Guarana and Weight Loss Guarana and Weight Loss

Traditional Uses

Guaraná is a rainforest vine that was domesticated in the Amazon for its caffeine-rich fruits.

Guarana plants are commercially cultivated exclusively in Brazil to supply the national carbonated soft-drink industry and natural product stores around the world.

Guaraná has long been used as a tonic and to treat various disorders in Brazil and abroad, and became a national soda in Brazil.

In the last two decades, guaraná has been a main ingredient in various ‘sports’ and energy drinks.

Guarana

Chemical Structure: biologically active component is the stimulant is guaranine. It has the same structure as caffeine.

Dosage: 180-450 mg/d (about 2-4 cups of brewed coffee, or 500-1000 mg guarana seed extract.)

Sources: Energy drinks, thermogenic weight-loss supplements, some sports drinks.

Media and Marketing Claims

Promotes positive mood

Supports mental performance

Suppresses appetite

Increases fat-burning

Safety

Decreases platelet aggregation and thromboxane synthesis, possibly increasing risk of bleeding when taken with: aspirin, anticoagulants such as Warfarin, and platelet inhibitors such as Ticlopidine (Ticlid), Clopidogrel (Plavix).

Do not combine with MAO-inhibitors

Symptoms of overdose: vomiting, abdominal pain, difficulty urinating, cramps, or spasms.

-Heartburn-Upset stomach-Loss of appetite-Constipation -Diarrhea-Nervousness-Irritability-Anxiety-Sleeplessness-Irregular heartbeats-Headache

Side Effects

- Heart problems

- High blood pressure

- Kidney disease

- An overactive thyroid (hyperthyroidism)

- Pregnant and breast feeding women are advised not to take guarana.

People who shouldn’t take them

Article 1• Objective: This study examined the acute effects of ingesting a widely used commercial formula

containing extracts of bitter orange, green tea and guarana (Gx) on the metabolic rate and substrate utilization in overweight, adult males at rest (study 1) and during treadmill walking (study 2).

• Subjects: Two different groups of 10 sedentary males with more than 20% body fat participated in studies 1 and 2.

• Design: In each study, subjects participated in two experimental trials during which they were given two 500mg capsules containing either Gx or a placebo (P) in a counterbalanced double-blind manner. Doses of the main active ingredients were 6mg of synephrine, 150mg caffeine and 150mg catechin polyphenols.

• Measurements: In study 1, subjects completed 7 h supine rest with baseline measures taken during the first hour, with expired gases, blood pressure, heart rate and venous blood being collected every 30 min for the remaining 6 h following ingestion of Gx or P. In study 2, subjects exercised for 60 min at 60% heart rate reserve following ingestion of Gx or P 1 h previously. Venous blood samples were collected twice at rest and at 5, 10, 15, 20, 30, 40, 50 and 60 min, with expired gas measurements taken at 4, 9, 14, 19, 29, 39, 49 and 59 min. In both studies, venous blood was analysed for NEFA, glycerol, glucose and lactate concentrations, while expired gases were used to calculate ATP production from carbohydrate and NEFA, as well as the total substrate utilised.

• Results and conclusion: The results did not show any significant effect of Gx ingestion on total ATP utilisation during 6 h rest orduring 60 min treadmill walking. Changes were observed in the relative contributions of CHO and NEFA oxidation to ATP production in both studies, such that there was an increase in ATP production from CHO and a decrease from NEFA. The increase in CHO oxidation was shown to be as high as 30% at rest

Article 2

International Journal of Obesity & Related Metabolic Disorders; Mar2001, Vol. 25 Issue 3, p316, 9p

OBJECTIVE: To examine in overweight humans the short-term safety and efficacy for weight loss of an herbal supplement containing Ma Huang, Guarana and other ingredients.

DESIGN: An 8 week randomized, double-blind placebo controlled study of a herbal dietary supplement (72 mg/day ephedrine alkaloids and 240 mg/day caffeine).

SUBJECTS: Overweight men and women (body mass index, ≥ 29 and ≤ 35 kg/m²). MEASUREMENTS: The primary outcome variable was body weight change. Secondary variables included anthropometric, metabolic and cardiovascular changes.

RESULTS: Sixty-seven subjects were randomized to either placebo (n = 32) or active Ma Huang/Guarana (n = 35). Twenty-four subjects in each group completed the study. Active treatment produced significantly (P< 0.006) greater loss of weight (X ± s.d.,-4.0 ± 3.4kg) and fat (-2.1 ± 3.0% fat) over the 8-week treatment period than did placebo (-0.8 ± 2.4kg and 0.2 ± 2.3% fat). Active treatment also produced greater reductions in hip circumference and serum triglyceride levels. Eight of the 35 actively treated subjects (23%) and none of the 32 placebo-treated control subjects withdrew from the protocol because of potential treatment-related effects. Dry mouth, insomnia and headache were the adverse symptoms reported most frequently by the herbal vs placebo group at the final evaluation visit.

CONCLUSIONS: This herbal mixture of Ma Huang and Guarana effectively promoted short-term weight and fat loss. Safety with long-term use requires further investigation

Questions

What, if any, beverages do you consume containing guarana?

For what reasons would you encourage or discourage people from drinking beverages or supplements that contain guarana?