Thinking Nutrition

Coffee and its surprising health benefits

• Dr Tim Crowe • Episode 4

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Coffee. For some, it is deserving of its own essential food group. But is coffee more than just a way to achieve functioning human capacity first thing in the morning? You may have seen media headlines in the past warning about health risks of coffee. But now that the science has matured, coffee turns out to be one of the most surprisingly positive health stories of recent years. Forget about the latest superfood trend, coffee is where it is at. In this podcast, I’ll look closer at those health benefits and give you the validation you’ve been seeking to justify your caffeine habit.

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Coffee. For some, it is deserving of its own essential food group. But is coffee more than just a way to achieve functioning human capacity first thing in the morning? You may have seen media headlines in the past warning about health risks of coffee. But now that the science has matured, coffee turns out to be one of the most surprisingly positive health stories of recent years. Forget about the latest superfood trend, coffee is where it is at. In this podcast, I’ll look closer at those health benefits and give you the validation you’ve been seeking to justify your caffeine habit.

Do you hear that sound? It’s one familiar to coffee lovers the world over. Nothing says happiness better than a bustling coffee shop with a barista hard at work plying their trade.

Coffee, brew, black gold or go juice. Whatever you call it, coffee is the world's second most popular beverage after tea. It has been estimated that over 2.2 billion cups of coffee are drunk each and every day.

So just what’s in your daily brew? Coffee contains a number of useful nutrients, including riboflavin, niacin, magnesium, potassium, and various antioxidants as well as a bunch other natural plant chemicals. In fact, one estimate has found that the typical Western diet provides more antioxidants from coffee than it does from fruits and vegetables combined. Hmmm…maybe time to replace the odd cup with a smoothie perhaps.

And then of course, there’s the caffeine. Caffeine is the most consumed psychoactive substance in the world – and I’m taking both legal and illegal here. Soft drinks, tea and chocolate all contain caffeine, but coffee is the biggest source.

Caffeine is a stimulant. In your brain, it blocks the function of an inhibitory neurotransmitter called adenosine. By blocking adenosine, caffeine increases activity in your brain and releases other neurotransmitters like norepinephrine and dopamine. This reduces tiredness and makes you feel more alert. That all means that caffeine can lead to a short-term boost in brain function, improving mood, reaction time, vigilance and general cognitive function. But any regular coffee drinker knows this already.

Coffee has been around for a long time and has often been maligned for many health ills — from stunting your growth to causing heart disease — but recent research shows that it may actually have many health benefits. Coffee is also a good example of how conflicting nutrition research gives mixed messages to the public. One day coffee is reported as being good for us, and the next day it is harmful. All the while, people continue to switch off to such conflicting reports and keep on enjoying their favourite coffee beverage of choice as part of their morning routine.

Fortunately, now that the research has really matured, we’re in a good position to see how the health ledger stacks up for coffee. The potential health benefits of coffee have been outlined in a major scientific review published in 2016 which I’ll link to in the show notes. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/773949

The review looked at over 1200 individual studies where coffee was studied in regards to any positive or negative health effects. The big ones included cancer, heart disease, type 2 diabetes, liver disease, neurological disorders and longevity and each was picked apart to see what the research said about coffee.

And after all that analysing and synthesising, what was the conclusion? The health benefits of moderate coffee consumption clearly outweighed the risk in almost all of the health outcomes looked at. A definition of moderate here was considered 3-4 cups of coffee a day – that definition of moderate agree with me a lot.

Going a bit deeper into the diseases looked at in the review. For T2DM, it has been seen that coffee drinkers may have up to a two-thirds reduced risk of developing this condition. One review of 18 studies involving almost half-a-million people found that for each daily cup of coffee, it was linked with a 7% lower risk of type 2 diabetes. And that was after making allowances for other lifestyle habits that regular coffee drinkers had that non-drinkers did not.

Coffee appears linked to a reduced risk of some cancers too. Coffee decreases the risk of liver and endometrial cancer with the level of evidence set at ‘probable’ by the World Cancer Research Fund. There is also some suggestive evidence that coffee can lower the risk of cancer of the mouth, pharynx and larynx as well as even skin cancer. And no concerns were made about it raising the risk of any cancer. https://www.wcrf.org/dietandcancer/exposures/non-alcoholic-drinks

Coffee also is linked to longevity with regular drinkers living longer although it is hard to put an exact number of years on it. Looking at particular causes of death, it seems coffee drinkers are less likely to die from infections, injuries, accidents, respiratory disease, diabetes, stroke and heart disease. Decaf coffee appears to have favourable benefits too so it’s likely not all to do with the caffeine, but a combination of all the antioxidants and other natural chemicals found in coffee working together that is giving the benefit.

Parkinson’s

Then we have neurologic diseases where the news looks promising. To start with. coffee drinkers are known to have up to a 60% lower risk of developing Parkinson's disease. And people who drink coffee may also be less likely to experience depression and conditions such as Alzheimer's. So, there seems a common link here with coffee having a favourable benefit on the neurologic system.

As an aside, extending the work done finding coffee is linked to reducing the risk of PD, one small clinical trial has found that people with Parkinson’s disease given a daily dose of caffeine gained improvements in their movement symptoms. Because of how caffeine works in the body, scientists have thought that it could have a potential benefit in controlling some of the symptoms of Parkinson’s disease such as daytime lethargy and drowsiness as well as muscle effects of poor coordination, muscle soreness and shakiness.

Researchers from McGill University gave people with PD a placebo pill or a 100-milligram caffeine tablet (equivalent to a strong cup of coffee) twice a day for 3 weeks and then increased to 200 milligrams twice a day for the following 3 weeks. I’ll link to the study in the show notes. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3414662/

The big improvement seen in the caffeine group was in motor symptoms, with a noticeable improvement in speed of movement and less muscle stiffness. This first study looking at caffeine dosing and Parkinson’s disease has provided some interesting results which will fuel future research. If validated in larger clinical studies, then caffeine, or the coffee it is found in, could become a cheap and very safe treatment for some of the symptoms of Parkinson’s disease.

Sport

Moving out of the world of health and into that of sport and human performance, coffee has a special place thanks to its caffeine content. Caffeine is one of the few sports supplements that have quality scientific evidence to support a real-world sports-performance benefit.

There is good evidence that caffeine enhances endurance and provides a small, but worthwhile, enhancement in performance over a range of exercise protocols from short-duration high-intensity events to endurance events. One estimate equates its benefit to ­ing time to exhaustion to about ~3%. In the world of elite sport, this is a huge benefit.

Caffeine works in sport because it acts as a neuromuscular stimulant where it can change perception of effort meaning it is possible to work at a higher rate for longer. It can also alter neurotransmitter function and increase in motor unit recruitment and muscle contractility so more power is available.

Initially it was thought caffeine worked because it ↑ed fat oxidation and could spare glycogen, but these effects are not universal and likely not important in overall performance effects.

And any concerns about its effect on hydration are very much over-stated as regular coffee and caffeine consumers do habituate to caffeine over time and any diuretic effect is normally offset by the fluid that it is consumed with it.

Caffeine is effective at quite low disease – around 3 mg/kg. To put that in context, for a 70kg athlete, that is the equivalent of about 2 cups of coffee. Caffeine is rapidly absorbed by most people with peak blood caffeine at around 45-90 mins following ingestion so it is taken on shortly before an event.

SDA have a great fact sheet on caffeine as well as a table with the caffeine content of a whole range of foods and beverages. No surprise that coffee comes out at the top of the list. I’ll link to the fact sheet in the show notes. https://www.sportsdietitians.com.au/wp-content/uploads/2015/04/110721-Caffeine-Fact-Sheet_SD-Version.pdf

Not everybody responds the same to caffeine and there is some evidence that this could be because of genetics where the presence or absence of a specific gene – called CYP1A2 - can mean a person is either a rapid or slow metaboliser of caffeine.

Health risks

But it’s not all good news when it comes to coffee, so I do need to talk about some the down sides and health risks. Drinking too much caffeine can lead to jitteriness, anxiety, heart palpitations and even exacerbated panic attacks. So, if you are sensitive to caffeine and tend to become overstimulated, you may want to avoid coffee altogether. Then there is the insomnia so cutting back on coffee, especially after 2pm, is an important part of good sleep hygiene if you suspect it could be keeping you up at night.

Caffeine can also have a blood pressure-raising effect and this spike seems to be stronger in people prone to high blood pressure and who don’t normally drink a lot of coffee. But these acute effects wear off after around 4 hours. What’s less clear is caffeine’s long-term effects on blood pressure. The overall long-term effects are inconclusive, but if you do have high blood pressure, it would be best to not over-indulge your caffeine habit.

For women who are pregnant, please take special note with a recent scientific review of many studies finding a 37 percent higher risk of miscarriage in women who consume more than 300 mg of caffeine a day. I’ll link to the study in the show notes.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5733907/

A link between caffeine and the risk of miscarriage has been known for some time which is why FSANZ advises that for pregnant and breastfeeding women daily caffeine consumption should not exceed 200mg. This is in contrast for to non-pregnant adults where 400 mg per day is considered unlikely to cause any harm. This advice mirrored by similar European and US regulatory bodies that advise that during pregnancy no more than 200 mg of caffeine, that’s about 2 cups of coffee, should be drunk per day.  

For regular coffee drinkers, there is likely little to be concerned about when seeing reports of a single research study indicating coffee is not so good for health; the weight of evidence points to coffee being a healthy habit for adults with the overall weight of science saying it will be doing your health more good than harm. It’s not a reason to start drinking coffee if you’re not partial to it, but for everyone else, keep calm, keep caffeinated and carry on.

Question

And to finish up I’d like to address question that came through sparked by my previous episode on IF. It came from Amanda who put her question into her Apple Podcast review – thanks for the positive review Amanda! She asked if being an active adult who is training for a triathlon who is thinking of trying IF for the potential metabolic benefits, if could impact her training. Great question, so my thoughts on this:

From a research perspective, there is little out there unsurprisingly on IF or TRE in athletic training. And on the surface, some of the principles of IF do seem to go against the core sports nutrition concepts of refuelling and spreading food intake (especially protein) over the day. But in fact, there could be some benefits from ‘training low’ at times where CHO especially is limited to promote favourable fat adaptation. This is offset by going ‘training high’ for high-quality training sessions and race day where peak performance is needed and where you would revert back to standard feeding regimens. So, IF could fit within into this type of protocol if it was periodised.

A 2019 review on this very topic of IF and athletic performance which I’ll link to in the show notes concluded that there is probably no great benefit to athletic performance while fasting. But everyone’s mileage is different here and your own performance will would be the best guide. This is separate though to using IF for weight loss to help improve power-to-weight ratio in a sport where a performance benefit would be likely, but IF is just one in a long-line of ways to achieve weight loss.  https://journals.lww.com/acsm-csmr/Fulltext/2019/07000/Intermittent_Fasting_and_Its_Effects_on_Athletic.6.aspx 

So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on if it supports it, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.

If you find this podcast of value, then please consider sharing it with your friends and colleagues. Or maybe even leave a review. This all helps increase the ranking and reach of the podcast which means a big win for credible evidence-based nutrition messages while helping to dilute out the crazy and making the world a slightly less confusing place.

I’m Tim Crowe and you’ve been listening to Thinking Nutrition.

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