is an exemplar of our research in this area. It has actively involved animal and human nutrition groups, with the aim to develop an international database of the protein quality of human foods. The Proteos project aims to evaluate protein sources for human consumption in a changing dietary landscape.

Distinguished Professor Paul Moughan of the Riddet Institute and project leader of Proteos says “With calls to shift the human diet more towards plant-based proteins and nutrition, a focus of the EAT-Lancet report, protein quality becomes very important, especially for some consumers. Animal-sourced proteins play an important role in providing adequate amounts of key amino acids and other important nutrients like lipids (fats, oils and some vitamins) vitamins and minerals”.

“One of the key realisations in recent years is that not all food sources are created equal and nor do they deliver the same level of nutrients to us when we consume foods”, Professor Warren McNabb, the Institute’s Deputy Director says. “There are many instances when bioavailability of nutrients (i.e. how easily the nutrient is extracted from food by our body) is not taken into account when designing a balanced diet. We cannot assume that all foods deliver the same amount of carbohydrates, amino acids, lipids, vitamins and minerals, even when they are compositionally similar. Bioavailability is a complex process which is affected by food composition, its structure, digestion, the environment a consumer lives in, sanitation levels and the intestinal uptake, gut microbiome and nutrient stores of an individual person”.

Bioavailability of some key nutrients from plant-based foods can be less than half that from animal-based foods.  Professor McNabb cites that “iron bioavailability from plant-based foods can vary from 5-10 %, while that from red meat is 12-18%. Zinc bioavailability from plant-based foods is between 15-30 % and that from red meat is 30-50%. The amino acids from animal-sourced proteins like those from meat and dairy foods can have a higher bioavailability than plant-sourced proteins. The bioavailability of amino acids from dairy proteins (milk or whey protein concentrate) actually exceeds 100% compared to about 80% for pea protein and less than 50% for rice protein.” 

Calcium is a good example of how complex the availability of nutrients from food can be. For a healthy diet, the total amount of any nutrient supplied is crucial, in addition to its bioavailability. For example, to get the same amount of calcium as in a single serve (250 ml) of milk, you could need to eat up to 16 equivalent servings of a specific plant food. Hence, the need for caution when assessing prescribed diets like those proposed by EAT-Lancet and others, where they do not adequately address the bioavailability, as well as the amount of all nutrients, says Professor McNabb.

Professor McNabb says, “New Zealand and our primary industries are likely facing a range of different possible future scenarios, and whilst it is not yet clear which paths New Zealand’s primary industries should follow, any decisions made at governmental, primary production or food production regulatory levels need to be well researched and supported by sound scientific advice”. The Riddet Institute brought together international and New Zealand thought-leaders with recognised expertise highly relevant to this conversation at a Summit in late 2018 in Wellington, New Zealand (http://www.riddet.ac.nz/riddet-summit-2018). Discussion revolved around what futures might exist for New Zealand’s primary industries, and what New Zealand’s future roles could be in providing sustainable nutrition to our export markets, whilst balancing people, planet and prosperity.