Introduction

Rapid changes in the human diet, particularly over the last hundred years, are thought to have promoted chronic diseases such as atherosclerosis, essential hypertension, obesity, diabetes and many cancers. Lean meat, fish, green leafy vegetables, fruits, nuts, berries and honey were the foods generally available to pre-agricultural man, and thereby were the foods that shaped the genetic nutritional requirements of modern humans. However, today about 17% of plant species provide 90% of the world's food supply, with the greatest percentage contributed by cereal grains. Three cereals, wheat, maize and rice account for most of the world's grain production. Thus human beings have become entirely dependent upon these cereal grains for the greater portion of their food supply. And yet, for the vast majority of the history of human kind, man rarely consumed cereal grains. Apropos of the discussion to follow, cereal grains are high in carbohydrates and omega-6 fatty acids, but low in omega-3 fatty acids and in antioxidants, particularly in comparison with green leafy vegetables. (1)

Modern dietary recommendations to reduce cardiovascular disease risk have focused largely on methods to achieve desirable blood lipid levels. These recommendations include a reduction in total dietary fat to 25% to 30% of calories, less than 7% of calories from saturated fatty acids, less than 1% of calories from trans fat, and less than 300 mg per day of cholesterol. (2) These recommendations represent a high carbohydrate, low-fat diet. Recent studies that have shown however that high-fat, low carbohydrate diets can easily substitute for the recommended “heart healthy” low-fat diets for those factors that increase the risk for cardiovascular diseases, diabetes and obesity. (3) In this 2-year trial, 322 moderately obese subjects were assigned to one of three diets: low-fat, restricted-calorie; Mediterranean, restricted-calorie; or low-carbohydrate, non–restricted-calorie. The mean weight loss was 2.9 kg for the low-fat group, 4.4 kg for the Mediterranean-diet group, and 4.7 kg for the low-carbohydrate group (P<0.001 for the interaction between diet group and time). The relative reduction in the ratio of total cholesterol to high-density lipoprotein cholesterol was 20% in the low-carbohydrate group and 12% in the low-fat group (P=0.01). (3) As will be discussed below due to a misunderstanding of the dietary fat content of lean beef products the “heart healthy” recommendations for reducing cardiovascular disease risk have led to the unnecessary restriction of nutrient-rich beef from the diet. Like fish, pork, poultry, milk, and eggs, beef has high-quality proteins, with sufficient amounts of all the essential amino acids. Beef is an excellent source of B vitamins, including niacin, vitamin B6, and vitamin B12, which is found only in animal foods. Lean beef provides heme iron, the organic iron that is about five times more useful to the body than non-heme iron, the inorganic form of iron found in plant foods. Beef is also an excellent source of zinc. However, as noted, despite the role of beef as an excellent source of many factors important in human nutrition, there has developed an unwarranted focus on beef fat content and composition and the notion that beef is not “heart healthy”.

Classes of Dietary Fats

Dietary fat consists principally of triglycerides with lesser amounts of phospholipids and sterols. Triglycerides and phospholipids are composed of fatty acids attached to a glycerol backbone. Fats and oils from animal and vegetable sources contain mixtures of saturated and unsaturated fatty acids. Saturated fatty acids (SFAs) contain only single carbon-carbon bonds and have limited chemical reactivity. Mono-unsaturated fatty acids (MUFAs) contain one double bond and polyunsaturated fatty acids (PUFAs) contain multiple double bonds. Chemical reactivity increases with the number of double bonds. The double bonds in the carbon chains are in either the cis configuration (hydrogen atom at either end of the double bond on the same side) or trans configuration (hydrogen atom at either end of the double bond on opposite sides). All dietary fat provides the same number of calories (9.3) per gram when metabolized for energy. Animal fats generally contain larger amounts of SFAs and are solid at room temperature; plant fats have a higher content of unsaturated fatty acids and are liquid (oils) at room temperature. Conjugated linoleic acid (CLA), a trans fatty acid found in beef, is a collective term for a group of isomers of the essential fatty acid, linoleic acid, which are characterized by alternating single and double bonds. (4)

Ratio of n-6/n-3 Fatty Acids

Humans are thought to have evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids of approximately 1. In modern Western diets the ratio is 15/1-16.7/1. The excessive amounts of omega-6 polyunsaturated fatty acids and high omega-6/omega-3 ratio have been shown to promote the many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases. Increased dietary omega-3 PUFA resulting in a lower omega-6/omega-3 ratio exert suppressive effects on these diseases. In the prevention of cardiovascular disease, a ratio of 4/1 is associated with a 70% decrease in total mortality. A ratio of 2.5/1 has been shown to reduce rectal cell proliferation in patients with colorectal cancer, while a ratio of 4/1 with the same amount of omega-3 PUFA had no effect. These and other similar studies have shown that a lower ratio of omega-6/omega-3 fatty acids is more desirable in reducing the risk of many of the chronic diseases of high prevalence in Western societies. (34)

 

Profile of Beef Fats

Beef fat is approximately half saturated fatty acids. The next most abundant lipid is composed of MUFAs and there is a small amount of PUFAs in beef. Also, a major portion of the total saturated fat in beef is stearic acid. Unlike other long-chain SFAs, stearic acid has been shown to be neutral in its effects on human blood cholesterol levels. (5,6) Naturally occurring trans fatty acids are found in low amounts in meats such as beef Most trans fatty acids are synthesized during the hydrogenation of fat and oils and are found in “hydrogenated” vegetable oils and products containing these oils. Beef is also an important source of CLA, which has been shown to have several potential health benefits, including reduced risk of some cancers and coronary heart disease in experimental animal models. When the CLA intake of U.S. adults is estimated by 3-day dietary records, beef provides approximately 32% of total CLA intake.

Beef Fat in Perspective

Due to its popularity in many diets, beef is a significant contributor to dietary fat intake. However its contribution is not as high as is often perceived. In the mid 1990s beef was the number one source of MUFAs, contributing 11.4% of total intake; the number two source of SFAs, contributing 11.7%; the number ten source of PUFAs at less than 2.0%; and the second major source of cholesterol at 16.1% (8). However, there has been a progressive movement toward more lean beef in the U.S. diet. The 1990 Nutrition Labeling and Education Act defined lean cuts of meat as those containing less than 10 g of total fat, 4.5 g or less of saturated fat, and less than 95 mg of cholesterol per 100 g.  There are 29 cuts of beef that meet these criteria. (9) By this standard a 3-oz serving of most lean beef cuts contains less total fat and saturated fat than a similar size serving of a skinless chicken thigh (9.2g and 2.6g respectively).

Recent studies have shown similar effects of lean red meats and lean white meats on serum lipid profile when. In this study, mean concentrations of total cholesterol were nearly identical in the both lean meat groups. HDL cholesterol (the "good" cholesterol) increased by approximately 2% in both groups and mean triglyceride levels remained similar to baseline values. (10)

Stearic Acid

Data accumulated during the past 50 years indicate that stearic acid (C18:0) is unique among the saturated fatty acids in the food supply (5, 11-13). Unlike other predominant long-chain SFAs – palmitic (C16:0), myristic (C14:0), and lauric (C12:0) acids - which increase blood cholesterol levels - stearic acid has been shown to have a neutral effect on blood total and low density lipoprotein (LDL) cholesterol levels (5, 11-14). This neutral effect on blood total and LDL cholesterol levels implies that stearic acid may not increase the risk for cardiovascular disease.

Despite subsequent findings supporting stearic acid’s neutral effect on blood total and LDL cholesterol levels (14, 15), stearic acid has continued to be grouped with other SFAs, thus continuing the misconception that all SFAs raise blood cholesterol levels and increase cardiovascular disease risk.

Separation of stearic acid from other SFAs should place fewer restrictions on foods and allow for more flexibility in planning diets to reduce the risk of cardiovascular disease. Unfortunately there is currently no practical way to incorporate stearic acid’s uniquely neutral effect on blood lipid levels into dietary guidance, current dietary recommendations are for total SFAs only. (2, 16)

Trans Fatty Acids

The primary trans fatty acids in beef is vaccenic acid. This differs from the trans fatty acids (elaidic acid) in partially hydrogenated vegetable oils. Elaidic acid is associated with an increased risk of coronary heart disease, while evidence suggests that ruminant-derived trans vaccenic acid may not have the same increased risk because of its conversion in the body to CLA, which appears to have health benefits. (17, 18, 19)

As noted all trans fatty acids are not created equal. There are two general categories of trans fatty acids: synthetic and naturally occurring. Synthetic trans fatty acids are created during a chemical process (hydrogenation) which adds hydrogen molecules directly to monounsaturated or polyunsaturated fatty acids, making them more saturated. This process converts liquid oils to a semi-solid form which adds shelf-life, provides flavor maintenance and textural properties. Approximately 90% of all trans fat consumed in the U.S. diet comes from processed and snack foods such as chips, cookies, crackers, vegetable shortening and commercial baked goods, as well as fried foods like French fries and fried chicken. (20)  While man-made trans fat derived from vegetable fats increases risk of coronary heart disease, naturally occurring trans fat of animal origin does not increase the risk, and may decrease it.  The highest intakes of vegetable trans fat were associated with a 78% increase in risk of cardiovascular disease (RR 1.78) while the highest intakes of animal trans fat had a 41% reduction in risk (RR 0.59). (17) In addition, Hodgson and colleagues also found that intake of man-made elaidic acid and trans-10 octadecaenoic acid was positively correlated with coronary heart disease, however intake of other trans fat, including naturally occurring vaccenic acid (found in beef fats), was not. (21) Thus, unlike man-made trans fatty acids, the two major trans fatty acids occurring in foods from ruminant animal sources appear to have beneficial health effects. These are conjugated linoleic acid (18:2 cis-9, trans-11 and trans-10, cis-12) and vaccenic acid  (18:1, trans-11).

Conjugated Linoleic Acid (CLA)

Conjugated linoleic acid is a naturally occurring trans fat that has been reported to have beneficial effects on genomic regulation, metabolic functions, and physiological outcomes although most of the work has been done in animal studies. (7) The major dietary sources of CLA are foods from ruminant animal sources, with about 70% from dairy products and 25% from red meat (beef, lamb and veal). (22) Animal studies have found that dietary CLA reduces total and LDL plasma cholesterol levels and suppresses cholesterol-induced atherosclerosis. (23, 24, 25)

Vaccenic Acid (VA)

Vaccenic acid is the other naturally occurring trans fat that may have beneficial health effects. (26) A significant percent of VA supplied in the diet is converted in vivo to cis-9, trans-11 CLA via endogenous synthesis. (26)

Potential Health Benefits of CLA

In vitro and experimental animal studies indicate potential health benefits of CLA. The predominant CLA isomer in beef, c9, t11 (rumenic acid), has been demonstrated to inhibit cancer at several sites, particularly the mammary gland (27), reduce cardiovascular disease risk factors (23, 24, 25), improve insulin sensitivity( 28, 29), and exhibit an anti-inflammatory effect (30). However, relatively few studies have been conducted in humans. Moreover, there is considerable variation between and among findings from experimental animal and human studies investigating potential health benefits of CLA, which may be attributed to differences in the sources and amounts of CLA used, among other factors. (31) There is a need for further research on the health benefits of CLA in humans as recognized in the 2005 Dietary Guidelines Advisory Committee Report (32) which acknowledges the unique biological effects and potential importance of naturally occurring fatty acids, such as CLA and its precursor, vaccenic acid. (31)

The Unique Qualities of Belted Galloway Beef

In late 2008, the Belted Galloway Society Foundation (BGSF) funded a study of the nutritional value of selected cuts of Belted Galloway beef. In this study rib eye steaks from 3 grain fed steers from Aldermere Farms and 3 grass fed steers from Caldwell Farms were analyzed for standard nutrient content (as dictated by USDA labeling requirements) and fatty acid analysis. The animals from Aldermere Farms were fed 8lbs of barley, 2-3lbs of oats and 5lbs of protein pellets containing 16% protein in addition to hay for the last 90-120 days prior to harvest. The animals from Caldwell Farms were fed on pasture composed of alfalfa, red clover, timothy and brome grasses from weaning to harvest. The table below shows the data from these analyses as compared with reference USDA values for the same cuts of beef. (CF=Caldwell Farms, AF=Aldermere Farms, USDA= USDA reference NDB#13095) (Data are listed as arithmetic mean, SEM=standard error of the mean with n=3) (All values are represented per 100g. sample)

       Table 1. Mandatory Nutrient Analysis Belted Galloway Beef

 

PER 100 g. SAMPLE	Ave CF	SEM	Ave AF	SEM	USDA*
Total Calories	119.00	2.31	176.67	3.84	274.00
Fat Calories	27.00	0.00	102.00	3.00	234.00
Total Fat(g)	3.00	0.00	11.33	0.33	22.07
Saturated Fat(g)	1.00	0.00	4.67	0.67	9.00
Cholesterol(mg)	11.33	1.20	47.33	3.33	68.00
Sodium(mg)	50.00	2.08	55.33	4.33	56.00
Total Carbohydrate(g)	0.00	0.00	0.00	0.00	0.00
Dietary Fiber(g)	0.00	0.00	0.00	0.00	0.00
Sugars(g)	0.00	0.00	0.00	0.00	0.00
Protein(g)	23.00	0.58	18.67	0.33	17.51
Vitamin A (IU)	0.00	0.00	0.00	0.00	0.00
Vitamin C (IU)	0.00	0.00	0.00	0.00	0.00
Calcium(mg)	17.67	1.67	15.67	0.33	10.00
Iron (mg)	1.56	0.05	1.98	0.29	1.87
Thiamine (mg)	0.06	0.01	0.07	0.01	0.08
Riboflavin (mg)	0.12	0.01	0.09	0.00	0.13
Niacin (mg)	5.41	0.76	5.78	0.87	3.23
Potassium (mg)	299.33	11.67	304.00	8.02	305.00
Phosphorus (mg)	189.33	1.33	176.33	3.53	168.00
Magnesium (mg)	16.67	0.88	17.67	0.33	18.00

 

*USDA reference NDB#13095 Beef, rib eye (ribs 10-12)  separate lean and fat trimmed to 0" fat, choice, raw

 

These data show the remarkable differences between Belted Galloway beef as compared with reference beef. On average the beef of the Belted Galloway is 46% lower in calories, 72% lower in fat calories, 68% lower in total fat, 69% lower in saturated fat, 57% lower in cholesterol, 19% higher in protein, 67% higher in calcium, and 73% higher in niacin. Table 2 shows the comparison of Belted Galloway beef lipid profiles in the Foundation study with reference USDA values (NDB#13095). On a total product content basis the USDA reference beef is higher in saturated, mono- and polyunsaturated fatty acids, shorter chain saturated fatty acids, palmitic, and oleic fatty acids. However it has less linolenic acid and conjugated linoleic acid. There is a marked difference in the total fatty acid content among the beef categories and as seen in Table 3, the absolute amounts of the lipid profile attributes correlate directly with the total amount of fatty acids present. USDA reference beef just contains considerably more total fatty acids consistent with the total fat content seen in Table 1. The Foundation study gives examples of pasture raised (CF) vs. intensive production system (USDA) as well as an example of a mixture of the two systems (AF). The data are consistent with the recent work of Kraft, et al (33) in examining the changes in lipid profiles with beef that is pasture raised versus raised in an intensive production system.

 

               Table 2. Beef Fatty Acid Composition (g. /100 g. beef)

	CF Mean	SEM	AF Mean	SEM	USDA
Saturated Fatty Acids (Acid Form)	4.03	0.94	9.10	0.57	9.00
Monounsaturated Fatty Acids (Acid Form)	2.40	0.61	6.79	0.25	9.58
Polyunsaturated Fatty Acids (Acid Form)	0.17	0.03	0.36	0.01	.77
Trans Fatty Acids (Acid Form)	0.55	0.15	0.76	0.08	0.7-0.9*
Total Fatty Acids (Acid Form)	7.57	1.81	17.73	0.52	20.15**
10:0 Capric	<0.02		<0.02		0.07
12:0 Lauric	<0.02		<0.02		0.05
14:0 Myristic	0.21	0.04	0.50	0.09	0.71
14:1 Myristoleic	0.02	0.00	0.08	0.00
15:0 Pentadecanoic	0.05	0.01	0.11	0.01
16:0 Palmitic	2.03	0.45	4.94	0.45	5.4
16:1 Palmitoleic	0.16	0.03	0.45	0.04	1.08
17:0 Heptadecanoic	0.11	0.03	0.22	0.01
18:0 Stearic	1.81	0.47	3.74	0.14	2.76
18:1 Oleic	2.22	0.58	6.25	0.25	8.47
18:2 Linoleic	0.12	0.02	0.30	0.01	0.10***
20:0 Arachidic	<0.02		0.03	0.00
20:1 Eicosenoic	<0.02		0.03	0.00	0.03
20:4 Arachidonic	<0.02		<0.02		0.02
18:3 Linolenic	0.06	0.01	0.07	0.00	0.009***
Total 18:1 trans	0.47	0.13	0.70	0.09
Total 18:1 cis	2.34	0.60	6.54	0.26
Total 18:2 trans	0.10	0.03	0.09	0.01
18:2 Conjugated Linoleic Acid	0.07	0.02	0.11	0.01	0.01 ***

                      Fatty Acids Calculated as Triglycerides

*USDA Fat and Fatty Acid Content of Selected Foods Containing Trans Fats 1993

**Estimated from sum of saturated, mono- and polyunsaturated and trans fatty acids

***Kraft, J. et al, J. of Agricultural and Food Chemistry 2008, 56, 4775-4782 (IPS)

 

The data in Table 3 demonstrate the relative composition of fat from the animals raised in different production systems and the difference in Belted Galloway versus USDA reference commodity beef. As seen in the table, Belted Galloway beef contains more stearic acid, less oleic acid, much more linolenic and conjugated linoleic acids and a markedly lower n-6/n-3 ratio.

       

           Table 3. Lipid profiles based on total fatty acid content

                       (Milligrams per gram of total fatty acids)

 

 

	CF	AF	USDA
Saturated Fatty Acids (Acid Form)	532	513	447
Monounsaturated Fatty Acids (Acid Form)	317	383	475
Polyunsaturated Fatty Acids (Acid Form)	22	20	38
Trans Fatty Acids (Acid Form)	73	43	40
10:0 Capric			3
12:0 Lauric			2
14:0 Myristic	28	28	35
14:1 Myristoleic	3	5
15:0 Pentadecanoic	7	6
16:0 Palmitic	268	279	268
16:1 Palmitoleic	21	25	54
17:0 Heptadecanoic	15	12
18:0 Stearic	239	211	137
18:1 Oleic	293	353	420
18:2 Linoleic	16	17	5
20:0 Arachidic		2
20:1 Eicosenoic		2	1
20:4 Arachidonic		1
18:3 Linolenic	8	4	0.4
Total 18:1 trans	62	39
Total 18:1 cis	309	369
Total 18:2 trans	13	5
18:2 Conjugated Linoleic Acid	9	6	0.5
Ratio  n-6/n-3 PUFA	2.0	4.25	15

 

Thus in summary based on the discussion of the health effects of beef lipid profiles given earlier in this report, it is clear that Belted Galloway beef is further uniquely important for human health. Not only is Belted Galloway beef lower in calories, lower in fat calories, lower in total fat, lower in saturated fat, lower in cholesterol, higher in protein, higher in calcium, and niacin, while providing a lower total fatty acid content, this nutritious beef maintains a beneficial CLA content and n-6/n-3 ratio.

 

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