Caffeine is a widely consumed stimulant found in many beverages and foods. The effects of caffeine on the body, particularly in the context of gut health and in eating disorder recovery, raise important questions. This blog post delves into the current guidelines on caffeine consumption, caffeine content in common foods and drinks, its effects on the body, and considerations for those recovering from eating disorders.
What Are the Guidelines on Caffeine?
Currently there are no specific guidelines for caffeine intake in the UK, other than recommendations for pregnant women (up to 200mg/day). However, the FDA and other health organisations worldwide suggest that moderate caffeine consumption can be safe for most adults. The general recommendation is up to 400 mg of caffeine per day, which is equivalent to about four 250ml cups of instant coffee. However, individual tolerance can vary widely due to factors such as genetics, age, and overall health.
How Much Caffeine Is in Usual Drinks and Food?
Understanding the caffeine content in common beverages can help us to manage our intake effectively.
- Instant coffee (250ml): 80-100 mg
- Double espresso (60ml): 125 mg
- Cup of tea or green tea (250ml): 75 mg
- Energy drinks (250ml): 80 mg
- Coke can (330ml): 34 mg
- Diet coke can (330ml): 46mg
- Dark chocolate (50g): 25mg
- Milk chocolate (50g): 10 mg
The Effects of Caffeine in the Body
Caffeine stimulates the central nervous system, leading to increased alertness and reduced fatigue. However, its effects can also include:
- Diuretic effect: Some evidence has suggested that caffeine intake can increase urine production. However, a 2015 meta-analysis of controlled studies found a small effect of caffeine on diuresis. The diuretic effect of caffeine was found to be more prominent in females than males. Interestingly, it also found that exercise negated the diuretic effect of caffeine.
- Increased blood pressure: The current evidence relating caffeine to increased blood pressure is mixed. There is more robust evidence suggesting that caffeine acutely increases blood pressure, but the chronic implications are not certain.
According to NICE guidelines, in individuals with hypertension, excessive consumption of caffeine is discouraged. - Sleep disturbance: Consuming caffeine late in the day can disrupt sleep patterns, contributing to fatigue and decreased cognitive function. Check out our last blog post on Creating a restful bedtime routine: can diet have an impact?
- Anxiety – because caffeine can increase some people’s heart rate, this can feel like anxiety or a panic attack. So reducing caffeine containing drinks and switching to de-caf can be useful.
Does It Affect Our Gut Health?
Caffeine can influence gut health in several ways:
- Gut motility: Caffeine has been found to be a common trigger of diarrhoea in up to 40% of IBS patients. It is thought that caffeine may increase gastrointestinal motility, which can lead to quicker transit times. However, the evidence at present comes from observational studies, therefore we cannot draw concrete conclusions from the current evidence base.
- Gastric acid production: Caffeine may also stimulate gastric acid secretion, which could aggravate conditions like gastroesophageal reflux. NICE guidelines state that whilst caffeine has been found to be a trigger for acid reflux in some individuals, it is not advised that people suffering with acid reflux should stop consuming caffeine as the current evidence is not sufficient.
- Microbiome influence: Some studies suggest caffeine may have a modulating effect on gut microbiota, potentially impacting overall gut health, though more research is needed in this area.
Understanding these effects is crucial if you have existing gastrointestinal issues.
What About in Eating Disorder Recovery – Should We Have Caffeine or Not?
For individuals recovering from eating disorders, the decision to consume caffeine should be approached with caution:
- Anxiety and Stress: Many individuals with eating disorders experience heightened anxiety. Caffeine may exacerbate these feelings, making it advisable to limit intake during recovery.
- Nutritional Considerations: Caffeine may suppress appetite in some individuals, which could complicate recovery efforts aimed at normalising eating patterns.
- Caffeine containing drinks, such as coffee, can be made up with a lot of milk, which can be a helpful source of calcium.
Ultimately, the decision to consume caffeine should be personalised, ideally made in consultation with a dietitian who understands your unique circumstances and recovery goals.
In Summary…
Many people around the world consume caffeine, but its effects on the body, gut health and recovery from eating disorders warrant careful consideration.
With that said, caffeine is present in many foods and beverages that we enjoy with friends and family and is present in many different cultures and activities.
Remaining mindful of the potential impacts of caffeine is important, as it allows us to make informed choices that support our overall health and well-being but should be balanced with enjoyment.
And if you would like more personalised advice, feel free to book in with us here.
Written by: Aishah Angell (Registered Dietitian) and reviewed by Jennifer Low (Registered Dietitian)
References
- British Dietetic Association. (2019). “Coffee and Health; it’s not just about the caffeine”
- British Heart Foundation. “Am I drinking too much caffeine?”
- Correa M, SanMiguel N, López-Cruz L, Carratalá-Ros C, Olivares-García R, & Salamone J. D. (2018). “Caffeine modulates food intake depending on the context that gives access to food: comparison with dopamine depletion.
- Food standards Australia and New Zealand. (2023). “Caffeine”
- NHS. (2024). “Foods to avoid in pregnancy”.
- NICE. (2023). “How should I manage a person with hypertension?”
- NICE. (2023). “How should I manage a person with proven GORD?”
- Rosa F, Marigliano B, Mannucci S, Candelli M, Savioli G, Merra G, Gabrielli M, Gasbarrini A, Franceschi F, Piccioni A. (2024). “Coffee and Microbiota: A Narrative Review.”
- U.S. Food and Drug Administration (FDA). (2024). “Spilling the Beans: How Much Caffeine is Too Much?”
- Varney J. Monash University. (2017). “Does caffeine affect IBS symptoms?”
- Zhang Y, Coca A, Casa DJ, Antonio J, Green JM, Bishop PA. (2015). “Caffeine and diuresis during rest and exercise: A meta-analysis”.