p-Synephrine is a compound derived from citrus aurantium (aka bitter orange, Zhi Shi or sour orange), which are small citrus plants. Synephrine gained popularity as a fat-burning agent following the ephedra ban as both share a similar chemical structure. Though they share chemical similarities, synephrine has many differing biological properties, the most intriguing of which is that it elevates metabolism without increasing blood pressure and heart rate. Synephrine binds to β-3 receptors on fat cells that enhance fat release and fat burning. As well, it has stimulant effects similar to that of caffeine, thus increasing focus, energy and appetite suppression.
The latest research published in the British Journal of Clinical Pharmacology indicates that taking a single high dose (3 mg/kg body weight) of synerphrine preworkout can immediately boost your peak rate of fat burning (during cardio) by almost 40%. Interestingly, resting metabolic rate was unchanged with acute synerphrine supplementation, as was total caloric expenditure during exercise. Instead, synephrine promoted a significant shift in metabolism— from carbohydrate utilization to fat burning—with maximum fat burning occurring at low to moderate exercise intensity (50% VO2max).
ACTION POINT: This study and others used single 3 mg/kg synephrine dosing without adverse health consequences; however, the authors reported no change in blood pressure or heart rate despite using a dose that is about 10x what is normally promoted. A study published in 2013 evaluated the safety of synerphrine supplementation and reported that 98 mg of synephrine daily produced no safety concerns. So, it seems that this stuff is safe at higher doses than traditionally recommended.
In an effort to maximize fat burning, especially if you are a proponent of low to moderate intensity fat burning cardio sessions, we recommend a single daily (starting) dose of 30-60 mg, taken 30-60 minutes before or doing cardio. If you feel the need (and based on tolerance), slowly build your dose to 3 mg/kg over the course of several weeks.
Gutiérrez-Hellín J, Coso JD. Acute p-synephrine ingestion increases fat oxidation rate during exercise. Br J Clin Pharmacol. 2016 Apr 1. doi: 10.1111/bcp.12952. [Epub ahead of print]
Kaats GR, Miller H, Preuss HG, Stohs SJ. A 60day double-blind, placebo-controlled safety study involving Citrus aurantium (bitter orange) extract. Food Chem Toxicol. 2013 May;55:358-62.
Beetroot extract is a reddish pink colored powder made from the roots of beets (Beta Vulgaris) and provides a very rich source of dietary nitrates. Dietary nitrates increase nitric oxide (NO) levels in the body– NO is used by the endothelium to trigger relaxation of blood vessels and promote increased blood flow. Beyond blood flow benefits, research shows that taking beetroot extract before training enhances muscle contractile efficiency, meaning you can push more weight with less energy cost.
A most recent study published in the Journal of Strength & Conditioning Research provides more data supporting the use of beetroot extract prior to training. In this randomized, double blinded, and placebo-controlled study, the effects a nitrate supplement on bench press performance were evaluated in physically active resistance-trained males. The researchers reported that, compared to placebo, nitrate supplementation resulted in 23% more repetitions completed to failure and a 19% increase in total weight lifted per 3 set bench press session.
ACTION POINT: As always, we recommend taking 500-750 mg of high nitrate standardized beetroot extract, 30-60 minutes before training.
Mosher S, Sparks SA, Williams E, Bentley DJ, Mc Naughton LR. Ingestion of a nitric oxide enhancing supplement improves resistance exercise performance. J Strength Cond Res. 2016 Apr 2. [Epub ahead of print]