“No”, it’s not #inMice, but “yes”, it’s sponsored research by the Kao Corporation about whose “High Octane Coffee” I’ve written last year, already. In their latest paper the Japanese authors of the paper (Watanabe 2019) investigated the effects of daily consumption of coffee enriched in chlorogenic acids (CGA) on abdominal fat area in a 12-wk randomized, double-blind, parallel controlled trial w/ healthy, overweight men and women (n = 150, body mass index (BMI) ≥25 to
The subjects were recruited from among men and women (it’s a bit suspicious that the authors don’t report the sex-ratio in the FT, though) residing in the Hokkaido area in Japan.
Must read: “Buying, Roasting, Grinding, Brewing: Coffee 101 — How to Do it to Get the Optimal Stimulant and/or Health Effects” | read the SuppVersity Classic
The inclusion criteria were as follows: body mass index #BMI ≥ 25 to <30 kg/m² (=obesity class 1; often just labeled as ‘overweight’); visceral fat area #VFA ≥ 80 cm² (rather high levels of pro-inflammatory organ fat); age 20 to <65 years.
- The exclusion criteria were as follows: allergy to drugs or food; current disease or history of severe disease related to the liver, kidney, heart, lungs, or digestive system; systolic blood pressure <90 mmHg or ≥160 mmHg; heavy drinking (>30 g alcohol/day) or smoking; extremely irregular dietary habits; and shift work or late-night work.
The scientists also (pre-)calculated the sample size based on data from the previously discussed paper assessing the effects of CGA-containing pre-packed coffee beverages on overweight subjects:
“The number of subjects (71 subjects/group) was calculated on the basis of the assumption of a change in VFA (ΔVFA) of 5 cm², standard deviation of 15 cm², significance level of α = 0.05, and power (1 − β) = 0.80. To account for the potential for dropouts, the target number of subjects was set at 150” (Watanabe 2019).
Moreover, the trial was registered at www.umin.ac.jp/ctr/ as UMIN000036011. Now, none of these parameters guarantee that the study is unbiased, objective, practically relevant, etc. but trial registration, power calculations, inclusion of only “healthy” overweight subjects, a study duration of 12 weeks, dietary control that shows a lack of differences between the two study groups (see Table 1) are indicators of study quality and real-world relevance of a study you will certainly see being referred to in adds for the instant coffee I previously labeled as “high octane coffee”.
|Composition and nutritional content of test coffee. CGA—chlorogenic acid (from Watanabe 2019); note the difference in energy content (and carbs 😯 that would suggest weight loss advantages for the control coffee)|
What’s in the high octane coffee? From the Coffee 101 on SuppVersity.com you know that you can control the CGA content of your coffee by buying, roasting, grinding, and brewing your coffee ‘the right way’. Even with your “greenest” roast and minimal processing, though, you’re unlikely to squeeze out >300mg of chlorogenic acid #CGA as a “minimum guaranteed amount per serving” while simultaneously decreasing the oxidant components through a previously described and tested adsorptive treatment with activated carbon (Ochiai 2009; Kajikawa 2019 | both studies show benefits for CV health).
In general, the coffee doesn’t differ much from your average instant coffee which is likewise prepared after spray-drying but contains less than 1/10th of the amount of CGA in Kao’s ‘high octane coffee’ – it’s thus quite credible that the scientists claim that their CGA coffee with 369 mg of CGA/serving and the 35 mg of CGA/serving control coffee were “indistinguishable”.
Only a single serving did the trick! All instant coffee was consumed (only) once daily for 12 weeks, with four-week pre- and post-observation periods. Abdominal fat area and anthropometric measurements were analyzed at baseline and at four, eight, and 12 weeks, and 142 subjects completed the study – that’s pretty much in line with what the power-analysis suggested to be necessary.
|Table 1: Dietary intake at 0 and 12 weeks in control and CGA groups. Data are presented as mean ± SD. Control (n = 70), CGA (n = 72). Group represents p-value in effect of group. Time represents p-value in effect of time. Group × time represents p-value in effect of group × time interaction – all analyses by repeated-measures ANOVA (Watanabe 2019).|
In conjunction with the absence of dietary changes illustrated in Table 1 (obviously the study wasn’t as controlled as a metabolic ward study), the weight … ah, I should say fat loss effects of the elevated CGA intake was quite impressive: The absolute values and changes from baseline in visceral (#VFA), subcutaneous (#SFA), and total (#TFA) fat area are shown in Table 2.
|Table 2: Changes in physical assessment parameters in control and CGA groups (|
As the authors point out, “[t]he CGA group exhibited a significant decrease relative to the control group at 12 weeks by t-test in VFA (CGA group: −9.0 cm², control group: −1.0 cm², p = 0.025) and changes in VFA from baseline, i.e., ΔVFA (p Watanabe 2019). In plain English:
Even in the absence of a meaningful conscious (or at least detectable) reduction in energy intake, a single cup of the high octane coffee shed 9.0 cm² visceral, i.e. metabolically particularly unhealthy fat – that’s 9x more than the obviously non-significant -1.0 cm² the subjects in the control group dropped on their 12-week journey.
|Is there such a thing as an optimal caffeine:taurine ratio? Plus MORE!|
How high should/can you probably go? You will remember the 25 cups a day study discussed in the SuppVersity News in early June. With those 25 cups you’d get 2-3 times the amount of CGA in the Kao Coffee – without, and that’s what the coverage of the pertinent study by Fung et al. (2019) seems to suggest increasing your risk of heart disease… Bad news for coffee junkies, though, the statistical analysis compared self-reported coffee consumption habits between only three groups, ie ≤1, 1–3, >3 cups/day – with the lowest group used as the reference in the analyses, the actual study doesn’t tell us anything about the health effects of drinking 25 cups of coffee per day (plus: subjects who consumed even mere were excluded from the analysis).
In contrast to what the FT of the study seems to suggest (there it says: “[t]he change in the TFA from baseline (ΔTFA) was significantly smaller [sic!] in the CGA group compared with the control group at 12 weeks” | Watanabe 2019), the significant group × time interaction (p = 0.001) and the group effect (p Table 2 #TFA) clearly favored the CGA coffee of which I am not even sure that it’s already on the market, as well.
|Figure 1: My plot of the absolute visceral (#VFA) and subcutaneous (#SFA) development in Watanabe 2019 shows: inter-group comparisons as I present them in the headline and relative changes as presented in the arrow an easily mislead you to overestimate the practical (in mirror) significance of the results.|
Against that background, it doesn’t come as a surprise that the CGA subjects also lost more body weight, BMI, and inches off their waists (#BW, #BMI, #WC | p = 0.025, p = 0.015, p = 0.001, respectively); a result the authors provide some additional substance to, when they write…
“[…] Δweight, ΔBMI, and ΔWC in the CGA group had a significant group × time interaction compared with the control group by repeated-measures ANOVA (p = 0.010, p = 0.006, and p = 0.012, respectively). Moreover, a significant group effect was detected for ΔWC (p = 0.023); i.e., WC in the CGA group was significantly decreased (0.8 cm) relative to that in the control group at 12 weeks (p = 0.001, t-test). With respect to Δweight and ΔBMI, the CGA group showed a decreasing trend relative to the control group (p = 0.080 and p = 0.071, respectively)” (Watanabe 2019).
What may be surprising and certainly not irrelevant for the discussion of the results in terms of the number of holes the subjects had to tighten their belts. With an average reduction in waist circumference of only 0.7 cm = 0.28 inches, they went from a somewhat tight, to a marginally more comfortable fit in their 36″ jeans, which should remind you of the “but” in the headline.
- Fung, Kenneth, et al. “9 Effect of coffee consumption on arterial stiffness from UK biobank imaging study.” (2019): A8-A10.
- Marventano, Stefano, et al. “Coffee and tea consumption in relation with non-alcoholic fatty liver and metabolic syndrome: A systematic review and meta-analysis of observational studies.” Clinical nutrition 35.6 (2016): 1269-1281.
- Mure, Kanae, et al. “Habitual coffee consumption inversely associated with metabolic syndrome-related biomarkers involving adiponectin.” Nutrition 29.7-8 (2013): 982-987.
- Kajikawa, Masato, et al. “Coffee with a high content of chlorogenic acids and low content of hydroxyhydroquinone improves postprandial endothelial dysfunction in patients with borderline and stage 1 hypertension.” European journal of nutrition 58.3 (2019): 989-996.
- Ochiai, Ryuji, et al. “Effects of hydroxyhydroquinone-reduced coffee on vasoreactivity and blood pressure.” Hypertension Research 32.11 (2009): 969.