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According to Scientists, This Is How Much Caffeine You Should Have in a Day

The Perks of Caffeine

You pull up to your favorite coffee shop on the way to work just to discover a long line of other bleary-eyed workers looking to jump-start their day. You might be late if you stop. You probably have coffee available at work, but there’s something about your cozy, inviting and fragrant local grind that starts your day off just right. As quaint as your favorite shop is, at least part of your daily ritual is influenced by the caffeine in your morning brew. Millions of people worldwide use caffeine every day to improve focus and concentration, increase energy, alleviate fatigue and improve wakefulness. It's addictive and a centuries-old practice, but do you ever wonder how much caffeine you should have in a day?

How Much Caffeine Should You Have in a Day?

Most healthy adults can consume up to 400 milligrams of caffeine daily, according to the Mayo Clinic. That equates to four cups of coffee or two sodas and two energy shots. However, your size, weight, and caffeine sensitivity all factor into the equation. Keep in mind that caffeine levels vary greatly depending on the size and product you choose. Four extra-large Big Gulps have a whole lot more caffeine than four standard-size sodas.

In a study conducted by the Institute for Scientific Information on Coffee, researchers suggest that if you’re healthy, caffeine has no adverse effects on you and has some significant health benefits. They report that even pregnant women can safely consume up to 200 milligrams of caffeine a day. They advise that three to five regular cups of coffee or an equivalent beverage is the range that gives you the most health benefits. The touted benefits are:

  • Reduced risk of cardiovascular disease
  • Reduced risk of type 2 diabetes
  • Increased fat loss

Be careful though. These three benefits can be negated by what you put in your caffeinated beverages. Watch the creams, sugars, caramels, and syrups that add flavor to your coffee or tea.

Another study by the US National Library of Medicine lists these additional effects:

  • Decreased reaction time
  • Increased alertness

Surprisingly, the study discovered that while cognitive and mood benefits are often attributed to caffeine, decaffeinated coffee has the same benefits. Researchers found this is due to the other compounds in coffee that interact synergistically with the caffeine. So you may not see these benefits with sodas and other artificial products that have caffeine in them.

A Spotlight on Caffeine Addiction

If you consume any amount of caffeine on a regular basis, you might be addicted. The more you use caffeine, the more caffeine-tolerant you become, which means you need more caffeine to get the same benefits. Just a few hours after skipping your usual dose you may experience:

  • Headaches
  • Sleepiness
  • Irritability
  • Lethargy
  • Constipation
  • Depression
  • Anxiety
  • Muscle pain, stiffness, and cramping
  • Lack of concentration
  • Insomnia
  • Flu-like symptoms

The amount, severity and duration of these symptoms depend on how much caffeine you regularly consume. The higher your daily intake, the more symptoms you are likely to experience and the more severe and long-lasting they may be. How long does caffeine stay in your system? The American Academy of Sleep Medicine says caffeine’s half-life is three to five hours. In that time, half of the caffeine you ingest will be gone, but the other half can take far longer to leave your system.

Janet Ashforth is a freelance writer who is an ACE certified personal trainer and licensed massage therapist. She has worked for many well-known gyms and previously owned her own fitness company. Janet also writes about food, cooking, baking, and nutrition.


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