Rice and Arsenic: The Parboiling Method That Reduces Exposure

Rice is considered light, easy to digest and suitable alongside almost any dish. What many people overlook is that the grain can accumulate arsenic, a contaminant found in the environment that builds up in the body. Researchers have now examined a cooking technique in greater detail that can substantially reduce its content without leaving the rice nutritionally depleted.

Why rice contains arsenic at all

Arsenic occurs naturally in rock layers. As these weather, it enters groundwater and rivers. This is precisely where the issue begins: in many areas, rice is cultivated in flooded paddies irrigated with water containing arsenic.

Because it grows in the standing water of flooded fields, the plant absorbs more arsenic than most other cereals, which tend to be grown in drier conditions. The substance therefore accumulates in the rice plant and ultimately in its grains.

"Rice accumulates arsenic particularly easily because it grows in flooded fields and is continually exposed to contaminated water."

The European Food Safety Authority (EFSA) classifies inorganic arsenic as a potential carcinogen. Persistently raised exposure has been linked, among other things, to a greater risk of skin cancer and other cancers. Studies also report cardiovascular disease and effects on the nervous system.

European limits – but no clear cooking guidance

To protect consumers, the EU has set maximum arsenic levels for rice. The requirements for polished white rice are stricter than those for wholegrain rice:

• White rice: no more than 0.15 milligrams of arsenic per kilogram
• Wholegrain rice (brown rice): no more than 0.25 milligrams of arsenic per kilogram

These limits are intended to prevent heavily contaminated batches from reaching shops in the first place. However, they do not indicate how to prepare rice at home with as little arsenic as possible. European authorities have not yet issued specific cooking instructions.

Other institutions have progressed further. In the United States, the Food and Drug Administration (FDA) has been looking for years at ways to reduce arsenic in rice through preparation, without losing all of its nutrients.

What common online tips actually achieve

TikTok and similar platforms are full of tricks claimed to make rice “healthier”. Some sound convincing, but do not stand up to scientific evidence.

Washing rice thoroughly: useful or a myth?

Many users swear by rinsing rice several times under running water until the water runs clear. This does remove starch and some surface dust.

Its effect on arsenic is limited, however. The contaminant is not present only on the outside, but within the grain as well. The FDA considers washing to be of little benefit for reducing arsenic. At the same time, some vitamins and minerals located in the outer layer are lost.

"Rinsing rice makes it fluffier, but barely lowers its arsenic content and costs nutrients."

Cooking in plenty of water: better, but with a drawback

The FDA recommends cooking rice in abundant water, as you would pasta. Its guideline is six to ten parts water for one part rice. Any water left after cooking is then drained away.

This approach can cut the arsenic content of cooked rice by around 40 to 60 percent. Some of the arsenic transfers to the cooking water and goes down the drain. Although that initially sounds like a good solution, it has a considerable disadvantage: valuable nutrients also dissolve into the water.

According to the FDA, between 50 and 70 percent of certain vitamins and minerals may be lost this way, including:

• Folate
• Iron
• Niacin (vitamin B3)
• Thiamine (vitamin B1)

For people who eat rice merely as a filling side dish, this may be an acceptable trade-off. But anyone who regularly relies on it as the main component of a meal loses many important nutrients over time.

The “parboiling method”: substantially less arsenic, nutrients retained

A research team at the University of Sheffield tested an alternative technique that offers a markedly better compromise. The method has the somewhat cumbersome name “parboiling with subsequent absorption”, but is surprisingly straightforward in the kitchen.

Rice parboiling method: step-by-step instructions

1. Measure out the rice as usual.
2. Put it in a pan with plenty of water.
3. Boil the rice vigorously for five minutes.
4. Drain away this first cooking water completely and discard it.
5. Add fresh water, this time using only enough for the rice to absorb fully as it cooks.
6. Cook over a medium heat until all the water has been absorbed.

The principle is that, during the first few minutes of cooking, a large proportion of the freely available arsenic leaves the grain and passes into the water. That water is then discarded. In the second stage, the rice cooks in the usual way, absorbing the water and becoming tender without taking up substantial further quantities of arsenic from its surroundings.

"With the parboiling method, the arsenic content of white rice fell by up to 73 percent in one study."

What the study found

The findings, published in the journal “Science of the Total Environment”, are clear:

• White rice: around 73 percent less arsenic
• Wholegrain rice: around 54 percent less arsenic

By comparison, conventional cooking in plenty of water achieves a reduction of only 40 to 60 percent, while causing considerably greater nutrient losses. The parboiling method is notably better at preserving minerals such as zinc. Rice is therefore not only lower in arsenic, but also more nutritious.

Who may benefit most

Most people in Europe eat rice only occasionally. For them, varying the type of rice and maintaining a varied diet is generally enough to keep the risk low.

There are, however, groups for whom lower-arsenic rice can be particularly worthwhile:

• Children who are frequently given rice cakes, rice pudding or rice porridge
• People following a gluten-free diet who often rely on rice products
• Households where rice is served almost every day
• Pregnant and breastfeeding people, for whom increased contaminant intake is particularly undesirable

For these groups, the additional step of brief pre-cooking and changing the water is far more worthwhile than simply rinsing the rice quickly or cooking it as normal.

Which rice varieties and alternatives are less concerning

Arsenic levels depend not only on preparation, but also on the variety and its origin. Wholegrain rice tends to contain slightly more arsenic because the grain retains its outer layers, where some of the substance collects. At the same time, wholegrains provide more fibre and minerals – a familiar trade-off.

Anyone wishing to play it safe can choose the following options more often:

• Basmati or jasmine rice from regions with lower contamination
• Parboiled rice, which often contains less arsenic as a result of its special processing method
• Other side dishes such as potatoes, millet, quinoa or bulgur, which naturally contain considerably less arsenic

Variety remains the key: simply avoiding large amounts of rice every day already reduces the risk substantially, without any complicated restrictions.

What arsenic does in the body – and why dose matters

With continued intake, arsenic accumulates in the body. Its effects depend heavily on both the amount and duration of exposure. At the levels permitted in Europe, acute food poisoning is virtually not an issue. The greater concern is long-term, slightly elevated intake.

Studies associate chronically higher arsenic exposure with:

• a higher risk of various cancers
• effects on the nervous system
• problems affecting skin and nails
• an increased risk of cardiovascular disease

It is almost impossible to avoid arsenic completely because it is present in many soils and water sources. However, people can considerably reduce their personal exposure by focusing on the main factors: eating large amounts of rice less often and paying attention to the cooking method.

Making the new cooking method practical for everyday use

In a busy daily routine, a two-stage cooking process may initially seem inconvenient. In practice, though, it is easy to incorporate: start by pre-cooking the rice while chopping vegetables or preparing a sauce.

For larger households or meal-prep enthusiasts, it can also be worthwhile cooking a bigger batch of rice using the parboiling method, allowing it to cool and reheating it later in a frying pan or microwave. Cooked rice keeps in the fridge for two to three days if it is cooled quickly and stored well covered.

Anyone who tries this technique a few times will soon find that it differs little from ordinary cooking in everyday life, yet offers noticeable benefits for contaminant exposure without the grains losing significant flavour or nutrient density.