Rice and arsenic: this cooking method cuts levels by 73 per cent

People who eat rice regularly may be consuming more than carbohydrates and fibre: they could also be taking in arsenic. This substance occurs naturally in soil and water, yet it can build up in the body and cause illness over the long term. Researchers have now tested a cooking method that substantially reduces the arsenic content of rice without washing away all of its nutrients.

Why rice can absorb so much arsenic

Arsenic is naturally present in rocks and soils. Rainfall and erosion carry it into groundwater and surface water. This is precisely where the issue arises, because rice is grown in water.

In flooded rice paddies, the plants are continually exposed to arsenic-containing water. They absorb the substance through their roots, with some of it being deposited in the grain. That grain ultimately reaches our plates as either white or wholegrain rice.

Rice absorbs arsenic far more readily than other grains, such as wheat or oats. For this reason, regulatory authorities monitor it particularly closely. The European Food Safety Authority (EFSA) links the intake of inorganic arsenic with a greater risk of several cancers, especially skin and lung cancer. Possible damage to blood vessels and effects on the nervous system are also under discussion.

Rice is a staple food worldwide, which is exactly why every reduction in its arsenic content matters to the health of so many people.

To limit exposure, the EU has defined maximum levels. White rice has a limit of 0.15 milligrams of arsenic per kilogram, while wholegrain rice is limited to 0.25 milligrams per kilogram. These rules apply to cultivation and trade. However, Europe currently has no specific everyday kitchen guidance on the best way to cook rice in order to remove arsenic.

What familiar TikTok and social media advice really achieves

Social media is full of suggestions: rinse rice several times, soak it overnight, cook it without draining, or prepare it in a rice cooker. Claims vary wildly, from “it cleans everything out” to “it makes no difference at all”.

The US Food and Drug Administration (FDA) has examined common approaches in more detail. It recommends cooking rice in a very large volume of water, using six to ten parts water to one part rice. Any excess water is drained off after cooking.

Cooking rice in plenty of water: effective against arsenic, poor for nutrients

This traditional pasta-style approach does work. It can lower arsenic levels by 40 to 60 per cent, because arsenic dissolves into the cooking water and is poured away down the drain.

The downside is that essential nutrients are lost with the water. According to the FDA, levels of the following fall by around 50 to 70 per cent:

• folate, a form of folic acid;
• iron;
• niacin, or vitamin B3; and
• thiamine, or vitamin B1.

For people who rely on rice as a regular source of nutrients, that means losing a significant part of its benefit.

Simply rinsing rice before cooking is also often recommended but overrated. The FDA says washing reduces arsenic only minimally, while potentially removing some vitamins and minerals from the grain surface too. The health benefit is therefore limited.

Rinsing rice alone is not enough, while cooking it in an enormous pot of water washes away too many vitamins.

The ‘parboil-and-absorb’ method: 73 per cent less arsenic in rice

Researchers at the University of Sheffield investigated a cooking technique that offers a much better compromise. The study was published in the specialist journal Science of the Total Environment and was subsequently reported by various media outlets.

The method brings together two principles: drawing arsenic into the water as early as possible, then cooking the rice gently without continuously leaching out nutrients. The researchers describe it as a technique involving pre-blanching followed by absorption cooking.

How to use the method step by step

This technique is easy to follow at home and does not require any specialist equipment:

1. Measure the rice and briefly cover it with cold water to remove coarse dust, if desired.
2. Bring the rice to the boil in plenty of fresh water.
3. Boil vigorously for five minutes.
4. Drain the water completely and discard it, as this is where much of the dissolved arsenic ends up.
5. Add fresh water, this time using only enough for the rice to absorb while cooking - around 1.5 to 2 times the quantity of rice, depending on the variety.
6. Cook over a medium heat with the lid on until the water has been absorbed and the rice has reached the desired texture.

The results are notable: arsenic content falls by an average of 73 per cent in white rice and 54 per cent in wholegrain rice. At the same time, most nutrients are retained more effectively than with the high-water method alone. Zinc in particular, which is important for the immune system and metabolism, largely remains in the grain.

Just five extra minutes at the hob can substantially reduce arsenic in rice without turning it into a nutritional desert.

Which rice varieties and groups are most affected

Arsenic levels depend heavily on both the growing region and the variety. Wholegrain rice generally contains more arsenic than white rice because more residues are found in the outer layers of the grain. Yet these are also the layers that provide fibre and minerals, creating a familiar trade-off.

Anyone who eats rice occasionally does not need to panic. The subject becomes more relevant for people who consume rice products very regularly, including:

• children who are often given rice cakes or rice porridge;
• adults who eat rice as an accompaniment several times a week;
• people who depend heavily on rice as their main carbohydrate source for cultural or personal reasons; and
• fans of rice drinks and rice noodles.

For these groups, every opportunity to reduce exposure is worthwhile, particularly where intake remains high over many years.

Practical everyday tips for cooking rice

The new cooking technique is an important element, but it does not replace common sense. Anyone wishing to take extra care can combine several strategies:

• Rotate rice varieties, including basmati, jasmine, parboiled and wholegrain rice.
• Vary carbohydrate sources by including potatoes, pasta, millet, bulgur or couscous.
• For babies and young children, choose products that have been explicitly tested for arsenic.
• Avoid making rice the main component of every meal every day.
• Use the pre-blanching and absorption-cooking method for rice eaten frequently.

Those using a rice cooker can adapt the method in part: first parboil the rice in a saucepan for five minutes, drain the water, then transfer the rice and fresh water to the rice cooker to finish cooking.

What arsenic does in the body - and why the dose matters

Arsenic affects various metabolic processes in the body. Inorganic arsenic, the form that may occur in rice, is associated with:

• a higher cancer risk, including skin, lung and bladder cancer;
• damage to blood vessels;
• impairment of the nervous system; and
• adverse effects on child development when exposure is high and long-lasting.

Acute poisoning from normal rice consumption in Europe is extremely rare. The concern here is the accumulated total of many small portions over the course of years. This is why authorities aim to lower exposure throughout the entire chain, from field to saucepan.

In practical terms, nobody needs to ban rice from the kitchen. Anyone who wants to continue enjoying their favourite curry or sushi can do so. Adjusting the cooking method and adding some variety to side dishes can significantly reduce long-term intake.

Knowledge check: what terms such as ‘inorganic arsenic’ mean

Reports often distinguish between organic and inorganic arsenic. Organic forms occur, for instance, in certain seaweeds and are considered less concerning. Inorganic arsenic is more closely linked to the riskier forms covered by the maximum limits.

When it comes to rice, the main issue is inorganic arsenic from soil and water. Laboratory analyses specifically separate out this form when assessing contamination. Anyone reading studies or reports from authorities should look out for these terms in order to interpret the figures correctly.

It remains striking that simple measures in a home kitchen can have major effects. The method described does not alter the taste of rice, requires only a few additional minutes of effort, and reduces a genuine risk that many people may never have expected to find on their plates.