This is the long-delayed Part II of my discussion on the new American dietary guidelines, the first part of which can be read here.
Back in early 2015, when the rough draft of the new 2015-2020 guidelines were released, media outlets widely reported about one of the biggest changes in these guidelines as compared to years past. In the draft, the guidelines included information about the environmental impact of different dietary patterns. These patterns included vegan, vegetarian, pescatarian, and several different meat-eating diets ranging from low-red meat, high-fish diets - such as the Mediterranean diet - to diets high in all meat types, such as the conventional American diet. The report concluded that replacing at least some of the meat in one's daily diet with plant-based foods would have a positive effect on the environment and that, on the whole, "dietary patterns that promote health also promote [environmental] sustainability."
The evidence upon which these conclusions were based was a rigorous systematic review of a decade and a half worth of scientific studies ranging from the year 2000-2014. Only fifteen of the most rigorous, well-designed studies made the cut, and all of these studies came from industrialized nations where dietary guidelines are used, making them ideal to be compared to the U.S. population. Many of the studies analyzed the effect of food production on the environment using Life Cycle Assessment (LCA), or "cradle to grave" analysis. LCA takes into account the resources and energy needed to extract, produce, transport, use, and dispose of products.
Life Cycle Assessment, or LCA, takes every step of goods production into account.
Even though the 15 studies used a variety of methods to define dietary patterns and measure the impact of food on the environment, there was little disagreement between them. After comparing the relative impact of these dietary patterns on the environment - including greenhouse gas emissions as well as land, energy, and water use - the report found that diets lower in meat consistently had a reduced impact on the environment.
Most of the reduction in energy consumption can be chalked down to the fact that animals (like cattle, pigs, chickens, and yes - humans) require a whole lot of energy and resources. Think about all the steps in the process that must happen to get food to your table (and Fido's bowl and Bessie's trough, too):
- Animals like us need energy in the form of digestible food (calories), and this food must be grown using water, fertilizer, and fossil fuels (such as the gas that runs the tractors that harvest the food).
- Consider your typical non-lactating range cow. Good ol' Bessie requires around 18 calories of food per day for every pound she weighs. This means that an average-weight 1,600-pound full-grown cow needs 25,400 kilocalories per day - typically in the form of grass, corn, sorghum, and alfalfa.
- As a readymade greenhouse gas, methane directly contributes to climate change. And the jokes you've heard about cow farts are true - ruminants (animals who chew their cud, such as cows and goats) produce much more methane than poultry and pork, and their flatulence contributes to 20% of global methane emissions.
- Feces must be cleaned up and put away somewhere. It's often stored in a liquid lagoon, which releases even more methane and requires ever more resources. Luckily, improvements can be make through recycling the manure for use as fertilizer to make more food, or as biomass to make more energy.
The average non-lactating cow requires 25,000 calories per day. Stop giving us the side-eye, Bessie. It's the truth.
Baby, you've changed.
Like your childhood best friend who went away to summer camp and returned with a newfound interest in boys (eww!) and training bras, summer was a time of change for the 2015-2020 U.S. dietary guidelines. Some time between February and October, the decision was made to exclude any discussion of sustainability within the guidelines. However the final dietary guidelines report issued in the fall of 2015 make no mention of the impact diet on the environment. As you may be able to tell, I am not in favor of this decision.
Not only do I pity the poor saps who did a tremendous job on the systematic review described in detail here that will never see the (official) light of day. I feel that it is short-sighted and unwise to argue that issues of environmental sustainability are not directly "health-related" and therefore do not belong in the scope of the U.S. dietary guidelines. The stated purpose of the guidelines is to "promote health, prevent chronic disease, and help people reach and maintain a healthy weight." So, yes - the primary goals of the guidelines are all related to helping us live the best, healthiest lives possible. Offering recommendations to reduce the consumption of meat due to its effects on health and on the environment is perfectly in line with these goals.
According to the World Health Organization (WHO), global climate change (caused primarily from the release of greenhouse gases into the Earth's atmosphere) affects several critical "determinants of health" including factors such as air pollution, the safety of drinking water, the availability of food, and access to safe shelter around the world. In fact, the WHO estimates that between the years 2030 and 2050, climate change will cause as many as 5 million extra deaths, most of them caused by starvation, disease, and heat stress. If the lives of 5 million people hanging in the balance isn't just cause to include a page or two about the effect of what's on our plate on the health of the earth, then I really don't know what is.
What Difference Does It Make?
Depending on whom you ask, food production and consumption contributes to anywhere from ten to 57 percent of global greenhouse gas emissions. The higher estimates tend to include secondary sources of emissions such as food processing, packaging, and transportation, whereas the lower estimates strictly look at the food's production.
While transportation is one important part of the overall picture of energy use in the agricultural sector, it is not the biggest factor. Imagine, for a moment, the energy and effort it would require to eat a 100% totally local food diet for a whole year. What's the definition of a 100% local food diet? In this instance, it means that every morsel of food you eat cannot have traveled via air, truck, train, or boat at all - zero fuel emissions released.
- There's no such thing as a "quick grocery trip." Your days would be consumed with walking, running, or biking (not driving) to the closest farm in your area to procure all foods you will eat, all year long, through snow, sleet, and rain.
- Quick trips to Starbucks or through the Wendy's drive-through when you're low on time are certainly out the window.
- Your all-time favorite cereal brand or soda that's shipped from across the country? Forget about it.
- Out to bars or dinner with friends? Hope you like water.
Imagine, for another moment, that for one year, you decide to replace every fourth piece of red meat with poultry or grains. Every fourth beef burger at your favorite joint becomes a turkey burger, you swap lentils in for beef in every fourth plate of spaghetti bolognese, and every fourth time you go out for Thai food, you grab the chicken panang curry instead of the beef. It might take a bit more planning, but after a couple of weeks, you'd get used to making these occasional changes. You might even find it fun to try new recipes and dishes when you're out. Due to the reduced fat content in some of your meals, you may even find yourself shedding a few pounds before the year is out. It's doable, isn't it?
Swapping chicken panang curry in for beef - I know, that's asking a lot, right?
Surprise: you just reduced your overall climate impact more effectively than if you had completely localized every bite of food for an entire year.
The point of this illustration is to show that when it comes to reducing the impact of your plate on the global climate, heroic measures need not be taken. You do not need to swear off all meat, or even your favorite cut of steak, forever. You don't even have to eat meat-free most days of the week. But by finding small, tasty, and manageable ways to reduce the resource-intensive foods eaten on a regular basis, you are already making a change that will make your diet more sustainable.
Regardless of whether you are more inclined to believe the lower or higher end, the fact remains that the impact of food production and consumption on the average American's climate footprint is not insignificant. There are many effective ways to use less energy and to reduce your impact on the environment as a consumer of goods and services, and scaling down meat consumption should be one part of the larger picture toward a more climate-friendly way of life.
What do you think? Should the 2015-2020 U.S. dietary guidelines have included a section on the sustainability of different diets? Have you made an effort to reduce your consumption of climate-friendly meats and meat alternatives? Let me know in the comments below.