The Sixth Sense for Fat

In medical school I learnt that we have four senses of taste: sweet, sour, salty, and bitter.

Several years ago a fifth sense, umami, was officially added to this list. Umami is stimulated by glutamate (as in MSG) and apparently allows us to taste protein (as in meat, sea food, or cheese).

Now, Jessica Stewart and colleagues from Deakin University in Australia show that a sixth sense, i.e. the ability to orally “sense” the fat content of foods may explain differences in fat preferences (British Journal of Nutrition).

Indeed, previous studies in animals have suggested that oral hypersensitivity to fatty acids (the building blocks of fat) are associated with decreased fat intake and body weight.

In the current study, the investigators first examined the taste thresholds for different types of fatty acids (olate, linolate, and laurate) in 31 normal weight subjects and classified them as hypo- or hypersensitive. Subjects also completed a fat ranking task using custard containing varying amounts (0, 2, 6 and 10 %) of fat.

Hypersensitive subjects reported lower energy and fat intakes, had an increased ability to rank the custards based on fat content and also had a lower BMI levels.

These data suggest that the increased ability to detect nutritional fat may result in lower energy and fat intake, which in turn may result in lower body weights.

Obviously, the idea here is that people who are less sensitive to fat are likely to need more fat in their foods to get that same level of enjoyment as people with more sensitive fat receptors. Because of fat’s high caloric content, this means that they may in the end also end up with more calories, and thus, weight gain.

I can think of a number of interesting questions that these findings may prompt:

1) Is the increased ability to taste fat genetic or are changes in fat-sensitivity determined by habitual fat intake (gustatory plasticity)?

2) Does weight loss affect people’s ability to taste fat (resulting in them searching out fattier foods when on a diet)?

3) Does going on a low fat-diet increase fat sensitivity thereby allowing people to get the same pleasure out of low-fat foods?

4) Can we develop artificial compounds that can stimulate the fat receptors thereby mimicking a higher fat content of foods (like we do with artificial sweeteners)?

Lots of interesting questions, which may not only explain why some people derive more pleasure from fatty foods than others but also open new possibilities for the food industry to manipulate the taste of foods (hopefully to our benefit).

I’d love to hear from my readers regarding their thoughts on “tasting” fat.

Edmonton, Alberta