Pyrroloquinoline quinone, or PQQ, is a compound that's been making waves in the world of cognitive health research. Found in small quantities in certain foods, PQQ has caught the attention of health enthusiasts for its possible cognitive benefits. Recent clinical studies have begun to unravel how PQQ might support brain function and improve memory. In this review, you'll learn the science behind PQQ and its effects on memory, examining the evidence from human trials that suggest this compound could play a significant role in cognitive health. Whether you're seeking natural ways to boost your memory or are curious about the latest developments in brain health supplements, understanding PQQ's potential is key to staying informed about cognitive enhancement strategies.
What Is PQQ?
Pyrroloquinoline quinone, better known as PQQ, is a vitamin-like compound discovered in aerobic methylobacterium in 1979 by J.G. Hauge at the University of Oslo in Norway. Through these experiments, it was discovered that PQQ takes part in redox reactions, which make it crucial for the survival of bacteria. Since its discovery, various authorities have proposed that PQQ be considered a new vitamin. However, since no deficiency syndrome in humans is associated with this compound, it is more correct to regard PQQ as vitamin-like.
Several studies have hinted that Pyrroloquinoline quinone may play roles in the following:
- Reducing inflammation
- Immune support
- Skin health
- Maintaining heart health
- Energy and stamina during exercise
- Neuroprotection
- Supporting healthy mood and stress levels
- Mitochondrial health
- Memory
Top Foods That Contain PQQ
Many common foods contain this substance, including but not limited to these.
| Food | Amount (ng/g) |
| Natto (fermented soy) | 61 |
| Papaya | 36.7 |
| Parsley | 34.2 |
| Green tea | 29.6 |
| Green peppers | 28.2 |
| Oolong tea | 27.7 |
| Kiwi | 27.4 |
| Tofu | 24.4 |
| Spinach | 22 |
As you can see, natto tops the list of PQQ-packed foods with 61 ng per gram, followed by papaya, which is a distant second. Spinach, a staple in most homes, is also in the top 10.
Pay special attention that the amounts are listed in nanograms per gram. A nanogram is one billionth of a gram. So, while yes, foods do contain pyrroloquinoline quinone, the natural amounts are far less than the dosages seen in PQQ supplements, which may have 40 mg or more.
Overview of PQQ Research
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PQQ Memory Research
To date, five human clinical trials have linked PQQ supplements to better cognitive function.
Study 1
When researchers evaluated 31 people with mild memory problems, PQQ supplements were shown to raise brain-derived neurotrophic factor (BDNF), an important protein that helps stimulate the growth of new brain cells and prolong the survival of existing neurons, too.
Additionally, BDNF strengthens synapses, the connections between brain cells. This helps neurons transmit information better and helps with information retrieval (memory) and thinking. Studies show higher BDNF levels are associated with improved memory and brain function.
One possible downside to this investigation was that the supplement (Alpha Hope PQQ) contained PPQ and magnesium. Thus, the results may not be the same as those of taking PQQ alone.
Study 2
In another study, researchers gave PQQ to 20 healthy men and women for 12 weeks. Everyone was in their 60s. Compared to placebo pills, supplement takers showed significant increases in hemoglobin and total hemoglobin in the brain's right prefrontal cortex. This portion of the brain plays critical roles in decision-making, problem-solving, and attention span, and emotion regulation.
Interestingly, no increase in hemoglobin was seen in the left prefrontal cortex, which facilitates speech, language, attention, and memory. Improving hemoglobin is intriguing, but unfortunately, the researchers did not perform before and after memory tests to see if the improved oxygen levels translated into real-life results.
Study 3
When researchers pitted PQQ supplements vs. placebo in 64 healthy men and women in their 70s, they reported that the supplement significantly improved composition memory, verbal memory, reaction time, and attention compared to those not taking it. The supplement used in this study was called MnemoPQQ.
Study 4
In this clinical trial involving the BioPQQ brand, the supplement was reported to prevent declines in both attention and working memory compared to people who took placebo pills for 12 weeks. Working memory allows us to retain small amounts of information for short periods. For example, working memory allows you remember where you parked your car while shopping at the mall.
Study 5
Researchers recruited 70 older and younger men and women and gave them PQQ supplements for 12 weeks. These researchers reported that PQQ supplements not only lead to significant improvements in overall memory in both younger and older people, but additionally, in the younger individuals, improvements in central processing speed began to be boosted after just 8 weeks.
PQQ Memory Research Video Review
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PQQ Memory Research Summary
| Study Title | Subjects | Dosage | Results |
| Effect of Dietary Pyrroloquinoline Quinone Disodium Salt on Cognitive Function in Healthy Volunteers: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Study (2021) | 64 healthy men and women in their 70s). 58 completed study. | 21.5 mg PQQ vs. placebo for 12 weeks. Supplement used was called MnemoPQQ | ↑ composite memory, verbal memory reaction time, complex attention, cognitive flexibility, executive function, and motor speed compared to placebo. |
| Pyrroloquinoline quinone disodium salt improves brain function in both younger and older adults (2023) | 70 younger and older men and women (ave. age 29 to 53 yrs). 66 people completed the study. Data analysis was on 65 people. | 20 mg PQQ per day for 12 weeks. Supplement used was called BioPQQ. Supplement taken with water after breakfast. | PQQ ↑overall memory in younger and older adults. In younger, PQQ ↑ processing speed, speed of understanding after 8 weeks. |
| Effect of the Antioxidant Supplement Pyrroloquinoline Quinone Disodium Salt (BioPQQ™) on Cognitive Functions (2016) | 41 healthy men and women (ave. age 58 yrs) | 20 mg BioPQQ vs Placebo for 12 weeks | PQQ appeared to prevent decline in attention and working memory |
| The impact of six-week dihydrogen-pyrroloquinoline quinone supplementation on mitochondrial biomarkers, brain metabolism, and cognition in elderly individuals with mild cognitive impairment: a randomized controlled trial (2024) | 31 older adults (ave age 72/ mostly females) with mild memory problems | Tablets of Alpha Hope PQQ supplement 2x per day, dissolved in 8 oz (250 ml) warm water before breakfast and dinner vs. placebo for 6 weeks. Alpha Hope is a combo of PQQ + molecular hydrogen (20 mg PQQ and 80 mg magnesium). | PQQ significantly ↑ BDNF. No change in placebo. Significant ↑ cerebral oxygenation saturation. PQQ takers showed significant ↑ in being mentally aware. The supplement contained more than PQQ so results may/may not apply to PQQ by itself. Control group had much lower baseline BDNF levels than supplement takers. |
| Effects of Antioxidant Supplements (BioPQQ™) on Cerebral Blood Flow and Oxygen Metabolism in the Prefrontal Cortex (2016) | 20 healthy men & women (ave age ~ 60. | 20 mg BioPQQ vs. placebo 1x /day for 12 weeks. | Significant ↑ in hemoglobin & total hemoglobin in right prefrontal cortex in PQQ takers (but not left side). Significant ↓ in state anxiety in those who already had high stress levels. Researchers did not test memory. |
What Does This Mean? Five Things To Know
Who Conducts the Research?
Most research papers are conducted by companies that make PQQ supplements, and some clinical trials are performed by employees of those companies. This is not necessarily a red flag, but given the results of these trials, it does beg the question of why non-company-sponsored research is not being conducted.
How Long Do The Studies Last?
The longest clinical trials so far have lasted three months (12 weeks). Most investigations do not involve large numbers of people, with the largest study including 64 people.
Does PQQ Help Alzheimer's?
Many memory-related studies involve healthy individuals or those with mild memory impairment. Whether PQQ benefits people with dementia, including Alzheimer's, requires more study.
What PQQ Supplement is Best?
While the best is open to interpretation, the most researched brand is BioPPQ, which is manufactured in Japan by the Mitsubishi Gas Chemical Company. This company makes the supplement and licenses it to other companies to use in their supplement formulations. This brand has at least seven peer-reviewed reviews and clinical trials in both humans and animals. BioPPQ has also been granted Generally Recognized As Safe status by the FDA.
How Much Works?
Most clinical trials involve 20 mg daily, taken soon after a meal. While supplements may contain more than this, no proof exists that taking higher amounts improves cognitive results.