Health for life

Low levels of vitamin D may be associated with longevity, according to a study involving middle-aged children of people in their 90s published in CMAJ (Canadian Medical Association Journal).

"We found that familial longevity was associated with lower levels of vitamin D and a lower frequency of allelic variation in the CYP2R1 gene, which was associated with higher levels of vitamin D," writes Dr. Diana van Heemst, Department of Gerontology and Geriatrics, Leiden University Medical Center, Leiden, the Netherlands, with coauthors.

Previous studies have shown that low levels of vitamin D are associated with increased rates of death, heart disease, diabetes, cancer, allergies, mental illness and other afflictions. However, it is not known whether low levels are the cause of these diseases or if they are a consequence.

To determine whether there was an association between vitamin D levels and longevity, Dutch researchers looked at data from 380 white families with at least 2 siblings over age 90 (89 years or older for men and 91 year or older for women) in the Leiden Longevity Study. The study involved the siblings, their offspring and their offsprings partners for a total of 1038 offspring and 461 controls. The children of the nonagenarians were included because it is difficult to include controls for the older age group. The partners were included because they were of a similar age and shared similar environmental factors that might influence vitamin D levels.

The researchers measured levels of 25(OH) vitamin D and categorized levels by month as they varied according to season. Tanning bed use, which can affect vitamin D levels, was categorized as never, 1 times per year and 6 times per year. The researchers controlled for age, sex, BMI (body mass index), time of year, vitamin supplementation and kidney function, all factors that can influence vitamin D levels. They also looked at the influence of genetic variation in 3 genes associated with vitamin D levels.

"We found that the offspring of nonagenarians who had at least 1 nonagenarian sibling had lower levels of vitamin D than controls, independent of possible confounding factors and SNPs [single nucleotide polymorphisms] associated with vitamin D levels," write the authors. "We also found that the offspring had a lower frequency of common genetic variants in the CYP2R1 gene; a common genetic variant of this gene predisposes people to high vitamin D levels.

These findings support an association between low vitamin D levels and familial longevity." They postulate that offspring of nonagenarians might have more of a protein that is hypothesized to be an "aging suppressor" protein. More research is needed to understand the link between lower vitamin D levels, genetic variants and familial longevity.

It is the first time that a scientific study associates high polyphenols intake with a 30% reduction in mortality in older adults. The research, published on Journal of Nutrition, is the first to evaluate the total dietary polyphenol intake by using a nutritional biomarker and not only a food frequency questionnaire. Research is signed by Cristina Andrés Lacueva, Montserrat Rabassa and Mireia Urpí Sardà, from the Department of Nutrition and Bromatology of the UB; Raúl Zamora Ros (ICO-IDIBELL), and experts Antonio Cherubini (Italian National Research Centre on Aging), Stefania Bandinelli (Azienda Sanitaria di Firenze, Italy) and Luigi Ferrucci (National Institute on Ageing, United States).

Polyphenols: diet improves health

Polyphenols are naturally occurring compounds found largely in fruits, vegetables, coffee, tea, nuts, legumes and cereals. More than 8,000 different phenolic compounds have been identified in plants. Polyphenols have antioxidant, antiinflammatory, anticarcinogenic, etc. effects.

The research published on Journal of Nutrition is based on a 12-year follow-up of a population sample composed by 807 men and women aged 65 or over from Greve and Bagno (Tuscany, Italy), within the InCHIANTI study. The group of the UB analysed the effect of polyphenol-rich diets by means of a nutritional biomarker -- the total urinary polyphenol (TUP) concentration -- as a proxy measure of intake. To be exact, UB researchers contributes to first literature erences on TUP application to epidemiological or clinical studies.

New biomarkers for nutritional studies

Professor Cristina Andrés Lacueva, head of the Biomarkers and Nutritional & Food Metabolomics Research Group of the UB and coordinator of the study, explains that "the development and use of nutritional biomarkers enables to make a more precise and, particularly, more objective estimation of intake as it is not only based on participants memory when answering questionnaire. Nutritional biomarkers take into account bioavailabity and individual differences. According to the expert, "this methodology makes a more reliable and accurate evaluation of the association between food intake and mortality or disease risk."

In conclusion, the research proves that overall mortality was reduced by 30% in participants who had rich-polyphenol diets (>650 mg/day) in comparison with the participants who had low-polyphenol intakes (<500 mg/day).

Raúl Zamora Ros, first author of the study, points out that "results corroborate scientific evidence suggesting that people consuming diets rich in fruit and vegetables are at lower risk of several chronic diseases and overall mortality." Moreover, the research stresses the importance of evaluating -- if possible -- food intake by using nutritional biomarkers, not only food frequency questionnaires.

The Biomarkers and Nutritional & Food Metabolomics Research Group, which participates in the project Fun-C-Food (Consolider Ingenion), collaborates actively with several national and international research groups. It focuses its activity on the analysis of new more effective and sensitive nutritional biomarkers based on the bioavailabilty of bioactive compounds in food and their activity, in order to associate the intake of certain foods (consumption markers) with their potential effects on peoples health.