Chlorogenic acid

Generality

Chlorogenic acid (CGA) is a phenolic compound.

It therefore belongs to the category of polyphenols, powerful antioxidants widely found in plants, many of which find their place in human nutrition.

Food Chlorogenic Acid

Chlorogenic acid in coffee

Chlorogenic acid is found in high concentrations in green coffee, while its bioavailability is reduced due to roasting (a compound originated from coffee roasting, called HHQ, seems to inhibit the action of chlorogenic acid in vivo).

One liter of coffee supplies 500 to 800mg of chlorogenic acid (250-400mg of caffeic acid).

Although green coffee is the subject of most research relating to the health applications of the CGA, mate is also a particularly generous source of chlorogenic acid. This famous South American drink seems to contain around 2.1mg per gram (over two grams per liter).

Chlorogenic acid in other foods

In addition to coffee, natural sources of chlorogenic acid are represented by various commonly used plant foods, such as apples, blueberries, peaches, pears, plums, tomatoes, aubergines, peanuts and potatoes.

Chlorogenic acid is one of the most abundant polyphenolic compounds in the human diet, which in case of generous consumption of coffee and plant foods can bring up to one gram per day.

Chemical Characteristics

Despite the name, chlorogenic acid has no chlorine atoms in its chemical structure. It owes its name to the Greek term χλωρός ("green"), attributed as a function of the green color of its oxidation products.

As anticipated, chlorogenic acid belongs to the family of polyphenols, which together has over 8, 000 compounds.

Polyphenols have in common the presence, in their chemical structure, of multiple phenolic groups, in turn formed by an aromatic ring (benzene) with one or more hydroxyl substituents.

Depending on the number of phenolic rings they contain and the structural elements that bind these rings to each other, the phenolic compounds could be divided into 10 general classes; among these, the most abundant in the vegetable kingdom are phenolic acids, lignans, stilbenes and flavonoids.

In turn, phenolic acids include two classes: those deriving from benzoic acid and those deriving from cinnamic acid. Chlorogenic acid falls into the latter category.

In particular, it derives from the esterification of caffeic acid with quinic acid and has several isomers, among which the most common form is 5-caffeolchinico acid (5-CQA).

Pharmacology and metabolism

The absorption capacity of chlorogenic acid by the human intestine appears to be limited. In studies on very modest rats, up to 8% by weight, the ingested CGA is hydrolyzed into caffeic acid and subsequently absorbed. In some studies conducted on ileostomised subjects, absorption percentages of 30% were recorded for chlorogenic acid and 95% for caffeic acid.

The action of the colon microbiota on unabsorbed chlorogenic acid appears rather important, as it participates in its digestion by releasing caffeic acid and other metabolites available for absorption by the colic mucosa.

The numerous metabolites of caffeic acid, produced and absorbed in the intestine, or at other levels, seem to be responsible for the biological effects of this substance; the most important metabolites include caffeic and dihydrocaffeic acid, hippuric acid, ferulic acid, vanillic acid and benzoic acid.

Indications

Why is chlorogenic acid used? What is it for?

In addition to the generic antioxidant effect, chlorogenic acid could have a modest hypotensive effect; moreover it has shown positive effects in slowing the release of glucose in the blood after a meal, reducing the absorption of sugar in the intestine.

Taken together, these effects could assist body weight loss induced by special nutritional and behavioral interventions (increased physical activity).

The integration with chlorogenic acid could therefore be particularly valuable for subjects suffering from metabolic syndrome.

Property and Effectiveness

What benefit has Chlorogenic Acid shown during the studies?

The most studied health applications of chlorogenic acid concern its hypotensive and blood glucose modulating effects.

Chlorogenic acid also exhibits interesting antioxidant, antibacterial and anti-inflammatory properties.

Some experimentalists attribute to chlorogenic acid also a possible positive effect in supporting mood.

Chlorogenic acid and hypertension

The integration with chlorogenic acid would seem to guarantee a reduction of about 4.5 mmHg for the maximum (systolic) pressure and 3.5 mmg Hg for the minimum pressure. The study with the most encouraging results indicates reductions in the order of 15mmHg for systolic and 5mmHg for diastolic after 12 weeks of treatment with 280mg of chlorogenic acid per day divided into two intakes.

Clinical studies to support these effects are scarce, limited to the Asian population and funded by chlorogenic acid producers. More extensive and independent trials would therefore be desirable

Chlorogenic acid as a hypoglycemic agent

Equally timid is the scientific evidence concerning the ability of chlorogenic acid to improve glucose tolerance, reducing post-prandial glycaemia.

Chlorogenic acid would seem to modify glucose metabolism especially in the intestine, reducing post-prandial glycemic peaks and opposing weight gain induced by a diet rich in sugars.

These evidences have been mainly collected on animal models, while sufficient confirmations in clinical studies are lacking (in the most encouraging one, 1g of chlorogenic acid administered to obese subjects has reduced the blood glucose values recorded after an oral glucose OGTT load on average by 15mg, reducing also insulin levels of −73 pmol / l).

Chlorogenic acid for weight loss

In a clinical study, consumption of coffee enriched in chlorogenic acid led to a 6.9% reduction in glucose absorption; in addition, regular consumption for 12 weeks led to an average weight reduction of 5.4kg in overweight people. Also in this case further investigations are necessary, since in other studies there have been no positive effects on body weight reduction.

Chlorogenic acid as an antioxidant

Chlorogenic acid has shown remarkable antioxidant properties, both in vitro and in vivo. As assessed by the ORAC tests, chlorogenic acid appears to have an antioxidant power comparable to that of caffeic acid, but lower than that of dihydrocaffeic acid.

Other properties

The use of chlorogenic acid as a food additive has been proposed to slow fruit withering after harvesting.

Doses and method of use

How to use chlorogenic acid

It has been estimated that those who consume coffee and other CGA-rich foods regularly consume from 0.5g up to 1g of chlorogenic acid a day; however, coffee roasting could generate compounds that reduce the bioavailability of chlorogenic acid present in the food. Those who do not habitually drink coffee and consume a diet low in fruit and vegetables could also take less than 25mg of CGA per day.

The most widely used intake ranges in the studies cited so far are in the order of 120-300mg of chlorogenic acid per day, distributed in a single or two daily intakes.

These are doses that can be reached simply by following a diet that includes moderate to high doses of foods rich in chlorogenic acid, in particular green coffee extracts, without the need for specific supplements.

Side effects

The use of chlorogenic acid is generally safe and well tolerated.

Only a small percentage of the chlorogenic acid taken with the diet is absorbed; this peculiarity has been related to the laxative effect produced by excessive consumption of fruits - such as prunes - which are rich in them.

Chlorogenic acid (as indeed coffee) seems to increase the levels of homocysteine in the blood, which is a known cardiovascular risk factor; however - given the positive effects on blood pressure and glucose uptake - it is unlikely that this increase will result in an actual increase in cardiovascular risk.

Contraindications

When chlorogenic acid should not be used

The use of chlorogenic acid is contraindicated in case of hypersensitivity to the active ingredient; in the literature there are reports of allergic reactions to green coffee and related extracts, but they do not appear to be attributable to chlorogenic acid.