Licorice Flavonoid Oil - More Muscle, Less Fat in 16-Week RCT W/ Human Subjects W/ Only 300 mg of LFO per Day

I know this will disappoint you, but as of now, it seems as if licorice would help you burn the invisible visceral fat, only. That's healthy(-ier) than subcutaneous fat loss, but probably not how you get from lean 15% to ripped 5% body fat.

In the fitness industry, licorice doesn't have a good reputation. While many report astonishing benefits of licorice extract when they recover from stimulant abuse, everyone appears to be afraid of their potential detrimental effects on testosterone; effects that are everything but well-proven (all studies from a single group of scientists, for example, i.e. Armanini, 1999, 2002, 2003 & 2004 and even the latter admit that their initial "results were not confirmed in another study, where the same amounts of licorice did not decrease salivary testosterone values" (Armanini, 2002)... For people with heart problems, the pro-cortisol effect may be an issue and many of the traditional uses, e.g. to reduce abnormal levels of the hormone prolactin, high cholesterol or cramping are likewise only supported by insufficient evidence.

If you want to mess with your cortisol rhythm overtraining is exactly what you "need"!

Heart Rate Variablity (HRV)

ABEL Sports Test + More

Overtraining & Undereating

Calculate your Energy Intake!

Take Control of 'ur Cortisol

Reinvent Your Training!

The reason Tetsu Kinoshita et al.'s latest study still made the SuppVersity "cut". Why's that? Well, firstly, the aforementioned lack of certainty is rather a reason than an argument against addressing recent licorice research. Secondly, Kinoshita's study is one of the few adequately powered human studies we have. And thirdly, scientists have been dabbling with the idea to use licorice to reduce visceral fat accumulation and improve blood glucose management has gotten some attention, anyway.

In the study at hand, all participants were undergoing rehabilitation treatment for knee osteoarthritis. Overall, fifty patients (7 males and 43 females, 54-90 years), none of which had sarcopenia or other health issues besides their knee osteoarthritis.

"The 50 participants were divided into either the LFO (n=26) or placebo (n=24) group by block randomization within the strata of sex, age, and muscle mass in agreement with an SAS program survey-select procedure. [...] Both of the participants and physical therapists were blinded to the results of random allocation. The LFO group consumed capsules containing 300mg of LFO per day after meals for 16 weeks. The placebo group consumed placebo capsules daily for 16 weeks. Participants were directed not to change their lifestyles during this trial, and [the scientists] confirmed this by monitoring their daily study diaries. All participants undertook nearly the same type of mild exercise, with eight participants of the LFO group and ten of the placebo group using ergometer exercise and the other participants undertaking even milder exercise. Between the groups, there was no significant difference in the intensity of their exercise" (Kinoshita, 2016).

Statistical analysis was performed for each measurement at five time points (week 0 = baseline, week 4, week 8, week 12, and week 16) during the intervention period.

Figure 1: Changes in body composition (LFO = black; PLA = white circles) as assessed with DXA and CT scans over the 16-week study on 300mg/day of licorice flavonoid oil in otherwise healthy subjects with osteoarthritis (Kinoshita. 2016)

Additionally, the results were subjected to a stratification analysis in which the participants divided into older participants (aged 75 and older | n=24; LFO 13, placebo 11) and younger participants (aged under 75 | n=24; LFO 12, placebo 11) to investigate whether the effects of LFO would differ
between the two age groups; and, for the osteoarthritis severity and the trunk fat there was an age effect with potential implications for the practical usefulness of LFO:

• 

  Table 1: Relative percentage of volatile compounds in licorice species root essential oils using gas chromatorgraphy–flame ionization detection measurements (n=3 | Quirós-Sauceda. 2016)

  the osteoarthritis score decreased age-dependently with significant reductions only in the young(er) subjects,
• the trunk fat percentage decreased sign. only in the older subjects (p = 0.04), while the effect in the younger individuals was there, but (potentially due to the lower # of subjects) non-significant (p = 0.08)

Ah, and no: There were no side effects. I have to admit that the study population is not exactly full of people who would note that their libido is dropping or any other low T symptoms begin to surface, but the fact that the authors didn't observe any other of the often-heard side-effects (increased blood pressure, lowered potassium, etc.) is still a relevant information.

Table 2: In vivo biological functions of compounds in licorice (Kao. 2014).

Since we don't know for sure which of the bioactive substances in licorice is to blame for the purported anti-testosterone effect, it is yet not even clear if this / these substance(s) can be found in sign. dosages in the average licorice oil.

For the same reason(s), it's yet not just difficult to assess the potential side effects. It's likewise difficult to predict potential additive bonuses. Let's take Licochalcone-A, for example. It's a flavonoid isolated from licorice root (Glycyrrhiza glabra) with potent anti-prostate cancer effects (Fu, 2004). Or, the anti h. pylori (and thus anti-gut cancer) effect of the sweet licorice root (Fukai, 2002). And the list of these health benefits is, as Table 2 goes to show you, long.  

Figure 2: Changes in body composition in 56 males, 28 females after 8 weeks of different doses of LFO, namely 300 mg, 600 mg and 900 mg; total body fat = DXA data visceral fat = CT scan (Tominaga, 2009).

So what? The study at hand, may be the first one that combined licorice with a physical exercise component, the results are yet consistent with previous studies which likewise found decreasing body fat levels (Tominaga, 2006, 2009, 2014 | see Figure 2) - observations of which Kinoshita et al. rightly point out that their sum indeed "suggests a general effect of the supplementation" (Kinoshita, 2016) that occurs in both Asian and US subjects (cf. results in Tominaga, 2014, a study with US participants). In contrast to age which appears to have at least a small effect, race does therefore not appear to affect the efficacy of licorice flavonoid oil as body composition modulator | Comment!

References:

• Armanini, Decio, Guglielmo Bonanni, and Mario Palermo. "Reduction of serum testosterone in men by licorice." New England Journal of Medicine 341.15 (1999): 1158-1158.
• Armanini, D., et al. "History of the endocrine effects of licorice." Experimental and clinical endocrinology & diabetes 110.06 (2002): 257-261.
• Armanini, D., et al. "Licorice consumption and serum testosterone in healthy man." Experimental and clinical endocrinology & diabetes 111.06 (2003): 341-343.
• Armanini, Decio, et al. "Licorice reduces serum testosterone in healthy women." Steroids 69.11 (2004): 763-766.
• Fu, Yue, et al. "Licochalcone-A, a novel flavonoid isolated from licorice root (Glycyrrhiza glabra), causes G2 and late-G1 arrests in androgen-independent PC-3 prostate cancer cells." Biochemical and biophysical research communications 322.1 (2004): 263-270.
• Fukai, Toshio, et al. "Anti-Helicobacter pylori flavonoids from licorice extract." Life sciences 71.12 (2002): 1449-1463.
• Kao, Tzu-Chien, Chi-Hao Wu, and Gow-Chin Yen. "Bioactivity and potential health benefits of licorice." Journal of agricultural and food chemistry 62.3 (2014): 542-553.
• Kinoshita, Tetsu, et al. "The Effects of Licorice Flavonoid Oil on Increasing Muscle Mass: A Randomized, Double‐Blind, Placebo‐Controlled Trial." Journal of the Science of Food and Agriculture (2016).
• Quirós-Sauceda, A. E., et al. "Licorice (Glycyrrhiza glabra Linn.) Oils." (2016).
• Tominaga, Yuji, et al. "Licorice flavonoid oil effects body weight loss by reduction of body fat mass in overweight subjects." Journal of health science 52.6 (2006): 672-683.
• Tominaga, Yuji, et al. "Licorice flavonoid oil reduces total body fat and visceral fat in overweight subjects: A randomized, double-blind, placebo-controlled study." Obesity Research & Clinical Practice 3.3 (2009): 169-178.
• Tominaga, Yuji, et al. "Effect of licorice flavonoid oil on visceral fat in obese subjects in the United States." Nutrafoods 13.1 (2014): 35-43.