Excessive intake of coffee can pose health risks, such as:

1. General Toxicity:

   • A lethal dose is estimated at 10g for a 65kg adult, but fatalities from as low as 6.5g have been reported. Common signs of caffeine toxicity include nervousness, irritability, insomnia, and heart palpitations.

2. Cardiovascular Effects:

   • Consumption exceeding 150mg may reduce heart rate, raise cholesterol, and increase blood pressure. Drinking more than four cups per day may elevate the risk of heart disease, though moderate intake (under 400mg/day) shows no significant impact on cardiovascular health.

3. Bone Health and Calcium Loss:

   • Caffeine increases calcium excretion through urine. Consuming over 760mg of caffeine (more than 1000ml of coffee) per day can lead to calcium loss, potentially increasing the risk of bone fractures.

4. Behavioural Changes:

   • Moderate caffeine consumption has been linked to improved memory, reaction time, and mental alertness. Higher doses may reduce tiredness but also lead to anxiety or irritability.

5. Cancer Risk:

   • While coffee contains acrylamide, a potentially cancer-causing substance, no strong evidence links moderate coffee consumption to increased cancer risk in humans. On the contrary, some studies suggest that coffee may reduce the risk of certain cancers like liver and endometrial cancer.

6. Fertility and Pregnancy:

   • Women: Caffeine intake over 300mg/day may affect conception, possibly due to hormonal changes or conditions like endometriosis.
   • Men: Caffeine levels above 400mg/day may reduce sperm motility in heavy smokers but generally does not affect male fertility.