Nutrition Myths
Does green coffee extract deplete nutrients?

SUMMARY

  • Green coffee extract contains chlorogenic acid which reduces the absorption of iron and possibly zinc.
  • Green coffee extract supplement should not be taken with meals to guarantee the optimal absorption of these nutrients from food.
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Does green coffee bean extract deplete nutrients?

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)

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)

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)

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)

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)

Vitamin B1

Chlorogenic acid was shown not to induce vitamin B1 deficiency, to what was believed before. (6)

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