Isabel Rosado smiles as she looks at her cake in an early ceremony to celebrate her 100th birthday in Ciales square in Ciales, Puerto Rico in this November 4, 2007 file photo. They may be a little wrinkly, and there may not be many of them, but centenarians are the fastest growing demographic in the developed world. Scientists believe people who live to 100 years or more hold valuable secrets in their genes that can reveal targets for medicines to tackle a wide range of age-related diseases, as well as improving longevity itself. To match feature AGE-GENES REUTERS/Ana Martinez

An underactive thyroid gland may make you live longer, according to a recent Dutch study from Reuters. However, the researchers emphasize it doesn't prove that a sluggish thyroid function delays aging. Further dedicated research and clinical trial is needed to establish the fact, it says.

According to a report in the Journal of Clinical Endocrinology and Metabolism, a study was conducted on 859 siblings from 421 long-lived families. The parents of these siblings had an average age of 93 years.

After rating the longevity of these parents, the team analyzed the thyroid hormones in the siblings. It shows a strong link to heredity. Located in the neck area, the thyroid is instrumental in controlling metabolism in our body. The researchers are of the opinion that the decreased activity of thyroid hormones could shift the body's energy expenditure away from growth and proliferation, keeping the body healthier longer. However, other factors could be associated with both thyroid function and longevity.

These results may come as (a) surprise as low thyroid function is commonly regarded as a risk factor for cardiovascular disease, said van Heemst. The prevailing recommendation therefore is to treat elderly with low thyroid function with hormone supplementation.