Amount of Evidence: High Potential Benefits: Reasonable Safety: Very High
TABLE OF CONTENTS
What is decaffeinated coffee?
Coffee is the most popular stimulant in many western countries. The decaffeinated form contains only about 2 mg of caffeine per cup and almost the same amount of polyphenols as regular coffee, which makes it a great choice if you love the taste of the beverage or you are trying to get the benefits of coffee without ingesting too much caffeine. In this article, we will look at the main benefits and side effects of decaffeinated coffee, and how to drink it the right way.
Potential benefits
It is important to note that all of the potential benefits mentioned below are dose-dependent. In general, the higher the dose you take, the more pronounced the effects will be. However, they do reach a plateau at a certain point. We will discuss how much decaf coffee to consume later in this article.
Also, there are many additional benefits and side effects associated with coffee that have to do with caffeine. The benefits mentioned below in this article are specifically related to coffee without caffeine.
Major benefits
Reduced inflammation – Coffee appears to decrease some inflammatory cytokines.
Fat loss – Unfortunately, this effect is not as strong or reliable as some people claim it to be. Regular coffee appears to be quite effective for fat loss but that seems to be because of the combination of polyphenols and caffeine.
Antioxidant effects – The polyphenols in decaffeinated coffee have been shown to decrease oxidation in the body. This is probably the main reason why coffee appears to lower the chance of cancer.
Minor benefits
Improved skin quality – A high intake of coffee polyphenols leads to an improvement in skin quality. Specifically, they are able to reduce acne.
Improved cholesterol levels – The polyphenols in decaf coffee have been shown to increase HDL cholesterol but do not appear to lower LDL cholesterol.
Improved dental health – Decaf coffee has been shown to have anti-microbial properties and can specifically protect your gums.
Reduced muscle soreness – This benefit is most notable if you overtrain or if you are a beginner at resistance training.
Increased blood flow – While the effect is not significant, the antioxidants in decaf coffee have been shown to increase blood flow.
Increased longevity – The polyphenols in decaf coffee (and coffee in general) have been associated with an increase in longevity in animal studies. Unfortunately, there are not enough human studies yet to know what the effect of these polyphenols is as far as slowing down aging.
Increased insulin sensitivity – Decaf coffee has mixed effects on insulin sensitivity but in general, it usually leads to an increase. This effect is most notable in unhealthy people with insulin resistance. Polyphenols in coffee have been linked to a reduction in fasting blood glucose levels but not fasting insulin levels.
Lowered blood pressure – The polyphenols can greatly reduce blood pressure, especially the blood pressure increase from caffeine.
Increased cognition – This effect is most notable in people with those who have a poorer cognition at baseline.
Protection from DNA damage – Coffee has been shown to reduce DNA damage. This effect appears to be most notable in unhealthy individuals, such as diabetics.
Lowered heart rate – This effect is likely caused indirectly and appears to be a byproduct of coffee’s ability to burn fat and lower blood pressure.
Metal chelation – The polyphenols in decaffeinated coffee can act as metal chelators and can help you detoxify from heavy metals.
Reduced iron absorption – Decaf coffee can lower iron absorption by around 10-30%. This can be seen as a benefit for those who have too much iron in their bloodstream, which is just as common (if not more common) as iron deficiency.
Increased well-being – Unfortunately, this effect has only been noted in unhealthy individuals. It may, however, apply to healthy people as well.
Unproven benefits
The effect of decaffeinated coffee on these parameters is either not sufficiently researched or the science shows little to no efficacy in these areas.
Metabolic rate – The polyphenols in decaffeinated coffee have not been correlated with increased metabolism. Coffee itself leads to a small increase in metabolism but that mostly has to do with caffeine, not the polyphenols.
Estrogen – There doesn’t seem to be any significant connection between decaffeinated coffee and estrogen levels.
Triglycerides – No influence on fasting or postprandial triglycerides was ever noted.
Bone health – Decaf coffee does not significantly influence bone mineral density.
CRP (C-reactive protein) – No strong connection between coffee and CRP has been observed.
Liver health – The evidence is somewhat weak in this regard. However, there is at least some amount of data that shows coffee may be beneficial for liver health in the long term.
Possible side effects
These side effects are dose-dependent and the risk for them increases (most often linearly but sometimes exponentially) as the dose is increased. Some of the side effects are relevant only at very high doses.
Decreased absorption of certain minerals – The polyphenols in decaf coffee worsen the absorption of iron by 10-30%, which may and may not be a concern to you. Since a somewhat high percentage of people are deficient in iron, you may want to avoid decaf coffee close to your meals to minimize this effect, especially if you are experiencing signs of iron deficiency. On the other hand, this effect can also be viewed as a benefit since many people have too much iron in their bloodstream, which can lead to iron toxicity and faster aging.
Nausea – Large amounts of decaf coffee can cause nausea. This is the most notable short-term side effect for most people. Nausea caused by decaf coffee is not linked to stomach damage.
Diarrhea – This effect can happen even at relatively low doses and varies from person to person. It is, however, not as common for decaf coffee as it is for regular coffee.
Who should not drink decaf coffee?
You should probably avoid drinking decaffeinated coffee if you:
suffer from an iron deficiency – The polyphenols in coffee have been shown to decrease the absorption of iron by 10-30%.
Who will benefit the most?
You should definitely consider drinking decaf coffee if you:
love the taste of coffee but do not want to take in the caffeine
have iron overload – coffee polyphenols can help you flush the excess iron out of your system.
How much decaf coffee can you drink?
Since decaffeinated coffee only contains around 2 mg of caffeine per cup, that is not something you have to worry about. You can drink as much decaf coffee as you want and it is not going to cause caffeine-related problems to any notable extent.
What we want to look at instead is how many cups of decaffeinated coffee will allow you to get most of the health benefits.
In general, 3 cups of decaf coffee are usually enough to derive most of the benefits. However, the benefits do not seem to plateau even if drink more than 5 cups a day.
While you could probably derive slightly more benefits from drinking more than 5 cups a day, it is by no means necessary and the benefits per cup will not be as significant then. As far as health goes, 3-5 is more than enough. If you wish to drink more because of the taste, definitely feel free to do so.
It is important to note that the effects of decaf coffee and the polyphenols in it are cumulative. Therefore, you need to take it on regular basis to notice long-term benefits.
Best time to drink decaf coffee
The time of the day you drink decaffeinated coffee doesn’t matter. However, there are two rules you need to follow:
1) Drink it on an empty stomach if you can (food worsens the absorption of the polyphenols in coffee). 2) Do not drink decaf coffee too close to your meal (because it can decrease the absorption of iron).
Also, if you consume caffeine, it is best to drink decaf coffee with it since the polyphenols in decaf coffee have a synergistic effect with caffeine.
Interactions with supplements
Caffeine The polyphenols in decaf coffee negate some of the potential side effects of caffeine. The combination also appears to be quite effective for fat loss and a few other effects.
Vitamin C Vitamin C appears to enhance the absorption of polyphenols in decaf coffee. It can also protect iron from becoming less bioavailable after you consume coffee polyphenols.
Ubiquinone Ubiquinone (a metabolite of CoQ10) increases the anti-oxidative effects of many polyphenols. Antioxidants in decaf coffee also increase CoQ10’s ability to protect the liver during reserpine toxicity.
Turmeric This combination appears to be very effective at preventing or slowing down the growth of colon cancer.
Iron Since decaf coffee and the antioxidants in it inhibit the absorption of iron by around 10-30%, they may increase your iron needs. If you notice a sign of deficiency or are prone to it, you may want to increase your iron intake and supplements are one way to go. Do not take iron together with coffee or its antioxidants though, so the absorption isn’t decreased. Also, do not take this as a call to action to start taking iron if you are not deficient because some people tend to have too much iron in their system. Excess iron in the blood can also lead to health complications.
L-Theanine This combination may protect you from cognitive decline to some extent.
Quercetin Quercetin can increase the absorption of coffee polyphenols.
Soy isoflavones The combination seems to lead to AMPK activation, which may have a positive effect on increasing lifespan.
Whey protein Whey protein negates many of the beneficial effects of coffee polyphenols.
Where to buy decaf coffee
Amazon seems to be the best option for ordering decaffeinated coffee in most countries. They offer some very affordable products that are backed by many positive reviews. Also, you can choose from a wide range of brands there without having to spend time searching through other markets on the internet.
FAQ
It is not yet known if you develop a tolerance for decaf coffee and its polyphenols over time. For this reason, it is best to cycle the coffee and not take it every once in a while. For example, you can take it on weekdays and not take it during the weekend.
Yes, there is only 2 mg of caffeine in an average cup, which will not impact your sleep in a notable way. The polyphenols in decaf coffee do not impact your sleep in any negative way either.
Decaffeinated coffee can lose potency over time.
Keep your decaf coffee in a cold, dark, and dry place and they will remain just as potent for many years.
In the short term, the peak plasma concentrations of the polyphenols are reached around 1-2 hours after you ingest coffee. After that, the concentrations start slowly diminishing until they become undetectable, which usually takes around 24 hours.
In the long term, it takes around a month to start noticing the benefits of decaf coffee. It is important to note that the effects of decaf coffee are cumulative. Therefore, you need to take it on regular basis to notice long-term benefits.
Decaffeinated coffee is extremely safe, assuming you don’t have an iron deficiency. If you do, the polyphenols in coffee can worsen it and deplete you of iron even further.
No, it is perfectly fine to drink coffee during a fast. In fact, the antioxidants in it are actually going to increase some of the benefits of fasting. One caveat is that drinking decaf coffee with sugar or milk in it would certainly break a fast.
References
Most of the information provided in this guide is based on scientific research that can be found and verified in the PubMed medical library. We excluded from consideration studies that are either confounded or have a high conflict of interest.
Anecdotal evidence (from reports on Reddit, YouTube, and other sources) is also taken into account unless it contradicts scientific research.
