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Q&A With Geneticist Dr. Bruce Ames

Recently the Dole Nutrition Institute had the honor of interviewing molecular geneticist Dr.Bruce Ames, internationally celebrated for his groundbreaking work on the link between nutrition and DNA integrity.A professor of Biochemistry and Molecular Biology at the University of California, Berkeley, Dr.Ames is also Senior Scientist at Children’s Hospital Oakland Research Institute.With over 450 publications in leading journals, he is one of the most widely cited scientific experts of all time.

He was gracious enough to share his thoughts on how what we eat affects how we age.In particular, he explains his famous “triage theory of DNA damage,” in which nutrition deficiencies cause our bodies to sacrifice the long-term health of our DNA in order to attend to the immediate needs of daily living.He also believes that such nutrition deficiencies may contribute to obesity, by interfering with the satiety signals the body needs to stop eating.Dr.Ames elaborates on these themes below.

DNI: Generally people have a positive association with metabolism in terms of weight loss.But you point out that there is a connection between aging and metabolism.

AMES: My interest has been in disease prevention.Originally I focused on DNA damage, which got me into cancer research and then the study of aging.Most of our DNA damage comes from our own metabolism.

In reading about aging I became interested in mitochondria — the power plants of the cell.Mitochondria harness the energy obtained from “burning” the fat and carbohydrates we ingest when we eat.This process forms ATP, high-energy molecules that power muscles, the brain, and metabolism.

In the process of making ATP, there are small amounts of free radicals formed, which can damage the mitochondria and our DNA.Healthy, young mitochondria keep that to a minimum, but with age they are less efficient and they pour out more free radicals.It’s like an old car engine that’s pouring out black smoke and is less efficient.

DNI: As we age, does our ability to manage this oxidative damage decrease at a steady rate or at an accelerating rate?

AMES: We’re all aging exponentially; all the degenerative diseases like cancer go up as we age.I believe much of this goes back to mitochondrial decay.

DNI: Is it possible to return the mitochondria to their younger version — i.e., to reverse the damage?

AMES: Some of the damage is nonreversible but some of it, like the leaking of free radicals, may be reversible.As the aging process advances, acetyl carnetine (ALC) is not being made as effectively.We found that when you get more of ALC, it helps the mitochondria to function.We also found that alpha lipoic acid (LA) helped reduce the leaking of oxygen radicals, which occurs at a higher rate in the aging rat.

DNI: So, in other words, once you have DNA damage it’s there.You can freshen up your mitochondria to keep you at the level you’re at — but you can’t reverse the damage that has already been done, right?

AMES: That’s right, it’s there.In WWII during the Dutch famine, there was mass starvation, and the women who were pregnant at the time found that later in life all sorts of health issues affected their children.For example, many of their babies turned out to have heart disease when they grew up.So, there are really long-term consequences.

The most important thing is the need to make sure we’re eating a good diet and getting exercise.But then there will be ways of tuning up the mitochondria.I think life expectancy is going to get a lot longer than anyone thinks.In 1900 we were living until 50 — by the time the century was over we were living 25-30 years longer.We’re going to continue to see advances.We don’t know the limit of life expectancy.

DNI: What kinds of things can people do to slow down — or speed up — aging?

AMES: Eating bad diets accelerates the aging process.I’ve been very interested in micronutrients — the vitamins and minerals you need to keep your system going.There are about 15 minerals and 15 vitamins that are part of normal metabolism.Organisms don’t make these so you have to get them from the environment.We are finding that in cell cultures, if you deprive them of particular nutrients, the cells age faster and you get massive DNA damage.Lower-income and obese populations are eating extremely poor diets — calorie-rich refined foods.Junk food, pastries, soda — these are all empty calories, with few vitamins and minerals.

It’s the lack of these nutrients — rather than the food itself — that I believe causes most of the problems.What happens when you don’t have enough of a vitamin or mineral? You get DNA damage.The pesticides and chemicals people worry about — that’s a distraction.If you don’t get your vitamins and minerals you get a lot of DNA damage and that leads to cancer down the road.

DNI: To what extent are these disease risks a function of genetics?

AMES: Whatever your genetics, you don’t want to smoke and you don’t want to eat a bad diet.Smoking and poor diet — those are the two things that age you faster.But getting adequate nutrients is key.For example, take folic acid: When you don’t have enough you get chromosome breaks.When NHANES and other surveys looked into who is getting this low level of folic acid — it’s the low-income population.They tend to get more obese; they’re destroying themselves because they’re not getting the nutrients they need to keep their metabolism going.

DNI: Tell us what you mean when you talk about the “triage theory” of disease.

AMES: Think about the 15 minerals.

Every living creature needs them — but of course the minerals are not present in nature in equal amounts.In times of scarcity, the body starts to prioritize, taking care of immediate survival needs first.It’s the DNA repair — and the long-term health needs — that get sent to the back burner.This is the triage theory: Nature attends to the immediate survival so the organism can successfully reproduce, rather than the long-term needs.

Long-term health benefits are sacrificed to get you through the short term.Life is a trade-off between long term and short term.In most of human history, calories were limited.The potato tripled the population of Europe.But now calories are dirt cheap and they’re not bringing in the vitamins and minerals.It’s not that excess calories are the only bad thing — it’s the lack of vitamins and minerals.

Published January 1, 2007

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