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What’s So Important About "Discovering" the "New Vitamin, PQQ?
Richard A. Passwater, Ph.D.
The recent news of the "discovery" of a new vitamin called Pyrroloquinoline Quinone (PQQ) was met by many as "Interesting, but so what?" I’d like to share my thoughts with you in this column on what I feel is so important about its "discovery."
My thoughts are still very much the same as when I discussed the "discovery" of PQQ as a nutrient in my December 1989 column. To me, the importance of the "discovery" doesn’t lie so much with the functions of PQQ, which I will discuss briefly, but with the importance of eating a balanced diet supplemented with important nutrients as opposed to relying on supplements first and diet second. A well-balanced diet and appropriate supplements are both extremely important and the absence of either one is detrimental to optimal health.
Fourteen years ago, my article was entitled "New Nutrient Discovery: PQQ." Now PQQ is said to be a vitamin. Who says? Is it now "official" the PQQ is a human vitamin? What is required to be "officially" designated a human vitamin?
Without a disease that can be easily recognized such as pellagra or beriberi, it is difficult to establish beyond doubt that a chemical is a human vitamin. That once was the definition of a vitamin – a deficiency of an organic chemical that produced a disease in humans. Now the accepted definition is an organic chemical that is needed in small quantities from the diet, as the body cannot produce it.
Afterall, it was only with much resistance that the National Food and Nutrition Board and Food and Drug Administration recognized vitamins such as Vitamin E and choline as human vitamins. Vitamin E was not "officially" recognized as essential to humans until 1968 and choline was recognized only as such in 2000. What disease is associated with either one? Perhaps the "establishment" is beginning to realize that the older definition of a vitamin is archaic and needs to be refined to consider optimal health rather than disease conditions.
Perhaps the "establishment" can appreciate more the role of several "conditionally essential" nutrients such as coenzyme Q-10. Should they be re-defined as true vitamins as well?
PQQ has been of interest since the 1960s, and I have been interested in PQQ because of its role in electron transfer and redox (oxidation – reduction reactions). It is an antioxidant and a quinone similar to coenzyme Q-10, but it is not involved in the respiratory chain to produce energy.
Figure 1. The chemical structure of Pyrroloquinoline Quinone (PQQ).
I will repeat the advice I gave in my 1989 column on PQQ. "How important this new nutrient is remains to be seen, but what is important is that a new nutrient has been discovered. Let me put it another way. – the nutrient may not be so important, but the fact that we do not know all of the nutrients yet is very important!
"Until the days comes that we absolutely know that we have identified all human nutrients, we have to be sure to eat a varied diet of whole foods. This, of course, begs the question in logic of how do we know when we know all there is to know? We can debate the philosophical answer, but the practical answer is that we can never be assured when that state of knowledge is reached.
"Any diet that relies heavily on highly processed foods is unlikely to supply optimal amounts of all human nutrients, known and unknown. Optimal health will not come from eating junk food and taking vitamin pills. Of course, taking vitamin pills will bring about better health than just eating the junk food alone.
"OK, so most of us know that we should eat a varied diet of whole foods. The problem is that few of us do. Therefore, some of us will have to try for second best, which is to eat as many whole foods as we can, and then fortify our remaining fractionated (processed) foods with food concentrates and specific supplements. My point here is that food concentrates are important, but they are becoming more and more overlooked as the newer exotic supplements are becoming available."
The newer, exotic supplements are great and certainly have their place, but we still must rely on whole foods and food concentrates to provide us with unknown or yet-to-be-discovered nutrients that are in them. These factors are not yet in dietary supplements.
As examples, a few decades ago, when people took brewers’ yeast, they were also getting the B-complex vitamins and trace minerals that were present, but not yet identified as human nutrients at that time. When they took wheat germ oil, they were also getting vitamin E, octacosanol and omega-3 oils. These food concentrates may also contain other nutrients that are essential to our health but remain unknown at this time. If you eat few whole foods and take specific supplements, you may miss any of these postulated nutrients. However, if a person also incorporates the traditional health food industry staples, he may be getting them.
I repeat what I said in the 1989 PQQ article. "I am hoping that health-conscious persons will continue to seek out whole foods in their natural state, choosing organically grown foods whenever possible. I would like to see a ‘back to basics’ trend with a renewed interest in food concentrates such as lecithin, wheat germ oil, desiccated liver, brewers’ yeast and yogurt. Then to meet individual biochemical and lifestyle needs, people can round out their diets with a wide-range multivitamin, multi-mineral, multi-nutrient supplement, and antioxidants and other specific micronutrients."
I have unsuccessfully chased an unidentified nutrient that I call "Growth Factor G for many years. I "know" that it exists as I can follow it in fractions of food. Synthetic diets containing all known nutrients are inferior to diets in which I add the food fraction that contains this growth factor. There must be many more such unidentified nutrients.
Lecture over, now let’s get back to PQQ. I first became interested in PQQ, not because it was an antioxidant, but because I saw similarities between PQQ and Growth Factor G. However, the symptoms produced by PQQ deficiency were not the same as produced by Growth Factor G deficiency.
PQQ was first researched in the 1960s and was postulated as being potentially an essential nutrient in 1979. Dr. Robert Rucker of the University of California at Davis has been a primary researcher on PQQ for decades. He and his colleagues published a report in Science (Aug 25, 1989) that described the PQQ deficiency symptoms in mice. They noted hair loss, skin fragility, poor collagen cross-linking, hunched postures and retarded growth.
The report in the April 24 issue of Nature by two researchers at the Brain Science Institute in Riken, Japan also noted impaired immunity, reduced fertility and roughened fur [Kasahara and Kato, Nature, 422(6934): 832 (2003)]. Drs. Takaoki Kasahara and Tadafumi Kato have classified PQQ as a new member of the vitamin B complex.
PQQ is found in citrus fruits, kiwi fruit, papaya, parsley, green peppers, green tea, egg yolks and some meats. The researchers favorite source of PQQ is natto, but that won’t become mine. If you are not familiar with natto, it is a pungent Japanese dish of fermented soybeans. It is called thau-nao in Thailand. Natto is prepared by infesting wet soybeans with Bacillus subtilis to produce a mucous-like gooey stringy mess that reeks of ammonia.
The biochemical role for PQQ that qualifies it to be a vitamin is that of a redox cofactor in some enzymes and it must be obtained in the diet as the body apparently can’t produce it. PQQ facilitates one- and two- electron transfers – it is an electron relay. PQQ catalyzes oxidation-reduction processes in the body. PQQ is a cofactor in a family of enzymes called quinoproteins. PQQ is a cofactor in PQQ-dependent dehydrogenase enzyme that is essential for the degradation of the amino acid lysine. This enzyme is also called lysyl oxidase. PQQ is a factor in quinoprotein enzymes that have been recognized as the third redox family following pyridine nucleotide- and flavin-dependent dehydrogenases. The systematic name of one of the enzymes in which PQQ is a cofactor is D-glucose:(PQQ) 1-oxioreductase. A related enzyme is quinate: (PQQ) 5-oxidoreductase. A third is aldehyde dehydrogenase (PQQ)-quinone.
At this stage of research, one really doesn’t need to know too much about PQQ. The important thing is that there are still many new nutrients to be discovered. Keep eating your whole foods and taking your supplements for optimal health.
© 2003 Whole Foods Magazine and Richard A. Passwater, Ph.D.
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