From google cache of California State University at Chico school of Agriculture
Omega 3: Omega 6 fatty acids:
Omega-3 fatty acids are considered essential fatty acids, which means that they are essential to human health but cannot be manufactured by most mammalian species. For this reason, omega-3 fatty acids must be obtained from food.
Essential fatty acids (EFAs) are polyunsaturated and grouped into two families, the omega-6 EFAs and the omega-3 EFAs. Although there are just minor differences in their molecular structure the two EFA families act very differently in the body. While the metabolic products of omega-6 acids promote inflammation, blood clotting, and tumor growth, the omega-3 acids act entirely opposite. However, it is important to maintain a balance of omega-3 and omega-6 in the diet as these two substances work together to promote health.
There are 3 major types of omega-3 fatty acids that are ingested in foods and used by the body: a-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Once eaten, the body converts ALA to EPA and DHA, the two types of omega-3 fatty acids that are most readily used by the body.
According to the University of Maryland, an inappropriate balance of these essential fatty acids (high omega-6/omega-3 ratio) contributes to the development of disease while a proper balance helps maintain and even improves health. A healthy diet should consist of roughly one to four times more omega-6 fatty acids than omega-3 fatty acids. The typical American diet tends to contain 11 to 30 times more omega-6 fatty acids than omega-3 and many researchers believe this imbalance is a significant factor in the rising rate of inflammatory disorders in the United States (Simopoulos, 1991; Simopoulos 2002).
Scientists discovered the many benefits of EPA and DHA in the early 1970’s when Danish physicians observed that Greenland Eskimos had an exceptionally low incidence of heart disease and arthritis despite the fact that they consumed a high-fat diet. More recent research has established that EPA and DHA play a crucial role in the prevention of atherosclerosis, heart attack, depression and cancer (Simopoulos, 1991; Simopoulos 2002; Connor, 2000). In addition, omega-3 consumption by individuals with rheumatoid arthritis has led to the reduction or discontinuation of their ordinary treatment (Kremer, 1989; DiGiacomo, 1989).
The human brain has a high requirement for DHA, low DHA levels have been linked to low brain serotonin levels, which are connected to an increased tendency for depression and suicide. Several studies have established a clear association between low levels of omega-3 fatty acids and depression. In fact, countries with a high level of omega-3 consumption have fewer cases of depression, decreased incidence of age-related memory loss as well as a reduction in impaired cognitive function and a lower risk of developing Alzheimer’s disease (Kalmijn et al., 1997a; Kalmijn et al., 1997b; Yehuda et al., 1996; Hibbeln, 1998; Hibbeln et al., 1995; Stoll et al., 1999; Calabrese et al., 1999; Laugharne et al., 1996).
There is some consensus among leading nutritionists who consider increases in chronic disease as no accident; they believe it is directly related to the change in our dietary patterns over the last 200 years. Our ancestors lived on an omega-6:omega-3 ratio of 1:1, while our current dietary habits are closer to 10-20:1 (Simopoulos, 1991; Pepping, 1999). Researchers believe the ideal omega-6 intake should be no more than 4-5 times that of our omega-3 intake. The National Institutes of Health recently published recommended daily intakes of fatty acids, specific recommendations include 650 mg of EPA and DHA, 2.22 g/day of alpha-linolenic acid and 4.44 g/day of linoleic acid. However, the Institute of Medicine has recommended DRIs for linoleic acid (omega-6) at 12- 17 g and 1.1-1.6 g for a-linolenic acid (omega-3) for adult women/men.
As with the human diet, cattle feed or the composition of the ration has a significant effect on the fatty acid profile of the final beef product. Cattle fed primarily grass enhanced the omega-3 content of beef by 60% and also produces a more favorable omega-6 to omega-3 ratio. Conventional beef contains a 4:1 omega 6:3 ratio while grass-only diets produce a 2:1 omega 6:3 ratio (French et al., 2000; Duckett et al., 1993; Marmer et al, 1984; Wood and Enser, 1997). Table 1 which shows the effect of ration on omega 6 and omega 3 fatty acid concentrations in beef, data is reported as g/100g of total fatty acids in meat produced from the various feeding regimes. The all grass diet produces the highest omega-3 concentration within the meat product while omega-6 levels stay fairly constant regardless of grain to grass ratio.
Table 1. Essential Fatty Acides by diet (g/100g of fatty acid) Treatment
Fatty Acid Grass silage + 4kg conc. 1kg hay + 8 kg conc. 6 kg grass (DM basis) + 5 kg of conc. 12 kg grass (DM basis) + 2.5 kg of conc. 22 kg of grass DM
n-6 fatty acids 2.96 3.21 3.12 3.04 3.14
n-3 fatty acids .91y .84y 1.13x 1.25wx 1.36w
n6:n3 ratio 3.61w 4.15w 2.86x 2.47x 2.33x
w,x,y,z Means within rows with common superscripts are not significantly different (P>.05) French, et al., 2000.
Rule et al., 2002, reported similar results in a direct comparison of n-3 and n-6 EFAs for cattle on grain vs. grass, i.e., grass-fed cattle produced higher percentages of omega 3 within the lipid fraction than grain-fed contemporaries. Table 2. Grass-fed Grain-fed
EFAs by diet
(as % of total fatty acids)
n-6 fatty acids 5.66 %a 3.92 %a
n-3 fatty acids 2.90 %b 0.64 %c
n6:n3 ratio 1.95d 6.38e
a,b,c,d,e Means within rows with common superscripts are not significantly different (P>.01) Rule, et al., 2002.
The amount of lipid per serving is highly variable and depends on the feeding regime, genetics and actual cut of beef, however when lipid content is standard (as in hamburger), a serving of grain-fed beef at 10% fat would provide 84 milligrams of omega-3 in a 100 gram serving according to French et al., 2000 (.84 g n-3/100g lipid; 100g serving at 10% lipid = 10g fat/serving; roughly 84 mg n-3). The same hamburger from grass-fed beef would produce 136 mg n-3/serving.
In general, grass-fed cattle are slaughtered at lighter weights than grain fed beef, producing leaner (lower fat) carcasses overall. Thus, whole cuts from grass-fed carcasses will not provide the same quantities of n-3 as described for hamburger at a constant % fat. Leaner carcasses have the advantage of an overall lower percent fat and a higher proportion of favorable unsaturated fatty acids. However, ultra lean carcasses (less than .3 inches of backfat) lead to cold shortening and reduced tenderness, in addition, lowered fat levels impact eating quality such as flavor and juiciness.
[...]
Conjugated Linoleic Acid (CLA):
The term conjugated linoleic acid and its acronym CLA is a group of polyunsaturated fatty acids found in beef, lamb, and dairy products that exist as a general mixture of positional and geometric conjugated isomers of linoleic acid (Sehat et al., 1999). These compounds are produced in the rumen of cattle and other ruminant animals during the microbial biohydrogenation of linoleic and linolenic acids by an anaerobic rumen bacterium Butyrivibrio fibrisolvens. (Pariza et al., 2000).
Nine different positional and geometrical isomers result from this process, of which, cis-9, trans-11 is the most abundant and is the biologically active form. Cis-9, trans-11 makes up 75% or more of the total CLA in beef (Ip, et al, 1994; Chin et al., 1992; Parodi, 1997).).
Over the past two decades numerous health benefits have been attributed to CLA in experimental animal models including actions to reduce carcinogenesis, atherosclerosis, onset of diabetes, and fat body mass.
[...]
CLA is found naturally in a variety of ruminant meats (French, et al, 2000) and dairy products (Dhiman, et al, 1999), due to the anaerobic activity of the rumen bacterium Butyrivibrio fibrisolvens. This rumen organism is responsible for the biohydrogenation of linoleic and linolenic acids into the conjugated isomers referred to as CLA. Because linoleic and linolenic acid is a precursor, diets rich in these compounds increase the concentration of the CLA within the fat depot of the animal. Lush green forages are particularly high in this precursor, therefore, grass-fed ruminant species have been shown to produce 2 to 3 times more CLA than ruminants fed in confinement on concentrate-only diets (French, et al, 2000; Duckett, et al, 1993; Rule, et al, 2002; Mandell et al, 1998). Conjugated Linoleic Acid (g/100g or g/3.50oz.)
Study Feedlot/Concentrate Range/Grass Amount Increased
French, 2000 .37 z 1.08 w 2.92 X
Duckett, 1993 .82 c 2.2 d 2.69 X
*Rule, 2002 .26 e .41 c 2.04 X
On average, grass-fed beef will provide approximately 123 mg of CLA for a standard hamburger at 10% fat. The same hamburger produced from grain-fed beef would provide 48.3 mg. (i.e., grass-fed = 1.23 g CLA/ 100g lipid; 12.3 mg/g lipid; 10% lipid/serving = 123 mg CLA).
Omega 3: Omega 6 fatty acids:
Omega-3 fatty acids are considered essential fatty acids, which means that they are essential to human health but cannot be manufactured by most mammalian species. For this reason, omega-3 fatty acids must be obtained from food.
Essential fatty acids (EFAs) are polyunsaturated and grouped into two families, the omega-6 EFAs and the omega-3 EFAs. Although there are just minor differences in their molecular structure the two EFA families act very differently in the body. While the metabolic products of omega-6 acids promote inflammation, blood clotting, and tumor growth, the omega-3 acids act entirely opposite. However, it is important to maintain a balance of omega-3 and omega-6 in the diet as these two substances work together to promote health.
There are 3 major types of omega-3 fatty acids that are ingested in foods and used by the body: a-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Once eaten, the body converts ALA to EPA and DHA, the two types of omega-3 fatty acids that are most readily used by the body.
According to the University of Maryland, an inappropriate balance of these essential fatty acids (high omega-6/omega-3 ratio) contributes to the development of disease while a proper balance helps maintain and even improves health. A healthy diet should consist of roughly one to four times more omega-6 fatty acids than omega-3 fatty acids. The typical American diet tends to contain 11 to 30 times more omega-6 fatty acids than omega-3 and many researchers believe this imbalance is a significant factor in the rising rate of inflammatory disorders in the United States (Simopoulos, 1991; Simopoulos 2002).
Scientists discovered the many benefits of EPA and DHA in the early 1970’s when Danish physicians observed that Greenland Eskimos had an exceptionally low incidence of heart disease and arthritis despite the fact that they consumed a high-fat diet. More recent research has established that EPA and DHA play a crucial role in the prevention of atherosclerosis, heart attack, depression and cancer (Simopoulos, 1991; Simopoulos 2002; Connor, 2000). In addition, omega-3 consumption by individuals with rheumatoid arthritis has led to the reduction or discontinuation of their ordinary treatment (Kremer, 1989; DiGiacomo, 1989).
The human brain has a high requirement for DHA, low DHA levels have been linked to low brain serotonin levels, which are connected to an increased tendency for depression and suicide. Several studies have established a clear association between low levels of omega-3 fatty acids and depression. In fact, countries with a high level of omega-3 consumption have fewer cases of depression, decreased incidence of age-related memory loss as well as a reduction in impaired cognitive function and a lower risk of developing Alzheimer’s disease (Kalmijn et al., 1997a; Kalmijn et al., 1997b; Yehuda et al., 1996; Hibbeln, 1998; Hibbeln et al., 1995; Stoll et al., 1999; Calabrese et al., 1999; Laugharne et al., 1996).
There is some consensus among leading nutritionists who consider increases in chronic disease as no accident; they believe it is directly related to the change in our dietary patterns over the last 200 years. Our ancestors lived on an omega-6:omega-3 ratio of 1:1, while our current dietary habits are closer to 10-20:1 (Simopoulos, 1991; Pepping, 1999). Researchers believe the ideal omega-6 intake should be no more than 4-5 times that of our omega-3 intake. The National Institutes of Health recently published recommended daily intakes of fatty acids, specific recommendations include 650 mg of EPA and DHA, 2.22 g/day of alpha-linolenic acid and 4.44 g/day of linoleic acid. However, the Institute of Medicine has recommended DRIs for linoleic acid (omega-6) at 12- 17 g and 1.1-1.6 g for a-linolenic acid (omega-3) for adult women/men.
As with the human diet, cattle feed or the composition of the ration has a significant effect on the fatty acid profile of the final beef product. Cattle fed primarily grass enhanced the omega-3 content of beef by 60% and also produces a more favorable omega-6 to omega-3 ratio. Conventional beef contains a 4:1 omega 6:3 ratio while grass-only diets produce a 2:1 omega 6:3 ratio (French et al., 2000; Duckett et al., 1993; Marmer et al, 1984; Wood and Enser, 1997). Table 1 which shows the effect of ration on omega 6 and omega 3 fatty acid concentrations in beef, data is reported as g/100g of total fatty acids in meat produced from the various feeding regimes. The all grass diet produces the highest omega-3 concentration within the meat product while omega-6 levels stay fairly constant regardless of grain to grass ratio.
Table 1. Essential Fatty Acides by diet (g/100g of fatty acid) Treatment
Fatty Acid Grass silage + 4kg conc. 1kg hay + 8 kg conc. 6 kg grass (DM basis) + 5 kg of conc. 12 kg grass (DM basis) + 2.5 kg of conc. 22 kg of grass DM
n-6 fatty acids 2.96 3.21 3.12 3.04 3.14
n-3 fatty acids .91y .84y 1.13x 1.25wx 1.36w
n6:n3 ratio 3.61w 4.15w 2.86x 2.47x 2.33x
w,x,y,z Means within rows with common superscripts are not significantly different (P>.05) French, et al., 2000.
Rule et al., 2002, reported similar results in a direct comparison of n-3 and n-6 EFAs for cattle on grain vs. grass, i.e., grass-fed cattle produced higher percentages of omega 3 within the lipid fraction than grain-fed contemporaries. Table 2. Grass-fed Grain-fed
EFAs by diet
(as % of total fatty acids)
n-6 fatty acids 5.66 %a 3.92 %a
n-3 fatty acids 2.90 %b 0.64 %c
n6:n3 ratio 1.95d 6.38e
a,b,c,d,e Means within rows with common superscripts are not significantly different (P>.01) Rule, et al., 2002.
The amount of lipid per serving is highly variable and depends on the feeding regime, genetics and actual cut of beef, however when lipid content is standard (as in hamburger), a serving of grain-fed beef at 10% fat would provide 84 milligrams of omega-3 in a 100 gram serving according to French et al., 2000 (.84 g n-3/100g lipid; 100g serving at 10% lipid = 10g fat/serving; roughly 84 mg n-3). The same hamburger from grass-fed beef would produce 136 mg n-3/serving.
In general, grass-fed cattle are slaughtered at lighter weights than grain fed beef, producing leaner (lower fat) carcasses overall. Thus, whole cuts from grass-fed carcasses will not provide the same quantities of n-3 as described for hamburger at a constant % fat. Leaner carcasses have the advantage of an overall lower percent fat and a higher proportion of favorable unsaturated fatty acids. However, ultra lean carcasses (less than .3 inches of backfat) lead to cold shortening and reduced tenderness, in addition, lowered fat levels impact eating quality such as flavor and juiciness.
[...]
Conjugated Linoleic Acid (CLA):
The term conjugated linoleic acid and its acronym CLA is a group of polyunsaturated fatty acids found in beef, lamb, and dairy products that exist as a general mixture of positional and geometric conjugated isomers of linoleic acid (Sehat et al., 1999). These compounds are produced in the rumen of cattle and other ruminant animals during the microbial biohydrogenation of linoleic and linolenic acids by an anaerobic rumen bacterium Butyrivibrio fibrisolvens. (Pariza et al., 2000).
Nine different positional and geometrical isomers result from this process, of which, cis-9, trans-11 is the most abundant and is the biologically active form. Cis-9, trans-11 makes up 75% or more of the total CLA in beef (Ip, et al, 1994; Chin et al., 1992; Parodi, 1997).).
Over the past two decades numerous health benefits have been attributed to CLA in experimental animal models including actions to reduce carcinogenesis, atherosclerosis, onset of diabetes, and fat body mass.
[...]
CLA is found naturally in a variety of ruminant meats (French, et al, 2000) and dairy products (Dhiman, et al, 1999), due to the anaerobic activity of the rumen bacterium Butyrivibrio fibrisolvens. This rumen organism is responsible for the biohydrogenation of linoleic and linolenic acids into the conjugated isomers referred to as CLA. Because linoleic and linolenic acid is a precursor, diets rich in these compounds increase the concentration of the CLA within the fat depot of the animal. Lush green forages are particularly high in this precursor, therefore, grass-fed ruminant species have been shown to produce 2 to 3 times more CLA than ruminants fed in confinement on concentrate-only diets (French, et al, 2000; Duckett, et al, 1993; Rule, et al, 2002; Mandell et al, 1998). Conjugated Linoleic Acid (g/100g or g/3.50oz.)
Study Feedlot/Concentrate Range/Grass Amount Increased
French, 2000 .37 z 1.08 w 2.92 X
Duckett, 1993 .82 c 2.2 d 2.69 X
*Rule, 2002 .26 e .41 c 2.04 X
On average, grass-fed beef will provide approximately 123 mg of CLA for a standard hamburger at 10% fat. The same hamburger produced from grain-fed beef would provide 48.3 mg. (i.e., grass-fed = 1.23 g CLA/ 100g lipid; 12.3 mg/g lipid; 10% lipid/serving = 123 mg CLA).
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