Eating green for our planet – Vegans and vegetarian diets part 3

“Nothing will benefit human health and increase chances for survival of life on Earth as much as the evolution to a vegetarian diet.”

This quote is attributed to Albert Einstein, who—according to his writings—supported a vegetarian diet, but didn’t strictly adhere to it. In fact he admitted, "I have always eaten animal flesh with a somewhat guilty conscience."

After discussing the health impact of vegan and vegetarian lifestyle on personal health, I’ll be devoting this third chapter to the important subject of the environmental impact of meat production, and how eating meat (especially lots of it) affects the health of the planet.

A shocking report published in 2006 by the United Nations Food and Agriculture Organization, showed that the livestock sector generates more greenhouse gas emissions (as measured in CO2 equivalents)—18 percent of all greenhouse gas emissions—than transportation, and is also a major source of land and water degradation. Livestock production uses about a third of the world’s arable land, and as land becomes scarce, expansion of livestock production encroaches into forest land and is causing mass deforestation.

Given the livestock sector’s enormous environmental impact, the report calls for it to become a focus of environmental policy, and says such changes will have a huge potential payoff.

The American Journal of Clinical Nutrition’s May supplement on vegetarian, vegan and plant-based diets and their effects on health included two studies that examined how our eating choices affect the planet.

In the first of these studies, a review paper looking at the greenhouse gas contribution of different foods gives number values to our food choices.

Which greenhouse gases are the by-products of food production? There’s widespread conversation about carbon dioxide, and its contribution to climate change, and fossil fuels are used in agriculture for fertilizers, transportation and other energy requirements.

But two other gasses produced mainly by agriculture have an even larger green-house effect: methane and nitrous oxide. Methane is produced by ruminant livestock (such as cattle, sheep and goats) and stored manures, but also from rice grown under flooded conditions. Nitrous oxide is generated through feed-production processes and is an animal waste by-product.

Comparing emissions

A study of 22 food items sold in Sweden shows that the greenhouse gas emissions associated with foods differ greatly. For this study, carbon dioxide, methane and nitrous oxide were assessed for the farm-to-table production cycle, so storage, transportation, preparation and processing all factored into this calculation.

Here are the findings:

• The lowest emissions are produced by domestic vegetables, cereals and legumes (excluding rice).

• The highest emissions are produced by domestic beef, which produces about 70 times more greenhouse gasses per kilogram (about 2.2 pounds) of food than fresh domestic veggies fruit and grain.

• All animal products have higher greenhouse gas emissions than plant-based products, with the highest emissions produced by beef, cheese and pork, in that order.

• Fowl meat and eggs are relatively climate-friendly compared to beef; a kilogram of chicken produces about a sixth of the greenhouse gasses generated by a kilogram of beef.

• Tropical fruit, flown by plane, had emissions that were similar to animal foods.

• Fruit and grain shipped by boat had about double the amount of emissions compared to domestic fruits and grains, but their emissions were still 1/40 of domestic beef.

• Rice has greater emissions—about three times more—than other grains.

• Fish may cause high emissions due to high use of fossil fuels for fishing. Many fish are on the verge or under a severe threat of extinction, and the article sees the fish option as environmentally unsound for the most part.

To put these emissions in perspective, the researchers compare food emissions to those of the average European car: Consumption of one kilogram of domestic beef equals driving for about 100 miles in green-house gas measures.

Looking at the findings above, you may argue that comparing a kilogram of carrots to a kilogram of beef is misleading, as beef provides lots of protein, and therefore a bigger emission footprint might be justified. The paper therefore provides a table that shows how many grams of protein different foods make per kilogram greenhouse gas emissions.

The best-for-the-planet winner is domestic whole wheat, but even vegetables such as green beans and carrots, which contain very little protein, are more climate-efficient than beef in producing protein.

How green is your dinner?

The authors then analyzed the green-house gas effect of three meals, each containing a vegetable, a fruit, cereal, and a protein source, and all with similar nutritional value (i.e., the same amount of calories and protein).

• Meal A contained domestic carrots, domestic whole wheat, soybean from overseas by boat, and an orange from overseas by boat.

• Meal B contained green beans, potatoes, pork meat, and an orange from overseas by boat.

• Meal C contained frozen vegetables, rice from overseas by boat, domestic beef, and tropical fruit from overseas by plane.

The emissions of meal C are about 11 times those of meal A, while those of meal B are three times the emissions of meal A. (I daresay that besides the tropical fruit flown by plane, meal C is a pretty typical American meal). By this analysis, meal A is the “greenest.”

The authors conclude:

"The analysis shows that changes toward a more plant-based diet could help substantially in mitigating emissions of GHG (green house gasses)."

Comparing diets

The second American Journal of Clinical Nutrition study compared the environmental impact of vegetarian and non-vegetarian diets. The researchers looked at the data from the Seventh Day Adventist cohort, which includes 34,000 Adventists, 50 percent of whom are vegetarian, and found 11 food groups that vegetarian and non-vegetarians consume in significantly different amounts, such as animal foods (vegetarians consume less), and fruits, nuts and beans (vegetarians consume more). The researchers then looked at water consumption, energy use, pesticides and fertilizers applied to produce these foods using federal, state and industry data.

The non-vegetarian diet required 2.9 times more water, 2.5 more energy, 13 times more fertilizer and 1.4 times more pesticides than the vegetarian one.

These results are not surprising at all, considering the fact slaughter animals raised in factory farms are usually fed plant food (grains, such as corn and soy), which they convert very inefficiently to the animal meat that we eat. It’s of course much more efficient for us to eat the grain directly.

I’ve touched upon the animal rights and welfare argument very briefly in a previous post, and indeed, I think the morality and ethics of food and eating are an unscientific subject rooted in personal values on which many people may not easily find common ground.

However, the health argument for moderating meat intake, especially red meat intake, is quite compelling and supported by plenty of evidence. I’d buy into that.

Clearly the environmental impact of the expanding meat industry is huge, and evidence shows that if we just reduced our meat intake we’d see substantial environmental gains for our planet.

Unfortunately, the demand for meat is still growing as developing countries aspire toward a typical Western diet. The current global average daily consumption of meat is about 100 grams or 3.5 ounces per person, but there’s great disparity: The US intake is about half a pound a day, and Africa’s is about an ounce a day.

It’s clear that meat production even at current levels is unsustainable. If we want to combat global warming, land and water degradation and all of the other ills caused by industrial meat production, we need to reduce meat consumption. And the major reduction needs to occur where meat intake is high—half a pound a day is seriously way too much from a health point of view even if it were beneficial for the planet.

Current public policies are very friendly to the meat industry. For example, the grain animals are fed is subsidized, and meat and poultry producers aren’t forced to treat the mountains of waste an industrial farm generates. This ensures relatively inexpensive meat, which encourages us to eat more animal products.

No matter what your reason, I believe if you eat lots of meat, reducing meat intake is a significant personal action you can take to help reduce greenhouse gasses and improve your health.

What do you think?
Dr. Ayala