Carbohydrate restriction may increase lifespan


Staff of life? Not really.

Carbohydrates are essentially just long chains of glucose molecules strung together. Glucose is a sugar, which requires insulin in order to be taken up by cells. When carbohydrates are metabolized (digested), the effect on the body is virtually the same as if one had eaten the same amount of sugar. The type of carbohydrate can make somewhat of a difference; fast-digesting carbohydrates, like those in white bread, pasta, or white potatoes, can cause a large enough glucose spike that is almost indistinguishable from eating the same amount of sugar; slower digesting carbs, such as in vegetables, not so much.

Glucose restriction extends lifespan in C. elegans

It’s been found that in the model organism C. elegans (a tiny worm frequently used in aging studies), restricting glucose from their diet results in longer life: Glucose Restriction Extends Caenorhabditis elegans Life Span by Inducing Mitochondrial Respiration and Increasing Oxidative Stress.

The fact that glucose restriction induces oxidative stress appears to be key here, since that makes glucose restriction a form of hormesis, which the authors dub “mitohormesis”, since it acts upon the mitochondria. As a form of hormesis, glucose restriction induces antioxidant enzymes such as catalase, and causes an upregulation of cellular stress defense mechanisms.

Antioxidants abolish lifespan extension

Importantly, treatment of these worms with antioxidants abolished life extension, which shows that the increased oxidative stress is necessary to for increased longevity. Glucose restriction also caused an increase in fat burning. Also importantly, disruption of the worm equivalent of AMPK abolished lifespan extension by glucose restriction, showing that activation of AMPK is necessary. As we recently saw, activation of AMPK alone, by whatever means, be they chemical compounds, drugs, exercise, or fasting, increases lifespan, since AMPK controls the aging process.

Addition of glucose shortens lifespan

Next, we see that the addition of glucose to the food of C. elegans does just what we would expect: it shortens lifespan. The authors refer to glucose in this regard as “a potent lifespan-shortening agent”.

Low-carb diets, antioxidants, and longer life

A co-author of this second study was Cynthia Kenyon, one of the most renowned aging researchers, who now works for Google in their start-up anti-aging company, Calico. When Kenyon made this discovery about glucose and lifespan, she gave up refined carbohydrates, and eats a diet that looks very much like paleo. I think the rest of us can take a lesson from this.

The fact that antioxidants abolished the effect of glucose restriction on lifespan means, in my opinion, that one should be careful about supplementing with them. On an intermittent fast, for instance, one shouldn’t take them, and if extra vitamin C is desired (which I take myself), it should be in rather small amounts, say 500 mg, and taken in the fed state and away from workouts.

Probably the biggest caveat here is that these studies were done in nematodes (worms), and to my knowledge it has not been repeated in mammals. However, glucose does increase insulin/IGF-1 signaling, and it is known that decreased insulin/IGF-1 signaling increases lifespan, so to me that’s a fairly compelling reason to think that these results are applicable to mammals.


Leave a Comment:

Lemmy caution says February 24, 2015

What do you think about blueberries? I tend to eat a lot of frozen blueberrieies. Like maybe a pound at a sitting. Is this going to be bad? I am pretty sure it is better than processed stuff, but still.

    P. D. Mangan says February 24, 2015

    A quick search turned up that a pound of blueberries has about 63 g carbohydrate including 45 g sugar, which is equivalent to about 9 teaspoons. Yeah, sounds like a lot.

A Low-Carb Diet Is an Anti-Aging Diet - Rogue Health and Fitness says April 10, 2015

[…] know that a greater amount of insulin is associated with a shorter lifespan. (See also my post, Carbohydrate restriction may increase lifespan.) Conversely, people and animals that have lower insulin levels or disrupted insulin signaling have […]

Benas says January 28, 2016

Interesting article! One question though – I read you recommend reservatrol, green tea and cacao/cocoa. As they are anti-oxidants, it would mean that they abolish the lifespan extension due to glucose restriction. What is your take on this?

    P. D. Mangan says January 28, 2016

    Hi Benas, the word antioxidant is misused by the public and the media. It used to be that many healthful substances were antioxidants, but they’re not. Those you mentioned act through hormesis. The only true antioxidants worth mentioning in this context are vitamins C and E.

      Ben says January 28, 2016

      Got it, thanks! A post on this topic would be useful though – which substances are antioxidants, and which act through hormesis. I think many people probably have this misconception.

        Rob H says January 28, 2016

        I agree with you Ben – I only worked this out recently (well, after Dennis clarified this to me). It appears that the beneficial effects of fruit and vegetables are not down to the antioxidants they contain, but rather the hormetic phytonutrients they contain. Supplementing with pure antioxidants is actually harmful as they result in a MORE than proportionate fall in endogenous antioxidants (eg glutathione, etc). It would certainly be useful to have a post outlining: avoid these ‘pure’ antioxidant supplements (which I am assuming would be vitamins C & E, betacarotene supplements, plus any others ??) To be fair though, I think Dennis has already clearly outlined which are the beneficial hormetic phytonutrients, but it would be good to see them all listed in one place, contrasted against the ‘pure antioxidant’ supplements which should be avoided… Just a thought!

          P. D. Mangan says January 28, 2016

          Yes, I should probably get it all down in one post so everyone is clear on that.

Rob H says January 29, 2016

Hi Dennis, following on from my above comment, I was thinking it might be most useful if you wrote a post on ‘Which supplements are best avoided’ – seeing as how you have written quite extensively on the benefits of phytonutrients already.. For example, in addition to listing out the ‘pure’ antioxidants such as Vitamins C, E, betacarotene (plus any other pure antioxidants to avoid??), you would probably want to include things like calcium supplements that I know you warned against in one of your posts. Also, until recently I was taking daily chromium picolinate supplements (as recommended by British nutritionist Patrick Holford) in order to assist with blood sugar and energy levels. However, new research suggests that it can actually be transformed into the carcinogenic form of chromium in the body: So that’s definitely another one to avoid!

One that you might be able to shed some light on is the zinc/ copper connection. some health writers believe that copper is good to supplement, particularly if you supplement with zinc, since they compete for the same pathways. I myself now take a daily supplement consisting of 15mg chelated zinc + 0.75mg chelated copper. However, other health bloggers such as Chris Kresser advise cutting down copper as much as possible.. One other big grey area for me : I currently take a high strength, timed-release daily vitamin B complex (B-100) at night. I was advised it helps to lower homocysteine, and that the nictotinamide helps promote autophagy, but then I also hear that taking large quantities of B vitamins can interfere with glycine supplementation to mimic methionine restriction. So now I’ve dropped down to a daily ‘low dose’ B-complex (ie just enough to meet 100% RDA requirements). I do remember reading that it is best to take B-vitamins all together as a complex, since they work together in tandem. But I’m not really sure which approach is best to take with supplemental B-vitamins – ie low dose, high dose or no dose (assuming a fairly decent paleo + legumes, nuts & seeds diet)?? Anyway, a post highlighting which supplements (and which types/ variations of specific supplements) NOT to take would be very enlightening!

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