Telomere length is considered a biomarker of aging:

shorter telomeres are associated with decreased life expectancy

and increased rates of age-related chronic diseases.

Telomere shortening has been shown to be accelerated

by oxidative stress and inflammation.

So since plant foods contain plenty of compounds

with antioxidant and anti-inflammatory properties,

it's plausible that their sustained consumption

might help counteract telomere attrition.

And indeed, if you pull all the best studies on the impact of nutrition

on telomere length, the consumption of vegetables, fruits, beans and nuts

has been associated with positive effects on markers of inflammation

and oxidative stress in parallel with longer telomeres.

By contrast, processed meats, alcoholic and sugar sweetened beverages,

and other foods rich in saturated fats, alcohol, and sugar

are linked to an increase in inflammation

and oxidative stress in parallel with shorter telomeres.

In my last video on telomeres, I featured a randomized controlled trial

showing a whole food, plant-based diet and lifestyle program

could actually lengthen telomeres. Is it just because they cut out the junk?

Those eating the most ultra-processed foods have been found

to have almost twice the odds of having short telomeres.

Maybe it's because they cut out the processed meat,

like bacon, ham, hot dogs, lunchmeat, sausage,

which has been associated with not only cancer and diabetes risk

but shorter telomeres as well, meaning accelerated cellular aging,

though just having something like a steak

was not similarly associated with telomere length.

Processed meat, but not unprocessed red meat,

is associated with shorter telomere length.

This is perhaps due to the particularly high concentrations of glycotoxins,

the advanced glycation end products, as well as carcinogenic nitrosamines

in the processed meat that may promote inflammation and oxidative stress.

The only unprocessed meat associated with shorter telomeres was poultry.

For dairy, it appears to be the milk fat.

A national survey of thousands of Americans

found an association between increased biological aging and

the consumption of high-fat milk.

Even with people just going up like 1% milk fat

(from like 1% milk to 2% milk, low-fat milk to reduced fat milk)

appeared to have more than 4 years of additional biological aging.

We think it's because of the saturated fat, given that saturated fats trigger

an inflammatory response. Not all plant foods are good for you, though.

French fries and potato chip consumption is associated

with shorter telomeres.

Yes, fiber intake goes hand-in-hand with longer telomeres,

as does higher vegetable and fruit consumption,

but that may be trumped by a deep fryer.

What about the consumption of a high fat whole plant food like nuts?

We know higher telomere-building enzyme activity is associated

with a higher dietary antioxidant score,

and botanically, seeds are packed with antioxidants

and by seeds, they mean any food you can put in the ground

and sprout a whole plant, like whole grains, beans, chickpeas, lentils, nuts.

They're naturally enriched in antioxidant compounds

that protect the seed DNA from damage.

Four weeks of Navy beans didn't seem to affect

telomere length, though. What about nuts?

Well, based on how much your telomeres shorten every year,

you can estimate the rate of aging.

In other words, two people can have the same chronological age,

same calendar age, but suffer more or less effective cellular aging.

So, for example, if you smoke a pack a day for a decade,

your cells may age about 3 years faster.

Or, if you drink soda every day,

it's like almost 2 years of additional aging.

So what about nuts?

U.S. adults of the same age would experience almost 2 years less

biologic aging per ounce of nuts and seeds consumed per day,

the amount I recommend in my free Daily Dozen app.

The estimated biologic aging advantage would be nearly 1 year

for each 100 calories of nuts and seeds consumed every day.

The researchers conclude that, clearly, consumption of nuts and seeds

accounts for meaningfully lower levels of biologic aging

in U.S. men and women. But that's just an association.

You don't know if nuts can slow telomere shortening until you put it to the test.

A randomized controlled trial investigating whether the inclusion

of one or two ounces of walnuts a day

for two years would help maintain telomere length,

which normally shortens with age.

In the control group, their telomeres shortened as expected

over those two years, whereas the walnut group telomeres maintained

their length, though the difference didn't reach statistical significance.

Now, that was measuring average telomere length,

and it's probably more telling to look at how long

the shortest telomeres are rather than the average,

and if you do that, look at the percentage of telomeres

that are particularly short,

the walnut group does edge out over the control group.

It's well established that the length of the shortest telomeres is

the key biomarker of the onset of senescence.

The researchers conclude that the inclusion of walnuts

in the regular diet for 2 years tends to delay

leukocyte telomere shortening in older individuals.

A study on pistachio consumption, 2 ounces a day for 4 months,

reduced signs of DNA damage, but did not significantly slow

the rate of telomere shortening.

And this study, which randomized people to eat more mixed nuts,

found a higher risk of telomere shortening in the nut group,

for which the researchers could offer no explanation.

So it's not clear whether nuts help with telomeres or not.

Most supplement intervention studies observed null effects

on telomere length as well, with the exception of green tea.

Thirty-six elderly women were randomly divided into two groups:

exercise alone or exercise with green tea consumption for 5 months,

and a significant boost in telomere length in the green tea group

with no change from the placebo.

Green tea is essentially a green leafy vegetable we dip in hot water.

How about eating green leafy vegetables, in fact the healthiest kind:

cruciferous vegetables like broccoli, cabbage, collards and kale.

They pitted raw versus cooked and found that cooked was better than raw

for reducing DNA damage from a carcinogen,

but raw was more anti-inflammatory. Consequently, to fully exploit

the complexity of the health-promoting potential

of Ethiopian kale, and by extension maybe other cruciferous,

a mix of both raw and cooked vegetables should be part of the diet.

OK, but what about for boosting

the telomere-lengthening age-reversal enzyme?

Raw or cooked. Which do you think?

A short-term dietary intervention showed that cooked but not raw

boosted telomerase activity in as short as five days,

eating one and a quarter cups of this kale a day.

It was thought that you'd need like 4 months of a change

to affect telomeres, but this study provides,

for the first time, evidence that telomerase activity

can respond in a matter of days to a food intervention,

but not just any food, but the healthiest food out there:

cruciferous dark green leafy vegetables.