Why do babies and young children prefer bananas to
broccoli and sweets to spinach? Is taste genetically determined or is it
cultivated through early exposures to food? To expound on this
interesting field of the development of babies taste preferences is
Professor Adam Drewnowski, Professor of Epidemiology, School of Public
Health and Community Medicine and Director of Nutritional Sciences
Program at the University of Washington, USA.
by Prof Adam Drewnowski
The following are some questions and his answers on this subject:
1. Are babies born with a mature taste bud? Please elaborate on the development of the sensory system.
The sensory system is pretty much complete by the time of birth. Taste buds mature by the last trimester of pregnancy. Newly-born
babies react to sweet, sour, and bitter tastes - but not so much to
salt. Some researchers believe that prenatal exposure to food odors,
derived from foods consumed by the mother in the course of pregnancy,
can influence future food preferences and eating habits. It is never too
early to surround the baby with positive and rewarding taste
2. What are the taste preferences of babies? Why are babies born with an innate liking for sweetness?
Babies like sweet and dislike bitter tastes. This can be read from
their facial expressions. A drop of sweet taste on the tongue makes the
baby smile and relax. Sweetness is nature's way of announcing that the
food is rich in calories and good to eat. The babies' feeding response
is driven by sweetness and babies quickly learn to consume sugar
solutions in preference to plain water. Sweeter sugars such as sucrose
are preferred over less sweet sugars, and intensely sweet solutions are
liked the best.
3. It is a known fact that the preferred level of sweetness in food differs across cultures. Why is that so?
Taste preferences for sweetness are maximal in infancy and childhood
and progressively drop during adolescence and adult life. Children adore
foods that would be much too sweet for adults. Children also select
foods that are more energy-dense than do adults, and hence their passion
for candy and chocolate.
So the basic liking for sweetness is an
innate human trait. The preferred level of sweetness is determined
first by age and only then by culture. Those cultures that did not have
cane, beet, or corn sugar in their staple diet are only now getting used
to increasing level of sweetness in food. I believe that the amount of
sugars in the diet is likely to increase; it is an inexpensive source of
4. Why do humans naturally reject the bitter taste of food?
Humans equate bitter taste with dietary danger, and rightly so. Plant poisons, toxic metals, spoiled proteins, and rancid fats all have an unpleasant bitter taste. The real puzzle is why so many unrelated
compounds can give rise to a single taste sensation - bitter. This is
probably nature's way of making sure that bitter is the main alarm
signal. It turns out that we may have as many as 80 different taste
receptors for bitter, as compared with only 2 or 3 for sweet. From the
evolutionary standpoint, avoiding bitter toxins is the most important
thing of all.
5. What are the factors that determine our taste preference from young? Do genes play a part as well?
Sensitivity to some bitter compounds - and there are so many - is a heritable trait. We have done studies with a compound called
6-n-propylthiouracil or PROP that is extremely bitter to some people but
is tasteless to others. Sensitivity to PROP correlates well with
sensitivity to some, but not all, bitter tastes. People who dislike PROP
also dislike caffeine and grapefruit juice, but may not be bothered by
other bitter foods.
6. Does taste sensation alter at different stages of life? If so, is it due to hormonal or other causes?
Sensitivity to bitter is highest at two critical life stages:
pregnancy and early life. Babies and pregnant women are most vulnerable
to bitter toxins and are most likely to avoid bitter foods. In the US,
aversions to coffee are very common among pregnant women. And as we all
know, babies and young children dislike bitter vegetables and even
bitter chocolate. Preferences for bitter and bittersweet chocolate are
very much related to age.
7. Please elaborate why most children dislike vegetables,particularly those that do not taste sweet, such as broccoli. How can we
overcome this natural dislike for such vegetables?
Vegetables strike out on two counts. They are bitter and they do not provide sufficient calories per unit volume to make them attractive to children. Remember that growing and active children have higher energy needs than do adults and must consume energy-dense foods. There is just
no way to pack enough calories into a dish of broccoli.
Here is where gastronomy comes to the rescue. Vegetables are usually prepared with fat, sugar or salt. They are sautéed, stir-fried, baked or braised. Adding fat, sugar or salt is a very effective way of minimizing bitter taste. Scientists are still figuring out how some tastes suppress each other and how bitter is suppressed by sweet. Of course, adding sugar or fat also increases energy density. But
the major thing is that vegetables ought to taste good - bitter glucosinolates in broccoli can be neutralized by the addition of sauce.
8. Some young children tend to be very selective in their choice of food and eat only those that they are familiar with. Is this normal or should it be a concern for mothers?
The babies' taste world is driven by only two things: bitter and sweet. In addition, foods that are familiar are preferred overthose that are not. The introduction of new foods, whether liquid or solid, should increase the range of food preferences. Some studies tried to expose young babies to the taste of garlic. However, in practice it is perfectly normal for babies and young children to stay with foods that are both familiar and sweet.
9. How does zinc play a role in taste acuity?
Some studies have linked zinc deficiency to taste abnormalities.
Clinical studies showed that ageusia (no taste) and dysgeusia
(persistent bad taste) could be treated with zinc supplementation.
However, most zinc deficient patients are also elderly, and zinc
deficiency is often the outcome of drug-drug interactions. So it is not
always clear if taste deficits are the result of aging, disease or drug
treatment. Among healthy older adults, few taste deficits are observed.
For the most part they involve bitter taste - we get to like broccoli as
we get older.
All content on this Website is provided solely for informational purposes and
is not intended as a substitute for medical and/or other professional advice
for your specific condition. Please do not disregard medical and/or other
professional advice or delay seeking it because of something you have read on
this Website. Always seek medical advice before starting any new treatments.