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鈥淣o, I don鈥檛.鈥� That鈥檚 my answer to the increasingly frequent questions I鈥檝e been asked about whether I take anti-aging supplements containing polyphenols or NAD+ (nicotinamide adenine dinucleotide) boosters. Those questions are clearly triggered by the number of articles and videos by 鈥渨ellness influencers鈥� who sing the praises of these supplements as being instrumental in combating aging. These influencers range from the likes of Gwyneth Paltrow, an actress with zero science background, to serious scientists such as Andrew Huberman.
I think it is fair to say that we are all interested in slowing the aging process. The multiplying wrinkles, achy joints and lapses in memory are hardly welcome. But the notion that any simple intervention is going to have a dramatic effect on retarding the very complex process of aging is primitive thinking.
As time passes, damage to our DNA accumulates, cells become less adept at disposing of debris, our microbiome changes, the immune system becomes less effective, stem cells are less likely to replace worn-out cells and the mitochondria, the so-called 鈥減ower houses of the cell,鈥� become less efficient at producing the energy needed to run the trillions of chemical reactions going on in our body every second 鈥� the reactions that taken together constitute 鈥渓ife.鈥�
While slowing aging is a 鈥減ie in the sky鈥� concept, extending our 鈥渉ealth span鈥� 鈥� meaning the number of years free of chronic disease 鈥� is a reasonable quest. Increasing blood levels of NAD+ has been suggested as a way of doing this.
That notion started with the discovery in the 1930s that NAD+ is found in all living cells and acts as a coenzyme, a helper molecule that allows enzymes 鈥� those special proteins that facilitate the chemical reactions going on in the body 鈥� to function. NAD+ plays an essential role in the cell鈥檚 production of energy and in the functioning of a family of enzymes 鈥� the sirtuins 鈥� that repair damaged DNA, dampen inflammation and help cells respond to oxidative stress.
The 鈥渂reakthrough鈥� for this molecule as an anti-aging factor came in the early 2000s with the finding that cellular levels in yeast, worms and mice fall with age and are paralleled by an accumulation of damaged DNA, an increase in markers of inflammation and reduced energy production by mitochondria. Could restoring NAD+ improve these age-related changes, scientists wondered?
The evidence is not mixed when it comes to studies of foods with a significant polyphenol content, such as berries.
The stumbling block was that NAD+ is a large, charged molecule that doesn鈥檛 cross cell membranes easily and is also readily broken down during digestion. That explains why feeding NAD+ to animals was ineffective. However, resorting to molecules from which a cell can make NAD+ 鈥� such as nicotinamide riboside (NR) or nicotinamide mononucleotide (NMN) 鈥� did in a sense rejuvenate old mice. Their mitochondrial function improved as did their insulin sensitivity. Blood vessels became more pliable and the mice increased their physical activity.
Obviously, that generated much excitement 鈥� especially when it was found that just like in mice, NAD+ levels also decrease with age in humans.
That excitement rose to a feverish pitch, at least among supplement manufacturers, when studies found that blood levels of NAD+ can be increased in people by taking supplements of NR or NMN. Some studies found changes in biomarkers such as insulin sensitivity, but the majority of human trials have failed to show any meaningful, reproducible clinical benefit such as improved muscle strength or lowered blood pressure as a result of increased NAD+.
While there is no doubt that it plays a critical role in our biology and that NAD+ levels in the blood, and consequently in some tissues, can be boosted with supplements, there is a paucity of evidence that this boost has an anti-aging effect. There certainly is no evidence for any benefit from intravenous administration of NAD+ as promoted by some anti-aging clinics. Also, there is the small but lingering concern that increasing mitochondrial action could inadvertently support the growth of incipient cancer cells that are hungry for energy.
Polyphenol supplements have received even more publicity and more hype than NAD+ boosters. Polyphenols are a family of compounds that share a basic molecular structure and are found in a variety of fruits and vegetables. When extracted and tested in the laboratory, they demonstrate an antioxidant effect, meaning they neutralize those nasty free radicals that are a byproduct of cells鈥� use of oxygen and are associated with some of the ravages of aging.
Capitalizing on such laboratory findings, polyphenol extracts form cocoa beans, olives, grape seeds, turmeric and green tea are marketed with claims of improving cognition, stemming arthritic pain, reducing blood pressure, lowering cholesterol, preventing heart attacks and cutting the risk of cancer. All of this translates to a supposed increase in longevity.
The clinical evidence for any of these effects is at best mixed, with some studies showing some benefit for some supplement while many others come up flat. In rare instances, certain green tea and turmeric supplements have even caused liver injury.
However, the evidence is not mixed when it comes to studies of foods with a significant polyphenol content, such as berries. Here the benefits are real and the risk zero.
Just a handful of berries contains 50 milligrams of anthocyanins, a class of polyphenols that give berries and vegetables their red, purple and blue hues. That鈥檚 an amount shown to cause a clinically relevant improvement in blood flow, blood pressure and the elasticity of blood vessels. One study even found a dose-response relationship between berry consumption and faster reaction times on attention tasks and improved short-term verbal memory retention.
An added plus is that polyphenols not absorbed from the intestine travel to the colon where they are feasted upon by Bifido and other beneficial bacteria, allowing them to multiply. These bacteria also break polyphenols into smaller molecules like the 鈥渦rolithins鈥� that are then absorbed and have effect on important biological pathways such as ones that tone down inflammation.
Different berries produce somewhat different effects. Blueberries take the crown when it comes to reducing arterial stiffness and lowering blood pressure. Their polyphenol content has also been linked with preventing the oxidation of LDL cholesterol, a process implicated in the formation of the arterial plaque that causes coronary disease. Berries are also a source of fibre 鈥� with raspberries leading the pack, but blackberries do not lag far behind.
The best bet is to regularly consume a mix of berries, fresh or frozen.
I remain unconvinced about the value of dietary supplements, be they NAD+ boosters or polyphenol formulations. But if I am asked whether I eat berries regularly, I have no hesitation in answering. 鈥淚 do. Every day. A 150-gram mix.鈥�
