Olive-sourced hydroxytyrosol effective in biscuits: Study

By Lynda Searby

- Last updated on GMT

© iStock.com / leonori
© iStock.com / leonori

Related tags: Olive oil, Nutrition

Olive oil phenol hydroxytyrosol has been shown to be highly bioavailable and to lower oxidised LDL (low density lipoprotein) levels when incorporated into biscuits, suggesting functional food applications could be on the horizon for this EFSA-backed polyphenol. 

“It can be concluded that HT [hydroxytyrosol], provided in HT-enriched biscuits, is highly bioavailable, extensively metabolised and rapidly eliminated, contributing to a decrease of plasma oxidised-LDL. Therefore, biscuits can be considered an efficient vehicle to deliver HT,”​ the Spanish researchers wrote in the journal Food Chemistry​. 

Olive oil phenol HT has been proven in numerous studies to positively influence cardiovascular health by protecting LDL particles from oxidative damage.

In 2011 this evidence was given the stamp of approval by the European Food Safety Authority (EFSA) when olive oil polyphenols was awarded a rare health claim. This captured the interest of the food and ingredients industry and since then the market for HT has been hot. 

Narrow scope

However, the scope of the EFSA claim is limited to the application of HT and its derivatives in the olive oil matrix and relates to ‘chronic consumption’. 

“Any claim with hydroxytyrosol in a different food matrix requires a study to assess the capacity of hydroxytyrosol to protect LDL against oxidation,” ​lead researcher Raquel Mateos told NutraIngredients. 

She explained: “Bioavailability of food components may vary positively or negatively depending on the food it is contained in. Previous studies have reported that the bioavailability of phenols in olive oil declines in food matrices other than olive oil. There are few studies on the bioavailability of hydroxytyrosol in foods other than oil and none in cereal based matrices, to our knowledge.”​ 

This research gap coupled with the restriction on how the EFSA claim could be applied prompted Spanish biscuit and pastries manufacturer Adam Foods SL to approach the Institute of Food Science, Technology and Nutrition (ICTAN-CSIC) to evaluate the bioavailability of HT in biscuits. 

From the researchers’ point of view, the driver for the study was to help encourage uptake of the phenol by facilitating its inclusion in an increased range of products. 

“Biscuits are widely consumed by all population groups, hence being an interesting food option for enrichment with bioactive ingredients to deliver healthy compounds to consumers. Therefore this study was aimed at assessing the absorption and metabolism of HT, contained in biscuits, in volunteers,”​ the researchers said. 

Study design

A randomised, controlled, crossover, double-blind study was carried out in 13 healthy subjects (three men and ten women), aged 22-37. On two different days, the participants consumed 30 g of control biscuits or biscuits enriched with HT. The HT biscuits were formulated to provide the recommended amount of 5 mg of HT per day with a single serving.

Analysis of blood and urine samples identified the presence of eight HT metabolites after consumption of the HT biscuits, whereas just a single metabolite could be identified after intake of the control biscuits. 

“It could be estimated that there was a total excretion of 3.7 mg of HT metabolites after the intake of HT-B, corresponding to 70% of the 5.25mg HT consumed…HT proved to be highly bioavailable after consumption of the HT-B biscuits by the volunteers, and much more than many other dietary flavonoids and phenolic compounds,” ​wrote the researchers. 

Postprandial oxidised-LDL concentrations were also shown to decrease with the HT biscuits.

The researchers said this was of particular note as the established effect of olive oil polyphenols protecting LDL against oxidative stress is associated with sustained consumption. 

Next steps

Based on the positive results observed in this acute (one day) study in humans, Mateos said the next step would be to assess the effects of chronic consumption of HT enriched biscuits on LDL particles, as well as on other biochemical parameters related to cardiovascular health.

 

Source: Food Chemistry​ 

Aug 15;205:248-56, doi: 10.1016/j.foodchem.2016.03.011

“Hydroxytyrosol in functional hydroxytyrosol-enriched biscuits is highly bioavailable and decreases oxidised low density lipoprotein levels in humans”

Authors: R. Mateos, S. Martínez-López, G. Baeza Arévalo, M. Amigo-Benavent, B. Sarriá, L. Bravo-Clemente 

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