Highlight HEALTH

Here’s another reason to enjoy your coffee. A recent study in the July edition of the Journal Hepatology found a significant inverse association (meaning opposingly related; an increase in one variable results in a decrease in another) between coffee drinking and the risk of primary liver cancer [1]. The study also found that serum levels of an antioxidant enzyme, elevated in people with low coffee consumption, were associated with an increased risk of developing the disease.

photo credit: Marcelo Alves

Primary liver and bile duct cancers are the sixth most common cause of cancer death in men and the tenth most common cause of cancer death in women [2]. Hepatitis B and C viral infections have been identified as causative factors in greater than 75% of liver cancers worldwide [3]. Interestingly, incidence rates are low in most developed countries except for Japan, where coffee drinking is relatively uncommon. Several studies have also identified an inverse association between coffee consumption and serum levels of gamma-glutamyltransferase (GGT), an enzyme involved in glutathione metabolism [4-5]. Glutathione plays important roles in antioxidant defense, nutrient defense and regulation of a variety of cellular events [6].

Residents of Finland consume more coffee per capita than the Japanese, Americans, Italians and other Europeans. University of Helsinki researchers examined the associations between coffee consumption and serum GGT levels in 60,323 Finnish participants between the ages of 25 and 74 who were cancer-free at the beginning of the study.

Participants were mailed a questionnaire about their medical history, socioeconomic factors, smoking habits and dietary habits. A subset of participants (n = 37,842) had clinical data available, including alcohol consumption and serum levels of GGT. Study participants were divided into five categories based on their response to the question “How many cups of coffee do you drink daily?”:

• Category 1:   0 — 1 cup
• Category 2:   2 — 3 cups
• Category 3:   4 — 5 cups
• Category 4:   6 — 7 cups
• Category 5:   8 or more cups per day

During a median follow-up period of 19.3 years, 128 participants were diagnosed with primary liver cancer.

The researchers observed that the cumulative incidence curve of liver cancer decreased with increasing amounts of daily coffee consumption (graph). When the analysis was restricted to surveys from participants that had clinical data available, a statistically positive association was found between serum GGT level and liver cancer risk. Joint association of coffee consumption and serum GGT level with liver cancer showed that participants who drank 0 — 1 cups of coffee and were in the top 25% of subjects sampled with respect to serum GGT had about 9.2 times increased risk for liver cancer compared to participants who drank at least 6 cups of coffee daily and were in the bottom 75% of subjects sampled with respect to serum GGT.

The study results are consistent with two meta-analyses published last year demonstrating an inverse relation between coffee consumption and liver cancer [7-8]. While a previous investigation found an inverse association between coffee consumption and serum GGT level, this study is the first large prospective study to suggest that a high level of serum GGT is a risk factor for primary liver cancer. The authors discuss a mechanism for the association between coffee drinking and serum GGT on liver cancer risk [1]:

Several other putative mechanisms behind the association of coffee drinking and serum GGT on liver cancer risk have also been proposed. Coffee contains many compounds, such as chlorogenic acid, which may have the potential to influence glucose metabolism processes to prevent hyperglycemia, and consequently oxidative stress.

Indeed, chlorogenic acid, a chemical largely responsible for coffee’s bitterness, may also be responsible for coffee’s effect on serum GGT level and, ultimately, coffee’s health benefits.

More information and support for patients with “Liver cancer” can be found at Organized Wisdom and MDJunction. Additionally, the American Liver Foundation, the nation’s leading nonprofit organization promoting liver disease prevention and liver wellness, provides research, education and advocacy for those affected by liver-related diseases.

References

1. Hu et al. Joint effects of coffee consumption and serum gamma-glutamyltransferase on the risk of liver cancer. Hepatology. 2008 Jul;48(1):129-36. DOI: 10.1002/hep.22320
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2. A Snapshot of Liver and Bile Duct Cancers. American Cancer Society. Atlanta, Ga. 2007.
3. Ferlay et al. GLOBOCAN 2002: Cancer Incidence, Mortality and Prevalence Worldwide. IARC CancerBase No. 5. version 2.0. Lyon, France: International Agency for Cancer Research; 2004.
4. Casiglia et al. Unexpected effects of coffee consumption on liver enzymes. Eur J Epidemiol 1993;9:293-297.
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5. Tanaka et al. Coffee consumption and decreased serum gamma-glutamyltransferase and aminotransferase activities among male alcohol drinkers. Int J Epidemiol 1998;27:438-443.24.
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6. Wu et al. Glutathione metabolism and its implications for health. J Nutr. 2004 Mar;134(3):489-92.
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7. Larsson and Wolk. Coffee consumption and risk of liver cancer: a meta-analysis. Gastroenterology. 2007 May;132(5):1740-5. Epub 2007 Mar 24.
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8. Bravi et al. Coffee drinking and hepatocellular carcinoma risk: a meta-analysis. Hepatology. 2007 Aug;46(2):430-5.
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Have you ever wondered if those healthy fast food meals are really any better for you? McDonald’s has the Fruit ‘n Yogurt Parfait, Wendy’s offers Garden Sensations salads and at Burger King you can even get a veggie burger.

Yogurt, salad, veggie burger … these are all healthy foods.

However, new research suggests that healthy fast food meals have the same effect on your cardiovascular system as a burger, fries and a soda.

The endothelium is a thin layer of cells that line the interior surface of blood vessels. Endothelial cells line the entire circulatory system, from small capillaries to veins and arteries to the heart. These cells are responsible for regulating blood flow and blood pressure through vasoconstriction and vasodilation.

High-fat meals have a negative effect on endothelial function, causing endothelial dysfunction, meaning there is less elasticity of blood vessels and reduced blood flow. Endothelial dysfunction is a marker for cardiovascular disease and can lead to atherosclerosis or high blood pressure, increasing the risk of heart disease and stroke.

Ten years ago, a study linked diet and endothelial dysfunction [1]. Twenty healthy men and women with normal levels of total and low-density lipoprotein cholesterol were fed four randomly administered breakfasts: a high-fat meal consisting of Egg and Sausage McMuffins with fried hash browns, a low-fat meal, a high-fat meal after taking the antioxidants vitamin C and vitamin E, and a low-fat meal with the same vitamin pretreatment. Ultrasound was then used to measure changes in blood vessel tone and blood flow in the brachial artery. The researchers found that decreased vasodilation occurred for up to 4 hours following the high-fat meal, while no significant changes were observed in blood vessel tone and brachial blood flow after the low-fat meal, the high-fat meal with vitamins or the low-fat meal with vitamin pretreatment. The study demonstrated the benefits of vitamins C and E, and the authors concluded that antioxidants help maintain normal endothelial function. Today, vitamin-rich side orders are prevalent throughout the fast food industry.

Researchers now have found that these presumably healthier alternatives to a burger and fries does not significantly differ with respect to their acute impairment of endothelial function [2]. Endothelial function, measured again using ultrasound, and cardiovascular disease risk markers were measured in 24 healthy volunteers who randomly received one of three fast food meals on three study days separated by 1 week:

• Big Mac with regular side orders (french fries, ketchup and Sprite)
• Vegetarian burger with regular side orders (french fries, ketchup and Sprite)
• Vegetarian burger with vitamin-rich side orders (salad, balsamic dressing, yogurt with fruit and Minute Maid orange juice)

Unexpectedly, all three meals resulted in decreased endothelial function. In contrast to the study ten years ago, even consumption of the vegetarian burger with vitamin-rich side orders resulted in decreased vasodilation. The researchers suggest that the reduced endothelial function may be attributable, at least in part, to the increase in baseline arterial diameter following a meal.

Why the conflicting results? The vitamin pretreatment given in the study 10 years ago was extremely high - over 10 times (1000 mg) the recommended daily intake of vitamin C and over 50 times (800 IU) the recommended daily intake of vitamin E [3]. While a salad, yogurt and orange juice are good, healthy foods, they contain substantially lower levels of antioxidants.

These results come in the wake of another study finding that fast food branding makes children prefer happy meals [4]. NewScientist reported that:

… children in the study were twice as likely to prefer the McDonalds-branded carrots as the plain-packaged ones. This suggests that marketing savvy could perhaps convince youngsters to make healthful choices. Some companies have already begun experimenting with this tactic by using Mickey Mouse cartoons to sell sliced fruit and placing Curious George stickers on bananas.
Last month McDonalds announced it would shift its advertising targeted to children under the age of 13 to focus on the 375-calorie Happy Meal, which it says meets current dietary standards outlined by the government.

What does all this mean? It means that eating a side salad with your burger or adding carrots in your child’s happy meal can’t prevent the harmful affects of fast food on the vascular system. Eating healthy doesn’t mean an apple here and a carrot there, it means a complete change in the types of meals we eat.

References

1. Plotnick et al. Effect of antioxidant vitamins on the transient impairment of endothelium-dependent brachial artery vasoactivity following a single high-fat meal. JAMA. 1997 Nov 26;278(20):1682-6.
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2. Rudolph et al. Acute effects of various fast-food meals on vascular function and cardiovascular disease risk markers: the Hamburg Burger Trial. Am J Clin Nutr. 2007 Aug;86(2):334-340.
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3. Dietary Reference Intakes: Vitamins. U.S. Department of Agriculture National Agriculture Library.
4. Robinson et al. Effects of fast food branding on young children’s taste preferences. Arch Pediatr Adolesc Med. 2007 Aug;161(8):792-7.
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I love my coffee. Who doesn’t want (or need for all you coffee addicts out there) a cup of freshly brewed java to start their day? However, the bitterness of coffee is something most of us could do without.

Now chemists in Germany and the U.S. say they have identified the chemicals that are largely responsible for coffee’s bitterness. Their study, one of the most detailed chemical analyses of coffee bitterness to date, was presented this week at the 234th national meeting of the American Chemical Society [1].

Contrary to popular belief, only 15% of coffee’s perceived bitterness is due to caffeine [1]. In fact, coffee is a complex mixture of chemicals and an estimated 25 to 30 compounds have been thought to contribute to coffee’s bitter taste. Surprisingly, however, the chemists found that coffee’s bitterness is due to two main classes of compounds produced during the roasting process; chlorogenic acid lactones and phenylindanes. Both compounds are antioxidants and are not present in green, unroasted coffee beans.

During roasting, chlorogenic acid, a polyphenol in raw beans, is converted to chlorogenic acid lactones. Further roasting results in the breakdown of the lactones to phenylindanes. The lactones are responsible for the mild bitterness of light- to medium-roasted coffee, while the second breakdown product, phenylindanes, produce the harsh, bitter taste of dark-roasted coffee.

Chlorogenic acid lactones have been known for some time to be produced by the roasting process [2], but their role as a source of bitterness was not known until now. Perhaps more importantly, the identification of phenylindanes adds to the growing body of knowledge investigating the health benefits of coffee.

What you say? Health benefits?

Indeed, coffee consumption offers a number of potential health benefits. The results of epidemiological research suggest that moderate coffee consumption may help prevent type 2 diabetes mellitus [3-4], Parkinson’s disease [5] and liver disease [6]. Although coffee consumption has not been found to be associated with significantly increased cardiovascular disease risk, it is associated with increases in several cardiovascular disease risk factors, namely blood pressure [7] and plasma homocysteine [8]. Some individuals may be more vulnerable to the adverse effects of caffeine in coffee, including people with hypertension, children, adolescents and the elderly. Nevertheless, habitual intake of caffeinated beverages may prevent heart disease in the elderly.

It’s been suggested that this research on coffee bitterness will lead to a “better cup of joe”. However, I wouldn’t be too surprised if the the compounds that give coffee its bitter taste also turn out to be responsible for coffee’s health benefits.

Have any tips for a great cup of coffee? I’d love to hear them!

References

1. Battling Bitter Coffee: Chemists Identify Roasting As The Main Culprit. ScienceDaily 2007 Aug 22.
2. Farah et al. Effect of roasting on the formation of chlorogenic acid lactones in coffee. J Agric Food Chem. 2005 Mar 9;53(5):1505-13.
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3. Salazar-Martinez et al. Coffee consumption and risk for type 2 diabetes mellitus. Ann Intern Med. 2004 Jan 6;140(1):1-8.
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4. van Dam and Hu. Coffee consumption and risk of type 2 diabetes: a systematic review. JAMA. 2005 Jul 6;294(1):97-104.
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5. Ascherio et al. Prospective study of caffeine consumption and risk of Parkinson’s disease in men and women. Ann Neurol. 2001 Jul;50(1):56-63.
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6. Ruhl and Everhart. Coffee and tea consumption are associated with a lower incidence of chronic liver disease in the United States. Gastroenterology. 2005 Dec;129(6):1928-36.
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7. Noordzij et al. Blood pressure response to chronic intake of coffee and caffeine: a meta-analysis of randomized controlled trials. J Hypertens. 2005 May;23(5):921-8.
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8. Olthof et al. Consumption of high doses of chlorogenic acid, present in coffee, or of black tea increases plasma total homocysteine concentrations in humans. Am J Clin Nutr. 2001 Mar;73(3):532-8.
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