Chocolate attachment

August 28, 2002

Hi All,

I forwarded a previous post and forgot that the attachment would not

automatically be attached.

Please see the attached this time.

Cheers, Al.

Alan Pater, Ph.D.; Faculty of Medicine; Memorial University; St. 's, NF

A1B 3V6 Canada; Tel. No.: (709) 777-6488; Fax No.: (709) 777-7010; email:

apater@...

[AJCN] [Nutrition Week 2003]

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American Journal of Clinical

Nutrition, Vol. 76, No. 3,

687-688, September 2002

Clinical Nutrition

--------------------

Letter to the Editor

Extra dietary copper inhibits

LDL oxidation

M Klevay

US Department of Agriculture, Agricultural Research Service Grand Forks

Human Nutrition Research Center PO Box 9034 Grand Forks, ND 58202-9034

E-mail: lklevay@...

Wan et al (1) fed cocoa powder and dark chocolate to subjects for 4 wk and

found that LDL oxidation was inhibited in vitro. This favorable effect on

cardiovascular risk status was attributed to flavonoids, a group of

polyphenolic compounds with antioxidant characteristics. An increase in

dietary copper during this experiment may have contributed to their

results.

The Western diet often is low in copper: approximately one-third of 849

diets that were analyzed provided 1 mg/d (2). The interquartile range was

0.91–1.86 mg/d. Milk chocolate and cocoa powder are in the upper quartile

of 235 foods evaluated by Lurie et al (3), ranking 186 and 232,

respectively, in copper concentration. Calculations using Lurie et al’s

values for chocolate and cocoa powder of 2.86 and 50.0 µg/g, respectively,

show that these supplements would have added nearly 1.15 mg Cu to the basal

diet each day. Dark chocolate contains more copper than does light

chocolate and would have increased this estimated amount even more. It

seems likely that the total daily intake of copper might have been 3 times

the daily estimated average requirement (0.7 mg) or twice the recommended

dietary allowance (0.9 mg) for adults (4).

Although copper salts (at 10 µmol/L) and LDL are highly reactive in vitro,

this phenomenon is probably irrelevant to human physiology because copper

ions are virtually nonexistent (1 amol/L) in vivo (5–7). Indeed, after

providing copper supplementation to middle-aged subjects, Rock et al (8)

found that the subjects’ erythrocytes were more resistant to oxidation in

vitro. Although this improvement occurred without an increase in the

activity of superoxide dismutase (EC 1.15.1.1), an enzyme that provides

defense against oxidative damage, the results may indicate that the

subjects ordinarily ate too little copper and had other means of defense.

Perhaps the usual copper intakes of the subjects studied by Wan et al were

too low also. Their basal diet probably was low in copper because it

excluded beans and soybeans, 2 foods in the top quartile (see above).

Control of the diets for copper intake as well as for intakes of caffeine,

cholesterol, fat, and fiber would have been informative because the

increased copper intake from chocolate seems smaller than some beneficial

amounts given by Rock et al (8). Perhaps chocolate enhances the

absorbability of copper.

Copper is an antioxidant nutrient for cardiovascular health (7) and has no

prooxidant activity at a considerably higher intake (8) than that given by

Wan et al. Diets low in copper are suggested as an explanation for much of

the epidemiology and pathophysiology of ischemic heart disease (9).

Chocolate is a pleasant dietary supplement.

REFERENCES

1. Wan Y, Vinson JA, Etherton TD, Proch J, Lazarus SA, Kris-Etherton PM.

Effects of cocoa powder and dark chocolate on LDL oxidative

susceptibility and prostaglandin concentrations in humans. Am J Clin

Nutr 2001;74:596–602.[Abstract/Full Text]

2. Klevay LM. Lack of a recommended dietary allowance for copper may be

hazardous to your health. J Am Coll Nutr 1998;17:322–6.[Abstract/Full

Text]

3. Lurie DG, Holden JM, Schubert A, Wolf WR, -Ihli NJ. The copper

content of foods based on a critical evaluation of published

analytical data. J Food Comp Anal 1989;2:298–316.

4. Food and Nutrition Board, Institute of Medicine. Dietary reference

intakes for vitamin A, vitamin K, arsenic, boron, chromium, copper,

iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and

zinc. Washington, DC: National Academy Press, 2001:7.1–27.

5. May PM, Linder PW, DR. Ambivalent effect of protein binding

on computed distributions of metal ions complexed by ligands in blood

plasma. Experientia 1976;32:1492–4.[Medline]

6. May PM, Linder PW, DR. Computer simulation of metal-ion

equilibria in biofluids: models for the low-molecular-weight complex

distribution of calcium(II), magnesium(II), manganese(II), iron(III),

copper(II), zinc(II), and lead(II) ions in blood plasma. J Chem Soc

Dalton Trans 1977;588–95.

7. KG, Klevay LM. Copper: an antioxidant nutrient for

cardiovascular health. Curr Opin Lipidol 1994;5:22–8.

8. Rock E, Mazur A, O’Connor JM, Bonham MP, Rayssiguier Y, Strain JJ. The

effect of copper supplementation on red blood cell oxidizability and

plasma antioxidants in middle-aged healthy volunteers. Free Radic Biol

Med 2000;28:324–9.[Medline]

9. Klevay LM. Trace element and mineral nutrition in disease: ischemic

heart disease. In: Bogden JD, Klevay LM, eds. Clinical nutrition of

the essential trace elements and minerals: the guide for health

professionals. Totowa, NJ: Humana Press Inc, 2000:251–71.

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