Is it better to avoid using "raw spinach" directly in cooking? A thorough explanation from a nutritionist's perspective on "situations to avoid" and "smart ways to use it"

1. What are the concerns about "Should raw spinach be avoided?"

The reason why raw spinach often becomes a topic of discussion is that, broadly speaking, there are points of concern regarding both "hygiene (food poisoning)" and "components (oxalic acid, nitrates, vitamin K, etc.)".

• Hygiene: Leafy vegetables can become contaminated with pathogens from soil, water, or animals at any stage from cultivation to distribution. There have been reported cases where spinach was linked to outbreaks of enterohemorrhagic E. coli (E. coli O157:H7). CDC Archive+1

• Components: Spinach is rich in nutrients but also high in oxalic acid, which under certain conditions can affect mineral absorption and increase the risk of kidney stones. Some studies suggest that heating can reduce oxalic acid. PubMed+1

• Infants: Some public agencies recommend caution regarding nitrates (→ nitrites under certain conditions) for infants. Aesan+1

In other words, it's not "absolutely forbidden," but the answer changes depending on who eats it, how it's eaten, and how much is consumed.

2. Risk ①: Food Poisoning (Washing is not enough)

2-1. Handling is crucial because leafy vegetables are "meant to be eaten raw"

While bacteria can be reduced by cooking meat and fish, salads and smoothies are often "consumed raw." Therefore, accumulating preventive measures at home becomes important.

The CDC (Centers for Disease Control and Prevention) provides practical advice on leafy vegetables, such as

• Washing hands (before and after preparation)

• Sanitizing utensils and work surfaces

• Separating from meat and seafood (to prevent cross-contamination)

• If labeled "ready-to-eat" or "triple washed," additional washing may not be necessary
  . CDC Archive+1

The FDA (U.S. Food and Drug Administration) also recommends basics such as "rubbing vegetables under running water" and that "soap or special detergents are unnecessary." U.S. Food and Drug Administration

2-2. Washing is effective, but not "complete removal"

This is important. The CDC clearly states that "washing removes dirt and some bacteria, but not all bacteria are removed." CDC Archive
Furthermore, studies analyzing spinach-related outbreaks have discussed the possibility that washing did not change infection rates, possibly due to factors such as internalization. PMC

Conclusion:

• Washing is important (better than not doing it)

• However, "washing doesn't guarantee 100% safety"

• Therefore, considering health conditions and the target (children, pregnant women, the elderly, etc.), "cooking" is also an option

2-3. Hygiene checklist for "eating raw" at home

When using raw spinach, keeping these minimum points in mind can reduce the risk of accidents.

• Wash hands for 20 seconds (before and after preparation) U.S. Food and Drug Administration

• Do not reuse the same cutting board/knife for meat, seafood, and eggs (or wash thoroughly each time) CDC Archive+1

• Gently rub spinach under running water (if the package says "washed," it may be okay as is) CDC Archive+1

• Do not leave soaking in water for long (the longer it stays in dirty water, the less beneficial it is)

• After washing, remove moisture with kitchen paper (slows down deterioration)

• Eat prepared salads quickly, do not leave at room temperature

3. Risk ②: Oxalic Acid (For those concerned about mineral absorption and stones, "prefer heating")

3-1. What is the problem with oxalic acid?

Oxalic acid, which is abundant in spinach, easily binds with calcium and other minerals in the body,

• reducing the "utilization efficiency" of calcium and iron

• Depending on constitution and medical history, it can be a risk factor for calcium oxalate stones
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In studies examining the reduction of oxalic acid through vegetable cooking, it has been reported that **boiling** significantly reduces water-soluble oxalic acid (with some variation depending on the ingredient). PubMed

Additionally, studies on spinach have shown that, under certain conditions, short-term heating significantly reduces oxalic acid. J-STAGE+1

3-2. Practical points for those concerned about stones or wanting to absorb calcium properly

• History of stones / high risk: Prefer boiling and discarding the water over eating raw (oxalic acid transfers to the water). PubMed+1

• For those eating for iron: The iron in spinach is non-heme iron, so the basic strategy is to consume it with vitamin C (lemon, citrus, bell peppers, etc.). Heating can also "concentrate" the amount (as the volume decreases).

• Combining with calcium: Placing calcium sources like dairy products or tofu in the same meal can bind oxalic acid in the intestines, making it less absorbable, which can be beneficial for those concerned about stone risk (individual differences apply).

4. Risk ③: For infants, there's a concern about "nitrates (→ nitrites)"

Spinach is treated as one of the vegetables high in nitrates. While nitrates themselves are not a major issue for most people, infants require caution under certain conditions.

For example, the Spanish food safety agency AESAN advises as a preventive measure to "avoid including spinach and chard in infant weaning foods until one year old" and provides guidance on intake frequency for ages 1-3. Aesan

Additionally, public documents warn that for vegetables high in nitrates (e.g., spinach), "pureeing in a raw state" or "leaving pureed food at room temperature after cooking" can easily increase nitrites. Hong Kong Centre for Food Safety

Conclusion (for baby food):

• For household safety design, for infants, cooking should be the basic approach.

• If making in advance, strictly manage refrigeration and freezing (do not leave at room temperature). Hong Kong Centre for Food Safety

• Recommendations vary by country and region, so if concerned, prioritize guidance from local authorities or pediatricians.

5. "Raw" has its benefits, and "cooked" has its benefits

5-1. Benefits of Raw

• Easy to eat quickly, lowering the barrier to cooking

• Versatile uses such as in salads, sandwiches, and smoothies

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