Salt Promotes Passive Overconsumption of Dietary Fat in Humans123

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Abstract

Background: Excess fat consumption has been linked to the development of obesity. Fat and salt are a common and appetitive combination in food; however, the effect of either on food intake is unclear. Fat taste sensitivity has been negatively associated with dietary fat intake, but how fat taste sensitivity influences the intake of fat within a meal has, to our knowledge, not yet been investigated.

Objectives: Our objectives were, first, to investigate the effects of both fat and salt on ad libitum food intake and, second, to investigate the effects of fat taste sensitivity on satiation responses to fat and whether this was affected by salt.

Methods: Forty-eight healthy adults [16 men and 32 women, aged 18–54 y, body mass index (kg/m2): 17.8–34.4] were recruited and their fat taste sensitivity was measured by determination of the detection threshold of oleic acid (18:1n–6). In a randomized 2 × 2 crossover design, participants attended 4 lunchtime sessions after a standardized breakfast. Meals consisted of elbow macaroni (56%) with sauce (44%); sauces were manipulated to be 1) low-fat (0.02% fat, wt:wt)/low-salt (0.06% NaCl, wt:wt), 2) low-fat/high-salt (0.5% NaCl, wt:wt), 3) high-fat (34% fat, wt:/wt)/low-salt, or 4) high-fat/high-salt. Ad libitum intake (primary outcome) and eating rate, pleasantness, and subjective ratings of hunger and fullness (secondary outcomes) were measured.

Results: Salt increased food and energy intakes by 11%, independent of fat concentration (P = 0.022). There was no effect of fat on food intake (P = 0.6), but high-fat meals increased energy intake by 60% (P < 0.001). A sex × fat interaction was found (P = 0.006), with women consuming 15% less by weight of the high-fat meals than the low-fat meals. Fat taste sensitivity was negatively associated with the intake of high-fat meals but only in the presence of low salt (fat taste × salt interaction on delta intake of high-fat − low-fat meals; P = 0.012).

Conclusions: The results suggest that salt promotes passive overconsumption of energy in adults and that salt may override fat-mediated satiation in individuals who are sensitive to the taste of fat. This trial was registered at the Australian New Zealand Clinical Trials Registry (www.anzctr.org.au) as ACTRN12615000048583.

Keywords

salt
fat
ad libitum food intake
satiation
fat taste sensitivity

Abbreviations

CCK
cholecystokinin
HF
high-fat
HS
high-salt
LF
low-fat
LS
low-salt
PYY
peptide YY

Cited by (0)

1

Supported by the National Health and Medical Research Council (project grant 1043780) and the School of Exercise and Nutrition Sciences of Deakin University, Victoria, Australia.

2

Author disclosures: DP Bolhuis, A Costanzo, LP Newman, and RSJ Keast, no conflicts of interest

3

Supplemental Table 1 is available from the “Online Supporting Material” link in the online posting of the article and from the same link in the online table of contents at http://jn.nutrition.org.