Digging deeper for human healthDigging deeper for human health
Digging deeper for human healthDigging deeper for human health

A greater number of health conscious consumers are spending time, money and consideration selecting food for optimum health and well-being. After all, seven of the top 10 causes of death are linked to diet.

With recent technological advances many more researchers and health experts are pointing to the human microbiome as playing a vital role in human health and well-being, not only physical but also mental health.

Your body is home to about 100 trillion bacteria and other microbes, collectively known as your microbiome.1 They live on the skin, in the saliva and mouth, in the eyes, and in the gut and the rest of the gastrointestinal tract.


Most of these bacteria live in our gut, helping our body break down food and absorb nutrients. The digestive system is home to several species of microbial bacteria not found anywhere else in the human body.

The National Institute of Mental Health awarded $3.7 million in grants during 2015 and 2016 to study the microbiome’s role in mental health, the US Office of Naval Research is also funding research on the issue, and a European project called MyNewGut2 investigated the gut-brain connection.

Diet and other environmental factors affect the composition of the microbiome, particularly that of the microbiota of the gut.


An imbalance in the gut flora has been linked with gastrointestinal conditions such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS), and diseases such as obesity, type 2 diabetes, and allergic reactions such as allergic rhinitis (hay fever), asthma and dermatitis.3 The microbiome is influenced by everything around us and everything that we put inside us, thus making dietary choices even more important.

But is this important breakthrough the beginning of health? Or should we be digging even deeper?

To understand where human health begins we need to enter another world. Another microbiome that is increasingly providing surprises: the world beneath our feet. We need to trace nutrition back to where it all begins — agriculture.

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The Food and Agriculture Organization of the United Nations (FAO) declared 2015 as the International Year of Soils and stated that healthy soils are the basis for healthy food production. So what is healthy soil and why is it so important to human health?

The FAO defines soil health as the ‘capacity of soil to function as a living system. Healthy soils maintain a diverse community of soil organisms that help to control plant disease, insect and weed pests, form beneficial symbiotic associations with plant roots, recycle essential plant nutrients, improve soil structure with positive effects for soil, water and nutrient holding capacity, and ultimately improve crop production. A healthy soil also contributes to mitigating climate change by maintaining or increasing its carbon content.’4 According to Kathy Merrifield, a retired nematologist (someone who studies roundworms) at Oregon State University, one teaspoon of soil can hold up to one billion bacteria, several metres of fungal filaments, several thousand protozoa, which are one-celled organisms, and scores of roundworms, also called nematodes.

This incredibly complex and interconnected microbiome beneath our feet is the foundation of the nutrient cycle. Particularly the bacteria and fungi, which act as decomposers that break down organic materials, making nutrients available for uptake by plants and other organisms.

‘All these things that live in the soil may seem unimportant,’ says Merrifield, ‘but they work together in a system that is truly the foundation of life.’


In many countries, and increasingly in South Africa, intensive ploughing and monocrop agriculture systems, that plant only one type of crop year after year by means of the intensive use of fertilisers, cause nutrient depletion and wide-scale soil erosion. Furthermore, over application of fertilisers and pesticides contaminate our soils and pollute our water.

Dr Donald R. Davis, a research associate with the Biochemical Institute at the University of Texas in Austin, analysed data5 gathered by the United States Department of Agriculture (USDA) in 1950 and 1999 on the nutrient content of 43 fruit and vegetable crops, discovering that six out of 13 nutrients had declined in these crops over the 50-year period – so it does appear that the fruits and vegetables we are eating today may have fewer nutrients than they did 50 years ago.


Everything we eat is linked to soil. If the soil is depleted of nutrients then so is our food. There is a rapid rise in diet-related non-communicable diseases (NCDs), such as obesity, heart disease, diabetes, respiratory disease and some cancers in South Africa. The health of citizens is reflective of the health of the food system, which in turn is reflective of the health of the soil.

Fortunately, there are farmers, such as organic and biodynamic farmers that have long cultivated healthy soil for a healthy society by using sustainable nutrient management techniques such as crop diversity, cover cropping, using natural fertilisers and crop rotation.

Soil health has been a central organising principle for sustainable and organic agriculture since the beginning. By building healthy soil the farmer becomes ‘soil rich’. This is the difference between soil and dirt.

According to the World Health Organization (WHO), agricultural policy and production often have a great effect on national diets. Governments can influence agricultural production through many policy measures.6

Digging deeper for human health


Agricultural policies affect the quality, biodiversity and cost of food, the health of families and communities, impacting the health of our nation. The safeguarding of soil health is essential. Government should also ask for a commitment from the broader agricultural community to work towards farming systems that focuses on regeneration and health of soil.

Health practitioners and particularly nutritional advisors could be important initiators in reconnecting people to food production and the importance of soil health.


Farmer and author Wendell Berry said ‘eating is an agricultural act’7 and this should be a constant reminder that our food choices do matter beyond our personal health. If we stand united for soil health then we help in safeguarding the health of South African citizens. Healthy people form healthy communities. As a nation we can no longer afford to be soil poor. We have treasure beneath our feet; let’s keep it safe.


  • Eat for the soil. Buy locally-grown food that comes from sustainable farms.
  • Support independent retailers, markets and organic online food stores. Ask the owners if they have information available to consumers on the farms they source produce from.
  • Get to know your farmer. Many sustainably aware farmers are only too happy to discuss their farm and methods of production.
  • Join a PGS (Participatory Guarantee System) and participate in how your food is grown. Contact PGS SA to find out where the nearest PGS is.
  • Contact SAOSO (The South African Organic Sector Organisation) and find out more about organic farms and where you can purchase third-party certified or PGS organic-endorsed food.
  • Plant your own vegetable garden. Soil for Life offers several practical courses and workshops.
  • Try making your own organic fertiliser using a compost bin.

Digging deeper for human health


  1. The study of the human microbiome has been furthered by technological advancements for performing culture-independent analyses. Robinson CJ, Bohannan BJ, Young VB. From structure to function: the ecology of host-associated microbial communities. Microbiol Mol Biol Rev. 2010 Sep;74(3):453–76.
  2. MyNewGut Special Issue: Unravelling the role of the gut microbiome in energy balance and brain development and function: the European project MyNewGut Preface Brigidi P, Sanz Y. Trends Food Sci Technol. 2016 Nov; 57(part B).
  3. Bull M.J., Plummer N.T. (2014) Part 1: The human gut microbiome in health and disease. Integr. Med. (Encinitas), 13, 17–22.
  4. Food and Agricultural Organization of the United Nations. Healthy soils are the basis for healthy food production.
  5. Changes in USDA Food Composition Data for 43 Garden Crops, 1950 to 1999. Donald R. Davis, PhD, FACN, Melvin D. Epp, PhD and Hugh D. Riordan, MD. Journal of the American College of Nutrition, Vol. 23, No. 6, 669–682 (2004) Published by the American College of Nutrition
  6. World Health Organization. Global Strategy on diet, physical activity and health. May 2004, the 57th World Health Assembly
  7. Berry W. What Are People For? New York, NY:North Point Press;1990.
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