Phenylalanine comes in several forms as a supplement:
L-phenylalanine is an essential amino acid. It's also found in protein in the foods we eat.
DL-phenylalanine, which contains both the D- and L-forms
Over the years, people have taken tribulus in an attempt to enhance athletic performance and for a wide range of health issues that may include heart and circulatory conditions and sexual issues.
But does it work? Limited studies show it might be helpful in lessening symptoms of angina and in enhancing athletic performance. There have also been some studies that show some benefit to those people with certain sexual problems and infertility.
Other studies are not as convincing. There isn't enough information to tell if tribulus can really make a difference for other health problems.
With a lack of research to draw on, it's not clear what a safe dosage is. Also, quality and active ingredients in supplements may vary widely from maker to maker. This makes it very hard to set a standard dose.
Can you get tribulus naturally from foods?
No. In fact it is unsafe to eat the spine-covered fruit. There have been reports of people getting collapsed lungs from eating it.
Risks. Lab tests on animals link tribulus to problems in fetal development. So stay away from tribulus if you are pregnant or breastfeeding.
Stop using tribulus at least two weeks before surgery to avoid blood sugar control problems.
Also, men should be aware that there are some concerns about possible links between tribulus and prostate problems.
Interactions. There don't appear to be any interactions between tribulus and foods or other herbs and supplements.
But tribulus may interact with certain medications. It may increase the effect of certain heart and blood pressure medicines, such as:
Calcium channel blockers
If you are taking diabetes medications, tribulus might make blood sugar go too low. It may also increase the effect that steroids have on your body.
The FDA does not regulate supplements. Be sure to tell your doctor about any you're taking, even if they're natural. That way, your doctor can check on any potential side effects or interactions with medications, foods, or other herbs and supplements. He or she can let you know if the supplement may be risky for you.