Hunger season approaching?

In some places, the harvest is preceded by “hunger season,” when stored crops are exhausted but the new crop is not ready. For many reasons, we’re wondering if the Earth is entering a long hunger season:

Food prices reached records in February, which may even have helped spark the political unrest that swept the Middle East. As Lester Brown of the Earth Policy Institute notes, a 10 percent rise in the price of wheat barely budges the price of bread in developed countries, but directly boosts the price of chapattis in India.

The population is expected to reach about 9 billion by 2050, and 3 billion people with rising incomes have a growing appetite for grain-intensive animal protein.

The World Food Program estimates that one person in seven goes to bed hungry. One reason is poverty: In this world, only the poor are hungry. But other reasons are related to supply and demand:

The end of civilization?

Depleted soil is a legacy of many failed civilizations, wrote soil scientist David Montgomery1 of the University of Washington. “In recent decades, archaeological studies confirmed pronounced episodes of soil erosion associated with the rise and subsequent decline of civilizations in the Middle East, Greece, Rome, and Mesoamerica, as well as other regions around the globe.”

Indeed, Montgomery writes, “a limiting lifespan of an agricultural civilization can be estimated by the time needed for conventional agriculture to erode through the native stock of topsoil,” which “predicts reasonably well the historical pattern of a 500- to several-thousand-year lifespan for major civilizations around the world.” These calculations, he says, support the argument “that it was not the axe that cleared forests but the plow that followed that undermined many ancient societies.”

Soil health is often gauged by the percentage of organic matter — the decomposing plant material that feeds microbes and soil animals, and enables soil to hold water and nutrients, says Jane Johnson, a soil scientist with the U.S. Department of Agriculture in Minnesota. “Most of the characteristics that we associate with high quality soil are directly or indirectly linked to soil organic matter.”

Therefore, the emphasis on protecting and improving soil so it can feed an ever-growing population often comes down to the level of organic matter. In the United States, much of the cropland has already lost 30 to 50 percent of its organic matter since Europeans started farming a couple of centuries ago, says Rattan Lal, a professor of environment and natural resources at Ohio State University.

Most productive soil in Africa and Asia has lost 70 percent to 80 percent of its organic matter, says Lal, an outspoken defender of the soil, and long ago crossed the line toward ruination. “There is a threshold — about 1.2 percent to 2 percent of carbon [the usual measure of organic matter] — to maintain soil health, water retention and other soil services.”

Many soils in Africa, India and China have only one-tenth that much carbon, Lal says, and that leads to a truckload of trouble. “When you add fertilizer, it washes into the groundwater because the organic matter is not there, and the same goes for pesticides and herbicides. These chemicals wash into rivers or the groundwater, or enter the atmosphere, where they cause human health and environmental problems,” without conferring much benefit to the crop.

Lal says a train in his native Punjab, India is dubbed the “Cancer Express” because it travels through a region where “many people are prone to cancer because of pollution of the drinking water. The soil does not have the capacity to hold water and pollutants. That is what the biological health of soil does; you get microbial decomposition, absorption of organic matter and retention of water. If crop residues are taken away, if dung is taken away for cooking, the soil has nothing left to provide the services. It essentially becomes a sand culture.”

Good soil, great benefits…

About the only bright spot in the grim picture of soil destruction is this: many solutions offer synergistic benefits. Leaving a crop residue on the surface cuts wind and water erosion, and raises the level of organic matter. Conservation tillage cuts erosion, reduces the need for irrigation, and stores carbon in the soil. Smart irrigation reduces water use, and the need to plant on steep, erodible slopes.

Soil – some still call it dirt – is not as popular as Facebook or Dancing with the Stars. But it’s a whole lot more important. “Our ability to feed humankind in the future depends on a stable, improved soil resource,” says Jerry Hatfield, director of the Agricultural Research Service lab in Ames, Iowa.

Or, as University of Minnesota soil scientist William Larson once said, “Soil is that thin layer on the planet that stands between us and starvation.”

Enough with the problems. Let’s look at some serious soil solutions.

Washing away

Because water erosion can rapidly flush nutrients, mineral soil and organic matter from hilly land, the battle against water erosion has been a focus of American farmland conservation since the 1930s. One common prescription is contour planting; rows planted across the slope are more resistant to erosion than those running up the slope.

A standard way to protect soil is to leave crop residues in place after harvest, but bioenergy proposals often suggest that these wastes be fermented into cellulosic ethanol. The best solution depends on the situation, Johnson says. “If the land is highly erodible, we should not take residue. But if the landscape has a low erosion risk, then if we can manage it to protect organic matter by leaving enough residue in place, chances are we will have more than enough cover for erosion control. I believe it is possible to take some residue off, but not everywhere.”

The focus in protecting soil has shifted from the mineral component of soil to its organic matter, which is more sensitive, says Johnson. “In most cases, protecting the organic matter will protect against erosion, but if you only manage for erosion control, that may be not enough to retain the organic matter.”

Gone with the wind

The “Black Blizzards” of the 1930s Dust Bowl proved beyond question that wind can transport large amounts of soil to the wrong place. Could we see a rerun of the Dust Bowl? “People say we will never have a Dust Bowl again, because of the conservation practices that we put in,” says Hatfield, but the Dust Bowl also followed years of severe drought, which further stripped farm fields of cover.

Furthermore, says Hatfield, co-editor of a new book on soil management,2 many of the windbreaks planted to slow wind erosion have been removed to allow the use of large farm machinery. “What would happen if, across the Great Plains, we had three or four years with hardly any rainfall? I dare say we would not see the extent of the Dust Bowl, but would our current conservation practices be sufficient? … How much can you expect when the land is naked?”

Confronting drought

The Dust Bowl shocked Americans, but drought is a common problem that has differing consequences. Recent reports show that California’s farm industry did well during the 2007-2009 drought, mainly because large farmers had access to irrigation water. But wheat production in Southwest Kansas is now expected to fall at least 25 percent due to drought. According to Bloomberg News, the state’s wheat crop “has suffered irreversible damage from the country’s driest spring in half a century…”

In places where irrigation is impossible or inadequate, standard soil-conservation techniques, including retaining organic matter in and on the soil, can improve water retention.

ENLARGE

Cities devour farmland

The 80 million people joining the population every year require 3200 square kilometers land for shopping malls, roads, airports and housing. Cruelly, much of that growth occurs in places with productive soil, says Charles Rice, a professor of agronomy at Kansas State University, because big cities typically start out in a region with productive farms. “Chicago is a prime example; the soils in northern Illinois are some of the best in the world, but unfortunately Chicago is growing. I hate to see that valuable productive land paved, built upon. In Asia and Europe, around the world, megacities are consuming land. We need to figure this out, but nobody has.”

Salty soil is worthless soil

A bright idea: reduce tillage, save topsoil

Perhaps the largest success story in protecting soil is the no-till revolution in agriculture. Rather than turning over soil to bury weeds and crop residues, a no-till machine plants directly in the stubble, then controls weeds with herbicide. The process saves diesel fuel and also retains organic matter, says Hatfield, who observes that carbon compounds oxidize rapidly when the soil is disturbed. “We need to protect the soil from within, with more organic matter, and from the external forces, like wind and water.” Sustaining the soil, he says, “Is really about building that organic matter reservoir.”

In 2010, no- or low-till farming occupied at least 20 million hectares each in the United States, Brazil and Argentina, with significant areas in Canada and Australia.

“If you go to South America and talk to producers,” says Hatfield, “they look at conservation practices as the normal accepted practice — if you used a moldboard plow [which turns over the soil and exposes it to erosion] they would probably shoot you! In the last 20 years, they have realized what a precious resources soil is, and to maintain its viability, they have preserved the organic matter.”

But worldwide, no-till occupies only 6 or 7 percent of the 1,500 million hectares under cultivation. “You could call that a success,” says Lal. “But in the places where it is needed most desperately, Africa, Asia, those desperate farmers cannot implement no-till.”

Summing up

Optimism is not a common response to discussions of the world’s degrading soils. Lal says two to three billion hectares already are degraded, but contends that problems related to energy use, global warming and clean water also have strong ties to land degradation.

To take two examples, surface water is easily polluted when it washes off eroded land, and healthy soil stores vast amounts of carbon, slowing global warming. “All these issues are linked with one another, and soil is the common link,” says Lal. “We have the IPCC [Intergovernmental Panel on Climate Change] to address climate change … but soil is addressed by nobody, even though … we cannot address water security, energy, biofuels, global warming, without soil.”

Not to mention the daily problem of putting bread on the table…

But here’s a reason for optimism: The measures that can solve individual problems often can solve multiple problems. Conservation tillage saves water, organic matter, topsoil, even energy. Drip irrigation reduces salinity and saves water and energy. Cover crops raise fertility and reduce erosion.

And, no coincidence, all of these soil-friendly practices also increase yields.

So if you like to eat, the time to think about soil is … now.

Fish in the Gulf of Mexico: How safe?

The fire and deadly explosion of the Deepwater Horizon drilling rig on April 20, 2010 spewed a gusher of crude oil — about 4.4 million barrels — into the Gulf of Mexico.

The blowout flooded all levels of the Gulf with oil. And that oil, combined with millions of gallons of an oil-degrading chemical, raised questions about the health of Gulf seafood, both shellfish and finfish.

Fishing is major in the Gulf of Mexico, which in 2008 produced 15 percent of total weight of U.S. commercial fishing, and which has more sport fishers than any other American region.

Within two weeks, as a precaution to prevent the sale of contaminated fish, the government began closing parts of the Gulf to commercial fishing.

A report published today in Environmental Health Perspectives reviews the aftermath: How big was the threat? Did the closures harm the fishing industry by giving, in effect, official endorsement to the idea that the fish were contaminated? Were there any gaps in protection?

Not very filthy

The report came to an optimistic conclusion: government-sponsored studies of Gulf fish since the blowout found no significant contamination with heavy, persistent compounds called polycyclic aromatic hydrocarbons. “I don’t know that we have any evidence that the fish were contaminated, ever,” says study first author Julia Gohlke, an assistant professor of environmental health science at the University of Alabama-Birmingham.

PAHs can cause cancer and are often used as a measure of hydrocarbon contamination. According to the new study, “Federal seafood testing results released to date” show PAH levels at roughly 1 percent of the “level of concern” that the Food and Drug Administration established for assessing food safety after the Deepwater blowout.

Other results, she says, have focused on total hydrocarbons derived from oil, rather than PAHs. “My analysis looked at what the government has done,” she says. “There are independent reports of contamination that I tried to include, but they did not measure PAHs, only total petroleum hydrocarbons.”

Large oil spills are so ominous that people can overreact, says Gohlke. “People see an oil spill and fisheries closures and assume everything must be contaminated, and nobody wants to eat anything. There is a misunderstanding of what is considered contamination. There is now a large dataset, at this point, to show there hasn’t been significant hydrocarbon contamination to date.”

Gohlke and colleagues looked at data on the BP blowout, and previous oil spills from around the world, to compare toxicity levels and evaluate the procedures used to close and open fisheries. The project was funded by a grant from the Walton Family Foundation to the Environmental Defense Fund.

Looking at samples taken during and after the blowout, no results suggested that eating fish – whether with shells or fins – would contain elevated levels of PAHs, says Gohlke, who cautions that monitoring should continue for years because buried oil may re-enter the water and contaminate fish.

After the BP spill, fishing was banned in as much as 37 percent of the Exclusive Economic Zone in the Gulf of Mexico, which extends 200 nautical miles from the coast. These bans were precautionary, since they were made in advance of contamination tests, says Gohlke.

Although “safe, not sorry” can be justified, closures can also have unintended consequences, or even backfire, she says. “Part of me thinks the precautionary approach is appropriate, but I don’t know how it has contributed to consumer confidence. Without sufficient risk communication, precautionary closures may create an expectation that the fish is contaminated. The last survey I saw, from February, suggested people were still considering Gulf seafood to be contaminated.”

“I think they make some pretty good recommendations to continue monitoring for PAHs,” says Ron Kendall, director of the Institute of Environmental and Human Health at Texas Tech University. “There is a lot of debate about underwater oil mats that are still floating, and how much oil may still be on the seafloor or in coastal marshes. With hurricane season approaching, we don’t know what kind of remobilizing of suspended oil and the mats will take place.”

To date, Kendall says, the data show that seafood has safe levels of PAHs, but “You’ve got to understand that all this oil is not gone. This story is still unfolding.”

The prospect of peak coffee raises the menace of massive caffeine withdrawal, with hordes of headachy addicts rendered into grouchy slackers. Could a cut in coffee production also cost us the many health benefits that coffee seems to provide?

For ages, the bitter black brew has been scorned as jet fuel for jittery insomniacs, providing nothing more than a momentary surge of focus and energy.

But recently, some researchers are starting to see java as the juice of the gods: In some studies, coffee appears to be protective against dementia, type 2 diabetes and even several types of cancer.

Coffee, it turns out, is loaded with polyphenols, anti-oxidant chemicals that fight damaging free radicals, which are implicated in many of the diseases of aging.

Caveat quaffer

Before we fill our cup with a discussion of the health benefits of coffee, remember these cautions:

For all these reasons, we are not prescribing coffee as medicine. But then, do we drink coffee for medicine, or for the taste, the excuse to talk things over with a friend, the acceleration physical and mental energy?

So bottoms up, and let’s check some recent studies showing how coffee affects dementia, diabetes, cardiovascular disease and cancer

Coffee: Good for your brain?

Many studies over the past decade have suggested that coffee can partly block Parkinson’s disease, a movement disorder that afflicts millions of elders. In 2006, ² researchers reported on a 22-year study of Finns – who boast Earth’s highest average coffee consumption – and found that people who drank more than 10 cups a day had about one-quarter the risk of Parkinson’s as non-drinkers. (Do Finns ever finish guzzling? While only 5 percent of the sample abstained, about 10 percent drank at least 10 cups a day!)

The researchers suggested that since Parkinson’s may be caused by oxidative attack on neurons, coffee’s protection may arise from its anti-oxidants.

Several studies – the results are inconsistent but suggestive – have linked caffeine and coffee with a reduction in Alzheimer’s disease. In 2010, after a 21-year study, researchers from Finland and Sweden³ reported that “coffee drinking of three to five cups per day at midlife was associated with a decreased risk of dementia/Alzheimer’s disease by about 65 percent at late-life.”

Research using mice with a genetic tendency to Alzheimer’s shows that coffee and caffeine improve learning and memory while reducing the beta amyloid plaques that mark Alzheimer’s. In 2011, when Gary Arendash and Chuanhai Cao of the University of South Florida compared coffee, caffeine and decaf,⁴ coffee was most effective at stimulating chemicals that apparently defend against Alzheimer’s. The researchers wrote that “coffee may be the best source of caffeine to protect against [Alzheimer's disease]” because another coffee chemical acts with caffeine to enhance protection.

Arendash did not respond to our email but said in 2009 that he’s seen “evidence that caffeine could be a viable ‘treatment’ for established Alzheimer’s disease, and not simply a protective strategy. That’s important because caffeine is a safe drug for most people, it easily enters the brain, and it appears to directly affect the disease process.”

Coffee ‘n cancer

Can coffee help protect against cancer? Sometimes.

Photo Florida Alzheimer’s Disease Research Center

Caffeine removed harmful beta amyloid plaques from the brains of mice that simulate Alzheimer’s disease.

A study of coffee and liver cancer followed 60,323 Finns for a median of 19.3 years. After adjusting for factors like age, alcohol and smoking, the hazard ratio of those who drank four to five cups was 0.44.

Hazard ratio means the probability of an outcome, compared to the reference group (non-drinkers, in this case). All other things being equal, abstainers were three times as likely to get liver cancer as those who swilled eight cups a day.⁵

To decipher conflicting or inconclusive studies, scientists can pool data using meta-analysis, a technique that sets standards for acceptable studies and then statistically groups the results.

In 2010, Mia Hashibe, in the department of family and preventive medicine at the University of Utah re-analyzed⁶ nine studies and found a 39 percent reduction in mouth and throat cancers among people who drank at least four cups. “Since coffee is so widely used and there is a relatively high incidence and low survival rate of these forms of cancers, our results have important public health implications that need to be further addressed,” said Hashibe. With such a large sample, “We had more statistical power to detect associations between cancer and coffee.”

If we shift the focus to all cancers, a new meta-analysis⁷ of 59 studies showed that each additional cup of coffee reduced the incidence of cancer by 3 percent.

The results concerning breast cancer are less encouraging. A 2008 report⁸, based on data from 85,987 women, found no significant link to coffee, decaf or tea, except for a slight reduction in breast cancer among post-menopausal women who ingested a significant amount of caffeine.

Similarly, a 2009 study in the Netherlands ⁹ found no association between coffee and breast cancer.

Ironically, coffee contains a chemical that could stimulate the many breast cancers that respond to estrogen by growing, according to Clinton Allred, an assistant professor of nutrition at Texas A&M University. Allred, who has found large amounts of a plant estrogen called trigonelline in coffee, says, “This is one of the least studied compounds I have ever been around.”

In the lab, Allred showed that trigonelline can affect cells even when it is thousands of times more dilute than the effective concentration of isoflavone, a common plant estrogen found in soy.

Allred is not worried about trigonelline, since people have been guzzling coffee for a long time, and plant chemicals consumed in a whole food or beverage act differently than they do in isolation in the lab. “People with a healthy diet that is high in plant products are exposed to these kinds of compounds all the time.”

A diabetes connection?

Could coffee slow the epidemic of type 2 diabetes, which disrupts sugar metabolism, which raises blood sugar that harms small blood vessels in the kidney, eye and heart? A 2006 study¹⁰ of 88,259 American women showed that drinking at least four cups of coffee reduced the diabetes rate to 53 percent of the rate among non-drinkers. Although both coffee and decaf (but not tea), were beneficial, diabetes prevention was most closely linked to coffee intake rather than caffeine intake.

According to a meta-analysis¹¹ based on more than 450,000 people from Asia, North American and Europe, “Every additional cup of coffee consumed in a day was associated with a 7 percent reduction in the excess risk of diabetes type 2. … Drinking three to four cups of coffee per day was associated with an approximate 25 percent lower risk of diabetes… .”

If coffee reduces diabetes, could it deter cancers associated with diabetes? A 2007 exploration¹² of the soaring rate of cancer after World War II in Japan linked coffee to reductions in liver and pancreatic cancer in men, and liver, colon and endometrial cancer in women. The authors speculated that coffee could reduce resistance to insulin, “and may thereby reduce the risk of diabetes-related cancers such as colon, liver, pancreas and endometrium.”

A matter of the heart

A 2010 study¹³ of 37,514 Dutch people found a slight benefit for coffee in heart disease: People who drank two to three cups a day had only 79 percent the rate of heart disease as abstainers, but the reduction was not statistically significant. Above 4 cups per day, the rate returned close to the no-coffee rate. Coffee did not affect the rate of strokes.

However, Swedish researchers studied¹⁴ people after a heart attack, and found that drinking one to three cups of coffee reduced the odds of dying to 68 percent of the risk for abstainers.

We put down our coffee mug with a jittery hand, wondered whether swilling coffee could harm the heart, and phoned Richard Page, a professor of medicine at the University of Wisconsin-Madison. Page, an expert in arrhythmias – the irregular heart rhythms that can cause deadly heart attacks – said, “It’s hard to demonstrate a relationship between caffeine consumption and arrhythmias, but there are case reports. I see a number of patients with arrhythmias, particularly atrial fibrillation, and occasionally we see some relationship with excessive consumption of caffeine.”

Although Page was not alarmed by coffee, he was not so sure about the mega-doses that were linked to health benefits in some studies. “I would be cautious; I have heard of a couple of adolescents developing atrial fibrillation (a hard-to-treat arrhythmia) after taking monster energy drinks; I don’t think such high doses of caffeine are good for people.”

The bottom line

If Captain C seems helpful against some cancers, dementia and diabetes, is it guaranteed to extend your life? No. A European study¹⁵, for example, found that “Neither coffee nor tea consumption was associated with stroke or all-cause mortality.”

A long American study, using data from 41,736 men (followed for 18 years), and 86, 214 women (24 years), found a slight, significant trend toward fewer deaths from all causes; those who drank at least six cups a day had a death rate just 80 percent (men) to 83 percent (women) of the non-drinkers. The main benefit was a reduction in cardiovascular disease.

However, coffee consumption did not affect cancer deaths, after adjusting for factors like obesity and smoking, and the authors concluded, ¹⁶ “The possibility of a modest benefit of coffee consumption on all-cause and cardiovascular disease mortality needs to be further investigated.”

Not exactly a ringing endorsement, but then, did we promise a simple answer?

Would you like your triple-espresso with soy milk?

You see them, and you sniff. Apples are as boring, as generic as a fruit can get. They lack the cachet of red grapes, oozing life-extending resveratrol. Unlike blueberries or pomegranates, they are not celebrated for supplying palate-pleasing megadoses of antioxidants.

So why did some wit observe, “An apple a day keeps the doctor away”? That question has been on the mind of Bahram Arjmandi, professor and chair of the department of nutrition, food and exercise sciences at Florida State University.

His answer, presented at the Experimental Biology 2011 meeting in Washington this week, admittedly seems too good to be true: Apples have a profound effect on total cholesterol, and also on the “good” and “bad” types of cholesterol. They caused a major reduction in inflammatory proteins that are implicated in a number of serious diseases.

Not only does this “medicine” taste good, but unlike cholesterol-control pills, it does not attack the liver. And last we heard, you can buy them without a prescription.

“An apple a day” or a “fateful fruit”?

In the Bible, “the apple was an evil food in the story of Adam and Eve,” Arjmandi says, “then someone said, ‘An apple a day…’ and that gave them a positive image. I thought, if there is that saying, there might be a reason for it, but you’d be amazed at how little has been done in clinical studies.”

Animals were apparently eating apples long before Adam and Eve. Photo: LASZLO ILYES

To get answers, Arjmandi rounded up 100 women who had just passed menopause — a time when dropping levels of estrogen lead to unhealthy changes in cholesterol levels that allow women to catch up with the male rate of cardiovascular disease.

Randomly dividing his volunteers, Arjmandi asked one group to supplement their normal diet with dried prunes. The treatment group got one-a-day packages containing 75 grams — about 2.5 ounces — of dried apple.

Arjmandi used dry apples rather than the equivalent one or two fresh apples as a way to standardize the “dose,” but he says fresh fruit is likely to be even more healthy.

If the object of these tests was a pill, the results after one year would certainly boost the stock of the drugmaker: among the apple-eaters, total cholesterol fell by 14 percent and low-density lipoprotein (LDL, the harmful fraction of cholesterol) fell 23 percent. High levels of both total cholesterol and LDL are linked to damage to blood vessels, heart attacks and strokes.

Meanwhile, the level of a protective type of cholesterol called high-density lipoprotein (HDL) rose 3 to 4 percent.

(Anti-) inflammatory results

Moving beyond cholesterol, the level of C-reactive protein fell 32 percent. “This is significant, and not just in a statistical sense but in clinical relevance,” says Arjmandi. “CRP is associated with inflammation, and is considered a marker for cardiovascular disease, cancer and Alzheimer’s disease.”

Does 'an apple a day...' translate into Japanese? Photo: Luca Moglia

Seeing such a major reduction from such a simple “treatment” is “amazing,” Arjmandi said.

And although the women in the test group were eating about 240 calories of dry apple each day, they lost an average of about three pounds over the year — perhaps because apple makes people feel full.

The study was partly funded by the United States Department of Agriculture, and got no funding from the apple industry. Although the report, as far as we know, has not been peer reviewed, talks at scientific meetings are routinely used to introduce new studies and new concepts.

And the active ingredient is…

What makes apples so healthy? Although both pectin, a soluble fiber, and chemicals called polyphenols are thought to confer health benefits, Arjmandi says, “an apple is more than these compounds. I’ve been working on functional foods [which give health benefits] for 20 years, and I find it’s not good to approach whole fruit or whole vegetables like drugs. If you isolate the component chemicals and take them, you get some benefits, but you will deprive yourself of greater benefits.”

Are some apples better than others? “For pectin, the firmer the better,” says Arjmandi. “Otherwise, most varieties, from jonathan to red delicious, give more or less the same benefit.”

Polyphenols are concentrated in the peel; pectin is found throughout the apple, he adds.

Last question: Did the study participants get sick of snacking on dry apple day after day? Some did, and quit the study, but “those who like them became addicted,” says Arjmandi. “The longer they were on it, the more they liked apple. Afterwards, some contacted us to ask if we can provide them with apple.”

Supermarkets, actually, carry apples side-by-side with other non-prescription produce.

Based on these results, Arjmandi would like to test the apple-a-day prescription more broadly. “I’d like to do a multi-state trial. Eating 75 grams of apple is not that difficult, and finding people with moderately high cholesterol is not that difficult.”

– David J. Tenenbaum

The “recall” of 550 million eggs (many of them already eaten) reminds us of the benefits of taking control of your food. We figure the recall will fuel an uptick in interest in backyard hens, which are now legal in some cities.

But avoiding salmonella (which can infect backyard chickens as well as commercial hens) is just one reason to favor urban agriculture. In the past few years, we’ve heard that it can:

• Reduce “food miles”: Food from the backyard or an empty lot across town will carry less of a diesel scent than veggies trucked in from California or Texas. Thus growing food locally may reduce the global warming impact of agriculture.
• Promote reality: Too many city people probably think food is made in a supermarket.
• Teach kids about work, the environment and cooperation.
• Get city people outside and liberate them from computer screens, phones and TVs.
• Grow fresher veggies, which should persuade more people to eat their vegetables, perhaps stemming obesity.
• Promote neighborhood solidarity by creating a gathering place.
• Earn money by selling at farm stands and farmer’s markets.

There are limits: City eggs and veggies will never replace the majority of our commercial supply. In January, Minnesota is not going to supply much lettuce compared, say, to California or Florida. Heavy metals found in many city soils can contaminate veggies, and finding enough sunny land is a constant hassle.

We figure people have been growing food in the city since the dawn of agriculture, and the modern rendition of urban ag can involve vegetables or animals. It can take place at home, on rented land, or on rural plots owned or rented by city people. The farms can be aimed at subsistence, the market, or both.

Serving

The Troy Community Garden in Madison, Wis., embodies many of these purposes. It has five acres devoted to an urban farm with a community supported agriculture operation, a five-acre community garden with 20-foot square plots, and a kids garden that hosts about 1,000 kids annually, says Christie Ralston, associate director of Community GroundWorks, the non-profit that runs the garden.

Interns at the five-acre farm at Troy Community Garden work on the harvest. The Why Files

The farm began in 2001 and is Madison’s oldest urban farm. Still, it’s a toddler compared to Fairview Gardens in Santa Barbara, Calif., which began as a community garden in 1895.

Troy also took part in a test project related to obesity. For three hours a day, five days a week, ten overweight high-schoolers have been learning to grow, prepare and eat vegetables as part of the UW-Madison’s GardenFit program. By increasing exercise and promoting vegetable consumption, the goal is to avoid a big summer jump in weight, a trend seen in overweight children. “We’re not necessarily trying to cause a lot of weight loss over the summer,” says Sarah Jacquart, a nutritional sciences graduate student, who runs the program. “We’re trying to prevent that rapid three- or six-pound weight gain that others have seen.”

This Asian squash, planted by Hmong gardeners, may have no English name. The Why Files

City gardens face unique challenges, such as obtaining approval for a new farm greenhouse, and serving immigrants who speak little or no English. Ralston says all-garden meetings are translated into Hmong, Lao and Spanish.

‘r chickens us?

Skeptics may doubt that urban agriculture will survive the dimming of its “new ‘n trendy” aura, and they are right that “farms” on vacant lots and railroad corridors will not put California’s fruit and vegetable farmers out of business.

So is urban agriculture today’s fad or a fact of the future? The Why Files shopped the aisles for a solid published assessment of the trend in the United States, but we wound up with an empty cart. “Since there’s no strict definition, it’s hard to say” how fast urban agriculture is growing, says Alfonso Morales, an assistant professor of urban and regional planning at the University of Wisconsin-Madison, and an expert on urban markets. “I am confident it is growing; there is all sorts of anecdotal evidence. The number of professional organizations around the different facets — urban poultry, urban gardening, urban beekeeping…”

But many of these organizations are less concerned with agriculture than with raising food for personal consumption. Sure, raising chickens in the city is legal in some places, but most people doing it are less interested in egg production than in having “a neat experience for the kids,” says Ron Kean, a poultry expert with the University of Wisconsin who advises backyard poultrophiles.

The “locavore” movement — which esteems local food for many of the reasons mentioned above — seems have boosted the number of small flocks raised on the fringes of the city, Kean notes, but most live in rural areas and sell directly to city people, and thus are not truly urban agriculture.

Dearth of data

Community gardens, which usually rent plots to people in the neighborhood, are a large part of urban agriculture, but urban mini-farms can also be run by a single operator who grows food for sale.

There are many explanations for the dearth of data on urban ag:

• Definitions: much of the new-found interest in urban agriculture concerns “local food,” but that is often grown in the countryside — even if the farmers live in the city.
• Size: Urban farms are small and their output is diverse and hard to measure.
• Age: Many urban farms are young, and any record of success would be short.
• Motivation: Urban farms often aim beyond food to social and psychological benefits, which are not captured by the yield and profit measures used to evaluate farms.

The “simple” task of approximating the number of “urban agriculturists” is difficult indeed. The United Nations Development Program produced a widely cited estimate that 800 million people practice urban agriculture, and 200 million grow for profit. Urban agriculture, the group said, produced the equivalent of 150 million full-time jobs.
But a 2010 publication¹ called these high numbers unreliable, since they emerged from a 1996 “thumbnail sketch” based on the authors experience. The 2010 survey saw wide variation in city-farming participation: from 11 percent of households in Indonesia to almost 70 percent in Vietnam and Nicaragua. More than 30 percent of city households in 11 of the 15 nations surveyed had a significant farm inside or outside the city.

In four nations, at least one urban household in three kept livestock.

Although the study also found that city farmers were eating better than non-farmers, farming may not explain that benefit, since in many cities farmers tend to be less poor than non-farmers.

The energy picture

Pamela Martin, an assistant professor geophysical science at the University of Chicago, agrees that data are short on the urban-ag phenomenon in the United States, largely because researchers are just now focusing on the topic. Local food has the potential to reduce the energy needed to grow and transport food – but does it actually do so?

According to the U.S. Department of Agriculture, agriculture produces about one percent of U.S. greenhouse gases, but food processing, distribution and marketing also are major users of fossil fuels.

The energy cost of urban agriculture varies with the farm location, the individual crop, and the methods used for growing, irrigating and transporting them. But do local vegetables save energy? No, said a recent New York Times commentary, which claimed that “The statistics brandished by local-food advocates to support such doctrinaire assertions are always selective, usually misleading and often bogus.”

Not so, says Martin. “One fact that was based on our research in Chicago was flat-out wrong, a pound of [local] lettuce does not embody the same number of calories” as a pound of lettuce that was shipped 2, 000 miles. At a city farm, “a piece of produce is grown, perhaps stored in a cooler overnight, then taken to market and it heads home. The whole supply chain is more direct than for conventional produce.”

Using a concept called “embedded-energy,” which counts how much energy is used, for example, in irrigation, tractors and fertilizer, Martin compared energy usage in conventional agriculture with local food and urban farming, based on reports from students who recorded what Chicago farmers grew and did.

To avoid polluted soil, many urban gardens import clean soil. Looks like Chicago's buildings are not stealing the sun from this garden! Courtesy: Linda N.

In first-year data from Chicago farms, local lettuce was much more energy-efficient than California lettuce, which is grown, irrigated, washed in California, and then shipped 2,000 miles, Martin says. “In terms of the environment, farms that grow lettuce in Chicago make a lot of sense. Energy and related greenhouse gases were lower than values for conventional produce, based on previous work that we did, on other studies, and on USDA [U.S. Department of Agriculture] data.”

Urban agriculture: modern melting plot?

Many advocates point out that urban farms are about growing neighborhoods as much as growing food, and this benefit has gained importance now that so many people are migrating. In the United States, urban farmers include a disproportionate number of immigrants, especially on the coasts, says Gail Feenstra, of the sustainable agriculture program at the University of California at Davis. “A lot of immigrant folks maybe don’t have enough money to purchase a whole farm, but are able to have a small plot of land, on the urban edge or in the city, where they can grow food, and they have a lot of expertise.”

Most urban immigrant farmers in California are Asian, Feenstra says, or in some neighborhoods, Hispanic. Joining a peaceful, productive enterprise can have social benefits, she adds. At a San Diego garden she recently visited, “Asian, Hispanic and African farmers grow food for sale or family use. This garden brings together these disparate ethnic groups, who have learned to cooperate; the amount of produce growing on that property is totally amazing. One gentleman exceeded a thousand pounds from his [20- by 30-foot] plot. Everything was packed really close, he did multiple cuttings, he knew what he was doing.”

Gardens can foster assimilation and health, says Feenstra. “These men were sitting around, watching TV, bored; it was not a good situation. Then, some of them started organizing: ‘We know how to grow food, we can do that for our families, can start eating more healthily.’ Now their kids are asking for vegetables, coming to the garden, hanging out with friends. The garden has made a huge difference in the neighborhood.”

A social mission

Social benefits are on the mind of David Iaquinta, a professor of sociology and demography at Nebraska Wesleyan University, who has studied urban gardening and agriculture in Germany, the Philippines and elsewhere. “Gardens allow immigrants to practice the new language, to learn about culture,” he says. “Gardeners like to talk to each other, to learn about different vegetables and different ways to grow them.”

In the United States and Europe, Iaquinta says, gardens are a “tremendous access point for subsistence, marketing, and exchange of ideas.” Many community gardens include a common area, sometimes with a playground, that makes a good site for informal language lessons. “Many of the gardeners come from cultures where women don’t attend much school, but that can happen in the garden.”

Urban gardens require a regulatory structure, which can become a means of teaching principles of democracy at the small scale, Iaquinta says.

Gardens also need land and access to water, which can be difficult to find in the city. “We need to see urban agriculture as a sector that needs to be planned for,” says Iaquinta. “Poor people are going to raise food rather than starve, and planners in urban areas need to add urban agriculture to their hand basket of tools to solve problem that do not appear to be food problems: the integration of people, dissemination and acquisition of democratic institution-building skills, poverty alleviation, childhood nutrition.”

"Allotment gardens" started in Germany more than a century ago, and have become a prototype of multi-purpose urban gardens that function rather like the American lawn, complete with the flowers and vegetables. Zurich, Switzerland, Roland zh

Making it work

Urban farms and community gardens need non-governmental support, says Feenstra. “Community buy-in is the basic requirement. If you come in from outside and try to impose something on the community, if a non-profit organization says ‘Start this,’ but the community has not bought in, it won’t last.”

Having outside advocates also helps, Feenstra adds, especially if the gardeners are recent immigrants. “They come here, have nothing, nobody respects them, understands them. Working with people who understand their culture and what skills they bring” can be essential to building an urban farm.

The ideal outside advocate is open-minded and “asset-oriented,” who can match skills to needs and turn obstacles into opportunities, Feenstra says.

A relationship with the surrounding community can even help neutralize development pressures. Feenstra points to Fairview Gardens, near Santa Barbara, which “was really pressured to sell out to development, and they decided to grow their relationship with the neighborhood, and started community-supported agriculture and a farm stand. They talked with neighbors, who helped them buy an easement on the land, because they were getting fresh vegetables from the farm.”

Training ground?

One of the major supposed benefits of participation in urban farms and gardens is the opportunity to learn business. Does this work? “I don’t know of any good assessment of that,” says Alfonso Morales of Wisconsin, who worked in, and now studies, city markets. “I predict, I am confident, that it will be a normal distribution. For a small fraction, it will be a life-changing experience, they will go on to become important business people. For most, it will be interesting experience, they will burden their children with stories about the city farm. And for some number, it will be a terrible experience that they would not wish on their worst enemy. But how much entrepreneurship will come about, we just don’t know.”

“I used to milk a cow,” says Morales, “and people said, ‘Go to college, you don’t want to be here all your life.’ Now all that experience I basically fled is important. It’s an interesting thing about urban agriculture, there is no single dominant entrée, nor any dominant outcome. People can weave their own tapestry from their activities. If a kid works at a laser tag shop, it’s a wage labor job. For people who garden, it’s an entrée into so many different parts of life.”

Restaurant menu, illustrated fruit on top, menu items like bad bananas foster, rotten apple pie.

Going to choose between cheesecake and lean beef? Between beefcake and chicken Caesar salad?

NBC’s storyboards may suggest that you eat lean, and you may want to become the biggest loser, but your food choices could be less the result of a conscious decision than a response to some tongue-twisting chemicals floating through your cerebral backwaters.

In fact, there are signs that this decision could result from the same mechanism that operates in fruit flies — but we’re flying ahead of ourselves.

A study of fruit flies published today in Current Biology explores a “dietary switch,” a chemical mechanism that forces the fly to eat what it needs. After a female mates, for example, the switch guides her toward the protein-rich fungus on a rotten peach.

The same thing happens, through much the same mechanism, in flies that are deprived of protein.

But when flies are deprived of sugar, they gravitate toward sugary food, says study author Pankaj Kapahi, a geneticist at the Buck Institute for Age Research.

Fruit flies are an ideal organism for studying biology: their genetics have been heavily explored, and genes are widely shared among organisms. “The genes that regulate many processes are conserved,” Kapahi says. “Over 400 human disease genes have been found in fruit flies, so it is very pertinent to use a model like this, where we can get the answer at a fraction of the cost, and get it quickly.”

Rather fight than switch?

“The dietary switch is pretty amazing,” says Kapahi. “During life history and development, all organisms, from simple insects up to humans, need to switch the type of nutrients they consume.” Growing animals need more protein than older ones, and the several dietary switches help ensure they get what they need.

Kapahi admits that the existence of such innate mechanisms has been controversial, and they may seem more old wives’ tale than hard-core science, but he insists they are legit. “When you do not get much protein, or much carbohydrate, there are homeostatic mechanisms that tell the organism, ‘We need to find protein,’ or ‘We are running low on carbohydrate.’”

It stands to reason that evolution would craft such switches, but reason and reality do not always agree. And yet in lab experiments with the fruit fly, Kapahi found evidence that such switches are working, and even tracked down some of their chemical mechanisms.

The activity seems to center on the TOR (target of rapamycin — don’t ask us…) pathway, which helps detect the level of nutrients in the animal, and is also involved in diabetes and cancer. To explore how proteins work in the TOR pathway, Kapahi and colleagues found that certain proteins that triggered the TOR pathway caused un-mated females to eat more yeast.

Although those proteins caused the virgin ladies to eat like mated females, they did not change the choices of mated females, suggesting that their dietary switch had already been activated.

Here's the perfect Atkins diet meal! But fruitflies that eat the Atkins die young, says study author Pankaj Kapahi.

The aging connection

TOR is known to be “a nutrition sensor that’s found from plants to humans,” Kapahi says. “It’s the link between nutrients in the environment and growth. When you eat protein, the TOR signal is part of an ancient natural sensor that says ‘There is now enough food around, let’s turn these nutrients into protein and grow bigger.’”

But the current study “suggests that TOR is also an important pathway for balancing the nutrients, specifically protein and carbohydrate,” Kapahi says. Kapahi observes that TOR has also been linked to aging in four species. “If you inhibit TOR, you get a lifespan extension,” and the mechanism may help explain the anti-aging effects of caloric restriction.

Eventually, monkeying with the TOR signal system could be the basis for drugs against diabetes, obesity, cancer or aging itself. But because TOR does multiple jobs, “that could potentially have effects on how the animal selects its diet,” Kapahi says.

Already, finding that ancient genetic pathways can affect food choice in the fruit fly reinforces the notion that cellular processes are working to decide what we eat. “We humans unconsciously go toward certain foods,” says Kapahi. “Why do we combine rice and beans in so many cultures?”

Neither rice nor beans has all the amino acids needed for a complete protein, but together “they make a very nice mix,” Kapahi says. “We have been practicing this for thousands of years, without realizing why, but it gives us an optimal amino acid balance.”