Diet pills have been a topic of controversy since the 1960s when prescription or over-the-counter amphetamines became widely available for the purpose of weight loss.
Although the drugs were widely effective at suppressing appetite, patients began to complain of rapid heartbeats and unpredictable mood swings. Doctors also began to notice patients’ blood pressure elevating to dangerous levels.
Since that time, there have been hundreds of prescription weight loss drugs introduced to the public and hundreds of recalls due to dangerous side effects. Many of these drugs, although containing different ingredients, have been associated with the same health risks, including high blood pressure, severe heart damage, kidney damage and stroke.
In the mid-1990s, there was an explosion of all-natural, over-the-counter, weight loss pills. With people feeling safe in the terms used to describe these pills, the over-the-counter diet pill sales peaked for several years. Studies done on many of these pills have shown they too can cause serious health problems regardless of being natural.
Then, in 2004, the FDA banned ephedra, which is an all-natural substance used in many popular weight loss pills. The ban was issued after 155 people died while on the supplement. Many diet pill manufactures are now looking for new suppressants and have turned to citrus aurantium.
Citrus aurantium, also known as bitter orange, is believed to have similar effects as ephedra and is now one of the most widely used dietary supplements. Citrus aurantium contains a compound called synephrine that, like ephedra, stimulates the central nervous system and may boost metabolism.
Manufacturers claim citrus aurantium safely boosts energy while suppressing appetite and increasing metabolic rate and caloric expenditure. However, Dr. Christine Haller, a clinical pharmacologist at the University of California Medical Center in San Francisco, questioned the safety of the substance in two supplements, Advantra Z and Xenadrine EFX, in a 2005 study.
For the study, Dr. Haller and colleagues examined participants randomly given Advantra Z, Xenadrine EFX, or a placebo on three separate occasions. They measured participants’ short-term cardiovascular responses and found compared with the placebo condition, Xenadrine EFX boosted blood pressure up to 10 points, while Advantra Z did not appear to affect blood pressure.
Both products elevated heart rates for as long as six hours after taking the supplement. Dr. Haller says the fact that Advantra Z contains only bitter orange extract as its active ingredient suggests it alone does not raise blood pressure; rather, the mixture of bitter orange extract, caffeine and various herbs contained in Xenadrine EFX is what affects blood pressure.