Can you learn to love the foods you hate? - The Food Chain podcast, BBC World Service

Key Concepts

• Food Aversions: Strong dislikes for certain foods, often rooted in sensory, psychological, or learned experiences.
• Neuroscience of Taste and Smell: The brain regions and mechanisms involved in processing food sensations and forming preferences or aversions.
• Amygdala: A brain region crucial for associating sensory properties of food with negative experiences (e.g., malaise), leading to avoidance.
• Insular Cortex & Orbital Frontal Cortex: Sensory regions of the brain involved in processing taste and smell, and integrating multimodal perceptions of flavor.
• Flavor Nutrient Conditioning: A learning process where liking for a new food develops, especially when consumed while hungry and providing energy, due to dopamine-mediated reward signals.
• Neophobia: An adaptive, evolutionary cautious response or fear of new foods or aromas, preventing consumption of potentially harmful substances.
• Multimodal Perception of Flavor: The concept that flavor is a complex perception integrating touch, taste, and olfaction (smell) in the brain.
• Olfaction: The sense of smell, particularly its powerful role in defining the "identity" of a food and influencing liking/disliking, often more so than basic tastes.
• Role Modeling: The influence of parental or caregiver food preferences and behaviors on children's food acceptance.
• Masking Technique: A strategy to overcome food dislikes by dipping the disliked food into a liked food (e.g., ketchup) and gradually reducing the masking agent.
• Top-Down Influences on Perception: How cognitive factors like context, labeling, and visual presentation can alter the brain's processing and perception of a food's flavor.
• Dopamine: A key neurotransmitter involved in learning, motivation, and the brain's reward system, crucial for forming positive associations with food.
• Post-Ingestive Consequences: The physiological effects of food consumption (e.g., energy, nutrients) that influence future liking or disliking.
• Fear-Based Avoidance: Avoiding a food due to a past negative experience (e.g., illness), leading to a conditioned fear response.
• Trust in Food Preparation: The importance of trust in the person preparing food, especially when trying to overcome aversions, to ensure a positive and safe experience.

Understanding and Overcoming Food Aversions

The discussion, hosted by Ruth Alexander, explores the complex nature of food aversions with neuroscientist Dr. Rachel Herz, neurologist Dr. Dana Small, and registered dietitian Clare Thornton-Wood. The central question is whether individuals can learn to love foods they initially dislike.

Personal Food Aversions and Their Origins

The experts share their own food dislikes:

• Dr. Rachel Herz: Inherently dislikes natto (Japanese fermented soybean dish) but believes other dislikes are psychologically induced and retrainable.
• Clare Thornton-Wood: Overcame a dislike for tomatoes but still cannot stand tinned fish (tuna, pilchards, sardines).
• Dr. Dana Small: Dislikes coconut, particularly in sweet liqueurs like Malibu, an aversion that has generalized to other coconut-containing foods and even coconut-scented suntan lotion, attributing this to psychological mechanisms.
• Ruth Alexander: Expresses a strong aversion to prawns, primarily due to their visual appearance (tentacles, tails), despite never having tasted them.

The Neuroscience of Food Likes and Dislikes

Dr. Dana Small explains the brain's role in food preferences:

• Distributed Brain Network: Food likes and dislikes involve a network including sensory regions like the insular cortex and orbital frontal cortex, as well as areas important for emotion and reward. These regions work together to code both sensory experience and the affective (emotional) layer of sensation.
• Role of the Amygdala: For disliked foods, the amygdala is crucial. If a negative experience (e.g., malaise) is associated with a food's sensory properties (e.g., taste of coconut), the amygdala changes its response, leading to avoidance and negative sensations upon future encounters. This effect can be long-lasting.
• Learned vs. Genetic Components: Food preferences are both learned and genetic.
  • Genetic: Individuals can genetically smell or taste certain compounds (e.g., coriander) differently.
  • Learning: A strong learning component begins in utero, with fetuses exposed to the mother's diet. Taste and smell are among the earliest functional senses, influencing preferences into childhood and adulthood.
  • Flavor Nutrient Conditioning: New foods can become liked if eaten when hungry, especially if they are energy-rich. The body's sensing of energy sends signals to the brain's reward system, releasing dopamine, which links the flavor to a positive post-ingestive consequence.

The Powerful Effect of Smell and Flavor

Dr. Rachel Herz highlights the profound impact of smell:

• Visceral Response: Food aromas trigger strong, often unconscious, positive or negative visceral responses.
• Neophobia: A cautious response to new aromas or foods, an adaptive evolutionary mechanism to avoid potentially harmful substances (e.g., "pretty red berry").
• "Flavor is in the Brain": Citing Gordon Shepherd, Dr. Herz explains that flavor is a multimodal perception, integrating touch, taste, and olfaction (smell localized to the mouth). The insular cortex is vital for this integration.
• Olfactory Dominance: After learning, the olfactory component is often more critical than taste in determining food liking. Basic tastes like sweetness or sourness are general, but the specific "strawberry-ness" of a strawberry is primarily an olfactory sensation.

Childhood Influences and Role Modeling

Clare Thornton-Wood emphasizes the significant impact of childhood experiences:

• Innate Sweet Preference: Newborns are naturally drawn to sweet foods (e.g., breast milk, formula). During weaning, parents are encouraged to introduce slightly bitter foods (e.g., sprouts, broccoli) to broaden children's palates.
• Parental Role Modeling: Children easily detect and adopt their parents' food dislikes, making parental attitudes crucial.

Strategies for Overcoming Food Aversions

The discussion presents various approaches to changing food preferences:

1. Psychological and Social Manipulations:

• Perception and Context: Ruth's aversion to prawns is linked to their "creepy crawly" appearance. Dr. Herz draws an analogy to insect consumption in different cultures, where perception dictates acceptance.
• Motivation: Clare Thornton-Wood stresses that motivation is key, especially for children. An example is a teenager who learned to eat pizza to socialize with friends.
• Social Setting: Sharing food with others in a social context can significantly alter perception. The example of spicy food shows that the "burn" of hot pepper, unpleasant in isolation, becomes "delicious" within a food context.
• Top-Down Influences: Dr. Dana Small explains that perception is malleable and shaped by context. The same odor can be disliked as "body odor" but liked as "fine French cheese" due to verbal labeling. Visual presentation (e.g., beautiful plating) and social context also influence acceptance.

2. Sensory Perception Modification:

• Masking Technique: Clare Thornton-Wood suggests dipping disliked food into a liked condiment (e.g., tomato ketchup, mayonnaise, apple sauce) and gradually reducing the amount of the masking agent.
• Adding Ingredients: Modifying the food itself, such as cooking prawns in garlic butter, can change its sensory profile.

3. Learning (Flavor Nutrient Conditioning):

• Hunger as a Catalyst: Dr. Dana Small highlights that eating a disliked food when genuinely hungry enhances its value. The body's sensing of nutrients and energy triggers the brain's reward system, releasing dopamine.
• Dopamine's Role: Dopamine links the food's flavor to positive post-ingestive consequences (e.g., energy). This creates a predictive association, leading to physiological changes (e.g., salivation), increased attention, and motivated behavior, eventually changing pleasure and leading to liking.
• Marcy Pelsa's Study (Monell Chemical Senses Institute): A study on food craving showed that subjects on a monotonous liquid Ensure diet for two weeks initially disliked it but later began to crave it, demonstrating how repeated exposure can lead to preference formation.

Practical Advice for Ruth's Prawn Aversion

Ruth proposes a plan involving a pleasant dining environment (best plate, tablecloth, candles, music), cooking prawns in garlic butter, and eating with a liked person. The experts add crucial elements:

• Be Really Hungry: Dr. Small emphasizes that being hungry will "ramp up the value" of the food.
• Address Fear-Based Avoidance: Clare Thornton-Wood advises that if a dislike stems from a past negative experience (e.g., "dodgy prawn"), it's important to know one can refuse or discreetly spit out the food (using a serviette) to overcome the social conditioning against spitting.
• Visual Modification and Trust: Dr. Herz recommends having a trusted person prepare the prawns, removing visually offensive parts (cartilage, tails, tentacles, "beady eyes"). Trust in the preparer's skills and intent is paramount, as being tricked into eating a disliked food can destroy trust and have the opposite effect.

Ruth's Prawn Tasting Experience

Ruth attempts to eat a prawn, guided by Clare's advice to smell, look, touch the lip, then the tongue, and take a tiny bite, with the option to spit it out. Ruth describes the experience as "quite textural," noting "a bit of a tail or something going down my throat" and "between my teeth," but feels brave for trying.

Conclusion

Learning to love a hated food is a multifaceted process influenced by genetics, brain mechanisms (amygdala, insular cortex), sensory perception (especially olfaction), childhood experiences, and psychological factors like motivation, context, and trust. While there's no single guaranteed method, strategies like flavor nutrient conditioning (eating when hungry), masking, modifying presentation, and creating positive social contexts can facilitate a shift in preference. The journey often involves trial and error, with the ultimate goal of changing the brain's perception of the food from an aversion to an accepted or even liked item.