Gene for Strong Bitter Taste Tied to Higher Sodium Intake

Marlene Busko

November 25, 2016

NEW ORLEANS, LA — A gene that enhances sensitivity to the bitter taste of foods such as broccoli may partially explain why certain people may eat more salt, a new study suggests[1].

Specifically, in a cohort of mainly overweight or obese women with at least two cardiovascular risk factors, those with a certain gene variant who perceived bitterness in foods more intensely than their peers were twice as likely to eat more than the recommended amount of dietary sodium (up to 2.3 g/day, or 1 tsp/day of salt).

But both groups consumed similar amounts of sugar, saturated fat, and alcohol.

"This confirms our hypothesis that having the bitter-taste genotype did influence sodium consumption," Jennifer Smith (University of Kentucky) summarized in a press briefing before presenting the study during a poster session here at the American Heart Association (AHA) 2016 Scientific Sessions.

The findings "are an important step in determining how genotypes affect eating behavior and how eventually that can affect our cardiovascular health," she said.

Intriguingly, the study "suggests that we may have a certain genetic predisposition to certain tastes," AHA spokesperson and past president Dr Donna Arnett (University of Kentucky, Lexington), told heartwire from Medscape.

Personalized precision medicine is a hot topic these days, and "I think this is one of those issues that begins to identify the many components of why human beings are so varied," briefing moderator Dr Mariell Jessup (University of Pennsylvania Heart and Vascular Center, Philadelphia) commented to heartwire.

Knowing that a person has a gene that drives their desire for salt might be similar to knowing that they have a strong family history of heart disease. "If patients understood why they crave salt, it might help them curb it a little bit," according to Jessup.

Using Salt to Mask Bitter Taste?

A previous study has shown that people with the GG or CG genotype of the TAS2R38 gene are more sensitive to bitter-tasting food and may have a heavy hand with the salt shaker to mask it.

Smith and colleagues hypothesized that having the GG or CG genotype vs the CC genotype of the TAS2R38 gene would be associated with greater consumption of salt, sugar, and saturated fat and decreased alcohol intake.

They examined the association in 407 participants at a cardiovascular risk-reduction clinic in Kentucky, who had a mean age of 51 years. Almost all (93%) were white, 73% were women, and all had at least two cardiovascular risk factors.

Most participants were overweight or obese (mean body mass index [BMI] 33 kg/m2) and nonsmokers (88%); 33% were taking an angiotensin-converting enzyme (ACE) inhibitor and 19% were taking an angiotensin II receptor blocker (ARB).

Participants provided a blood sample for DNA analysis and filled in a food-frequency questionnaire.

Smith and colleagues determined whether participants adhered to the recommended daily intake in the Dietary Guidelines for Americans for sodium, sugar (<10% of total calories), saturated fats (<10% of total calories), and alcohol (no more than one drink/day for women, two or fewer drinks/day for men).

They examined whether having the GG or CG vs the CC genotype of TAS2R38 affected how participants adhered to dietary recommendations and controlled for age, gender, body-mass index (BMI), smoking status, and use of an ACE inhibitor or ARB.

Compared with CC homozygotes, participants with the GG or CG genotype of TAS2R38 were almost twice as likely to exceed the daily recommended level of sodium intake (odds ratio 1.99; 95% CI 1.1–3.5, P=0.02).

Adherence to daily sugar, saturated fats, or alcohol recommendations were similar in the GG or CG genotype vs the CC genotype groups.

"The bottom line is people want their food to taste good," Smith said. "We need to look at how they are tasting it and what we can do to help them" still enjoy food, but make better choices.

Beware of Hidden Salt; Need Larger, Longer Studies

According to a US Food and Drug Administration website, "surprisingly, some foods that don’t taste salty can still be high in sodium, which is why using taste alone is not an accurate way to judge a food’s sodium content." Some foods that are high in sodium such as pickles and soy sauce taste salty, but many foods such as cereals and pastries contain sodium but don’t taste salty.

The researchers did not analyze the data to find out the source of sodium in the diet, Smith told heartwire.

About 80% of white individuals carry the bitter-taste allele, so the study findings of almost exclusively white participants cannot be extrapolated to the general population, Arnett cautioned. Also, the effect of the variant is fairly small, and many other factors may determine dietary intake.

"We need larger and longer studies to see how this impacts patients," she said, with which Smith agreed.

The study was funded by the University of Kentucky Center for the Biologic Basis of Oral/Systemic Diseases, Centers of Biomedical Research Excellence, National Center for Research Resources, and National Institutes of Health Resources and Services Administration. The authors report no relevant financial relationships.

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