Green Coffee Beans extract depletes nutrients

Does green coffee bean extract deplete nutrients?

Pawel Malczewski
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Short summary:

Chlorogenic acid – the main active ingredient in green coffee extract – significantly reduces zinc and non-heme iron absorption. For a quick answer click here.

Explanation

Many claims without references to the scientific studies have been made that chlorogenic acid is a “drug mugger” of magnesium, iron, zinc and vitamin B1.
These claims are related to a recommendation that if green coffee extract is taken, it should be accompanied by trace mineral supplements containing all of these minerals. Since there are no strong scientific references to back-up those claims, here is a summary of the studies:

Zinc
Studies on rats showed that chlorogenic acid binds with zinc and prevents its absorption. It is highly probable that a similar effect occurs in humans. (1)Coudray C, Bousset C, Tressol JC, Pépin D, Rayssiguier Y. Short-term ingestion of chlorogenic or caffeic acids decreases zinc but not copper absorption in rats, utilization of stable isotopes and inductively-coupled plasma mass spectrometry technique. Br J Nutr. 1998 Dec;80(6):575-84. Available here.

Iron
Phenolic compounds such as chlorogenic acid contained in coffee and black tea inhibit the absorption of iron. There is evidence that absorption of non-heme iron decreases with an increased concentration of coffee. (2)Fairweather-Tait SJ. Iron nutrition in the UK: getting the balance right. Proc Nutr Soc. 2004 Nov;63(4):519-28. Available here.

When black tea is taken with a meal it reduces absorption of non-heme iron from that meal by 62% (35% by coffee). The reduction in absorption of iron is believed to be due to polyphenolic compounds such as chlorogenic acid. (3)Hallberg L, Rossander L. Effect of different drinks on the absorption of non-heme iron from composite meals. Hum Nutr Appl Nutr. 1982 Apr;36(2):116-23. Available here.

Another study showed that beverages containing 20-50mg of polyphenols such as chlorogenic acid reduce the absorption of non-heme iron by 50-70%. Beverages containing 100-400mg of polyphenols decreased absorption by 60-90%. Black tea showed the highest reduction in absorption of 79-94%. (4)Hurrell RF, Reddy M, Cook JD. Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. Br J Nutr. 1999 Apr;81(4):289-95. Available here.
A cup of coffee taken with a hamburger reduced the absorption of iron by 39% and a cup of black tea by 64%. When the strength of coffee increased, the absorption fell even further. (5)Morck TA, Lynch SR, Cook JD. Inhibition of food iron absorption by coffee. Am J Clin Nutr. 1983 Mar;37(3):416-20. Available here.

Vitamin B1
Chlorogenic acid was shown not to induce vitamin B1 deficiency, contrary to what was believed before. (6)Horman I, Brambilla E, Stalder R. Evidence against the reported antithiamine effect of caffeic and chlorogenic acids. Int J Vitam Nutr Res. 1981;51(4):385-90. Available here.

Conclusion

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Green coffee extract contains chlorogenic acid which has been shown to reduce the absorption of iron and possibly zinc. The Green coffee extract supplement should be taken preferably away from meals to insure the optimal absorption of these nutrients from food.

References   [ + ]

1. Coudray C, Bousset C, Tressol JC, Pépin D, Rayssiguier Y. Short-term ingestion of chlorogenic or caffeic acids decreases zinc but not copper absorption in rats, utilization of stable isotopes and inductively-coupled plasma mass spectrometry technique. Br J Nutr. 1998 Dec;80(6):575-84. Available here.
2. Fairweather-Tait SJ. Iron nutrition in the UK: getting the balance right. Proc Nutr Soc. 2004 Nov;63(4):519-28. Available here.
3. Hallberg L, Rossander L. Effect of different drinks on the absorption of non-heme iron from composite meals. Hum Nutr Appl Nutr. 1982 Apr;36(2):116-23. Available here.
4. Hurrell RF, Reddy M, Cook JD. Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. Br J Nutr. 1999 Apr;81(4):289-95. Available here.
5. Morck TA, Lynch SR, Cook JD. Inhibition of food iron absorption by coffee. Am J Clin Nutr. 1983 Mar;37(3):416-20. Available here.
6. Horman I, Brambilla E, Stalder R. Evidence against the reported antithiamine effect of caffeic and chlorogenic acids. Int J Vitam Nutr Res. 1981;51(4):385-90. Available here.

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