Irene ‘Rene’ Nadal lives at MHA Westbury Grange care home in Newport Pagnell, which was decorated with balloons and banners for the occasions.
She spent the day with her two sons Brian and John as well as other residents and staff members.
Home manger Julie Roche said: “Rene has been with us since 2017, and it was thanks to her son Brian, who volunteers at the home, that she came to stay here.
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“The highlight of her day is having a cup of tea, she loves tea and it has to be a strong builder's tea."
Julie added: “Rene is a very direct, feisty and strong willed character. She is still going at the age of 100 and she is definitely someone who has to be in the right mood if she wants to do something!
“She is a very particular and content person, who enjoys sitting in her room and watching the birds.”
Julie said Rene had a “lovely time” at the party and the highlight was her telegram from the Her Majesty the Queen.
“We made sure there was plenty of delicious food and drink as well as a lovely Romanian cake for her birthday.”
Experts say a strong, hot brew of tea contains more antioxidants, which health experts say slow down or halt oxidising damage that can cause cancer and heart disease.
A recent study published in European Journal of Preventive Cardiology involved more than 100,000 adults in China and found those who regularly drank tea were less likely to develop atherosclerotic cardiovascular disease or die prematurely from any cause, particularly stroke, compared to others during a seven-year follow-up period.
The link was especially strong among habitual tea drinkers, defined as those who enjoyed a cuppa at least three times a week.
Based on the findings, a 50-year-old frequent tea drinker might develop heart disease almost a year-and-a-half later or live about a year longer than someone who never or seldom drank tea, the study concluded.