BACKGROUND
On December 23, 2005, the Food and Drug Administration (FDA) announced that whole grain barley and barley-containing products are allowed to claim that they reduce the risk of coronary heart disease (CHD). Consequently, consumers can expect to see whole barley and dry milled barley products such as flakes, grits, flour, meal, and barley meal bearing the health benefit claim. Coronary heart disease (CHD) is the cause of almost 500,000 deaths annually. Risk factors for coronary heart disease (CHD) include high total cholesterol levels and high levels of low density lipoprotein (LDL) cholesterol. Scientific evidence shows that adding barley to one's diet can provide health benefits of serum cholesterol lowering. [1] FDA suggested an example of the health claim:
"Soluble fiber from foods such as [name of food], as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease. A serving of [name of food] supplies [X] grams of the soluble fiber necessary per day to have this effect."
Further, researchers from Idaho State University and Indiana University reviewed various clinical studies and concluded that most oat and barley products are reasonable options to incorporate into a healthy dietary pattern to lower LDL-C. Other dietary interventions can be added to viscous fibers to produce larger reductions in LDL-C. A majority of the LDL-C-lowering effect of statin therapy is achieved at the starting dosage. Each subsequent doubling of the daily dosage produces an additional LDL-C reduction of ~6%. Therefore, inclusion of certain amounts of oat or barley flakes produces an effect equivalent to one to two doublings of statin dosage. (23)
THE KEY HEALTH BENEFITS OF BARLEY
The health benefits of barley are related to its cholesterol-lowering effect:
(1) Increased fecal cholesterol excretion
Lupton JR and co-workers from Texas A&M University found that barley bran flour increased the daily fecal weight significantly by 48.6 g. They also found that barley bran flour decreased gastrointestinal transit time by 8.02 hours from baseline [2] These two observations suggest that the food "travels" faster than usual in the gut in the presence of barley, this fast transist does not allow sufficient time for cholesterol absorption. Thus, if this explanation is true, the cholesterol excretion should increase. Two years later, Lia A et al, University of Goteborg, Sweden, proved that barley increased cholesterol excretion in ileostomy subjects [3]
On the other hand, barley may increase the intestinal fluid viscosity. The increased viscosity slows down the diffusion process decreases cholesterol absorption but increases cholesterol excretion. Wang L et al, Montana State University showed that barley beta-glucans altered intestinal viscosity in chicks and this altered viscosity was related to plasma cholesterol concentration. [4]
However, some scientists just simply explained that the cholesterol-lowering effect of barley was related to increased fecal cholesterol excretion or the high soluble fiber content [5-6]
(2) Lipid Metabolism Regulation
As early as 1980, Qureshi AA et al reported that the cholesterol-lowering activities of barley were related to a decreased HMG-CoA reductase and increased acetyl-CoA carboxylase activities from their experimental study using chicks. [7] In 1982, the same group reported that high-protein barley flour produced significant reductions in hepatic HMG-CoA reductase, plasma cholesterol and induction in several lipogenic enzymes in birds. They suggested that their high-protein barley flour contained an inhibitor(s) of cholesterol biosynthesis and a growth factor(s). [8] While, Burger WC et al, reported that barley kernel constituents decreased hepatic beta-hydroxy-beta-methylglutaryl CoA (HMG-CoA) reductase, cholesterol 7 alpha-hydroxylase (7 alpha-hyd) but increased fatty acid synthetase (FAS) in their studies using chickens. [9]
In 1986, Qureshi AA et al reported that they purified the non-polar fraction of high protein barley (Hordeum vulgare L.) using HPLC to yield 10 major components. They found that components I and II were potent inhibitors of cholesterogenesis in vivo and in vitro. They used mass spectrometry to identify that component 1 was d-alpha-tocotrienol. The molecule differs from tocopherols (vitamin E) only in three double bonds in the isoprenoid chain which appear to be essential for the inhibition of cholesterogenesis. [10]
Wang L et al, Montana State University, extracted barley oil with hexane from the grain of a high oil waxy hull-less barley. They found that barley oil had an effect in suppression of Total plasma cholesterol concentration and Plasma low density lipoprotein cholesterol in chicks compared to margarine. Barley oil suppressed low density lipoprotein cholesterol but not high density lipoprotein cholesterol in chicks compared to corn oil. They considered the greater weight gain of the chicks fed barley oil as these chicks had normally functioning digestion and absorption. They found alpha-Tocotrienol and gamma-tocotrienol content of the barley oil were 24 and 17 times greater, respectively, than those observed in the corn oil and none in the margarine (same fraction). Finally, they considered that alpha-tocotrienol and polyunsaturated fatty acids are hypocholesterolemic components in barley oil. [11]
Finally, Yang JL et al, Changwon University, Korea, found that barley beta-glucan lowers serum cholesterol based on the up-regulation of cholesterol 7alpha-hydroxylase activity and mRNA abundance in cholesterol-fed rats. [12]
CLINICAL OBSERVATIONS
The health benefits of barley have been shown in many studies and some key studies are summarized as follows:
Early Studies (1990-2000)
In 1990, Zhang JX at al, University of Umea, Sweden, reported that brewer's spent grain (a concentrated barley fibre source from the by-product of brewing) lowered the cholesterol and bile concentration and decreased ileal and jejunal epithelium height in hamsters. [13]
One year later, McIntosh GH et al, CSIRO, South Australia reported that consumption of barley relative to wheat foods was associated with a significant fall in both plasma total cholesterol and in low-density-lipoprotein cholesterol whereas triglyceride and glucose concentrations did not change significantly from their clinical study (n=21 mildly hypercholesterolemic men aged 30-59). [14]
Lupton JR et al, Texas A&M University, reported the cholesterol-lowering effect of barley bran flour and oil on 79 men and women with hypercholesterolemia [15]
Ikegami S et al, National Institute of Health and Nutrition, Japan, fed 20 men with boiled barley-rice (50/50 w/w) for four weeks and they found a significant fall in serum total cholesterol, LDL-cholesterol, phospholipids and LDL and VLDL-lipoproteins. [16]
Studies after 2000
Scientists from Taiwan and scientists from Department of Agriculture confirmed Barley's cholesterol-lowering effect.
Yu YM et al, China Medical College, Taiwan, reported inhibition of hyperlipidemic atherosclerosis by barley leaf essence with a decrease in plasma lipids and an increase in anti-oxidative abilities from the study using rabbits. [17]. Two years later, this group reported that this extract could reduce total and LDL-cholesterol (LDL-C) levels based on their clinical study of 40 hyperlipidemic smokers and/or non-smokers. And, barley leaf extract had a stronger anti-oxidative effect on the prevention of LDL oxidation than adlay. [17]
Behall KM et al, US Department of Agriculture, reported that the diet contained 3 or 6 g beta-glucan/d from barley lowered total cholesterol significantly compared to diet contained no beta-glucan from their five-week clinical study using 18 female and 7 male subjects. [18] Again, in the same year, this group reported that barley lowered total cholesterol and LDL cholesterol were significantly from their clinical study (n=18 moderately hypercholesterolemic men (28-62 y)) [19]
In 2003 and 2004, Li J, et al, Medical University of Yamanashi, Tamaho, Japan and Wilson TA et al, University of Massachusetts-Lowell, reported the beneficial effects of intake of barley on lipid metabolism and/or glucose tolerance from the animal studies using rats and hamsters. [20]
Importance of the soluble fibers in the cholesterol-lowering activities (ie the benefits) In 1993, Japanese researchers, Oda T, Aoe S, Sanada H and Ayano Y at Technical Research Institute, Saitama found that none of the insoluble fiber preparations (from barley) had any significant effect on liver and plasma cholesterol concentrations. But, all of the soluble fiber preparations suppressed liver cholesterol accumulation, but they did not suppress the elevation of plasma cholesterol concentrations. [21]. In 1994, the same group reported that barley gum which had no significant effect on liver cholesterol; it suppressed only the elevated serum and liver triglyceride concentration in hypertriglyceridemic rats. [22]
There are always different results...
Finally, Keogh GF et al, University of Auckland, New Zealand found no significant change in total, LDL, or HDL cholesterol or in triacylglycerol, fasting glucose, or postprandial glucose from their single-blind study (n=18; hyperlipidinc men, dose= 8.1-11.9 g beta-glucan/d (scaled to body weight)). [22]
For recent studies, please review Reference 23.
REFERENCE
[1] FDA Allows Barley Products to Claim Reduction in Risk of Coronary Heart Disease, FDA News, December 23, 2005.
[2] J Am Diet Assoc. 1993 Aug; 93 (8): 881-5].
[3] Am J Clin Nutr. 1995 Dec;62(6):1245-51.
[4] J Nutr. 1992 Nov;122(11):2292-7]
[5-6] Zhang JX et al, University of Umea, Sweden; J Nutr. 1991 Jun;121(6):778-84;
Martinez VM et al, Montana State University, J Nutr. 1992 May;122(5):1070-6.
[7] J Nutr. 1980 Mar;110(3):388-93.]
[8] Lipids. 1982 Dec;17(12):956-63]
[9] Atherosclerosis. 1984 Apr;51(1):75-87]
[10] J Biol Chem. 1986 Aug 15;261(23):10544-50]
[11] Plant Foods Hum Nutr. 1993 Jan;43(1):9-17]
[12] J Nutr Sci Vitaminol (Tokyo). 2003 Dec;49(6):381-7].
[13] APMIS. 1990 Jun;98 (6):568-74].
[14] Am J Clin Nutr. 1991 May;53(5):1205-9]
[15] J Am Diet Assoc. 1994 Jan;94(1):65-70]
[16] [16] Plant Foods Hum Nutr. 1996 Jun;49(4):317-28].
[17a] Jpn J Pharmacol. 2002 Jun;89(2):142-8]
[17b] Biol Pharm Bull. 2004 Jun;27(6):802-5]
[18] Am J Clin Nutr. 2004 Nov;80(5):1185-93]
[19] J Am Coll Nutr. 2004 Feb;23(1):55-62].
[20] Metabolism. 2003 Sep;52(9):1206-10; J Nutr. 2004 Oct;134(10):2617-22]
[21] J Nutr Sci Vitaminol (Tokyo). 1993 Feb; 39 (1):73-9]
[22a] J Nutr Sci Vitaminol (Tokyo). 1994 Apr;40(2):213-7]
[22b] Am J Clin Nutr. 2003 Oct;78(4):711-8]
(23) Liana L. Guarneiri et al, Viscous fiber from oats and barley: keep them in your cholesterol-lowering portfolio, Ann Transl Med. 2024 Feb 1; 12(1): 18.