Should People with Osteoporosis Avoid Spinach? The Truth About Oxalates

December 29, 2025 •

3 min read

A 1988 study published in The American Journal of Clinical Nutrition found that only about 5.1% of the calcium from spinach is absorbed by the body, compared to 27.6% from milk. This low absorption rate is why many people with osteoporosis question if they should avoid spinach entirely.

Quick Summary

Spinach is high in oxalates, which significantly hinder calcium absorption, making it a poor calcium source for those with low bone density; it should not be relied upon for calcium intake.

Key Points

Oxalates reduce calcium absorption: The high oxalate content in spinach significantly decreases how much calcium your body can utilize from it.
Poor calcium source: Despite its calcium content, spinach should not be counted as a reliable calcium source for individuals with low bone density.
Enjoy in moderation: You don't need to completely eliminate spinach, as it still provides other valuable nutrients like Vitamin K.
Choose better alternatives: For dietary calcium, opt for low-oxalate leafy greens like kale, broccoli, and collard greens.
Cooking can help: Boiling spinach can help reduce its oxalate content, improving the potential for absorption of other nutrients.
Timing matters: Avoid eating spinach at the same meal as a major calcium source or a calcium supplement to maximize absorption from the better source.

Understanding the Role of Oxalates in Bone Health

Oxalates, also known as oxalic acid, are natural compounds found in plants like spinach. They bind to minerals such as calcium in the digestive tract, forming salts that are difficult for the body to absorb. This process reduces the amount of calcium available for bone health, which is a key concern for individuals with osteoporosis.

While spinach contains calcium, its high oxalate level makes it an inefficient source of the mineral. However, spinach does offer other beneficial nutrients like Vitamin K, which is important for bone metabolism. The primary issue for those with osteoporosis is that spinach isn't a reliable way to get the calcium needed to maintain bone density.

Better Leafy Green Alternatives for Calcium

For individuals with osteoporosis seeking calcium from leafy greens without the high oxalate content of spinach, several excellent options are available:

Kale: Offers high calcium with lower oxalates and provides Vitamin K.
Broccoli: Contains calcium and other vital nutrients for health.
Collard Greens: A good source of bioavailable calcium and other bone-supporting nutrients.
Bok Choy: A low-oxalate choice providing calcium and vitamins.
Turnip Greens: Another valuable source of calcium for bone health.

How to Manage Spinach in Your Diet

If you enjoy spinach, you can still include it in your diet, but consider its other nutrients rather than relying on it for calcium. To minimize oxalate impact:

Boil Spinach: Boiling can significantly reduce oxalate levels as they leach into the water. Remember to discard the cooking water.
Timing: Avoid eating spinach at the same time as calcium-rich foods or supplements to ensure better calcium absorption from those sources.

Comparison Table: Spinach vs. Kale for Bone Health


Feature	Spinach (High Oxalate)	Kale (Low Oxalate)
Calcium Content	High	High
Calcium Bioavailability	Very Low (approx. 5%)	High
Oxalate Content	Very High	Low
Primary Role for Bones	Vitamin K source, not calcium	Excellent calcium and Vitamin K source
Consumption for Osteoporosis	Moderation; not for calcium	Recommended; for calcium and Vitamin K
Cooking to Improve Absorption	Boil to reduce oxalates	Less necessary; calcium is already bioavailable

The Bottom Line for Osteoporosis Patients

So, should people with osteoporosis avoid spinach? While complete avoidance isn't usually necessary, it's crucial to understand that spinach's calcium is poorly absorbed due to oxalates. Those with osteoporosis should prioritize easily absorbable calcium sources like dairy, fortified foods, supplements, and low-oxalate greens. Enjoy spinach in moderation for its other benefits, but don't count it towards your main calcium intake. Making informed food choices supports bone health.

Conclusion: Making Informed Dietary Choices for Bone Health

Diet plays a vital role in managing osteoporosis. Although spinach has many nutrients, its high oxalate content makes it a poor source of calcium. Instead, focus on diverse foods with more bioavailable calcium. By choosing alternatives and planning meals thoughtfully, you can help ensure your body gets the necessary nutrients for strong bones. Always consult a healthcare professional or registered dietitian for personalized dietary advice. For more information, the Bone Health & Osteoporosis Foundation provides useful nutritional guidelines.

Frequently Asked Questions

Spinach contains high levels of oxalates, which are compounds that bind to calcium during digestion, forming calcium oxalate. This insoluble salt is not absorbed by the body, making the calcium in spinach largely unavailable.

Excellent low-oxalate leafy green alternatives include kale, bok choy, collard greens, turnip greens, and broccoli. These vegetables offer significant amounts of bioavailable calcium.

Yes, cooking methods like boiling or blanching can reduce the oxalate content in spinach. For maximum reduction, discard the water used for boiling.

Yes, you can still eat spinach in moderation. Just do not rely on it as a primary source of calcium. It still provides other important nutrients, so it can be part of a healthy diet.

Yes, other foods high in oxalates include rhubarb, beet greens, and some beans. While healthy, they should be considered in context, especially concerning calcium intake.

Spinach is a good source of Vitamin K, which plays a role in bone metabolism. It is also rich in other vitamins and minerals that support overall health.

To maximize calcium absorption from other sources, it is best to avoid consuming high-oxalate foods like spinach at the same time. Consider timing your meals to separate them.