Scientists have known for a long time that the ability to repair broken strands of DNA is vital for cells to stay healthy and avoid irregularities like cancer. But they haven’t been able to pinpoint why that ability, like most things, breaks down with age — until the discovery of the molecule NAD.
Dr. David Sinclair is a professor in the Department of Genetics at Harvard Medical School. He recently authored a study published in the journal Science that details the discovery of a critical step in the process of DNA repair.
Cellular DNA & Aging
DNA is the instruction manual for our cells to grow and create proteins — but those vital instructions can be erased or altered by mutations, or changes to the code. When that happens, we rely on our cells’ ability to repair the DNA so it can function normally. But as we age, the ability to bounce back declines — and Sinclair said our cells “lose that information and become dysfunctional over time.”
Even more importantly, according to Sinclair, is that scientists have recently learned that “broken DNA also alters how the chromosomes are structured within the nucleus and that can actually accelerate the aging process itself.”
NAD is a simple molecule in our cells that our bodies use for chemical reactions. “This molecule is very essential for being able to repair DNA,” Sinclair said. The problem? As we get older, the levels of NAD in our bodies go down.
By the age of 50, he says, our bodies make about half of the amount of NAD that they used to. “We see a correlation between the loss of NAD and the inability of people to repair their DNA.”
So Sinclair’s team tried to reverse the process in mice. They discovered that when they boosted NAD levels in mice up to youthful levels, their cells could “rapidly repair DNA” and fix some of the aging problems in their tissues.
Our bodies make their own NAD and it’s in many of the foods we eat, according to Sinclair. The problem is quantity – the molecule, though small, is still too big to easily get through the membrane and be taken up by cells.
Sinclair has been working to create molecules that are small enough for cells to take up rapidly and convert into NAD. “Think of them like vitamins,” he said.
For mice, “we put what we call precursors to NAD into their water supply.” He says they’ve been able to routinely extend the lifespan of mice by 20 or 30 percent.
Now the challenge is to create those effects in humans. Sinclair says he's working to develop a pill or capsule you can take once a day to raise energy levels and strengthen your body. He predicts that within the next decade, a pill that can extend your lifetime by about five years will be on the market.
Sinclair hopes to go to clinical trials with a version of that pill by the end of the year.
The findings about the process of DNA repair and aging have implications for the field of medicine.
Sinclair says chemotherapy and radiotherapy are “good for killing cancer cells. But a lot of the good cells in the body also remain damaged." He hopes the pills they’re developing can start repairing that damage and improve the health of cancer patients post-chemotherapy and radiotherapy.
And then there’s the potential application that came as a surprise even to Sinclair and his team – space travel.
Astronauts experience DNA damage in space that can lead to cancer and premature aging, so when news of the study began to circulate, NASA got in touch. Sinclair has another project now — “What we've been working on with the NASA scientists is to formulate the [NAD] pill for a journey to Mars,” Sinclair said.