Ciltep by Natural Stacks is a nootropic "stack," or combination of supplements, designed to increase your ability to focus, concentrate, and remain alert. It's a fairly simple supplement, basing its efficacy on only a couple of ingredients.
Ciltep includes vitamin B-6 for energy and focus, in the form of pyridoxal-5-phosphate. It provides 250% of your recommended daily intake in three capsules, which is the recommended dosage, so it should be more than enough to cover any dietary deficiencies—the real question is if larger amounts like this have cognitive enhancing properties.
The supplement also includes two amino acids, phenylalanine and acetyl-L-carnitine. These are provided at levels of 500 and 750 mg, respectively.
Finally, Ciltep uses two herbal extracts which are supposed to boost alertness and concentration. These are coleus forskohlii extract—also known as forskolin—and artichoke extract (cynara scolymus), which is included for its caffeoyiquinic acid content. As the name might suggest, caffeoylquinic acids are a category of compounds that are found in coffee beans. Some health experts suspect that these compounds contribute to the positive health benefits of consuming caffeine (1). If you could isolate them and gain the benefits, you wouldn't have to deal with some of the negatives of caffeine consumption.
While there haven't been any direct clinical trials of the efficacy of Ciltep as a whole, we can analyze its constituent ingredients to see what kind of cognitive benefits they could bring about.
Vitamin B6 is thought to be an important factor for brain function. A 1996 study by researchers at the Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University examined 70 elderly male subjects, testing them for their cognitive functioning and comparing the data to blood levels of various B vitamins (2). The researchers found that the men who had higher concentrations of vitamin B6 in their blood tended to do better on two batteries of tests that measured memory, but that vitamin B6 did not affect spatial reasoning. This suggests that vitamin B6 could be a memory-booster.
Not all evidence on vitamin B6 is positive. A review study published in 2007 by Ethan Balk, Gowri Raman, and Athina Tatsioni in the Archives of Internal Medicine looked over several scientific studies on direct B-vitamin supplementation and analyzed how it affected cognitive function (3). After the data analysis was complete, Balk, Raman, and Tatsioni found no evidence that supplementing B vitamins had a beneficial effect on brain functioning.
When it comes to the amino acid phenylalanine, the evidence is similarly scant. While phenylalanine is known to be a precursor to L-DOPA and dopamine, which are very important neurotransmitter compounds, there is no research connecting phenylalanine supplementation to better cognitive performance.
However, acetyl-L-carnitine (technically a metabolized form of an amino acid) does have some evidence for its efficacy. It's been investigated as a treatment for Alzheimer's disease: in a 2003 study published in the scientific journal International Clinical Psychopharmacology, researchers tested various dosages of acetyl-L-carnitine in a group of patients with early Alzheimer's disease (4). They found that the acetyl-L-carnitine had a substantial effect on clinical measurements of cognitive function and direct psychometric tests.
Similarly, a year-long evaluation of acetyl-L-carnitine in the treatment of Alzheimer's disease published in 1991 found that the supplement had a slower rate of cognitive deterioration in almost all of the outcomes the study evaluated (5).
When it comes to the herbal ingredients in Ciltep, the evidence is less compelling. While forskolin is well-researched as a metabolism-boosting and weight-loss inducing supplement, its efficacy for improving cognitive function is unproven. They hypothesis seems to be that, if forskolin boosts your metabolism, it will also make you more alert. This is how caffeine works. But there isn't enough evidence to draw that conclusion just yet.
The caffeoylquinic acids contained in the artichoke extract have been studied for their neuroprotective effects—they seem to protect your brain from the kind of damage associated with the malformed proteins implicated in causing the progressive degeneration in neurological disorders like Alzheimer's disease (6). That being said, there's no research on their direct cognitive benefits. Yes, they might be able to slow the progress of neurodegeneration, but do they actually boost brain power? It's hard to say.
Fortunately, the side effect profile of Ciltep is likely to be mild—it is not chock-full of untested or unproven ingredients. Forskolin is worth a closer look, since weight loss supplements (with their metabolism-modifying behavior) are often risky, but so far, there are no reports of negative effects from forskolin. A 2005 scientific study on forskolin for weight loss noted no adverse effects (7).
Surprisingly, vitamin B6 is associated with mild negative side effects when taken in large doses. It can cause transient tingling or numbness in your skin, though according to Harvard Health, this is usually only observed in doses of 100 mg or more—Ciltep only has 5 mg per serving (8).
There is a rare genetic disorder called phenylketonuria which prevents people from being able to process phenylalanine. In this case you should definitely avoid Ciltep, as well as all other sources of that amino acid.
The Bottom Line
Ciltep is more of a long-term cognitive functioning supplement. It doesn't have any ingredients with strong evidence for an immediate effect on your brain functioning, but several of its ingredients do appear to have neuroprotective effects. If you are getting older and want something in addition to exercise (mental and physical!) and a good diet to ensure brain health in your golden years, Ciltep might be worth a closer look. If you're a college student cramming for a big test, or a consultant working on a big project, it's probably not what you want.