Waste as a Resource: Can "Humanure" Help Save the Planet and our Food System?

 Written By: Jordan Monson; SLU Dietetic Intern

Did you know that human waste was once a valuable resource? For centuries, in cultures worldwide, composted human waste, often called “humanure” was valued for its ability to fertilize soil and improve crop yields. In 18th century Japan, for example, “night soil” was so prized that farmers would trade fresh produce for it or buy it, ensuring a sustainable nutrient cycle between urban and rural areas. This was even the cause of many squabbles, particularly between tenants and landlords, who often claimed rights to their tenants' waste. Because human waste was a valuable commodity, the farmland was fertile and the cities clean, unlike many other large cities at the time, where overflowing latrines, smelly gutters, and widespread diseases were the norm.  

 

But these practices faded with industrialization, as the invention of modern sewage systems in the mid-20th century revolutionized sanitation and health, reducing diseases like cholera and dysentery. However, it also broke the nutrient cycle and the reciprocal relationship between urban and rural areas. Today, most waste travels miles through underground pipes to treatment plants, where it becomes sludge- most of which ends up in landfills. A small portion is recycled into fertilizers, but these biosolids often carry “toxic compounds, nanomaterials, hormones, dangerous pathogens… PCBs, flame retardants, heavy metals, and endocrine disruptors that all collect and are not filtered out by the sanitation process” which raises safety concerns, particularly if this sludge ends up back on agricultural land.  

 

A Crisis for Soil, Sewage Systems,  and Food Security 

Sewage systems have played a vital role in improving public health by reducing waterborne diseases and improving overall urban cleanliness, but today, these aging infrastructures face significant challenges. In the U.S., 15% of wastewater treatment plants have reached or exceeded capacity, and over 23,000 sewer overflows occur annually. These overflows contaminate clean drinking water, harm aquatic life, and release methane, a potent greenhouse gas, contributing to climate change.  

 

Simultaneously, agriculture is grappling with a fertilizer crisis. Since 2021, the price of nitrogen-based synthetic fertilizer has skyrocketed by 300% (and this was exacerbated by the outbreak of the Russian war in Ukraine in 2022, as Russia is a major producer of synthetic fertilizers), forcing farmers to either spend more or scale back on production. For consumers, this means higher grocery bills and reduced access to affordable food. Compounding this problem is the potential scarcity of phosphorus, a critical nutrient for growing crops. Most of the reserves of phosphorus are concentrated in just a few countries around the world, making global food systems vulnerable to geopolitical instability, as we have already seen some impact from.  

 

Here’s where the potential of humanure becomes revolutionary. Human waste is a natural and renewable source of the nutrients plants need to grow- nitrogen (N), phosphorus (P), and potassium (K)- all conveniently found in what we flush away daily. Instead of burying phosphorus deep underground or extracting energy-intensive synthetic nitrogen, we could tap into this abundant, overlooked resource.  

 

Rethinking Human Waste: The Nutrient Cycle 

To understand the connection between human waste and agriculture, consider another reciprocal relationship between humans and plants found in the air. Just as we breathe out carbon dioxide for plants to absorb and return oxygen for us to inhale, nutrients cycle through us and return to the soil in forms ready for plants to use. These nutrients, excreted as waste, can feed plants, which in turn grow into nutrient-rich foods ready for us to eat again.  

 

This nutrient cycle is a natural and sustainable solution that could replace synthetic fertilizers altogether. Synthetic options, while temporarily effective, require vast amounts of energy to produce and wash away easily from farmland into waterways. This runoff creates oxygen-depleted “dead-zones”, algal blooms, polluted drinking water, and acid rain. In contrast, humanure’s sticky organic properties help it bind to soil, preventing it from washing away and delivering nutrients more efficiently and long-term.  

 

Risks of Synthetic Fertilizers 

While synthetic fertilizers have played a significant role in increasing agricultural productivity, their drawbacks are becoming increasingly evident: 

1. Water Pollution: These fertilizers leach easily into water systems, causing algal blooms, oxygen-depleted “dead zones,” and contaminated drinking water that is unsafe for human consumption. 
2. Rising Costs: Synthetic fertilizer prices have surged, placing economic pressure on farmers and contributing to higher food prices for consumers. 
3. Soil Depletion: Long-term use of synthetic inputs weakens soil health by reducing its organic matter, compromising its ability to retain water and nutrients effectively. 
4. Climate Harm: The production and transportation of synthetic fertilizers emit significant greenhouse gases, exacerbating climate change and undermining global food security. 
5. Lower Crop Quality: Soils degraded by overuse of synthetic fertilizers produce less nutritious crops, impacting human health and reducing the overall quality of food. 

 

Benefits of Humanure 

Humanure addresses these challenges by leveraging natural processes to enhance agriculture while minimizing environmental harm: 

1. Environmental Impact: Recycling nutrients from human waste prevents harmful runoff and protects water sources, soil, and surrounding ecosystems. Its use helps mitigate the environmental damage caused by synthetic fertilizers. 
2. Economic Opportunity: By reducing dependence on costly synthetic inputs, humanure can stabilize farming expenses and support sustainable, locally driven food systems.  
3. Human Health & Nutrition: Crops grown in nutrient-rich, naturally fertilized soil are healthier, often containing higher levels of vitamins and minerals, which benefits both individual and public health. Initial studies are also showing improvements in crop yield with the use of humanure.  
4. Climate Resilience: Humanure’s low-energy processing reduces greenhouse gas emissions, while its application supports carbon sequestration in healthy soils—an essential strategy for combating climate change and securing future food production. 

A Solution Rooted in Sustainability 

Humanure not only addresses the environmental risks posed by synthetic fertilizers but also offers a viable path toward a more sustainable, circular agricultural system. Its ability to enhance soil health directly influences crop quality and resilience, making it a cornerstone of sustainable food security efforts. By rethinking waste as a resource, we can move away from extractive, harmful practices and embrace methods that regenerate both ecosystems and food systems for future generations. 

 

Sustainable Solutions in Action 

Rich Earth Institute (Vermont) The Rich Earth Institute is at the forefront of transforming human waste into valuable agricultural resources. By conducting groundbreaking research, promoting education, and advancing innovative technologies, they focus on urine-diversion programs. These programs harness the nutrient-rich potential of urine—particularly nitrogen, phosphorus, and potassium—found in the waste of those in industrialized areas with "highly digestible diets" Their work highlights how human waste can be safely and effectively reintegrated into agricultural systems. 

 

A spinoff from Rich Earth Institute, Bright Water Tools, builds on this mission by creating systems that separate water from toilet waste, turning it into non-potable reusable water and natural fertilizers. These tools help reduce wastewater management costs, prevent harmful runoff, and provide sustainable nutrient sources for agriculture and landscaping. 

 

Washington D.C. Wastewater Treatment Plant: The Blue Plains Advanced Wastewater Treatment Plant is a leading example of large-scale waste reuse. This facility repurposes biosolids, energy, and nutrients from wastewater into valuable products. Their “Class A biosolids,” sold under the brand name Bloom, serve as a slow-release recycled fertilizer. Additionally, the plant employs thermal hydrolysis to extract energy from waste, reducing its carbon footprint while powering its operations. 

 

Paris Pee Diversion Project: A broader effort can be seen across France to integrate green practices into upgrading its aging sewage systems. In the SVP eco-neighborhood, low flush toilets and dry urinals connect to a separate urine-connection network with on-site treatment plants that turn urine into concentrated fertilizers to be used locally. The La Fumainerie project in Bordeaux has been experimenting with composting feces and using dry toilets.  

 

Sanivation: Operating in Kenya, Sanivation addresses inadequate sewage systems by creating waste-to-energy solutions. Their projects include converting fecal sludge into briquettes, which serve as efficient, low-emission fuel alternatives. By improving urban sanitation, reducing pollution, and creating jobs, Sanivation not only mitigates environmental issues but also enhances the quality of life for underserved populations. 

 

S.O.I.L: In Haiti, SOIL (Sustainable Organic Integrated Livelihoods) offers a model for addressing sanitation and agricultural challenges simultaneously. Their initiative, EkoLakay, provides urban households with container-based toilets, which are collected weekly. The waste is then composted into eco-friendly fertilizers, revitalizing Haiti’s depleted soils. This program simultaneously promotes public health, creates local employment, and supports sustainable farming. 

 

Looking Ahead 

 

From small-scale community programs to city-wide wastewater treatment innovations, these projects underscore the transformative potential of human waste when managed sustainably. By implementing these systems globally, we can protect natural resources, bolster food security, and advance climate resilience, ensuring a healthier future for both people and the planet. 

 

Don't Let the Darkness Loom Over Your Health: Everything You Need to Know About the Sunshine Vitamin

 Written By: Dylan Moffatt; SLU Dietetic Intern

As the clocks fall back into standard time, we are officially into the season of cozy sweaters, shorter days, and the undeniable craving for sunshine again, though some people may like the darkness. We are on standard time until March 9th, 2025, when we spring forward to Daylight Savings Time. One way to remember which way the clocks go is in the Fall we fall back an hour; in the spring we spring forward an hour. So as our daylight slowly falls away, it’s time to talk about what we all love, the sunshine and the incredible nutrient it brings us Vitamin D!

Sunshine does not just lift our spirits or warm our faces on a winter day but its also our personal health ally, helping our body produce Vitamin D, nicknamed the sunshine vitamin, rightfully so. This powerful vitamin is a key role in our body’s quest to maintain health. Although the sun is all around us, just under half of all Americans are deficient (42%). Let’s bundle up and let the sunshine some light on Vitamin D and reveal why it is so important.

Why is vitamin D important?

Vitamin D promotes calcium absorption in the gut and helps maintain adequate levels of minerals to enable bone health and prevent low levels of calcium, which may cause cramps or spasms. Vitamin D is needed for bone growth and bone remodeling throughout our lifespan and without it our strong bones can begin to weaken, become brittle, or misshape. This vitamin also plays a role in reducing inflammation, cell growth, neuromuscular and immune function and glucose metabolism. It also may help improve your mood as the dark winter approaches and the winter blues come hollowing in.

What are symptoms of deficiency?

There are many symptoms to vitamin D deficiency and its always best to consult a doctor to determine if you are at risk and should be tested. A doctor can also prescribe the right dosage based on your test results. It should be noted that symptoms can be subtle and could also be part of a different problem. Some symptoms may include frequent illness/infections, fatigue, tiredness, bone/back pain, impaired wound healing, and bone loss. It’s best to consult a doctor to determine if your symptoms may be from a vitamin D deficiency.

What is the difference between Vitamin D2 & D3?

The only difference between them is in their chemical structure, and both can be well absorbed into the small intestine. Vitamin D is a fat-soluble vitamin which means it absorbs well when fat is present in the small intestine, though some of it still absorbs when no fat is present. There is no difference in absorption between the two, the only main difference is D3 usually is found in animals and D2 is usually found in plants.

How much do I need?

Below is a table based on age and there is no difference between sexes. Vitamin D is also required on all food labels under the nutrition facts, so I can easily be found at the bottom. Fun fact: Vitamin D, Calcium, Iron, and Potassium are the nutrients considered mandatory for every food label.

How do I get Vitamin D?

The best food sources that contain vitamin D are trout, salmon, tuna and mackerel. Animals’ diet affects how much vitamin D is found in their meat. Other sources also include beef liver, egg yolks, and cheese, though they have small amounts. Some mushrooms contain vitamin D as well, and when exposed to UV light it increases their levels of the vitamin just like us! Fortified foods are where most Americans get vitamin D. The milk supply usually has vitamin D added as it helps with calcium absorption as well. Other products that are fortified include breakfast cereals, some orange juices, yogurt, and other dairy products. From the sun it is best during midday during the summer, making it the smallest amount of time needed to have enough vitamin D production, it can take anywhere between 10-30 minutes to have enough exposure. Too much sun can cause damage to the skin and have serious consequences. The more skin that is exposed to sunlight, the greater the exposure in less time, and it is best not to use sunscreen as it will affect the UV rays absorbing into the skin. It is best to limit overall sun exposure due to risks like sunburn, eye damage, aging skin, heat stroke, and skin cancer. When in the winter months it is best to either consume foods which contain vitamin D or are fortified with it. You can always ask your doctor if a vitamin D supplement is right for you in the winter months.

What are the top sources of Vitamin D?

3 oz of Trout provides 16.2 mcg

3 ounces of sockeye salmon provides 14.2 mcg

1 cup of fortified 2% milk contains 2.9 mcg

1 serving of fortified breakfast cereal contains 2.0 mcg

1 large egg provides 1.1 mcg

Can I overdo it on Vitamin D?

Like overloading hot chocolate with too many marshmallows, too much vitamin D can cause issues. It is best to stick to recommended amounts or talk to your healthcare provider.

As you embrace the colder months with blankets and warmth do not let the winter months dim out your vitamin D. You can soak in the limited sun or enjoy a bowl of cereal or OJ remember the winter won’t last forever. The winter darkest may be upon us but that does not mean our health has to enter a dark period as well.

Happy Gut, Happy Life: 10 Simple Steps to a Healthier Digestive System

Written By: Elizabeth Link; SLU Dietetic Intern

Have you ever wondered why everyone is so obsessed with gut health these days? Or found themselves on #guttok ? There is a social media craze, leading to companies hopping on the trend to produce new products containing prebiotics, probiotics, fiber, and so much more. We see drinks, supplements, and bizarre diets, all marketed as ways to “heal the gut” which can seem overwhelming and lead to the question: does it really work? 

Before we answer that question, let’s look at the prevalence of gastrointestinal (GI) disorders across the world. A global survey of over 73,000 adults from 30+ countries found that more than 40% of surveyors self-reported GI disorders such as IBS or constipation. Some say that the increase in ultra-processed food production and consumption over the last several decades is part of the reason why we have seen such an increase in GI issues. However, there are so many other factors that contribute to the function of one’s gastrointestinal tract: sleep, stress, medications, physical activity, and even your own genetics. 

All of the chit-chat surrounding gut health has sparked interest not only on the internet, but researchers as well. Recents studies have shown that increasing the diversity of gut microbiota—the “good” bacteria in your digestive system—can enhance immune function, support mental health by alleviating conditions like depression, improve sleep quality, and cardiovascular health. However, recent social media trends around “gut health” can be misleading and harmful. As University of London senior lecturer Stephanie Alice Baker explained in a 2022 New York Times article, these trends are a form of “self-optimization.” In other words, a way to promote diet culture and unattainable body ideals. By reframing weight loss as “gut healing,” social media influencers often encourage extreme, unhealthy diets. Many of these influencers lack medical expertise and may even promote products simply because they’re being paid.

So, what can we do? Sadly there is no “quick fix” or “magic pill” to cure our gut health at a rapid pace. However, here is a list of 10 practical tips you can follow to improve your gut health over time:

     1. Eat a balanced diet with fiber 

         Eat a variety of fresh, whole foods, especially fruits, vegetables, legumes, beans, nuts, and whole grains. These foods are high in fiber, which can help with digestion, reduce the risk of GI disorders, and feed healthy gut bacteria. 

     2. Eat fermented foods 

        Fermented foods like yogurt, kimchi, sauerkraut and kombucha can increase the diversity of good bacteria in the gut. One study found that people who ate six servings of fermented foods each day saw gut health benefits. Of course, take that with a grain of salt—fermented foods are a great addition to a diet, but don’t need to be the majority of one. 

    3. Eat smaller meals 

        Avoid overfilling your stomach, which can cause reflux. Instead, eat small, frequent meals throughout the day. 

    4. Practice mindful eating 

        Slow down at meal times. Turn off the T.V., put the phone away, and focus on the meal. Chew your food well before swallowing and listen to your body’s own hunger cues to know when satiety hits. 

    5. Limit late-night snacking 

        Your GI tract is most active during the morning and the daytime, so try to incorporate your             nutrition into those hours instead of late-night meals. 

    6. Manage your stress 

        Stress can make it harder for your body to digest food. Try relaxation techniques like mindfulness, breathing, or exercise. 

    7. Get enough sleep 

        Adults should get 7-9 hours of sleep per night. Roughly 65% of adults report not sleeping the recommended amount. 

    8. Stay hydrated

        Water is necessary to maintain digestive health by allowing absorption of key nutrients and aiding in gut motility. Light yellow or pale straw urine indicates good hydration. 

    9. Consider probiotics 

        Talk to your doctor about taking probiotics, which are supplemental healthful bacteria that may help with constipation and IBS. 

    10.Avoid highly processed foods 

        Ultra-processed foods are stripped of fiber and digested in the stomach, which can starve your microbiome. 

So next time before you follow the influencer diet that promises to “de-bloat” your belly, or you reach for a brand new gut health supplement, consider these tips. You may be surprised at how much better you feel just by following step #1- a balanced diet with whole foods, lots of color from fruits and vegetables, and lean proteins. And if you ever need extra assistance, contact a registered dietitian for all your questions and concerns–not the self proclaimed “health coach” on social media. New diet and lifestyle changes/habits take time to implement so desired results can follow. You got this!