Microbiomes and Sustainable Nutrition


Did you know that around 10% of your daily energy intake is supplied by intestinal microbes? Or that many plants and animals that we rely on for food are dependent on microbes for their survival? Although the connections between the microscopic world and the global scale of sustainable nutrition are not obvious, microbes play a significant role in the way our food is produced, processed and digested.

The term microbiome refers to a collection of microbes in a certain location. For example, the human gut microbiome consists of the microbial population living in our intestinal tract, which is receiving increasing attention as we recognise its importance in human health.

Microbiomes exist in diverse locations, many of which form part of the global food system. The role of these microbiomes in delivering sustainable nutrition for the global population is increasingly clear.

Cereal crops are a staple food source for the global population, providing predominantly energy and protein. These crops rely on soil nutrients, such as nitrogen, to grow and produce the protein we then consume. Often these nutrients are applied to cropland as fertiliser, produced either industrially or from animal sources. Management of fertiliser application is essential to avoid environmental damage caused by excess nutrients in soils and waterways.

Nitrogen can also be captured directly from the air by soil and root microbiomes, and microbes associated with roots can increase the availability of micronutrients to the plant. These microbes also increase the resistance of crops to soil pathogens. Moreover, soil microbes play a role in reducing soil erosion by producing products that bind the soil together. Current soil microbiome research is tackling the problem of reduced crop yields due to microbiome depletion and working to understand how the beneficial impacts of soil microbes can be harnessed. Learn more

In addition to plant-sourced food products, microbiomes are essential in the production of animal-sourced foods. An example of this is the rumen microbiome. Much of the forage consumed by ruminants cannot be digested by the animal’s own digestive enzymes; instead, the action of rumen microbes converts resistant plant matter, such as cellulose, to nutrients that can be absorbed by the animal’s digestive tract. These microbial products form the majority of energy intake for many domesticated ruminants. The action of the rumen microbiome is thus an important step in converting inedible plant material into animal-sourced food products in our own diet.

Rumen microbiome research currently has a strong focus on minimising the production of methane, a greenhouse gas and by-product of digesting plant material, by the rumen microbiome. This research is unpacking what causes certain microbiomes to produce less methane than others, and what the impact of different animal feeds is on methane production. Learn more

Continuing along the food supply chain, microbes are responsible for the production of common fermented foods. Fermented foods include cheeses, yoghurts, kimchi, sourdough and fermented meats, and are produced via the introduction of microbial populations to the raw food material. Apart from changing the taste, texture and appearance of these foods, the fermentation process enables perishable foods to be stored for longer periods, which can reduce food waste. The nutritional value of fermented foods is also enhanced in many cases. For example, the fermentation of cabbage to sauerkraut results in vitamin B12 synthesis, a nutrient not available in unfermented cabbage. There is also the probiotic capacity of fermented foods: their consumption can introduce beneficial bacteria to the human gut microbiome. Learn more

Microbiomes continue to play a role in the food system even after food is eaten. Although there are microbiomes in different sections of the human digestive system, the gut microbiome is intensively studied for its impacts on human nutrition and health. The make-up of our microbiome is in part determined by our diet, which forms the major food source for intestinal microbes. Just as our own ten trillion human cells require the nutrients we eat to carry out their function, so too do our equally numerous microbial cells. Current research is demonstrating increasing links between gut microbiome composition and various outcomes for human nutrition and health. This includes links to energy and nutrient yield from the diet, roles in intestinal disease and even impacts on brain function and mood. It is now recognised that we cannot have a full appreciation of human nutritional health without consideration of the gut microbiome. Learn more

A sustainable food system is one that ensures food security and nutrition for all, without compromising the future of the economic, social and environmental bases that the system depends on. Microbiomes are a critical element of a sustainable food system. Soil microbiomes enable and enhance crop growth, while playing a protective role in minimising the environmental damage of farming. Animal microbiomes are essential for the conversion of inedible plant material to animal-sourced foods, essential for food security in many developing parts of the world. Fermented foods are an integral constituent of the diet in many cultures and provide a means of preserving perishable foods, as well as adding nutritional and financial value. Finally, the human microbiome in part determines the nutrition we obtain from the foods we eat.

Microbiomes are present throughout the food system, and touch on all aspects of sustainability. As such, designing sustainable food systems for the future must involve consideration of the microbial element.


Glossary

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Food Systems Dashboard

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The Food Systems Dashboard has been developed by a range of global collaborators to help visualise and understand complex food systems.

The dashboard combines data from 35 sources to view over 150 indicators of food systems at a country or regional level. Indicators include food supply chain information, food environments, individual demographic factors, consumer behaviour, diets and nutrition, and macro drivers. The dashboard can help users visualise and prioritise improvements. Users can compare and analyse food system indicators globally, regionally, by country, food systems type, or income classification. Users can also track progress of changes or interventions over time.

The dashboard provides useful information and insights about global food systems, now and over time. This is similar to the DELTA Model, which aims to create better understanding of sustainable food systems and how improvements can be made to sustainably feed the world with the nutrition required.

However, the dashboard does not tell users where key nutrient gaps lie against requirements. In addition, the dashboard can’t be used to identify what foods are required to close nutrient supply gaps, not just in isolation, but critically in combination. The DELTA Model has the ability to do this, by generating food production scenarios and using food composition data to predict the nutrition available to the average global citizen both now and in the future. The DELTA model also provides insightful information on contribution of different foods towards total nutrition and different individual nutrients.

On the other hand, the DELTA Model does not have many of the indicators included in the dashboard, such as macro-economic, environmental and supply chain measures. The DELTA Model is primarily focused on the nutrition aspect.

The models are different, but each take their own approach in understanding food systems and identifying opportunities for improvements.

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The cheapest nutritionally adequate diet contains both plant- and animal-sourced foods

A recent paper published in Nature Food asked what foods would be in the cheapest diet that satisfies nutritional requirements. Combining the prices and food composition data for common food items in the US, the authors determined the cheapest way to feed one person a nutritionally adequate daily diet.

The cost of the diet was calculated as US$1.98 per day (NZ$3.02). It consisted of 15 foods, all of which could be found in the average US home kitchen. The top five contributors were milk, legumes, rice, potatoes and corn tortillas.

The authors also analysed what level of price increase to animal-sourced foods was necessary before the cheapest diet became entirely plant-based. Between 200-1,150% increases in the cost of animal-sourced foods was required, and the plant only diet would cost US$3.61 per day (NZ$5.51). The plant only diet overlapped with the original diet for many foods, but also included soy beverages, green peas and peanut butter.

The authors highlighted that the bioavailability of consumed nutrients was not considered in this study. Inclusion of bioavailability would likely increase the cost of both diets but would have a greater impact on the plant-based diet, due to the lower bioavailability of many nutrients in plant foods. The daily diets proposed by the authors are not recommended diets – a limit of 15 different foods is not feasible – but the work does show that animal-sourced foods can be a cost-effective way to get adequate nutrition.

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Emissions on farm vs off farm

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The Environmental Working Group breaks down the life cycle analysis of total greenhouse gas emissions for common protein foods and vegetables.

As expected, animal foods have significantly higher greenhouse gas emissions. Lamb, for example, has the highest because it generates methane through enteric fermentation and produces less edible meat relative to the sheep’s live weight. Most emissions from meat, dairy and fish occur during production. However, most emissions from plants are generated after crops leave the farm. This is primarily because of the energy needed to cook plant-based foods. For example, post-farmgate emissions account for 65% of dry beans’ total emissions and 59% of lentils’ total emissions.

This does not mean plant-based foods have greater net post-farmgate emissions. For example, 65% of dry bean’s emissions is post-farmgate, which equates to 1.3kgCO2e. On the other hand, while only 10% of beef’s emissions is post-farmgate, this is a larger total of 2.7kgCO2e. The key message is that the main sources of emissions vary among different foods, depending on production and food preparation methodology. This means it is inappropriate to only compare footprints at the production stage. A more holistic view of environmental impact is required for a fair comparison.

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From a good idea to reaching millions: learning from CGIAR’s work on biofortification

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Consultative Group on International Agricultural Research (CGIAR) have been developing and implementing biofortified crops to address micro-nutrient deficiencies.

Deficiencies in micro-nutrients poses serious and widespread threats to health and economic development. This is known as ‘hidden hunger’. The conventional response has been supplementation or food fortification. However, these solutions involve high and recurrent costs, can be hard to organize in poor rural areas, and cannot always solve the problems.  CGIAR scientists proposed that the same health impacts could be achieved by breeding vitamins and minerals into the staple crops that people eat every day, such as sweet potato, wheat and rice. This is known as ‘biofortification’. CGIAR have been working on this for almost 25 years and invested $900m into development and implementation. More than 290 new varieties of 12 biofortified crops have been released or are in testing. This has benefited 10 million farming households globally to date.

The DELTA model can be used to scenario test various food systems with the view of adequate sustainable nutrition for the global population. This repeatedly demonstrates that on a global scale, animal-sourced foods are needed to meet nutrient requirements. However, this is based on the fact that current conventional crops do not have the same content of bioavailable micro-nutrients and trace elements that animal-sourced foods do. There may be potential for biofortified plants to better contribute to global nourishment and reduce requirements for animal foods. However, what is still unclear is whether those micro-nutrients in biofortified plant-based foods would have the enhanced bioavailability that characterises animal-sourced foods. In addition, biofortified plant-based foods may not have the ability to enhance the uptake of micro-nutrients from plant-derived sources, in the same way animal foods do as part of a meal. For example, haem iron from meat helps with the uptake of non-haem iron from plant sources. The ability of biofortified plants to do the same needs to be determined before concluding that biofortified crops can replace the role of animal foods in the global food system.

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Australia’s changing landscape of protein production

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A study by the Australian Farm Institute tells us that despite the trend towards alternative proteins, large opportunities exist for animal proteins in the future.

The Australian population is growing, forecast to be nearly 29 million by 2030. This will inevitably result in an increased demand for protein. While alternative protein substitution has increased and will continue to do so in the next 10 years, this will not diminish the demand on animal agriculture. Rising demand for protein driven by that population growth will outweigh any additional market share that alternative proteins may gain. However, the current production systems have finite resources. Therefore, both animal and plant production will need to become more efficient and productive if Australia wants to avoid relying solely on food imports to sustain their future population

It is worth noting that the current global food system is plant-based and animal-optimised. Approximately 85% of all biomass leaving the world’s farms is plantsourced. For any sustainable food system to nourish the global population, both animal and plantsourced foods will continue to be required. Animal-sourced foods are particularly important to meet global requirements for micro-nutrients such as iron, zinc and vitamin B12. In fact, scenario testing of possible global food systems with the DELTA model repeatedly demonstrates that animal-sourced food production will not only continue to be needed to provide adequate nutrition to a global population, but that production will also need to be sustainably increased.

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‘Meat is part of a sustainable world’: Professor Louise Fresco

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Professor Louise Fresco (President of the Executive Board, Wageningen University & Research) argues that taking meat out of the food system is not the solution.

The future of the world will be characterized by eating less meat as we shift towards flexitarian and reductionist diets. However, meat should remain as part of a sustainable food system. Fresco highlights the valid point that grazing animals utilize land that cannot be used for anything else, converting inedible plants into valuable food. Nutrient-rich meat also becomes increasingly important, particularly with the aging population.

This is consistent with results from testing food production scenarios with and without meat for their ability to provide adequate nutrition for the global population, using the DELTA model. Key micro-nutrient requirements such as iron, zinc and vitamin B12 cannot adequately be sourced for the global population without the inclusion of animal-derived foods in the food supply system. In other words, animal-derived foods are necessary to nourish the global population. Meat, as well as dairy, should continue to be a part of our diets. However, effort must be made to ensure it is produced in the most sustainable way. This increases the pressure for research to reduce on-farm emissions, reduce water usage and improve water quality, and increase productivity from animal agriculture.

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Study shows the EAT-Lancet diet is unaffordable for at least 1.6 billion people

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A study has found the EAT-Lancet diet is unaffordable to 1.6 billion people, mostly in sub-Saharan Africa and South Asia.

The ‘planetary health diet’ costs a median of USD $2.84 per day, which is about 60% more expensive than a diet that meets our minimum nutritional requirements. The study found that the diet costs between 3% to 73% of national average incomes. Fruit and vegetables and animal-sourced foods are the most expensive components of the EAT-Lancet reference diet.

The EAT-Lancet diet has many flaws, it is not the perfect diet. But it generates good discussion about what needs to be done to make a healthy and sustainable diet affordable for the global population. A cost-effective diet must be optimised on cost per nutrient or bundle of nutrients. The issue with the EAT-Lancet reference diet is that it involves switching from low cost sources of nutrition to more expensive sources to deliver the nutrients we need. Even then, the EAT-Lancet diet falls short on supplying nutrients such as iron and calcium in adequate amounts, and the protein quality of the diet is lower.

Furthermore, switching to more expensive sources of nutrition means supply and demand can get out of balance due to demand increasing from those who can afford those foods. Supply may not be able to react quick enough, for example, tree nuts take 3 to 10 years before the trees start producing nuts. As a result, prices will increase, and food will become even less affordable to some of the population.

To make a sustainable diet affordable by the global population, the cheapest source of quality, bioavailable nutrients should be prioritised. For example, in the US, dairy is the lowest cost source of dietary calcium, riboflavin and vitamin B12, and should therefore be prioritised.

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Eat less red meat, scientists said. Now some believe that was bad advice

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An international collaboration of researchers concluded that the advice to eat less red meat is not backed by good scientific evidence.

If there are health benefits from eating less beef and pork, they are small, and not sufficient to tell individuals to change their meat-eating habits. Links are mostly in studies that observe groups of people, and even then, are only detectable in the largest groups.

This raises questions about the longstanding dietary guidelines urging people to eat less red meat. There have been concerns for years that red meat causes heart disease, cancer and other illnesses. However, if this is not backed by good scientific evidence it should not influence dietary guidelines. Red meat plays a key role in the contribution to multiple micro-nutrient requirements such as iron, zinc and vitamin B12. Research from the Global Burden of Disease study found that 11 million deaths and 255 million disability-adjusted life years were attributable to dietary risk factors, however the key risk factors were under-consumption of whole grains and fruits, and meat was found to have very little impact. It may be that high consumption of red meat is not inherently unhealthy, but rather a lack of choice and/or poor choice means a high level of red meat in the diet results in lower consumption of other healthy foods in the diet. In other words, is not red meat itself causing disease, but the lack of other foods as part of a balanced diet.

Therefore, it may not be in individual’s best interests to decrease red meat consumption, instead we should focus on consuming a balanced diet of healthy foods and sufficient nutrients.

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Reducing agriculture emissions through improved farming practices

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McKinsey’s latest report, Agriculture and climate change offers a perspective on how 25 proven GHG-efficient farming technologies and practices could reduce emissions by about 20% by 2050.

This is equivalent to a combined 4.6 GtCO2eq by 2050 compared with business-as-usual emissions. The top 15 measures cover four key areas; energy, animal protein, crops, and rice cultivation. For example; adopting zero-emissions on-farm machinery and equipment, improving animal health monitoring and illness prevention, employing greenhouse gas-focused genetic selection and breeding, and improving rice paddy water management. The top 15 practices would contribute 85% of the emission reduction potential.

The report addresses the issues with greenhouse gas emissions from agriculture, forestry, and land-use change, and recognises that major changes are needed to reduce emissions. These changes may be more challenging for agriculture than for other sectors. In addition to this, the agriculture sector has a complicated set of objectives to consider including global nutrition need, food security, biodiversity and the livelihood of farming communities. This cannot be ignored in efforts to reduce emissions. It is therefore essential to take these suggested efficient farming actions to reduce greenhouse gas emissions, while still considering the importance of still being able to produce sufficient food to nourish the world with the nutrients they require.

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