How much caffeine is too much? Two cups of coffee? Maybe three? Or how about the new Tim Hortons extra-large cup size, roughly equivalent to four cups?

Tim Hortons' new 24 oz. cup size launches today across Canada. The extra-large contains approximately 240 mg of caffeine, a Timmies rep confirmed (although some experts have estimated other amounts). When HuffPost Canada asked holistic nutritionist Sandra Vella of Beanstalk Health Inc. if she would welcome the new extra large caffeine rush, she answered with a resounding "no."

"We live in a society where we get more and more... People think they're getting more bang for their buck," she says, "but they're introducing more problems into their lives."

Although Health Canada recommends no more than 400 mg a day, caffeine's negative health effects -- even in moderate doses -- can vary widely depending on the individual, says Dr. Ahmed El-Sohemy, Canada Research Chair in Nutrigenomics and an Associate Professor in University of Toronto's Department of Nutritional Sciences.

"A small amount of caffeine could have acute adverse effects like increasing anxiety, nervousness or jitteriness. In a different individual, the same amount could increase their energy, elevate mood and increase alertness," he says "There is growing evidence that these harmful or beneficial effects depend, to some extent, on an individual's genetic profile."

Other factors include age, body mass, medication use, health conditions (e.g. anxiety disorders), according to the Mayo Clinic. And, of course, the amount of caffeine a person is accustomed to consuming also plays a role.

For instance, if a person regularly consumed the previous extra large, which measured 200 mg in caffeine, a 40 mg bump of caffeine might not have the same dramatic effect it would on a person who typically drinks a small cup. So why the health concern over bigger cup sizes?

After all, caffeine can also have positive health effects, such as reducing the risk of liver disease, and researchers have linked it to a lower risk of depression in women. And Health Canada says healthy adults consuming less than 400 mg daily probably aren't at risk for caffeine's adverse effects, such as hypertension and heart disease. In this respect Tim Hortons is in the clear, unlike some other coffee chains and beverages whose caffeine counts are significantly higher.

Vella's concern is that caffeine consumption is a slippery slope, especially since it can increase levels of the "stress hormone" cortisol.

"It's a catch-22. The more coffee (people) are consuming, the more cortisol they're excreting," Vella says. "And the worse it's going to get and the less they're going to be able to handle stress. So they need more."

An increased intake of caffeine can, in some cases, lead to a host of negative health effects, as it can deplete minerals, lead to dehydration, fatigue, has been linked to certain types of cancer, and can thin out stomach lining, which can lead to leaky gut syndrome, according to Vella.

In this instance, bigger isn't always better and revisiting Tim Hortons small -- excuse us, it's now an extra small -- or choosing a drink with less caffeine, might be just what the nutritionist ordered.

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  • 24 Oz. Cup

    Tim Hortons' <a href="http://www.huffingtonpost.ca/2012/01/16/tim-hortons-releases-larger-cup-coffee_n_1208677.html" target="_hplink">extra-large 24 oz. cup of coffee</a> might be enough for the amateur coffee drinkers, but we're holding our breath until they roll out a keg. <em>Photo credit: Tim Hortons Inc. </em>

  • Espresso-Based Coffees

    Tim Hortons went head-to-head with Starbucks for coffee market domination when it started <a href="http://www.thestar.com/business/article/1079694--tim-hortons-to-offer-real-espresso-at-2-a-cup" target="_hplink">serving up espresso-based coffees</a>, including lattes, mocha lattes and cappuccinos for around $2 or less. <a href="http://www.torontolife.com/daily/daily-dish/caffeine-high/2011/11/16/tim-hortons-espresso-stuart-ross/" target="_hplink">How do they taste</a>? Well, they cost $2. <em>Photo credit: Tim Hortons Inc. </em>

  • Lasagna

    "Would you like some lasagna with your coffee?" we <a href="http://www.huffingtonpost.ca/2011/10/17/tim-hortons-lasagna_n_1016236.html" target="_hplink">asked</a> back in October. Overwhelmingly, the answer was "No," followed by "ewwww." <em>Photo credit: Lisa Yeung</em>

  • Real Fruit Smoothies

    The health craze is lost on some of us, and according to <a href="http://www2.macleans.ca/2011/05/02/smoothie-operator/" target="_hplink">many</a> <a href="http://www.avivaallen.com/General/tim-hortons-real-fruit-smoothies-buyer-beware.html" target="_hplink">many reviews</a>, Tim Hortons didn't quite get it right either when it introduced its Real Fruit Smoothies.

  • Double Double Ice Cream

    "I'll take two creams and two sugars. And hurry, before it melts!" Timmies teamed up with Cold Stone Creamery to concoct the <a href="http://www.huffingtonpost.ca/2011/08/30/tim-hortons-double-double_n_941875.html" target="_hplink">Double Double ice cream flavour</a> back in August, effectively combining one addiction with another.