The Journal of Physical Chemistry Letters
A cranberry, honey or a candy bar – which tastes the sweetest? These foods contain sugars that humans can perceive differently. A cranberry seems tart, whereas a candy bar can be excessively sweet, and honey is somewhere in the middle. Now, in a study in ACS’ The Journal of Physical Chemistry Letters, researchers have shown that the perception of sweetness depends on molecular interactions between specific sugars and water in the saliva.
The sugars mannose, glucose, and fructose have almost identical chemical structures. Yet fructose (found in many candy bars) is about twice as sweet as glucose (found in honey), whereas mannose (found in cranberries) is considered tasteless. Sugars stimulate specific protein receptors on the taste buds of the tongue, which sends a signal to the brain that a food tastes sweet. But scientists don’t know why we perceive some sugars as being sweeter than others. Because these interactions take place in saliva, which is mostly water, Maria Antonietta Ricci and colleagues wondered if water might play a role.
The researchers used a technique called neutron diffraction with isotopic substitution to probe the structures of mannose, glucose, and fructose in water. They found that none of the sugars substantially disrupted how water molecules interact with each other. However, the three sugars interacted with water molecules in different ways. Mannose, the least sweet of the sugars, formed longer and weaker hydrogen bonds with water than glucose or fructose. Fructose, the sweetest of the sugars, formed the shortest and strongest hydrogen bonds with water. The researchers surmise that shorter hydrogen bonds with water could allow the sugar molecule to bind more snugly with the protein receptor, causing greater stimulation and perception of sweetness.
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Alcohol intake appears to have detrimental effects on blood pressure, particularly among men, according to two reports in the Journal of the American Heart Association.
In the first, a meta-analysis comprising over 360,000 adults and 90,000 new cases of hypertension, researchers observe that men who averaged 1-2 drinks daily had increased risk for hypertension relative to nondrinkers (relative risk, 1.2), with risk increasing as alcohol intake increased. Among women, hypertension risk began to increase at 3 or more drinks per day.
The second study included 4700 adults aged 18-45 who answered survey questions about binge-drinking. Roughly 25% of men and 12% of women reported binge-drinking more than 12 times in the past year, and 29% of men and 25% of women reported doing so 1-12 times. After multivariable adjustment, men who binge-drank had higher systolic BP than non-binge-drinkers, and those who binge-drank more than 12 times/year had higher systolic BP than those who binge-drank less (122 vs. 119 mm Hg). This association was not observed among women.
An editorialist writes, “An individual’s decision to drink, and at what level, should be motivated by their own personal circumstances. … Ultimately, our job boils down to empowering an individual to make an informed decision about their level of alcohol intake and how this may influence their long- and short-term health.”
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