The Practically Primal Guide to Conventional Beef, Part 3: Nutritional composition

7/13/11 update:  I decided that I don't want to endorse or appear to endorse the use of any meat produced by conventional methods of feeding the livestock grains, primarily corn and soybeans.  Since animals consume 80% of the grain and soy produced by U.S. agriculture, this system drives the ongoing destruction of our topsoil both through crops and through grazing.  Animal food production consumes 87% of all freshwater used in the U.S. each year, and thus is the primary driver of depletion of water reserves.  This system also produces most of the water pollution occurring in the U.S.  Our conventional livestock production system has enormous costs detailed in this article from Cornell University.  Since I have known of these costs for more than 20 years, I feel embarrassed and remorseful that I wrote this series and other articles that endorsed the use of conventional animal products.

To reiterate, in this series of posts I only aim to discuss primarily whether or not conventional meats presents health risks to the consumer, not whether the methods used to raise conventional grain-fed meats produces the best environmental effects.  I have already discussed hormones in part I, and antibiotics and chemicals in part II. 

The next concern is the nutritional composition, including total fat content, fatty acid composition, omega-6 to omega-3 ratio, and vitamin and mineral content. 

Duckett et al compared the effect of grain- or grass- finishing systems on the nutritional composition of beef.  Comparing lean meat from grain- and grass- fed animals, they found that the grass-fed product had:

• Increased moisture content
• Decreased total lipid content by 43%
• 288% greater vitamin E content
• 54% greater b-carotene content
• Twice as much riboflavin
• Three times as much thiamin
• 30% more calcium
• 5% more magnesium
• Roughly the same amount of omega-6 PUFA
• Three times the omega-3 PUFA
• Similar saturated fat content
• 20% lower MUFA

Ducket et al found that grass-finished and grain-finished beef had, respectively, 1.65 and 4.84 times as much omega-6 as omega-3 fat, but, as noted, the absolute amount of omega-6 did not differ significantly between the two finishing strategies.  Thus, grain-feeding does not increase the omega-6 content, it only decreases the omega-3 content, of the meat.  This graph from EatWild.com shows the effect of grain-finishing on omega-3 content of meat from cattle:

Faucitano et al compared the effects of grain- or grass- finishing, either with or without hormonal growth promotants, on beef composition and palatability.  They raised all cattle to the same level of back fat deposition before slaughter, and found:

• Meat from cattle fed grain and growth promotants had a tendency to appear dark in color whereas that from cattle fed grass had a more desired red color.
• Meat from cattle given growth promotants tended to have a tougher texture.
• Meat from grass-finished cattle was just as tender as grain-finished if allowed to grow to the same level of back fat deposition.
• Types of feed did not alter omega-6 levels in meat
• Meat from grass-finished animals given no growth promotants had about 50% more omega-6 fatty acids than animals given growth promotants regardless of feed type.
• The more grain given to animals, the lower their omega-3 content of their meat, in a dose-dependent fashion (same finding as Ducket et al above).
• Meat from exclusively grass-finished animals had 2.5 times as much omega-3 fatty acid as meat given a finishing diet of 70% grain.
• The omega-6 to omega-3 ratio ranged from 1.2 in grass-finished meat to 2.2 in 70% grain-finished meat.
• Meat from grass-finished animals had slightly more CLA than meat from grain-finished animals.

This is the first study that I have seen showing that use of hormones in cattle decreases the amount of omega-6 fat in the meat from these animals. It also contradicted the usual belief that grain-finishing increases tenderness, indicating that if we allow grass-finished animals to accumulate back fat to levels equal to grain-finished animals, meat from these animals will have tenderness equal to meat from grain-finished animals.

Rule et al compared muscle fatty acid profiles of bison (range vs. feedlot), beef (range vs. feedlot), elk (wild), and chicken. They found:

• Generally, range fed beef and bison have higher total amounts of PUFA and a higher PUFA/SFA ratio than feedlot finished, due to higher contents of omega-3 fatty acids.
• Range-fed beef and bison had omega-3 fatty acid levels similar to wild elk and 3 to 4 times that found in feedlot-finished meat.
• Feedlot feeding increased total fat content (g/100g) by 50 to 100%.
• Range-finished beef and bison had total fat contents (g/100g) similar to wild elk and skinless chicken breast.

This graph from EatWild.com depicts the findings of Rule et al:  

Rule et al found the following ratios of omega-6 to omega-3 fatty acids:

• Range-fed bison, 2.09
• Feedlot bison, 7.22
• Range-fed beef, 2.13
• Feedlot beef, 6.28
• Elk, 3.14
• Chicken breast, 18.5

Rule et al concluded:

“Range-fed bison and range-fed beef cows would provide consumers with very lean meat that is comparable to meat from free-ranging elk with respect to fatty acid profiles currently regarded as the most healthful. The feeding regimen for bison production affects the leanness and fatty acid profile of the meat. Range bison production should be emphasized to obtain the leanest bison meat with the lowest cholesterol concentration possible.”

Grass provides greater amounts of selenium than grain, so grass-finished animals have higher levels of these minerals than grains. Marchello and Driskell [Great Plains Research 11 (Spring 2001): 65-82] found that grassfed bison have as much as four times more selenium (an essential trace mineral) than grainfed bison. Eating just three ounces of grassfed bison, for example, supplies more than 100 mcg. of selenium, which is several times the daily minimum requirement.  Selenium plays an important role in thyroid function, protects the body from mercury, and appears to have anticancer and cardioprotective effects.

Obviously, grass-finished meat (lean cut) gives you substantially greater nutritional value than grain-finished meat, particularly for vitamin E complex, B-carotene and mixed carotenoids, riboflavin, niacin, selenium, and omega-3 fats, along with a lower levels of total, saturated, and monounsaturated fat.  

The Omega Issue

A high dietary ratio of omega-6 to omega-3 fatty acids may have adverse effects.  In August 2010, Massiera et al reported results of a study in which they fed mice a diet containing 35% of energy as fat, and 28 times as much omega-6 as omega-3 fat, over successive generations—a situation similar to the typical Western diet.  The results reported in the abstract:

“Offspring showed, over four generations, a gradual enhancement in fat mass due to combined hyperplasia and hypertrophy with no change in food intake. Transgenerational alterations in adipokine levels were accompanied by hyperinsulinemia. Gene expression analyses of the stromal vascular fraction of adipose tissue, over generations, revealed discrete and steady changes in certain important players, such as CSF3 and Nocturnin. Thus, under conditions of genome stability and with no change in the regimen over four generations, we show that a Western-like fat diet induces a gradual fat mass enhancement, in accordance with the increasing prevalence of obesity observed in humans.”

Stephan Guyenet discussed this research in detail here.  Thus, it appears that a high n-6:n-3 ratio may promote obesity and adversely affect gene expression across multiple generations. As Stephan demonstrates in a series of articles on the topic of fats, a high intake of omega-6 oils also appears to promote cardiovascular disease, cancer, osteoporosis, liver disease, and several other diseases of civilization.  However, we should note that in the three studies I have quoted, the ratio of omega-6 to omega-3 in grain-finished beef or bison did not exceed 7.22, a far cry from the 28 to 1 ratio used in this study. In contrast, chicken breast has a ratio of 18.5.

Furthermore, the absolute amount of omega-6 fat in any of these foods is relatively small.  Using the USDA database, we find the following (food, weight, omega-6 mg):

• Grain-finished beef chuck with ¼” fat, 100 g, 218 mg
• Grain-finished beef chuck with ¼” fat, 1 pound, 1 g 
• Game meat, bison, chuck, shoulder clod, separable lean only, raw, 100 g, 114 mg

In cattle and bison, both ruminants, it appears that the microbes in their guts consume or transform most of the omega-6 in feed grains, such that, as noted in the studies cited above, the absolute amount of omega-6 in their tissues remains constant regardless of finishing method.  Their tissues develop a high n-6:n-3 ratio by route of feed grains lacking omega-3s that they would get from grass or other foraged foods. 

Now compare USDA data for lamb and pork:

• Grain-finished lamb, domestic, composite of trimmed retail cuts, separable lean and fat, trimmed to 1/8" fat, choice, raw, 100 g, 1 g  (0.330 g n-3)  
• Grain-finished lamb, domestic, composite of trimmed retail cuts, separable lean and fat, trimmed to 1/8" fat, choice, raw, 1 pound, 5g (1.5 g n-3) 
• Pork, fresh, composite of trimmed retail cuts (leg, loin, shoulder, and spareribs), separable lean and fat, raw, 100 g, 1.3 g (0.09 g n-3)
•  Pork, fresh, composite of trimmed retail cuts (leg, loin, shoulder, and spareribs), separable lean and fat, raw, 1 pound,  6.0 g (0.4 g n-3)

Lamb and pork have about 5 to 6 times as much omega-6 as beef and bison.  Lamb has in its favor a relatively high content of omega-3, with a n-6:n-3 ratio of 3:1.  This makes it a really good choice for a practically paleo diet.  Pork has a less favorable ratio (15:1), so I would suggest keeping pork to a smaller fraction of the total diet.

Now take a look at the omega-6 levels in the following (food, serving,  omega-6):

• Chicken thigh with skin, one pound, 13.6 g
• Chicken thigh without skin, one pound, 9.5 g
• Chicken breast with skin, one pound,  6.4 g
• Chicken breast without skin, one pound,  2.7 g
• Walnuts, 1 ounce (14 halves), 10.8 g
• Walnuts, 100 g, 38 g
• Safflower oil, one teaspoon, 3 g
• Safflower oil, one tablespoon, 10 g. 

Some comparisons:

• Chicken thigh with skin thus has a little more than twice as much omega-6 as lean grain-finished pork, and nearly 14 times as much as fatty grain-finished beef chuck.  
•  Chicken thigh without skin supplies about 50% more omega-6 than grain-finished pork, and 9.5 times as much as fatty grain-finished beef.   
• Chicken breast with skin provides about half as much omega-6 as pork and 6.4 times as much as the fatty chuck.   
• Chicken breast without skin has nearly 3 (2.7) times as much omega-6 as fatty beef on a weight basis.  
•  Just one ounce of walnuts provides six times more omega-6 than a whole pound of pork, and 10.8 times more than a whole pound of fatty grain-fed beef.   
• Just one teaspoon of safflower oil provides nearly twice as much omega-6 as a whole pound of pork shoulder, and 3 times as much as a whole pound of fatty grain-fed beef.

So, if you want to avoid excess omega-6, you should focus on eliminating chicken skins; limiting dark meat poultry, pork and chicken breasts; limiting nuts high in polyunsaturates (most are); and most importantly eliminating all vegetable oils except olive, palm, avocado, and coconut.  If eating grain-finished meats as staples, focus on using beef, bison, and lamb.  Use less of leaner cuts of pork and poultry.

The balancing act

These data make it very clear that the best way to reduce your intake of excessive omega-6 oils lies in restricting intake of chicken and eliminating most tree nuts and vegetable oils from your diet.  If you do this, you can easily attain a healthy total diet ratio of omega-6 to omega-3 even if you eat only grain-finished beef, lamb, pork, and bison, by including some fatty fish like salmon, sardines, or sea bass in your diet. 

As we saw above, a pound of fatty beef has 1.0 g of omega-6.  Assuming that you limit all other significant sources of omega-6 in your diet, if you consume 6 pounds of beef in a week, you will get 6 g of omega-6.  To get an ideal 1:1 ratio of omega-6: omega-3 in your overall diet, you will need to eat something that will provide 5 g of omega-3s with almost no omega-6, such as salmon or sardines.  Take a look at the USDA figures for the amounts of omega-3s in these canned fish:

• Salmon, pink, canned, solids with bone and liquid, 100 g, 1.7 g
• Sardine, Pacific, canned in tomato sauce, drained solids with bone, 100 g, 1.7 g

Thus, 350 g (12 ounces) of either salmon or sardines in the week will give you enough omega-3 to balance out 6 pounds of beef.  So I could eat a pound of beef each day 6 days each week, then have three-quarters of a pound of salmon on the 7^th day, to get the desired ratio.  Alternatively, I could eat my pound of beef daily with a few sardines to achieve the same result.

Now let’s say that you make a mistake that I made, and eat 100 g of walnuts daily.  This would provide you with 266 g of omega-6 each week.  You can see that you would have to eat a ridiculous amount of salmon or sardines – namely,  15 kg/34 lbs – each week to achieve a 1:1 ratio of omega-3 to the omega-6 in those walnuts.

You can also see that you could easily consume excessive amounts of omega-6 eating a diet based on “lean” grain-fed poultry rather than red meat.  A primal dieter gets the best results by basing the diet on meat of ruminants and hindgut fermenters, not poultry.

Eat fish, not fish oils

Some may wonder about using fish oils to achieve the balance of omegas.  I don’t recommend the isolated fish oils, because oils packed removed from fish often go rancid, and research suggests that they may not have the benefits of eating fish, and may increase mortality. In contrast to fish oils, whole fish supply a number of nutrients other than omega-3 fats that may promote health, including vitamin D, magnesium, and selenium.

Summary

• Meat from grass-finished cattle, bison, or other ruminants provides higher amounts of several important vitamins, minerals, CLA, and omega-3 fatty acids than meat from grain-finished animals. 
• Meat from cattle treated with hormones has less omega-6 than meat from cattle not treated with hormones.
• Feeding ruminants (cattle, bison, lamb, etc.) or hindgut fermenters (e.g. pigs) grain instead of grass results in significantly lower levels of omega-3 fats, but has very little effect on the absolute amount of omega-6 in the meat.
• Meat from ruminants finished on grain concentrate has low levels of omega-6 compared to meat from grain-fed poultry, most tree nuts, or nut or seed oils.
• You can easily achieve a desirable omega-6:omega-3 fat ratio while eating large amounts of meat from grain-finished ruminants or hindgut fermenters by consuming reasonable amounts of fatty fish like salmon, sardines, and mackerel.
• The main sources of omega-6 oils in most diets include meat from grain-finished poultry, tree nuts, oil seeds, and nut or seed oils.
• If you include significant servings of any of the items listed in that previous sentence, you will have great difficulty achieving a desirable ratio of omega-6 to omega-3 oils because you will have to consume unrealistic amounts of fish or fish oils.
• Regular intake of fatty fish can easily counterbalance the omega-6 found in grain-finished beef, pork, bison, or lamb, so long as you minimize intake of chicken, temperate tree nuts, oil seeds, and nut or seed oils.

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