The effects of junk food on microbiota and mental health

Junk food, omnipresent in our daily lives, seduces us with its addictive taste and accessibility. Yet behind its tempting packaging lie deleterious effects on our health. In addition to promoting obesity and cardiovascular disease, regular consumption of ultra-processed foods has a direct impact on our intestinal microbiota and, by extension, our mental health. Let's decipher together the dangers of junk food and the importance of a balanced diet in preserving our physical and mental well-being.

What is junk food?

Junk food is ultra-processed food, rich in saturated fats, refined sugars, salt and additives, but low in essential nutrients: everything we love but our bodies hate. Among the most commonly consumed are :

• Fast-food burgers, fries and pizzas
• Industrial snacks: potato chips, chocolate bars
• Sodas and energy drinks
• Ultra-processed ready meals (fast, convenient, and anything but good for the microbiota)

Although these foods provide instant pleasure, their repeated consumption can have harmful consequences for our gut microbiota and our brain.

The impact of junk food on intestinal microbiota

The intestinal microbiota, also known as the "second brain", is made up of billions of bacteria that play a key role in digestion, immunity and mood regulation. An unbalanced diet, especially one rich in ultra-processed foods, leads to :

• A reduction in bacterial diversity (dysbiosis), essential for a healthy intestinal balance.
• A proliferation of harmful bacteria to the detriment of beneficial ones.
• Increased intestinal inflammation, which weakens the immune system and impairs brain function.

One study has shown that intermittent exposure to junk food, even for short periods such as 3 days a week for 4 months, is enough to disrupt the gut microbiota and cause alterations similar to those seen with daily junk food consumption.

A direct impact on mental health

The link between the gut and the brain is now well established. An unhealthy microbiota can affect the production of neurotransmitters such as serotonin and dopamine, aka the happiness hormones.

The consequences are manifold:

• An increase in stress and anxiety
• Sleep and attention disorders
• Increased risk of depression and cognitive decline

The ALIMENTAL study, conducted between 2021 and 2023 on more than 20,000 participants, revealed that junk food consumption was associated with a higher risk of depression, particularly in young adults and women after 35.

Why is junk food so addictive?

The combination of excess sugar, salt and fat activates the reward circuit in our brains, releasing dopamine and creating an addictive effect. The more you eat, the more you want! This phenomenon is comparable to an addiction, which explains why it's so hard to say no to a second slice of pizza... or a third... or a fourth.

How can you protect your microbiota and your brain?

- Eat a high-fiber diet: fruits, vegetables, whole grains and legumes.

- Eat probiotics and prebiotics: yoghurts, kefir, sauerkraut, garlic, onions... (we'll forgive the breath if it's for a good cause)

- Limit consumption of ultra-processed foods and favor homemade products.

- Keep your body hydrated by drinking enough water to promote good digestion.

- Adopt regular physical activity, beneficial for intestinal balance and mental health.

Junk food may seem harmless in the short term, but its impact on our intestinal microbiota and our mental health is very real. Reducing consumption and adopting a more balanced diet not only preserves our physical well-being, but also boosts our brainpower and morale.

Why not start pampering your microbiota today? Your body (and mind) will thank you! 😉

By Candice Lhomme