Does coffee cause cancer? New coffee related cancer warning in California ignores science.

California: coffee-cancer warning controversy.

The following title recently appeared on CNN News: “Coffee may come with a cancer warning label in California”.

The article states that a “Label would warn customers about acrylamide, which the State lists as a carcinogen”.

The California court released a statement in the beginning of April 2018, saying that companies “failed to meet their burden of proof on their Alternative Significant Risk Level affirmative defense” and ruled against them.

The controversial preliminary decision of the Superior Court judge in Los Angeles to introduce mandatory warnings on labels relates specifically to acrylamide, a “probable” carcinogen chemical present in coffee. (1)

This article will show that not only does coffee contain insignificant amounts of this toxin, especially in comparison to other foods, but that there is no association between acrylamide and cancer in humans.

Therefore, why is this decision is being even considered? Ego? Power? Politics?

Does coffee increase the risk of cancer?

Coffee consumption not only doesn’t increase the risk of cancer, but possibly even lowers the risk of some cancers. Drinking coffee also has numerous health benefits that outweigh its negative effects, provided that you are not caffeine sensitive.

So why write this article?

This article is in response to the emerging controversy in California.

In short, acrylamide is a chemical that all available epidemiological studies show has no association with cancer in humans. There are no studies to indicate this effect in humans (only in rodents).

 It is also important to note that acrylamide is present in brewed coffee in much smaller amounts than in other very common foods, such as potato chips, biscuits, breakfast cereals and French fries. 

Therefore, if this chemical is such a concern, why only focus on coffee?

The evidence is clear and available to this judge. So, why the new legislation?

What is acrylamide?

Acrylamide is a chemical that acts as a neurotoxin in humans. In rodents, it also acts as a neurotoxin.  However, it has also shown to be carcinogen.

Acrylamide is categorized as a “probable” carcinogen for humans, because studies on rats show that very high amounts of this chemical form various types of cancer. In terms of carcinogenicity, it is considered as “group 2A”.

It has always been present in our diet.  However, it was first detected in 2002. (2)

There are three major sources of acrylamide that humans are exposed to:

1. Smoking – burning tobacco releases acrylamide.
2. Industrial workplace exposure – it has an industrial chemical most commonly used in the production of polyacrylamide and grouting agents.
3. Thermally processed foods – mainly formed during high temperature (over 120 Celsius – 248 Fahrenheit) food processing (Maillard reaction). (3, 4)

Acrylamide is oxidized in the body to form glycidamide, in both humans and rats.

Glycidamide, considered as genotoxic metabolite of acrylamide, binds with DNA bases forming so-called adducts. (5, 6, 7, 8, 9)

MAIN POINTS

• Acrylamide is a neurotoxin and probable carcinogen
• The most common sources are cigarettes, food cooked in high temperatures or industrial exposure.

What is the evidence that acrylamide causes cancer?

So far, only studies on animals show an association between acrylamide and cancer.

Studies on rodents

Rodents and humans absorb acrylamide at different rates and metabolize it differently. (10)

It is important to note that lab studies on rats use amounts of acrylamide 1,000 to 100,000 times higher than what they normally get from food.

Animal studies have shown that acrylamide has carcinogenic effects, with a significant prevalence of tumors occurring in rats in their: thyroid glands, central nervous system, uterus, clitoral, oral gland and tissue, mammary glands and testes. (11)

Studies on humans

Epidemiological studies that investigated the connection between acrylamide exposure from food and various cancers (including: bowel, kidney, bladder, renal cell, colorectal, oral, esophageal, laryngeal, ovarian and prostate cancers) and have not found any significant proof of this association. (12, 13, 14, 15) 

No other types of studies show that such an association exists.

Please note that high amounts of acrylamide may be neurotic for humans in high amounts. (16)

MAIN POINTS

• Studies on rats show carcinogenic effects of very high amounts of acrylamide.
• Epidemiological studies on humans don’t show an association between acrylamide and cancer.

What is tolerable daily intake of acrylamide?

The tolerable intake of acrylamide for neurotoxicity is estimated to be 88mcg*/lb (40mcg/kg) of body weight per day. (e.g. 2,400mcg for 130lb/60kg person).

Although the association with cancer in humans hasn’t been made, the tolerable intake for cancer has been estimated to be 5.7mcg/lb (2.6mcg/kg) per day for acrylamide and 35mcg/lb (16mcg/kg) per day of its by-product, glycidamide. (e.g. 156mcg and 960mcg for 132lb/60kg person, respectively per day) (17)

*mcg = micrograms

How much of acrylamide do we intake per day?

NOTE: Industrial exposure is difficult to estimate – it depends on each individual case.

How much acrylamide do we get from food?

A study on the Dutch population showed that the mean acrylamide intake of the surveyed participants was 1mcg/lb (0.48mcg/kg) body weight per day (e.g. 28.8 mcg/day intake for a 132lb/60kg person).

This result is more or less consistent with other studies estimates. (18) For instance, a study on the German population has estimated that about 60mcg per day is taken up by a non-smoking person. (19)

These estimated amounts of acrylamide are below the tolerable levels and, therefore, the risk of neurotoxicity is negligible. (16, 20)

However, whether these amounts are negligible for cancer risk is not know at this stage, since the association between cancer and acrylamide in humans has not been found so far.

How much acrylamide do we get from coffee?

Roasting coffee beans is a good example of how acrylamide is formed through the Maillard reaction. 

Medium roasted coffee surprisingly has more acrylamide (10mcg/liter) than dark roasted coffee (5mcg/liter) (21)

Robusta coffee (the lower quality coffee which is used in instant coffee products) contains much higher amounts than Arabica (used in espresso machines, usually served in cafes and restaurants) (22)

Therefore, drinking one liter of dark roasted coffee per day will add 5mcg of acrylamide to your daily intake,  since the newly formed chemical is not removed by grounding and brewing and ends up in our body.

A study of the population in Denmark estimated that, on average, the intake of acrylamide from coffee is (for the age group of 35-45):

• Females: 9 mcg per day
• Males: 10 mcg per day

This intake, however, varies between light coffee drinkers (6.5mcg/day) and heavy coffee drinkers (18mcg/day). These amounts of acrylamide are only a fraction of what comes from food.

So far, there are no methods of extracting acrylamide from coffee. (23)

How much acrylamide do we get from smoking?

A German study concluded that smoking tobacco contributes considerably to the daily acrylamide intake.

While non-smokers had about 0.6mcg/liter of acrylamide in their blood, smokers had 2.3mcg/liter (around 4 times higher). (19)

MAIN POINTS

• Non-smokers intake about (66-132mcg/lb) 30-60mcg/kg of acrylamide per body weight per day
• If you drink coffee, it may add on average 22mcg/lb (10mcg/kg) per body weight
• Brewed Arabica coffee has lower amounts of acrylamide than Robusta coffee used in instant coffee.
• These amounts are below the tolerable daily intake of acrylamide
• Smokers’ intake four times higher amounts of acrylamide than non-smokers

What foods contain acrylamide?

Acrylamide is formed by processing foods in high temperatures, such as in frying, roasting or baking.

The longer the cooking time and the higher the temperature, the more acrylamide is formed. (24)

The most common sources of this chemical are carbohydrates and specifically starch-rich foods, such as: (23, 25)

1. Potato products (e.g. baked potatoes, French fries, potato chips)
2. Grain products (e.g. crackers, bread, cookies/biscuits, toast, breakfast cereals)
3. Coffee (see section below).

The following is a general summary of acrylamide contents per food group: (18)

1. Heated carbohydrate-rich foods, such as potatoes, beetroots and crispbread: 330-8,818mcg/lb (150-4,000mcg/kg)
2. Heated protein-rich foods, such as meats, fish and dairy: 12mcg/lb (5.5mcg/kg)
3. Boiled or steamed foods: <11mcg/lb (5mcg/kg)
4. Unheated/raw foods (undetected)

MAIN POINTS

• The main food sources of acrylamide are starch and carbohydrate products, processed in high temperatures, such as potato, grain products and roasted coffee.
• Boiled, steamed and raw foods have either negligible amounts or no acrylamides

Contents of acrylamide coffee vs in other foods

How much acrylamide does coffee have in comparison to other foods? Very little!

Roasted, fried or baked foods may also contain up to about 6,613 mcg/lb (3,000 mcg/kg), averaging a few hundred mcg/lb (kg).

A Dutch study revealed that foods with the highest average contents of acrylamide are: (16)

1. Potato crisps: 2,753mcg/lb (1,249mcg/kg)
2. French fries: 773mcg/lb (351 mcg/kg)
3. Starch containing snacks that have been heated to high temperatures: 2,337mcg/lb (1,060 mcg/kg)
4. Gingerbread: 1,962mcg/lb (890 mcg/kg)

Unbrewed roasted coffee – dry product (either beans or ground coffee) contains amounts of acrylamide that are comparable to many roasted foods. However, since we don’t munch on the beans, it is more relevant to know that the brewed coffee contents are on average not more than 10 ppb.

The following table contains a list of common foods, processed at high temperatures by using roasting, frying or baking. It can be easily seen that the amount of acrylamide in brewed coffee is tiny, in comparison to other food products. For the detailed list, please click here. (26)

NOTE: The foods were picked at random. The amounts of acrylamide vary between the samples of foods.

MAIN POINTS

• Brewed coffee, in comparison to foods that have been produced in high temperatures, have negligible amounts of acrylamide
• Comparing unbrewed coffee is irrelevant, since coffee is consumed after brewing, rather than dry.

How  do you limit exposure to acrylamide?

The following are the most effective methods of limiting the exposure to acrylamide: (27, 4)

• Don’t smoke.
• Avoid working environments where acrylamide exposure is common
• Limit frying, roasting or baking carbohydrate rich foods. Boil or steam instead. Microwaving potatoes with their skin on, doesn’t produce acrylamide either.
• Storing potatoes in the fridge increases acrylamide during cooking. Store them in cool, well- ventilated and dark places (e.g. pantry)
• Toast a slice of bread just enough to get crunchy, but before it gets brown.
• Fry French Fries until they become golden yellow rather than brown.
• Reduce the surface of the chips. Thicker chips have less acrylamide than thinner chips.

For more acrylamide reducing methods of French Fries, read here. (23)

MAIN POINTS

• To reduce the exposure to acrylamide, don’t smoke, limit frying, roasting and baking carbohydrate rich foods.
• To reduce the acrylamide amount in French Fries, follow the above-mentioned suggestions.

NUTRITION FACTS VS NUTRITION MYTHS

You will find a summary of the most common nutrition myths and evidence-based nutrition facts here.