Nicotinamide riboside supplement safely boosts levels of important cell metabolite linked to multiple health benefits

In the first controlled clinical trial of nicotinamide riboside (NR), a newly discovered form of Vitamin B3, researchers have shown that the compound is safe for humans and increases levels of a cell metabolite that is critical for cellular energy production and protection against stress and DNA damage.

Studies in mice have shown that boosting the levels of this cell metabolite--known as NAD+--can produce multiple health benefits, including resistance to weight gain, improved control of blood sugar and cholesterol, reduced nerve damage, and longer lifespan. Levels of NAD+ diminish with age, and it has been suggested that loss of this metabolite may play a role in age-related health decline.

These findings in animal studies have spurred people to take commercially available NR supplements designed to boost NAD+. However, these over-the-counter supplements have not undergone clinical trials to see if they work in people.

The new research, reported Oct. 10 in the journal Nature Communications, was led by Charles Brenner, PhD, professor and Roy J. Carver Chair of Biochemistry at the University of Iowa Carver College of Medicine in collaboration with colleagues at Queens University Belfast and ChromaDex Corp. (NASDAQ: CDXC), which supplied the NR used in the trial. Brenner is a consultant for ChromaDex. He also is co-founder and Chief Scientific Adviser of ProHealthspan, which sells NR supplements under the trade name Tru NIAGEN®.

The human trial involved six men and six women, all healthy. Each participant received single oral doses of 100 mg, 300 mg, or 1,000 mg of NR in a different sequence with a seven-day gap between doses. After each dose, blood and urine samples were collected and analyzed by Brenner's lab to measure various NAD+ metabolites in a process called metabolomics. The trial showed that the NR vitamin increased NAD+ metabolism by amounts directly related to the dose, and there were no serious side effects with any of the doses.

"This trial shows that oral NR safely boosts human NAD+ metabolism," Brenner says. "We are excited because everything we are learning from animal systems indicates that the effectiveness of NR depends on preserving and/or boosting NAD+ and related compounds in the face of metabolic stresses. Because the levels of supplementation in mice that produce beneficial effects are achievable in people, it appears than health benefits of NR will be translatable to humans safely."

The next step will be to study the effect of longer duration NR supplementation on NAD+ metabolism in healthy adults, but Brenner also has plans to test the effects of NR in people with diseases and health conditions, including elevated cholesterol, obesity and diabetes, and people at risk for chemotherapeutic peripheral neuropathy.

Self-study precedes clinical trial

Prior to the formal clinical trial, Brenner conducted a pilot human study - on himself. In 2004, he had discovered that NR is a natural product found in milk and that there is pathway to convert NR to NAD+ in people. More than a decade of research on NR metabolic pathways and health effects in mice and rats had convinced him that NR supplementation had real promise to improve human health and wellness. After consulting with UI's institutional review board, he conducted an experiment in which he took 1 gram of NR once a day for seven days, and his team analyzed blood and urine samples using mass spectrometry. The experiment showed that Brenner's blood NAD+ increased by about 2.7 times. In addition, though he reported immediate sensitivity to flushing with the related compound niacin, he did not experience any side effects taking NR.

The biggest surprise from his metabolomic analysis was an increase in a metabolite called NAAD, which was multiplied by 45 times, from trace levels to amounts in the micromolar range that were easily detectable.

"While this was unexpected, I thought it might be useful," Brenner says. "NAD+ is an abundant metabolite and it is sometimes hard to see the needle move on levels of abundant metabolites. But when you can look at a low-abundance metabolite that goes from undetectable to easily detectable, there is a great signal to noise ratio, meaning that NAAD levels could be a useful biomarker for tracking increases in NAD+ in human trials."

Brenner notes this was a case of bidirectional translational science; having learned something from the initial human experiment, his team was able to return to laboratory mice to explore the unexpected NAAD finding in more detail.

First mice, then men and women

Brenner's mouse study showed that NAAD is formed from NR and confirmed that NAAD levels are a strong biomarker for increased NAD+ metabolism. The experiments also revealed more detail about NAD+ metabolic pathways.

In particular, the researchers compared the ability of all three NAD+ precursor vitamins - NR, niacin, and nicotinamide - to boost NAD+ metabolism and stimulate the activity of certain enzymes, which have been linked to longevity and health benefits. The study showed for the first time that oral NR is superior to nicotinamide, which is better than niacin in terms of the total amount of NAD+ produced at an equivalent dose. NR was also the best of the three in stimulating the activity of sirtuin enzymes. However, in this case, NR was the best at stimulating sirtuin-like activities, followed by niacin, followed by nicotinamide.

The information from the mouse study subsequently helped Brenner's team design the formal clinical trial. In addition to showing that NR boosts NAD+ in humans without adverse effects, the trial confirmed that NAAD is a highly sensitive biomarker of NAD+ supplementation in people.

"Now that we have demonstrated safety in this small clinical trial, we are in a position to find out if the health benefits that we have seen in animals can be reproduced in people," says Brenner, who also is co-director of the Obesity Research and Education Initiative, professor of internal medicine, and a member of the Fraternal Order of Eagles Diabetes Research Center at the UI.

The coenzyme NAD+ plays a main role in aging processes. In mice and roundworm adding the substance can both extend life and postpone the onset of aging processes. New research conducted at the Center for Healthy Aging and the American National Institute of Health shows that this new knowledge will eventually be able to help patients with Alzheimer's and Parkinson's disease.

As we live longer and longer, a lot of people are occupied with their state of health and, not least, quality of life in old age. Therefore, researchers all over the world are trying to understand aging mechanisms, as this knowledge may eventually help to postpone physical aging and extend life. None of the existing explanations of physical aging are able to explain all the biological aspects of human aging.

Substance Bridges Gap

Previous research has shown that a main process in aging is the capacity of the cells to keep our genes, our DNA, more or less intact. However, changes in the cells' power stations, the mitochondria, also affect aging processes. An international team of researchers from the Center for Healthy Aging at the University of Copenhagen and the National Institute of Health in the United States has shown that the substance NAD+ bridges the gap between two main aging theories - repairs to the DNA and poor functioning mitochondria. The results have just been published in the leading journal Cell Metabolism.

'Our new study shows an age-dependent decrease in the level of NAD+, and this decrease is far greater for organisms with early aging and a lack of DNA repairs. We were surprised to see that adding NAD+ postponed both the aging processes of the cells and extended life in worms and in a mouse model', says Professor Vilhelm Bohr from the Center for Healthy Aging and the National Institute of Health.

The researchers have bred mice and roundworm with the illness Ataxia telangiectasia, A-T, for the purpose of the study. In A-T patients the part of the brain that is responsible for coordination gradually degenerates, DNA repairs are lacking, and they experience other symptoms characteristic of early aging.

Adding NAD+ Postpones Aging

'We know from previous studies that a drop in the level of NAD+ results in metabolism errors, neurodegeneration and aging, but the underlying mechanisms remain unclear to us. Our new study stresses that the substance NAD+ plays a main role both in maintaining the health of the cells' power stations and in their capacity for repairing the genes', says Professor Vilhelm Bohr.

The study also indicates that damage to the DNA can result in poor functioning mitochondria, and that this can lead to increasing neurodegeneration in A-T patients. Adding the substance NAD+ can stop the damage to the mitochondria.

Help for Patients in the Future

Even though the researchers have only examined the effect of the substance on model organisms and not administered the substance to patients, they expect to see the same effect in humans, as the cell repair mechanisms are universal for the cells of all living organisms. Understanding the universal mechanisms at cell level is key to understanding human aging and why we become more susceptible to illness as we grow older. Hopefully, this new knowledge will be able to help postpone physical aging processes and prevent illnesses such as Alzheimer's and Parkinson's disease.


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The NAD story took off toward the end of 2013 with a high-profile paper by Harvard's David Sinclair and colleagues. Sinclair, recall, achieved fame in the mid-2000s for research on yeast and mice that suggested the red wine ingredient resveratrol mimics anti-aging effects of calorie restriction. This time his lab made headlines by reporting that the mitochondria in muscles of elderly mice were restored to a youthful state after just a week of injections with NMN (nicotinamide mononucleotide), a molecule that naturally occurs in cells and, like NR, boosts levels of NAD.

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In early February, Elysium Health, a startup cofounded by Sinclair's former mentor, MIT biologist Lenny Guarente, jumped into the NAD game by unveiling another supplement with NR. Dubbed Basis, it's only offered online by the company. Elysium is taking no chances when it comes to scientific credibility. Its website lists a dream team of advising scientists, including five Nobel laureates and other big names such as the Mayo Clinic's Jim Kirkland, a leader in geroscience, and biotech pioneer Lee Hood. I can't remember a startup with more stars in its firmament.

A few days later, ChromaDex reasserted its first-comer status in the NAD game by announcing that it had conducted a clinical trial demonstrating that “a single dose of NR resulted in statistically significant increases” in NAD in humans—the first evidence that supplements could really boost NAD levels in people. (See below)

(ChromaDex also brandishes Nobel credentials: Roger Kornberg, a Stanford professor who won the Chemistry prize in 2006, chairs its scientific advisory board. He’s the son of Nobel laureate Arthur Kornberg, who, ChromaDex proudly notes, was among the first scientists to study NR some 60 years ago.)

The NAD findings tie into the ongoing story about enzymes called sirtuins, which Guarente, Sinclair and other researchers have implicated as key players in conferring the longevity and health benefits of calorie restriction. Resveratrol, the wine ingredient, is thought to rev up one of the sirtuins, SIRT1, which appears to help protect mice on high doses of resveratrol from the ill effects of high-fat diets. A slew of other health benefits have been attributed to SIRT1 activation in hundreds of studies, including several small human trials.

Here's the NAD connection: In 2000, Guarente's lab reported that NAD fuels the activity of sirtuins, including SIRT1—the more NAD there is in cells, the more SIRT1 does beneficial things. One of those things is to induce formation of new mitochondria. NAD can also activate another sirtuin, SIRT3, which is thought to keep mitochondria running smoothly.

The Sinclair group's NAD paper drew attention partly because it showed a novel way that NAD and sirtuins work together. The researchers discovered that cells' nuclei send signals to mitochondria that are needed to maintain their normal operation. SIRT1 helps insure the signals get through. When NAD levels drop, as they do with aging, SIRT1 activity falls off, which in turn makes the crucial signals fade, leading to mitochondrial dysfunction and all the ill effects that go with it.

NAD boosters might work synergistically with supplements like resveratrol to help reinvigorate mitochondria and ward off diseases of aging. Elysium is banking on this potential synergy—its NR-containing supplement includes a resveratrol-like substance called pterostilbene (pronounced tero-STILL-bean), which is found in blueberries and grapes.

Why pterostilbene instead of resveratrol?

While resveratrol has hogged the anti-aging spotlight over the past decade, unsung researchers in places like Oxford, Miss., have quietly shown that pterostilbene is a kind of extra-potent version of resveratrol. The pterostilbene molecule is nearly identical to resveratrol's except for a couple of differences that make it more "bioavailable" (animal studies indicate that about four times as much ingested pterostilbene gets into the bloodstream as resveratrol). Test-tube and rodent studies also suggest that pterostilbene is more potent than resveratrol when it comes to improving brain function, warding off various kinds of cancer and preventing heart disease.

Elysium isn't the only pterostilbene vendor. In fact, ChromaDex also offers pterostilbene for supplements separately from Niagen.

Duchenne is the most common and severe form of muscular dystrophy. Because of this genetic disease, one out of every 3,500 children spends their 12th birthday in a wheelchair. This disorder progressively leads to general paralysis, and most patients die of respiratory failure. The disease is caused by a genetic mutation that prevents a protein required to keep muscle cells intact from being produced. While most research focuses on repairing the defective gene, researchers at EPFL have come up with a different strategy. As part of their work on nutrition and aging, they discovered that large doses of a vitamin called nicotinamide riboside were remarkably effective in countering the progress of the disease in animals. Their work has been published in Science Translational Medicine.

Patients suffering from Duchenne muscular dystrophy are unable to produce dystrophin. This protein is mainly responsible for connecting the various parts of muscle cells; without it, the cells cannot deform correctly. As a result, cell movement mechanically triggers an inflammatory response, which in turn gradually destroys the muscles.

A highly damaging second cycle

Johan Auwerx's team showed that the disease leads to a second cycle of events inside the cells, a series of reactions that exacerbate the disease's damaging effects.

Several processes are at work in the second cycle. First, the 'primary' inflammation overactivates a certain gene, which then consumes a large quantity of an essential component called NAD+.

This causes a shortage of NAD+ within the cell. But this component acts as a fuel for the powerhouse of cells, the mitochondria, which are especially important in muscle tissue. The NAD+ deficiency therefore weakens the muscle, an effect similar to that of mitochondrial deficiency in older people.

Yet the consequences are even worse than they appear. Deprived of energy, the dysfunctional mitochondria aggravate the inflammation that causes muscle loss. So much for what could have initially appeared to be just a minor side effect of the disease.

Reversing course with a vitamin: nicotinamide riboside successfully tested on animals

What if it were possible to reduce muscle inflammation - and thus muscle loss - by providing the worn-out mitochondria with fuel? That would mean administering nicotinamide riboside, the vitamin precursor of NAD+. This is the hypothesis that the researchers wanted to test after having already successfully investigated this vitamin's effect on muscle aging in their work on nutrition.

They tried out their approach on animals, using C. elegans worms and mice that had been genetically modified to develop the disease. The effect was remarkable. When large doses of nicotinamide riboside were administered, the worms did not develop any of the disease's symptoms. The mice presented much lower muscular inflammation, and existing lesions were attenuated.

"We have good reason to think that humans will also respond to this treatment and that we'll be able to reduce inflammation," said Auwerx, the lead author. "But we don't know to what extent. It's important to remember that we're not going after the primary cause of the disease, dystrophin deficiency." Which means it is difficult to predict the treatment's effectiveness. "Regardless, it would still be quite an accomplishment if we can prolong the patient's life by several years and increase their comfort."

Clinical tests may be possible within two years

Nicotinamide riboside is a vitamin precursor to NAD+. This molecule is commercially available and presents no known toxicity, even in high doses. The vitamin is water soluble, and any excess amount is evacuated in the urine.

According to Auwerx, because nicotinamide riboside is readily available and harmless, clinical tests could be possible in the very near future, maybe within two years. "We will need to test the doses," says the researcher. "In the animals that we tested, the quantities were so large they could not be administered through diet. To see if our strategy works on humans, we will have to use massive doses of synthetic molecules."

The genetic mutation that causes Duchenne muscular dystrophy was discovered 30 years ago. 2016 is thus an anniversary year, and it has already been marked by the FDA's recent approval of a promising treatment that partially corrects the defective gene in certain patients. "My hope is that we will give people suffering from Duchenne muscular dystrophy a second reason to celebrate in 2016," says Auwerx.