Good news has become scarce in 2020, it feels. So, let’s appreciate the ones we have: A coffee shortage is not in sight. Reason enough for me to write another “latest coffee research”-article. One that turned out to be a chlorogenic acid (#CGA) article because …
well, it’s still 2020, so scientists drink coffee to speed up their warp-speed operations and don’t spend time investigating the effects of the stimulant the world is craving (Think you’re drinking a lot of coffee? Are you a Fin?).
Needless to say that previous research shows (Sinisi 2017) that – coffee, and the previously mentioned polyphenol CGA, can take on respiratory viruses and would thus make a good addition to the warp-speed agenda – cannot be worse than all the b*s* about vitamin D 😉
Chlorogenic acid (5-CQA) content of plant dietary sources (Lu 2020)Review of chlorogenic acid discusses 5-CQA’s including neuroprotective, cardiovascular protective, gastrointestinal protective, renoprotective, hepatoprotective, glucose and lipid metabolism regulatory, and anticarcinogenic effects (Lu 2020 | cf. Figure 2).
The review is very detailed and honestly rather something for science vs. coffee nerds. This, however, turns out to be its strength. After all, you’d probably not have the extensive information about the chlorogenic acid content of non-coffee sources of CGA in a less comprehensive review.
You can find this data in the tabular overview on the right. The values are far lower than those in green, raw coffee beans, but the not so humble purple-orange carrot powder rivals a lightly roasted coffee, be it Arabica (~12 mg/g of beans | 7 minutes of roasting) or Robusta (~14mg/g of beans | 5 minutes of roasting).
I am sure that all of you know the SuppVersity Coffee Brewing 101, right?
Now, most of us don’t eat our coffee powder by the pound. In fact, the #1 way to consume coffee is not Starbucks (yet?), but the good old filtered coffee (learn more about filtered coffee in this older special and how it relates or, rather, doesn’t relate to high cholesterol) Hence, it is important to know how much of the CGA can actually be extracted by common preparation methods and the data in Figure 1 originally collected by Budryn et al. (2009) who probed the effect of different extraction methods on the recovery of chlorogenic acids, caffeine and Maillard reaction products in coffee beans:
Figure 1: 5CGA and total CGA content (total includes all sorts of caffeoylquinic acids, as well as caffeic acid and ferulic acid) of coffee brewed or cooked in and pressurized into 100ml of water (Budryn 2009); if we assume you absorb 100% of the CGA, this means that a cup (237ml) of coffee should yield between 0.72 grams and 0.011 grams (720mg and 11mg) per cup, for water-boiled green (no roast) and dark roast, respectively – not shabby, considering supplements contain 0.1-0.3 g only, no? The values have been calculated based on 100 ml samples that were prepared with 5g of the respective type of coffee. How much of the CGA that is contained in the coffee (which was then dried to analyse it) would finally end up in your blood is still debated, or as the authors of the review argue wrt #bioavailability.”Figure 2: Physiological actions of 5-CQA (Lu 2020).[…]
However, the absorption and bioavailability of 5-CQA are still controversial due to the large interindividual variations in its utilization, metabolism, and excretion in both basic and clinical studies.” (Lu 2020)
Ah, and just in case you already forgot why on earth you’d drink coffee not just for its taste and #theBuzz but also as your #1 chlorogenic acid source (let’s be honest: how many purple-orange carrots have you had today?), I decided to include a nice visual illustration of 5CQA’s physiological actions (Figure 2), which I found in the very same review in the aptly named journal Comprehensive Reviews.
Coffee works instantly, that’s why people love it … and guess what the same goes for the heart-health benefits of CGA! And even a single cup of mildly roasted coffee (total CGA content, i.e. 5CQA + all other forms per 160mg/100ml for arabica and 255mg/100ml) delivers effective doses of CGA. Let’s assume you like it bitter and choose the lightly roasted robusta coffee and pour a regular cup of brewed coffee, that would be 237ml of coffee with ~604mg total CGAs. The type of beans and, even more so, degree of roasting is key. After all, from a dark-roasted arabica coffee, you’ll get only 90mg (note: most cheaper commercially sold coffees are blends), according to the data presented in the previously discussed review (Lu 2020).
It’s not impossible that the 90mg would have a beneficial effect on your cardiovascular system, too, but the lowest dose tested in an international study by Naylor et al. (2020) was 156mg CGA from a green coffee bean extract. The subjects were healthy, normal-weight, and in the age range from 45–65 y (women were post-menopause) and the study seems to confirm what some people won’t believe: Yes, you can have too much coffee – even decaffeinated one.
Figure 3: Flow-mediated dilation in healthy 45–65 y-olds 0-24h after the ingestion of low (302mg) or high (906mg) increases significantly over placebo wit the lower dose, not with the high one (Naylor 2020).In fact, the lowest dosage of decaffeinated green coffee extract (302 mg DGCE, 156.4mg total CGA), was the only one (302, 604, and 906mg were tested) to significantly increase flow-mediated dilation (%FMD) compared to a placebo. Both, the medium and high dose failed to produce consistent (significant benefits) in the 5 female and 16 male subjects in the first 8.5 h, 12 h, and 24 h after product intake.
More doesn’t help more – That’s not unusual for polyphenols. As Naylor et al. point out previous studies on CGA and other polyphenols also observed a nonlinear relation between coffee compounds and FMD, with “several meta-analyses of randomized controlled trials which [finding] that the relation between the doses of different types of polyphenols and FMD follow an inverted U-shape and that high doses of polyphenols [, including those from blueberries, for example (Rodriguez-Mateos 2013), can] have smaller effects on endothelial function than lower doses” (Naylor 2020).. Finally, a previous study testing the effect of purified CGA (5-CQA) at different doses (450 and 900 mg) did not show any significant effect on peak FMD response relative to control although a post hoc analysis found a significant effect on the continuous FMD assessment compared with control at 1 and 5 h, respectively (14).
- If you look at the magnitude of the effect, though, you will realize that the increase, as statistically significant as it may be, amounted to no more than a 1% – So the question is:
How relevant is a small 1% increase in FMD?
How do you even answer this important question? Well, if we look to the left and the right we see studies “similar acute effects on FMD” for purified compounds or extracts from other polyphenol-containing foods such as cocoa, tea, grape, apple, and blueberry. In other words: It’s by no means a prerogative of coffee or its polyphenols. In fact, for cacao flavanols (~200mg | Heiss 2005) FMD increases from 4.5% to 6.9% have been reported, similar improvements were seen with trans-resveratrol (300 mg | Marques 2018), and a single dose of blueberry anthocyanins (160 mg | Rodriguez-Mateos 2019) acutely improved FMD by 1.3% and 1.1%. So, coffee’s CGA is nothing extra-ordinary, here, but what about the more general question: Does 1% even matter?
Yes, it matters: “Every 1% increase in FMD has been associated, in several systematic reviews and meta-analyses, with a 10%–13% lower risk of cardiovascular events” (Naylor 2020).
So, your morning joe, and your afternoon cup will contribute to heart health… also because they contain CGA (and related polyphenols). There are two questions that new research will have to answer: (a) Whether the caffeine in regular coffee may (partly) reverse the effects (Buskemi et al. 2010 would suggest just that, but epidemiological data indicate a net positive effect in form of a J-shaped relation between coffee consumption and the risk of developing CVD, stroke, heart disease, or acute coronary syndromes). And (b) which of the CGA-related polyphenols and their metabolites is eventually the driving force behind the benefits Naylor et al. observed is not yet clear, though, and should – just like the effects of darker roasts with less CGAs as well as the effect of co-administration of caffeine – be investigated in future studies.
Needless to say that someone already cashes in on the purported health benefits of purple (-orange) carrots. I’d still advise against consuming liquid calories – avoid juices and start thinking about smoothies as a meal, not a superfood.Cheers ☕! I have to warn you about your morning Joe’s caffeine content, though. While it seems to contribute to your metabolic (especially liver) health, it seems that it counters and even overcompensates the acute FMD%-improving effect of CGA and other coffee polyphenols, but … it’s certainly better to bridge periods of acute fatigue with a good cup of coffee than with alternatives such as energy drinks or pre-workouts. Ah, and let’s not forget: After having read both items in today’s coffee research update, you know that there’s a non-energizing alternative: purple-orange carrot smoothies as a snack 😋 | Comment on Facebook!
- Budryn, Grażyna, et al. “Effect of different extraction methods on the recovery of chlorogenic acids, caffeine and Maillard reaction products in coffee beans.” European Food Research and Technology 228.6 (2009): 913-922.
- Buscemi, S., et al. “Coffee and endothelial function: a battle between caffeine and antioxidants?.” European journal of clinical nutrition 64.10 (2010): 1242-1243.
- Heiss, Christian, et al. “Acute consumption of flavanol-rich cocoa and the reversal of endothelial dysfunction in smokers.” Journal of the American College of Cardiology 46.7 (2005): 1276-1283.
- Marques, B. C. A. A., et al. “Beneficial effects of acute trans-resveratrol supplementation in treated hypertensive patients with endothelial dysfunction.” Clinical and Experimental Hypertension 40.3 (2018): 218-223.
- Naylor, et al. “Acute dose-response effect of coffee-derived chlorogenic acids on the human vasculature in healthy volunteers: a randomized controlled trial.” Am J Clin Nutr. 2020 Dec 16;nqaa312. doi: 10.1093/ajcn/nqaa312. Online ahead of print.
- Rodriguez-Mateos, Ana, et al. “Intake and time dependence of blueberry flavonoid–induced improvements in vascular function: a randomized, controlled, double-blind, crossover intervention study with mechanistic insights into biological activity.” The American journal of clinical nutrition 98.5 (2013): 1179-1191.
- Rodriguez-Mateos, Ana, et al. “Circulating anthocyanin metabolites mediate vascular benefits of blueberries: insights from randomized controlled trials, metabolomics, and nutrigenomics.” The Journals of Gerontology: Series A 74.7 (2019): 967-976.
- Sinisi, Valentina. “Coffee: A Rich Source of Antimicrobial and Antiviral Compounds.” Clinical Immunology, Endocrine & Metabolic Drugs 4.1 (2017): 19-32.