Sirtfoods
• Sirtfoods are so named because they activate sirtuins.
• Sirtuins are proteins (enzymes) with anti-inflammatory and antioxidant properties, associated with anti-aging, a lower cardiovascular risk, and weight reduction (the activation of sirtuins can trigger effects similar to caloric restriction).
• Sirtuins, or SIR (Silent Isoform Regulators), comprise a group of 7 isoforms. The first discovered was Sir2, in 1984, in yeast. Interest in this protein grew when it was found to promote longevity in yeast, nematodes, and flies. Research then showed that caloric restriction in mammals increased the expression of sirtuins.
• Seven isoforms have been identified in mammals. Isoforms 1, 2, 6, and 7 are found in the nucleus, the 3, 4, and 5 in the mitochondria, and 1 and 2 may also be found in the cytoplasm.
• They regulate cell proliferation and differentiation, participate in DNA repair, genome stability, energy homeostasis, prevention of some cancer types, tissue regeneration, etc. They also regulate gluconeogenesis, fatty acid oxidation, expression and maturation of adipocytes, plasma glucose levels, mitochondrial energy capacity, insulin secretion, tissue insulin sensitivity, and cholesterol homeostasis.
• Sirtfoods are rich in polyphenols, which mimic caloric restriction, leading to a 20 to 40% reduction in nutrient intake.
• Polyphenol-rich sirtfoods include: arugula, buckwheat, capers, celery, chili pepper, cocoa (85% dark chocolate), coffee, extra virgin olive oil, garlic, green tea, kale, dates, parsley, red chicory, red onion, soy, turmeric, walnuts, apples, citrus fruits, and saffron. Red wine grapes are not only high in polyphenols but also in resveratrol. Strawberries and blueberries, besides being rich in polyphenols, are high in anthocyanidins. The root of sorrel is particularly rich in resveratrol (about 100 times more than the skin of black grapes).
• Just as with functional foods, superfoods and sirtfoods share significant common ground, as they are rich in bioactive nutrients, particularly polyphenols, fibers, vitamins, and minerals.
• For this reason, it is not surprising that many foods appear in both groups, even though superfoods generally lack scientific validation, while sirtfoods have a defined biological mechanism.
• The authors of the Sirtfood Diet are British nutritionists Aidan Goggins and Glen Matten. The initial popularity of the diet was not matched by scientific proof. Apparently, weight loss is mainly due to caloric restriction rather than being based on sirtfoods. This does not mean that sirtfoods are not effective in promoting health and weight loss. It simply means that, like superfoods and functional foods, they should be part of an overall healthy diet.