Aaron Deere is a sports nutritionist, functional medicine consultant and advanced personal trainer. He is based in London.
What are sirtuins?
Sirtuins (SIRTs) are a class of enzymes which were originally observed to influence longevity of yeast cells. Further research has uncovered at least seven similar human proteins, named SIRT1 through to SIRT7, which have the ability to efficiently silence and activate the expression of a variety of genes that are involved in a wide diversity of biological processes.
What roles do they play in the body?
Continuing research has since shown that SIRT pathways act as ‘master regulators’ of our whole metabolism, modulating fat burning, increasing lean muscle mass, and enhancing cellular fitness.
SIRTs are thought to play a key role in apoptosis (programmed cell death), inflammation, ageing and transcription (the first step of gene expression).
They are thought to be significantly involved in responses to stresses, such as heat or starvation; controlling circadian rhythm, and energy efficiency, including responsibility for the lifespan-extending effects of following a calorie-restricted diet. In addition, early research in animal models showed that increased expression of SIRT6 lengthened lifespan by as much as 15.8%, and that increased expression of SIRT1 were shown to reduce the development of Alzheimer disease[1,2].
What is their specific role on positive body composition changes?
The up-regulation of certain SIRT pathways has been shown to directly stimulate mitochondrial biogenesis (the process by which new mitochondria are formed in a cell), increase rates of fatty acid oxidation (fat burning), prevent enlargement and development of fat cells, and induce the programmed death of mature fat cells[3,4].
Therefore, by modulating these specific pathways, we can increase rates of fat burning within the body. Calorie restriction has been identified as a functional link to the up-regulation of fat burning SIRT pathways, with the up-regulation of these pathways is believed to be one of the key modulating effects of calorie restricted protocols, such as intermittent fasting.
The ability to promote SIRT expression has also been linked to positive effects on muscle repair and muscle adaptations to stress, with up-regulation of specific SIRT pathways shown to also induce rapid skeletal muscle fibre hypertrophy, block atrophy and increase proliferation of muscle precursor cells.
How can these pathways be up-regulated?
Research has shown that it is largely plant-based foods that have the greatest modulating effects on SIRT pathways. Plant polyphenols have shown to be potent modulators of these pathways, with foods high in resveratrol, such as raspberries, blueberries, grapes and peanuts, shown to impart a wide range of biological effects.
Quercetin, which is found in capers, apples, onions, green vegetables and most berries, has also been shown to be a strong modulator, resulting in strong anti-inflammatory and protective properties. Along with polyphenols, flavonoids found in foods such as cocoa, green tea and coffee have also been shown to enhance SIRT pathways, offering protective effects along with regulating lipid metabolism via modulating gene expression, or activating transcription factors that regulate the expression of numerous genes, many of which play an important role in energy metabolism[7,8].
Therefore, these foods contain specific nutrients that are capable of activating powerful SIRT pathways within the body that have the ability to act as master regulators of our metabolism. These pathways control key metabolic activities, such as our ability to burn fat, build muscle, increase overall cellular fitness and can potentially result in life extension.
1 Kanfi, Yariv, et al. “The sirtuin SIRT6 regulates lifespan in male mice.” Nature 483.7388 (2012): 218-221.
2 Bonda, David J., et al. “The sirtuin pathway in ageing and Alzheimer disease: mechanistic and therapeutic considerations.” The Lancet Neurology 10.3 (2011): 275-279.
3 Guarente, Leonard. “Sirtuins in aging and disease.” Cold Spring Harbor symposia on quantitative biology. Vol. 72. Cold Spring Harbor Laboratory Press, 2007.
4 Nakagawa, Takashi, and Leonard Guarente. “Sirtuins at a glance.” Journal of cell science 124.6 (2011): 833-838.
5 Pardo, Patricia S., and Aladin M. Boriek. “The physiological roles of Sirt1 in skeletal muscle.” Aging (Albany NY) 3.4 (2011): 430.
6 Allard, Joanne S., et al. “Dietary activators of Sirt1.” Molecular and cellular endocrinology 299.1 (2009): 58-63.
7 Ali, Faisal, Amin Ismail, and Sander Kersten. “Molecular mechanisms underlying the potential antiobesity-related diseases effect of cocoa polyphenols.” Molecular nutrition & food research 58.1 (2014): 33-48.
8 Duarte, Diego A., et al. “Polyphenol-enriched cocoa protects the diabetic retina from glial reaction through the sirtuin pathway.” The Journal of nutritional biochemistry 26.1 (2015): 64-74.