Friday, May 27, 2011

Going hormonal over beef

The mention of hormone use in beef often stirs visceral reactions. Uncomfortable with a seemingly “unnatural” production method, consumers may seek relief in USDA Organic brands or Reserve programs where such a practice is shunned. Although synthetic hormone use carries a heavy stigma (yeah, thanks, baseball players), its actual use in livestock production is far more simple, safe, and even beneficial than you’d think.

Beef producers choose to use hormones to increase efficiency by 20% (Wileman et al., 2009): cattle gain more lean muscle on less feed. Remember the carpool effect discussed in the blog post Food Routing: Local or HOV? The more lean muscle material (lean meat) that can be piled onto fewer body frames means less maintenance energy wastage, less fecal/urinary excretion, smaller carbon footprint, less environmental impact per pound of beef. Some are concerned that animal bodies are weighing down too heavily onto their skeletal frames, causing lameness and breakage, but this is impossible given that estrogen improves bone density and strength, and in some cases causes bones to continue growing (Felson et al., 1994). Consumers derive most of their fear from the inaccurate suspicion that they ingest the hormones that the animals are given; they fear that the substances given to live animals linger in meat.

We’ll get one thing straight: hormones are never injected. The dose from a dissolvable pellet per animal immediately begins to signal for muscle building and breaks down after it “delivers its message”. There is no hormone blood-pooling, no accidental over-dosing; it’s just not possible, nor profitable (cattleman common sense: implanting with more than one is a waste of money, does not amount to increased growth, and could get you jailed). Growth promotants are implanted as a slowly-dissolving pellet in the ear, or they are fed in trace amounts. Animals are not allowed to be slaughtered until the compounds have had more than enough time to decompose and reduce down where they reach an equilibrium at a natural blood concentration. This is why, over and over, the FDA and USDA report that beef from implanted cattle are insignificantly different than non-implanted cattle. Despite the following reasons why, on a most basic biochemical level, there is nothing to fear, the FDA and USDA stringently regulate growth promotant use and routinely test for residues in meat. Secondly, the beef industry excels at self-regulation and mutual accountability through the Beef Quality Assurance program.

Beef producers use two kinds of growth promotants:
1.      Hormones (low-dose ear implants, usually a form of estrogen) signal for continued lean tissue development after the animal reaches sexual maturity (Trenkle, 1997).
2.      Beta agonists (mixed in feed) block amino acid breakdown so that the same weight isn’t maintained as the body "idles" and generates heat, but increases as the animal eats dietary protein (Borohov et al., 1987; Dawson et al., 1988).
Both chemicals are naturally occurring in us and in cattle. Being chemically unstable and having limited half-lives, they degrade all the way down until they reach a normal equilibrium concentration in the animal’s body.

A meta-analysis of ten studies by Taylor et al. (2009) summarized that no significant relationship between conventional beef consumption and breast cancer (mammary tissue being most sensitive to estrogen intake) could be alleged.

Let’s put things into perspective (Preston et al., 1997):
1.      Milk estrogen concentration: 0.12 parts per billion (nanograms/gram)
2.      Unimplanted beef: 0.16 ppb
3.      Implanted beef: 0.22 ppb
4.      Eggs: 35 ppb
5.      Soy flour: 1,510,000 ppb !!
6.      Female daily production: 5,000,000 ng
7.      Male daily production: 100,000 ng

Consequently, vegetarians have repeatedly tested positive for higher circulating androgens because of high consumption of soy products (Armstrong et al., 1981; Thomas et al., 1999).

You’ve heard the rumor about precocious development in females (recent generations of girls hitting puberty earlier)? Blaming this on milk and meat consumption doesn’t make sense, but blaming it on diets higher in starch and sugars does. These simple carbohydrates cause insulin levels to rise, which sets off this chemical chain reaction in the body: Insulin --> GnRH (gonadotropin releasing hormone) --> LH (luteinizing hormone) & FSH (follicle stimulating hormone) --> increased estrogen production (Poretsky et al., 1999; Ultrianen et al., 2009; Rosenfield et al., 2009). In starch and sugar, I believe, you have the culprits for early puberty and possibly even ovarian cysts. Similarly, there are  several beef cattle studies that use  high energy diets to increase blood sugar (--> blood insulin) to ultimately decrease the age of puberty in heifers (Corah et al., 1977; Moseley et al., 1977; 1982; Randel & Rhodes, 1980…).

For more information on why growth promotant use in beef production is safe, refer to Avery & Avery’s 2007 study.

What do you Think?   

Friday, May 20, 2011

Is The Grass(-finished beef) Always Greener?

Two years ago, I would have never written what you’re about to read. I was so convinced that “you are what you eat and you are what you eat, eats” that I not only assumed, but willed for the absolute superiority of grass-finished over conventional beef. I scoffed at the scientists and lecturers that disagreed with my thoughts in defense of conventional beef production. I inspected hairline fractures in their arguments while I leaped over logic gaps to follow “food revolutionists”.

After completing my studies in beef cattle nutrition, I have found that, frankly, the good news I used to hear about grass-finished beef is not all that great, and the bad news about conventional beef is not all that bad. Although I respect niche-market cattlemen for their creation of an artisanal product—I really am particularly fond of the grass-finished taste—I can finally admit that whatever you and I have heard from a handful of avant-garde critics about ecological and nutritional superiority is…hype.

USDA defines “Grass-Fed” as the product of animals whose diet is solely forage-based, without any inclusion of grain. I’m using the term “Grass-Finished” because all cattle, no matter the system, are reared on their grass-consuming mother’s milk and eat forage until the “finishing” stage that brings them up to harvest weight. They either remain on pasture and keep eating forage or enter a feedlot and consume a mixed diet of corn, grain and oilseed by-products, and preserved forages like alfalfa hay or silage. I’ll refer you to Anne Burkholder’s blog if you’d like to know more about how a feedyard is managed.  

Nutrition Facts
While studying ruminant nutrition, I learned that “you are what you eat” somewhat applies to humans and other monogastrics (pigs, horses, etc.), but not quite as much to ruminants. Sort of in the same way milk cultures in to yogurt, ruminants use microbes to “culture”, or ferment, their diet into metabolic intermediates (volatile fatty acids…like lactic acid in yogurt) and microbial bodies (microbial crude protein…like what most of yogurt consists of). What a cow actually digests is much different than what she originally ingests. That helps explain…

1.      Omega 3 content: 0.052 g (3 oz. Grass-fed); 0.039 (3 oz. conventional); Yes, grass-fed beef will consistently have a statistically significant increase in Omega 3, but this difference is inconsequential compared to a 3 oz. serving of salmon, which has 1.83 g. The daily recommended intake of Omega 3 is 1 g…fish oil, yes please…60 ounces of grass-fed beef, no thank you. Indeed, the ratio of Omega 3 to 6 in grass-finished beef, being lower than conventional beef, is more optimal (about 1:4 vs. 1:10; Schmid et al., 2006; Leheska et al., 2008) in the way of reducing arterial swelling, improving circulation, and reducing triglycerides (Morris et al., 1993; Harris, 1997; I will make a qualifying statement about ratios in the section on Fats). I have seen data showing that some grass-finished beef has as much as 0.10 g Omega 3 (Leheska et al., 2008; French et al., 2000), but this value is not likely to improve because of microbial fatty acid alteration in the rumen (natural biohydrogenation – turning polyunsaturated fats like omega 3's into saturated and trans fats). In fact, beef from feedlot-fed cattle have much greater potential to increase in Omega 3 values because of the higher passage rate which reduces microbial interference with the dietary fats. If feedlot animals are fed Omega 3s with linseed or algal oil, their beef increases in Omega 3 to the same level as grass-finished beef (Razminowicz et al., 2007).
2.      Vitamins A and E from grass-fed beef might be found in quantities 7 times higher than conventional beef, but a serving will only provide up to 2% of the daily value for both vitamins (Daley et al., 2010). Beef in general is not a good source of these vitamins.
3.      Fats: Although grass-finished beef has consistently less fat overall than does conventional beef (about 10% less fat, Leheska et al., 2008), the types of fat grass-finished beef offers concerns me. If you ever eat a burger made of grass-fed beef, you'll notice something strange. The grease that falls from the burger to your plate will in a few minutes harden into a hard wax-like substance, reminiscent of candle drippings. Conventional beef patties drip grease that remains oily and doesn't harden much as it cools. As someone with hypercholesterolemia, I am very sensitive to monounsaturated fat—saturated fat ratios. When I lived in Spain during college, I didn’t watch this and almost went on statin medication as a skinny 21-year-old! Monounsaturated fat (MUFA; think olive, canola, pecan oils) makes my HDL (good) cholesterol rise, while saturated fat (SFA; think hard fats like butter, grizzle) makes my LDL (bad) cholesterol rise. Your HDL/LDL can reflect your MUFA/SFA dietary intake (Adams et al., 2010; Gilmore et al., 2011). Grass-fed beef has less MUFA than SFA (ratio of 0.71 – 0.95), while conventional beef has a more optimal ratio of 1.1 – 1.31. Keep in mind that I may cancel out beef's positive "ratio" effects by over-consuming Omega 6 or SFA, so that my overall diet ratio may be far from optimal. Grain-finishing deposits more MUFA, especially where the beef is marbled, while grass-finishing deposits more SFA and even trans fats (3 g in Choice grass-finished beef vs. 0.14 g in Choice conventional beef per serving) because of ruminal biohydrogenation (Smith et al., 2009; other data c/o Dr. Smith). For lower amounts of trans-vaccenic fats, I recommend buying conventional beef or grass-fed beef that grades USDA Select or lower.
4.      CLA: The alleged benefits of CLA (conjugated linoleic acid, a fatty acid only available in products from the cattle/sheep family) are that it fights cancer, reduces arterial inflammation, and lowers body fat. These have been confirmed in laboratory rodent studies (Schultz et al., 1992; Parodi, 1994; Belury, 1995; Nicolosi and Laitinen, 1996; Pariza et al., 1996) but not in human studies (Brown et al., 2010). Grass-finished beef can offer up to two or three times as much CLA as conventional beef, but both are still a good source at ranges of 0.1 – 0.15 g per serving (Leheska et al., 2008; French et al., 2000).

While scientific credence for health advantages of grass-finished beef wanes, I still buy both types of beef, because both provide 29 different cuts of lean (< 10% fat) meat that don’t even need seasoning like other meats do. As someone prone to anemia and upper respiratory issues that is also at risk for Alzheimer’s disease, it’s good to know that a serving of beef has three times as much iron, six times as much zinc, and seven times the vitamin B12 of chicken. Plus, it’s nice to get as much iron in one serving of beef as there is in three cups of raw spinach, or as much protein as 230 calories of raw tofu, 374 calories in beans, or 670 calories in peanut butter (25g protein from 180 calories of lean beef!). 

Environmental Facts
Any animal management system that does not advance the growth rate of its animals will be inadvertently spending resources for maintenance more so than production, which is wasteful. Slow growing animals will consume more food and water and excrete more solid and gaseous waste per unit of meat or milk they produce. Grass-finished cattle go to market at almost twice the age and at lighter weights than do grain-finished cattle. In light of this…

1.      Land Use: Some neo-agricultural purists advocate finishing all beef produced in this country on pasture. Putting climatic limitations and weather capriciousness aside, let’s say all the acres of grain crops used to finish cattle at feedlots were converted to pasture. It requires 3 times more land to finish cattle on grass than it does to grow crops for finishing cattle in a feedlot (Avery & Avery, 2007). In order to produce the same amount of beef, an additional 60 million acres of non-forested land that receives > 38” annual rainfall would be required to support this goal (Capper et al., 2009). Did anyone find Atlantis yet?
2.      Methane Production: Cattle consuming grass produce as much as 3 times more methane than cattle on a feedlot diet. This has to do with different fermentative pathways that can operate in response to different diets. Since I’m a nutrition nerd, please post a comment and ask about it you’re curious. However, I typically view cattle methane production as a moot point because cattle contribute to only about 15% of world totals (Wahlen et al., 1993…see post “Bitten hands that feed…”).
3.      Sanitation:  Free-ranging cattle like those on a grass-finished system are free to excrete wastes directly into groundwater. Waste deposited by feedlot cattle is contained and treated. Feedlots must follow stringent regulations for water quality control. They must submit a site-specific Pollution Prevention Plan that is engineered to “prevent and limit discharge of pollutants to surface and ground waters” and must include a plan for a catastrophic 100-year, 24-hour rainfall event. For more details, read Avery & Avery, 2007.

I buy beef in general because it keeps open range and wildlife habitat profitable as ranchland instead of as pavement or row crops. Beef cattle management protects 75% of wildlife habitat in the United States from development. 

What do you think?

Wednesday, May 11, 2011

Food Routing: Local or HOV?

Foodies (like me!) love fresh produce, picked at its peak. We love gardening, but we also love the next best thing, farmers markets. While supporting local businesses, we appreciate the eye contact, small talk, and regular relationships we develop. This love affair may have prompted almost a 4-fold increase in operating U.S. Farmer’s Markets from 1,755 in 1994 to 6,132 in 2010 (USDA-AMS Marketing Services Division, 2010).

We may have heard that buying locally-produced food and buying produce in season are ways to be more environmentally-friendly consumers. However, the assumption that going Green means shopping at farmers markets instead of grocery stores, or buying products from people that use “rustic” vs. “factory”-farm practices, just isn’t true.

We all know carpooling cuts down on fuel expenditures per person. More accomplishment on fewer running motors is a good thing. More food production on fewer body frames or more food transported on fewer, larger vehicles makes production and transportation per unit of food less environmentally costly. A small-scale, perhaps local, operation would use a pickup truck to transport just over a thousand dozen eggs to a retail outlet. A large-scale operation, presumably much farther away from a city, would use a 6-axle, refrigerated tractor-trailer to transport tens of thousands of dozens to a retail outlet. One might compare three egg cartons: one from a local farm, one from the farmers market (from a small farm 138 miles away), and one that came from a few states over, 1,291 miles away from the grocery store. You picked one up at the local farm 44 miles away, another at the farmers market 11 miles from home, and the other is from a grocery store 2.4 miles away. You were driving a car that gets 21 mpg, while the farm truck gets 18 and the tractor-trailer gets 5.5 mpg. Which of the three systems requires the most fuel to transport food?
Conveniently, Dr. Jude Capper and others from Washington State University figured this all out for her presentation, entitled “Demystifying the Environmental Sustainability of Food Production” at the Cornell Nutrition Conference for Food Manufacturers, 2009. Here were the results:

Fuel expenditure per dozen eggs:

1.      Local farm: 2.4 gallons, car
2.      Farmers’ market: 0.63 gallons (0.01, farm truck + 0.62, car)
3.      Farmers’ market with hybrid vehicles: 0.40 gallons (0.01, farm truck + 0.39, hybrid car)
4.      Grocery store: 0.14 gallons, (0.01, tractor-trailer + 0.13 personal auto)
It’s quite shocking that the grocery store model presents the most fuel-efficient choice of the four! In following the model of Capper et al. (2009), it seems that filling your car with groceries from the grocery store to reduce trips, or walking/biking to the grocery store or farmers’ market would clearly present options that expend the least fuel. No more guilt trips to the grocery store, literally! What do you Think?