Coffee is made from roasted coffee beans and can be enjoyed in many different ways, such as with cream or milk, sugar or sweetener, or just plain black. Coffee plants are cultivated in over 70 different countries worldwide. Green (unroasted) coffee beans are one of the most traded agricultural commodities in the world. The earliest credible evidence of coffee-drinking appears in the middle of the 15th century, in Yemen, Sufi shrines, in southern Arabia. Coffee is a complex mixture which has more than 800 volatile compounds, whereas caffeine and chlorogenic acids are the most common compounds. The health-promoting properties of coffee are often attributed to its rich phytochemistry, including caffeine, chlorogenic acid, caffeic acid and hydroxyhydroquinone (HHQ).
The main chlorogenic acid in coffee is 5-caffeoylquinic acid, although other caffeoylquinic, feruloylquinic, and di-caffeoylquinic acids are present in significant quantities (1). Some people might think that chlorogenic acid is “destroyed” during roasting. However, when green coffee beans are roasted under high temperatures, chemical reactions between amino acids and carbohydrates, known as Maillard reactions, create a number of unique components. This can create a rather unique difference between a light and a dark roast.
Chlorogenic acid isn’t destroyed, but is rather transformed into other beneficial compounds.
Brewed ground coffee isn’t very rich in nutrients, but espressos do contain decent amounts of vitamin B3 and magnesium.
Coffea arabica normally contains about half the caffeine of Coffea robusta. The coffee sack (similar to the French press and other steeping methods) is shown to extract more caffeine from dark roasted seeds, while the percolator and espresso methods extract more caffeine from light roasted seeds.
Each cup of brewed coffee contains ~100mg of caffeine, which all depends on the roast, climate, age, origins and coffee type.
Caffeine is completely absorbed by the stomach and small intestine within 45 min of oral ingestion. The hydrophobic properties of caffeine allow its passage through all biological membranes and the peak plasma concentration is reached within 15 – 20 min after oral ingestion in humans (1). Caffeine is metabolized in the liver by the cytochrome P450 oxidase enzyme system, specifically the CYP1A2 enzyme, into three primary metabolites: paraxanthine (84%), theobromine (12%), and theophylline (4%) (1).
In healthy adults, caffeineʼs half-life time is approximately 3 – 4 h.
Caffeine aids in digestion by increasing gastric acid and salivary alpha-amylase (which is involved in polysaccharide digestion), but it also leads to a slight decrease in the efficiency of calcium, iron and cholesterol absorption in the gastrointestinal tract (2, 3). This is like a double-edged sword. Coffee increases satiety in some, but I have found that it is able to create fake hunger, due to the gastric acid release. This effect is most prominent when I drink it black.
Coffee is one of the most researched substances there is, and as of may 2017 on Pubmed, the term “coffee” produced 12583 hits, 998 reviews and 1666 clinical studies (4).
Meta-analysis has found that the average consumption of 5 cups of coffee a day is the healthiest (1).
Coffee boosts dopamine & is a nootropic
Caffeine is one of the most well-known nootropics out there and it’s been shown to
1) enhance cognitive performance, 2) decrease mental fatigue, 3) enhance short-term memory, 4) increase the ability to concentrate, focus and pay attention (5, 6, 7, 8).
The way caffeine exerts this effect, is by specifically antagonizing adenosine receptors. In humans, there are four types of adenosine receptors, namely A1, A2A, A2B and A3. Although coffee/caffeine doesn’t directly boost dopamine levels, it does so indirectly by antagonizing adenosine receptors. Dopamine receptor D2 and the adenosine receptor A2A exist as heteromeric complexes. Antagonizing one agonizes the other, for example, activating D2 will inhibit A2A and vise versa (9). A2A receptor agonists have a motor-depressant effect, whereas D2 agonists have a motor-activating effect. Caffeine antagonizes A2A, which then automatically agonizes the D2 receptor and exerts its stimulating effect. To confirm this, A2A agonists increase dopamine receptor sensitivity, by decreasing the affinity of dopamine D2 receptors for dopamine.
So antagonizing A2A will increase dopamine binding to D2, yet this will also reduce dopamine receptor sensitivity by a small amount. So what I’m saying, is that caffeine indirectly increases dopamine, by antagonizing A2A. Caffeine does release dopamine in the very ventral part of the striatum, in an area called the shell of the nucleus accumbens; by acting on adenosine A1 receptors localized in glutamatergic and dopaminergic terminals.
Paraxanthine, the main metabolite of caffeine in humans (as mentioned above), has a very strong psychostimulant effect in rats, and is correlated with a significant dopamine release in striatal areas of the brain, where caffeine is ineffective. In addition to being an A1 and A2A receptor antagonist, it is also a selective inhibitor of cGMP-preferring phosphodiesterase (PDE), and thus plays a role in potentiating nitrous oxide transmission, preventing oxidative stress, DNA damage or neurotransmitter degeneration. (10)
Caffeine is only slightly dopaminergic, but paraxanthine is significantly more potent than caffeine, in that aspect, so the net effect of drinking coffee will still lead to higher dopamine levels.
Adenosine A1 receptors are also found to antagonistically modulate the D1-mediated regulation of the strioentopeduncular pathway. D1 receptors localized in the entopeduncular nucleus were also found to facilitate GABA release. (11) Adenosine is an endogenous inhibitory neuromodulator which prompts feelings of drowsiness and even depression (12).
Antagonism of A1 also results in elevated extracellular acetylcholine (which promotes focus, attention, memory formation and recall, etc) (12).
Coffee (not caffeine), has anti-opioid activity which is primarily caused by the presence of 4-caffeoyl-1,5-quinide (4-CQL), and to a lesser extent, by other cinnamoyl-1,5-quinides.
A cup of coffee contains the equivalent of one‐third of a dose of naxolone (a drug used to block the effect of opioids). (13)
Opioids have a mind-numbing effect which causes a struggle to focus and to feel motivated, where coffee antagonizes this effect and can help you to focus and increase motivation. Dopamine is antagonized by endogenous opiate peptides, and/or endorphins, such as β-endorphin and enkephalins.
The release of prolactin is kept in-check by dopamine, and the ability of exorphins to release prolactin is often simply explained through dopamine antagonism.
Exorphins increase opioid activity, and coffee inhibit opioid activity and keeps prolactin in check, and dopamine high. Chlorogenic acid, upon roasting, is partly oxidized to 3,4-dihydrozyphenyl propionate, which has a very similar structure to dopamine (32).
This possibly identifies additional dopaminergic substances in roasted coffee.
Monoamine oxidase (MAO) is a mitochondrial outer-membrane flavoenzyme involved in brain and peripheral oxidative catabolism of neurotransmitters and xenobiotic amines, including neurotoxic amines. It is also a well-known target for antidepressant and neuroprotective drugs. Recent epidemiological studies have consistently shown that coffee drinkers have an apparently lower incidence of Parkinson’s disease (PD), suggesting that coffee might somehow act as a purported neuroprotectant. Subsequently, the pyrido-indole (β-carboline) alkaloids, norharman and harman, were identified and isolated from MAO-inhibiting coffee, and were good inhibitors on MAO A (harman and norharman) and MAO B (norharman) isozymes (14).
Caffeine is able to increase dopamine, acetylcholine and GABA, via blocking adenosine receptors and MAO, and increasing cognitive function further by antagonizing opioids.
Coffee posses potent anti-oxidants & is anti-inflammation
Coffee has an antioxidant power three to five-fold greater than that of red wine and tea. In this study, researchers gave individuals a daily dose of 5mg/kg caffeine for 7 days.
7 days of caffeine administration reduced lipid hydroperoxides (peroxyl radicals can remove hydrogen from lipids, producing hydroperoxides) by 70%, MDA (an aldehyde representing the main product of polyunsaturated fatty acid peroxidation) by 67%, and oxidized glutathione (GSSG) by 41%. It also increased glutathione by 106%, and the GSG/GSSG ratio by 249%. This indicates a significant increase in anti-oxidative defense capacity, and a reduction in lipid peroxidation and oxidative stress. Caffeine also makes LDL cholesterol resistant to oxidation and prevents DNA damage (15).
Chlorogenic acids and their metabolites, inhibit cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and attenuate inflammatory markers, such as IL-1β, IL-6, TNF-α and NF-κB, in a dose-dependent manner (1). This leads to blood pressure reduction through improved endothelial function, and nitric oxide bioavailability in the arterial vasculature. This is one of the reasons why coffee drinkers have lower incidents of cardiovascular disease; due to a reduction in inflammation (1).
Cafestol and kahweol are lipid (fat) fractions found in coffee which act as safeguards against some malignant cells by modulating and upregulating key anti-oxidant and detoxifying enzymes. (1)
Coffee contains potent anti-oxidants, down regulates inflammation and inflammatory enzymes and increases the detoxification of toxins.
Coffee invigorates exercise performance
Caffeine is found in almost all pre-workouts, due to its beneficial effect on exercise.
- power output,
- reduces pain by releasing β-endorphins,
- aids in the contraction of muscles
- increases 1RM strength in upper body exercises (such as bench press),
- increases muscular endurance during sets and throughout the workout (16, 17, 18, 19, 20).
One of caffeine’s main mechanisms for improving exercise performance is via antagonizing adenosine, as increasing concentrations of
adenosine produced during exercise acts to inhibit the sympathetic nervous system (reduced sympathetic nervous system tone will reduce exercise performance).
Caffeine post-workout will aid in filling the muscles up with glycogen and controlling the glucose load. There is evidence for both increased insulin secretory responsiveness and increased insulin sensitivity after caffeine ingestion (1). Caffeine improves skeletal muscle glucose uptake by increasing expression and translocation of GLUT 4. A 2.5-fold increase in glucose transport was described as an additive action with insulin (greater responsiveness and sensitivity) (1). The polyphenols in coffee stimulate GLP-1, which is a major intestinal hormone that activates glucose-induced insulin secretion from β-cells (1).
Caffeine increases glucose tolerance (can help you to tolerate carbs better), especially if you are having trouble with insulin. As seen in this study; 6 cups of coffee per day is associated with a 33% lower risk of type 2 diabetes. Coffee appears to act primarily, if not exclusively, through postprandial, as opposed to fasting, glucose homeostasis (1).
Is healing to the liver
Coffee consumption of, equal to and more than, 2 cups per day is associated with a lower risk of elevated ALT levels (liver enzyme indicating liver damage) by 44% and a lower risk of chronic liver disease, compared to non-coffee drinkers. Patients with preexisting liver disease who drank 2 cups of coffee per day were associated with a lower incidence of fibrosis and cirrhosis, lower hepatocellular and carcinoma rates, as well as decreased mortality. Additionally, chlorogenic acid reduced liver fibrosis and the expression of collagen I and III.
In experiments with rats, caffeine ingestion showed a reduced concentration of VEGF, TGF-β, and α-smooth muscle actin (1).
The diterpenes (lipids) in coffee, cafestol and kahweol, may offer protective effects against aflatoxin B1-induced liver damage in vitro (1). Cafestol and kahweol may also induce the synthesis of glutathione, which has a role in detoxification and the prevention of liver damage. As seen above, coffee does increase GSH and liver detoxification.
Coffee consumption decreases liver stiffness, which indicates less fibrosis and inflammation in patients with nonalcoholic fatty liver disease, and hepatitis C and B virus infection (1). All in all, coffee is shown to be greatly beneficial to liver health.
As a liver cleansing / liver healing protocol I would advise
- caffeine in doses up to 1200mg; which is very effective, especially when combined with
- vitamin K2 (45mg+, MK-4 only),
- taurine (4g+),
- glycine (2g+),
- magnesium (400mg+) and a
- lipotropic agent such as choline/inositol and protein (would be best consumed through food sources instead of supplementation).
Intensifies Fat Burning
Most fat burners contain a decent amount of caffeine to aid in thermogenesis (heat production) and lipolysis (fat release from fat stores). Caffeine is shown to 1) increase daily energy expenditure, 2) have a significant thermogenic effect which lasts up to and over 3 hours (even if the individual is used to drinking coffee), 3) increase fat oxidation, while sparing muscle glycogen, 4) increase catecholamine secretion, which activates β-adrenergic receptors, and 5) increase adiponectin levels, which increases insulin sensitivity and beta-oxidation. (21, 22, 23, 24)
Coffee also downregulates genes that are associated with increasing fat mass, such as WNT10B and galanin, as well as the TLR4-mediated pro-inflammatory pathway. TLR4 is a membrane protein that increases the intestinal absorption of endotoxins, which then increases serotonin levels. Gut serotonin levels are twice as high in obese individuals than in normal individuals as gut serotonin is correlated with increased fat mass. Coffee blocks this effect, and prevents the increase in serotonin and therefore the synthesis of new fat cells.
100mg (approx 1 cup) of caffeine is shown to increase the resting metabolic rate of lean individuals by 3-4% over 150 min (32). Also, repeated caffeine ingestion of 100mg, every 2 hours, over a period of 12 hours, is shown to increase energy expenditure by 8-11%. The effect, however, is greater in lean individuals than in over-weight individuals.
600mg of caffeine (about 6 cups of coffee) can help you burn an extra 350+ calories/day, with higher doses being naturally more effective.
More on fat burning substances here…
Coffee can help you to burn a little fat even if you’re just sitting at home. But of course, only drinking coffee is no excuse to continue having a poor diet. Real fat loss comes from following a good meal plan.
Coffee augments Testosterone
In this rat study, caffeine intake increased the concentrations of testosterone, 5-alpha reductase, DHT and AR tissue expression. Chronic caffeine intake from puberty increases androgenic signaling (25, 26).
In this study, caffeine ingestion increased the testosterone response to resistance exercise in a dose-dependent manner. Exercise increased testosterone response by 40% and 800mg of caffeine increased it further to 60%. However, the biggest dose given (800mg), produced a moderate 52% increase in cortisol, which decreased the testosterone:cortisol ratio by 14% (27).
Epidemiological studies have reported a positive association with caffeine intake and elevated bioavailable testosterone levels in adult men (e.g., Svartberg et al., 2003).
Data from this (Stuart, Hopkins, Cook, & Cairns, 2005) study (unpublished observations) suggested that ingested caffeine might elevate endogenous testosterone levels in humans regardless of exercise (27). Among men, consumption of caffeinated coffee increased total testosterone and decreased total and free estradiol (27).
A caffeine tolerance is built up and the cortisol response is greatly reduced after just 5 days of use. (28) Longer periods of time could result in normal cortisol levels, despite high caffeine intake.
Coffee increases cAMP (cyclic adenosine monophosphate) and cGMP (cyclic guanosine monophosphate) levels via phosphodiesterase (PDE) inhibition, which increases testosterone production.
cAMP increases steroidogenic acute regulatory protein (StAR) and P450scc. StAR transports cholesterol from the outer mitochondria to the inner mitochondria, where cholesterol is then converted to pregnenolone by the P450scc enzyme and then onto testosterone.
cAMP also causes the release of GHRH (growth hormone releasing hormone) which leads to a rise in growth hormone. (30)
However, ingesting caffeine prior to the workout will dampen the growth hormone response from the workout (31), probably because of the rise in free fatty acids.
Coffee positively increases androgens, such as total and free testosterone, DHT and decreases estrogen, via an increase in cAMP, dopamine, total anti-oxidant status and a general improvement in health.
Are there Side effects?
Some people experience symptoms of jitteriness from coffee, as they are very sensitive to it as a stimulant, while others don’t. This jittery feeling is mainly because of compromised liver function and the slow breakdown of caffeine, as well as having inadequate glycogen stores to fuel the increase in metabolism, thus resulting in a stress reaction. Serotonin (A), cortisol (A), estrogen (A), polyunsaturated fats, endotoxins and inflammation are greatly involved in liver damage. Lowering these stress hormones, detoxing PUFAs and inhibiting endotoxins, while consuming saturated fat, will greatly aid in healing the liver.
If you’re a caffeine-sensitive individual, it’s advised not to drink coffee after 2 or 4pm as it might interfere with sleep. My wife and I can drink coffee right before we go to bed and it doesn’t interfere with our sleep, but if it does interfere with yours then it’s best to not drink too late.
The only ‘side effect’ that I know of is that it increases gastric acid secretion, and that can stimulate fake hunger, although coffee is also known to blunt appetite for others.
Either way, this gastric acid secretion actually helps with food digestion.
Does coffee cause dehydration?
Coffee, when consumed in moderation (3-6 cups daily) provides similar hydrating qualities to water. (32) High dose caffeine pills might be slightly dehydrating if the diet doesn’t contain a lot of liquid food, such as milk and fruit. Coffee might increase urination as it lowers estrogen, and thus reduces edema (excessive water retention), but is not dehydrating in the least.
Choosing your coffee
When choosing your coffee, be sure to get it from a local coffee shop that roasts fresh beans every day (if possible). This way your coffee will be freshly roasted and ground.
It would be best to grind your own beans, because when ground coffee stands for too long, the oils start to go rancid and the coffee loses a lot of its benefits. Also make sure to get the organic beans, and preferably shade grown. As commercial coffee is heavily sprayed with pesticides, which is detrimental to your gut and health.
Lighter roasts are higher in caffeine, whereas the darker roasts contain more antioxidants. However, all roasts contain the same amount of caffeine when measured gram for gram (as coffee beans which are roasted for longer will naturally weigh slightly lighter than coffee beans which contain more moisture). Hence, the longer the beans are roasted, the lighter they become in weight. Dark roasts have a much stronger taste than lighter roasts and we personally prefer a dark roast over a medium roast.
As for how to prepare your coffee… we use a glass french press, to avoid plastic and bleach (from the filters) seeping into our coffee.
This way you can really just enjoy your coffee without any feelings of guilt and be comforted to know that it’s not just your taste buds that are lovin’ the goodness. : )