Oxalates and Antinutrients

Spinach has more iron than beef, according to nutrition labels. Almonds are loaded with calcium. Whole grains are mineral-rich.

On paper, these foods look impressive. In the body, it's more complicated.

What Antinutrients Are

Antinutrients are compounds in plants that interfere with nutrient absorption or cause other problems. They exist because plants can't run away from predators—chemistry is their defense.

Major antinutrients include:
• Oxalates — Bind calcium, iron, and other minerals
• Phytates — Bind zinc, iron, calcium, magnesium
• Lectins — Can damage gut lining, interfere with nutrient absorption
• Goitrogens — Interfere with thyroid function
• Tannins — Bind proteins and minerals

This isn't a reason to avoid plants. It's a reason to understand them.

The Oxalate Problem

Oxalic acid binds to minerals, forming insoluble crystals that pass through the body unabsorbed.

High-oxalate foods include:
• Spinach (highest common food)
• Swiss chard, beet greens
• Rhubarb
• Almonds, cashews
• Sweet potatoes
• Beets
• Cocoa/chocolate

The spinach-iron myth: Spinach contains about 2.7 mg of iron per 100g. But oxalates bind most of it. Actual absorption is minimal. Meanwhile, beef liver at 6.5 mg per 100g provides iron in heme form with no binding—absorption rates 5-10x higher.

Calcium blocking: Spinach is often cited as a calcium source. In reality, you'd absorb more calcium from a glass of milk than from a pound of spinach. The oxalates capture it before your body can use it.

Oxalates and Babies

For adults, moderate oxalate intake is usually fine—the body handles it. For babies:

Concerns:
• Smaller body, higher relative dose
• Developing kidneys processing oxalates
• Nutrient needs are critical—can't afford binding losses
• Gut still developing

Practical approach:
• Don't make spinach a staple green
• Prefer low-oxalate greens: kale, bok choy, arugula, lettuce, zucchini
• Sweet potato occasionally is fine; daily might be excessive
• Nut butters (almond, cashew) in moderation

Low-oxalate alternatives: | Instead of | Try | |------------|-----| | Spinach | Kale, arugula, lettuce | | Swiss chard | Bok choy, cabbage | | Almonds | Macadamia, coconut | | Sweet potato daily | Rotate with white potato, squash |

The Phytate Problem

Phytic acid, found in grains, legumes, nuts, and seeds, binds minerals in the digestive tract.

High-phytate foods:
• Whole grains (especially bran)
• Legumes (beans, lentils)
• Nuts and seeds
• Soy products

What phytates bind:
• Zinc (critical for growth and immunity)
• Iron (in its non-heme form)
• Calcium
• Magnesium

Traditional Preparation Reduces Phytates

This is where traditional wisdom becomes essential. Every grain-eating culture developed preparation methods that reduce phytates:

Soaking: Activates phytase enzyme that breaks down phytic acid. Soak grains and legumes 12-24 hours, discard water.

Sprouting: Germination dramatically reduces phytates. Sprouted grain flour has 50-75% less phytic acid.

Souring/Fermentation: Sourdough bread has far less phytic acid than quick-rise bread. The long fermentation allows phytase to work.

For baby food:
• If using grains, choose soaked, sprouted, or fermented versions
• Commercial baby cereals are NOT prepared traditionally
• Sourdough bread (real, long-fermented) is preferable to regular bread
• Consider whether grains are necessary at all in the first year

Lectins: The Gut Disruptors

Lectins are proteins that can bind to the gut lining and potentially cause damage.

Highest lectin foods:
• Raw or undercooked legumes (especially kidney beans)
• Raw grains
• Nightshades (tomatoes, peppers, potatoes, eggplant)
• Peanuts

Important: Cooking destroys most lectins. This is why raw kidney beans are toxic but cooked ones are safe.

For babies:
• Always cook legumes thoroughly (pressure cooking is most effective)
• Don't serve raw tomatoes early on; cooked tomato sauce is fine
• Peel and seed nightshades when possible
• Peanuts are a separate allergen concern regardless of lectins

Goitrogens: Thyroid Interference

Goitrogenic compounds can interfere with iodine uptake and thyroid function.

Sources:
• Raw cruciferous vegetables (broccoli, cauliflower, cabbage, kale, Brussels sprouts)
• Soy products
• Millet

The key word is "raw." Cooking significantly reduces goitrogens. Lightly steamed broccoli is fine. Raw kale smoothies daily might be problematic.

For babies:
• Cook cruciferous vegetables (you should anyway for texture/safety)
• Limit soy products
• Ensure adequate iodine (seafood, iodized salt after 12 months)

The Practical Hierarchy

Not all antinutrients are equal threats. Here's how to prioritize:

High Priority (Actively Manage)

Oxalates in spinach/chard: These greens shouldn't be staples. Use occasionally, not daily. Choose lower-oxalate greens as defaults.

Phytates in grains: If using grains, prepare traditionally. Or minimize/delay grains entirely—babies don't need them.

Raw lectins: Never serve undercooked legumes. Always cook thoroughly.

Medium Priority (Be Aware)

Nut-based foods: Moderate use. Don't make almond butter a daily staple.

Sweet potatoes: Great food, but rotate rather than serving daily.

Nightshades: Cook them, peel when practical, no need to avoid.

Lower Priority (Don't Worry Much)

Cooked cruciferous vegetables: The goitrogen concern is overblown for cooked vegetables in reasonable amounts.

Occasional high-oxalate foods: A serving of spinach now and then is fine.

What Traditional Cultures Understood

Pre-industrial cultures didn't know the word "phytate," but they observed that unprepared grains caused problems. Over generations, they developed:

Nixtamalization — Mesoamerican corn processing that increases niacin availability

Sourdough fermentation — European bread-making that reduces phytates

Dosa/idli fermentation — Indian rice and lentil preparation

Miso/tempeh fermentation — Asian soy preparation

Soaking and sprouting — Universal practices for grains and legumes

When we eat these foods without traditional preparation, we miss the wisdom encoded in these practices.

The Nutrient Competition Frame

Think of it this way: your baby has limited stomach capacity and enormous nutrient needs.

Every meal is a choice:
• Serve spinach, and the "iron" on the label mostly passes through
• Serve liver, and bioavailable iron actually reaches tissues

You're not just choosing foods—you're choosing nutrient delivery systems.

High-antinutrient foods aren't poison. But for a baby with critical nutrient needs, why fight against absorption when you could work with it?

Practical Summary

Best Greens for Baby

Zucchini (very low oxalate)

Kale (lower oxalate than spinach, cook lightly)

Bok choy (low oxalate, calcium actually absorbs)

Peas (moderate, well-tolerated)

Green beans (low antinutrients)

Grains If You Use Them

True sourdough (not "sourdough flavored")

Sprouted grain products

White rice (lower phytates than brown)

Well-cooked oatmeal (soaked overnight first)

Legumes

Pressure cook or long simmer

Lentils are lower in antinutrients than most beans

Traditional preparations (dal, hummus) are time-tested

Nuts and Seeds

Moderate use, not daily staples

Macadamias are lowest in antinutrients

Nut butters occasionally, not as primary fat source

The Balance

This isn't about fearing plants. Vegetables are valuable. The point is:

1. Don't rely on high-antinutrient foods for minerals. Get iron from liver, not spinach. Get calcium from dairy or bone broth, not almonds.

2. Prepare foods traditionally when possible. Soaking, sprouting, and fermenting aren't hippie trends—they're ancestral wisdom.

3. Rotate rather than fixate. A varied diet naturally limits any single antinutrient.

4. Prioritize nutrient density. In a tiny stomach, every bite should deliver.

Your baby needs building materials. Choose delivery systems that actually deliver.