Auditors were sent to forest city to investigate the high number of retirees. It turns out it was Guaraná (Paullinia cupana).

Even though you may have never had contact with a tribe deep into the Brazilian Amazon, you may still have heard, read, or watched on tv about the shamans, tribe members specialists in using nature to heal people. The shaman is responsible for dealing with the sick of the tribe and often this means combining forest medicine with a sacred ritual. Medicine men and women are frequently regarded as wise people and treated with extreme respect.
One of the responsibilities of the shaman is to collect all kinds of plants, fungi, and insects that may assist them in the healing rituals. To walk in a shaman’s workspace feels a lot like walking in a modern-day pharmacy, with a shelf containing diverse sorts of vines, leaves, extractions, infusions, etc…
There still is in Brazil the Mawé indigenous culture that has successfully preserved a big part of its culture and the tribe has even been featured in a National Geographic piece about the ritual of passage in which the men of the tribe dance for around 10 minutes while wearing gloves full of ants known to have the most painful stings in the world:
Beyond the painful ant glove ritual, the Mawé are also known around the whole world because of a plant that grows abundantly in the area that the tribe is located which has been growing in popularity not only as a coffee substitute (it contains from 4x to 6x more caffeine than beans of coffee) but also as a performance and mood enhancer, the name of this plant is Guarana (Paullinia cupana).
Guaraná is not only used by the shaman in healing rituals but it is also used daily among the ordinary people in Amazonian tribes, a habit that has gradually extended to the rest of the Brazilian territory and more recently, the world.
People from the Mawé community and many other Brazilian cities have incorporated this plant into their everyday lives very much in the same way that we drink coffee before going to work. The common way to consume Guarana is to mix it with water and sugar, or with juice early in the morning to prepare the body and spirit for a hard day of work.

The Guaraná is rich in effective substances such as caffeine, theobromine, teofilina, among others. Research has pointed to Guarana as an aphrodisiac (sexual enhancer), tonic, astringent, anti-fever, diuretic, and effective to improve stamina and against tiredness.
Theophylline and theobromine have a bronchoprotective effect, and immunomodulatory and anti-inflammatory action, delaying the aging process and inhibiting the deposition of cholesterol in the arteries, allowing better blood irrigation throughout the body. (KUSKOSKI et al., 2005). —
Furthermore, Paullinia cupana is rich in antioxidants which assist our body to deal with the natural wear and tear of every-day-life; this could be one of the big contributors to the longevity effects of guaraná. In fact, this nut is so effective in keeping the elderly alive that the social security of Brazil got suspicious about the great number of retired people registered in the Mawé community in the Amazon and sent auditors to check it out.
The auditors interviewed the elderly people around the Mawé community and were shocked to realize that the unusually high number of healthy retirees in the area was not due to fraud. In fact, they were all very much alive and well. With further investigation, the Brazilian government came to the conclusion that one of the possible causes of the longevity of these people came from their habit of consuming the guaraná several times a day.
In 2019, DW News released a piece about the Guarana and the lives of the indigenous peoples of the region, check it out:
Guarana the Coffee Alternative
Coffee is the most popular drink in the world, the caffeine-rich bean has gained the world as a practical way to keep our heads in the game at any time. Adding coffee to offices around the world has made a tremendous impact on people’s professional and personal lives.
It is easy to find people who feel like they need to start their day with a cup of coffee and frequently take breaks during the day to savor the drink. However, there are other alternatives out there that can also bring other health benefits. Guarana has been gaining popularity among coffee drinkers who want to try alternatives in taste and effects.
If you are a responsible researcher, or collector interested in religious plants and wish to investigate for yourself, I can recommend the House of Exotic Genetics, all the sales go to the research of sacred natural tools:

Guaraná (Paullinia cupana)
Guaraná (Paullinia cupana) powedered for collection and research.
Moustakas D, Mezzio M, Rodriguez BR, Constable MA, Mulligan ME, Voura EB (2015) Guarana Provides Additional Stimulation over Caffeine Alone in the Planarian Model. PLoS ONE 10(4): e0123310. doi:10.1371/journal.pone.0123310
D.O. Kennedy, C.F. Haskell, B. Robertson, J. Reay, C. Brewster-Maund, J. Luedemann, S. Maggini, M. Ruf, A. Zangara, A.B. Scholey,
Improved cognitive performance and mental fatigue following a multi-vitamin and mineral supplement with added guaraná (Paullinia cupana), https://doi.org/10.1016/j.appet.2007.10.007