Spinach: Nutritional Superstar or Potentially Harmful?

antinutrients

Hello Runners,

I’ll admit I struggled during a recent run. However, it wasn’t with the run itself, but instead with coming up for a topic for this blog post. COVID-19 has disrupted our lives in many ways, and for runners that has included cancelled and postponed events, which has affected training. This has also affected the schedule of blog posts I was going to write and share. So, now I’m trying to be creative and write about other topics that may be beneficial.

One topic that I have heard about in the past and have heard some physicians and nutritionists talk about more recently are antinutrients. So, in this post I thought I would talk about one of these antinutrients and how it might affect you.

What Are Antinutrients and What Do They Do?

Antinutrients are toxins commonly formed in plants to keep animals, bugs, and fungi from eating them. Antinutrients reduce the body’s ability to absorb nutrients. The main categories of antinutrients include lectins, phytates, and oxalates.

In this post, I will specifically discuss oxalates, which are common in some of the vegetables that are considered to have the highest nutritional value. In future posts, I will discuss the other classes of antinutrients.

What Are Oxalates?

Oxalates, also referred to as oxalic acids, are natural compounds found in a variety of food sources. Some of the most common oxalates in food can be found in plant sources such as fruits, vegetables, nuts and seeds. Oxalates can also be produced naturally by our body. In fact, most of the oxalates we have in our body are from those our body has produced.

In the body, oxalates can combine with calcium and iron to form either calcium oxalate or iron oxalate crystals, which are then excreted in urine, and thus are not be an issue. However, high amounts of oxalates can build up in the kidneys, leading to the formation of kidney stones. An estimated 80% of kidney stones are formed from calcium oxalate.

Also for people sensitive to oxalates, consuming even a small amount can cause burning in the mouth, eyes, ears, and throat. Large doses can lead to muscle weakness, abdominal pain, nausea, vomiting, and diarrhea, especially in people with a high amount of oxalates already in the body.

Besides forming kidney stones, oxalates affect the absorption and bioavailability (ability to be used in the body) of calcium. This is significant because calcium serves several important functions for health and running performance (see below).

Foods High in Oxalates

Although oxalates are found in virtually all foods, there are several foods that are high in oxalate content. Green vegetables, especially spinach, beet greens, okra, leaks, and collards have some of the highest concentrations.

Here is a list of other foods high in oxalates:

Fruits: blackberries, blueberries, raspberries, kiwis, tangerines, figs

Vegetables: broccoli, rhubarb, okra, leeks, beets, potatoes, eggplant, sweet potatoes, zucchini, carrots, celery, olives, rutabaga, chicory parsley, peppers

Leafy Greens: spinach, escarole, beet greens, kale, collards, Swiss chard

Nuts and Seeds: almonds, cashews, peanuts, sesame seeds

Legumes and Soy Products: miso, tofu, soy milk, green beans and kidney beans

Grains: bulgur, corn grits, wheat germ, whole wheat bread, amaranth, buckwheat and quinoa

Beverages: cocoa/chocolate, chocolate milk, black tea, instant coffee, dark beers

I decided to pick on spinach in this post for two reasons. One, spinach has one of the highest oxalate contents of any food. Second, spinach was discussed in a recent interview I heard with Dr. Jayson Calton. In the interview, Dr. Calton spoke on deficiencies that can occur due to lack of micronutrients in our diet and bioavailability of these micronutrients from the foods we consume. Specifically, Dr. Calton discussed a patient of his, who happens to now be his wife, who had advanced stage osteoporosis in her early 30s. Dr. Calton’s wife was consuming a lot of raw vegetables, including a raw spinach salad every day. He shared that by having her minimize the intake of raw spinach, as well as other raw vegetables, and supplementing with specific nutrients, including calcium, she was able to significantly improve her bone health.

So, should we stop eating spinach? Isn’t spinach a nutrient powerhouse?

Benefits of Spinach

Spinach is considered to be one of the world’s healthiest foods, with researchers identifying more than a dozen different types of flavonoid antioxidants alone that are present in spinach, not to mention all of its other vitamins, minerals and essential nutrients. Also, spinach has significant anti-inflammatory and antioxidant properties, and if you combine that with its very low amount of calories, it is easily one of the most nutrient-rich foods in existence.

Spinach contains many important nutrients, which serve many important functions including the following:

  • Protects Against Cancer
  • Defends Against Heart Disease
  • Boosts Immunity
  • Stabilizes Blood Sugar
  • Maintains Healthy Vision
  • Supports Bone Health
  • Keeps Skin Glowing
  • Aids in Detoxification
  • Preserves Brain Health
  • High in Magnesium

For more of details on the benefits of spinach click here

In addition, spinach does contain a significant amount of calcium, which has several important functions for health and running performance.

Important Functions of Calcium 

In addition to its importance for health of the bones and teeth, calcium serves the following important functions:

  • Optimal nerve transmission
  • Blood clotting
  • Hormone secretion
  • Muscle contraction
  • Appetite control
  • Weight loss
  • Controls levels of magnesium, phosphorus and potassium in the blood
  • May help prevent certain cancers

Click here to learn more about the specific benefits of calcium.

Spinach: Nutritional Superstar or Potentially Harmful?

So, now getting back to the question of this post. Should we stop consuming spinach, although it has many nutritional benefits? I have heard some physicians and nutritionists recommend this because of the high concentration of oxalates in spinach and the effect these have on calcium absorption and bioavailability, as well as the possible formation of kidney stones.

However, there are ways to potentially reduce the number of oxalates in certain vegetables, such as spinach, kale, broccoli and sweet potatoes that relate to how these vegetables are prepared. Boiling and steaming are techniques that can reduce oxalate content. Personally, I prefer steaming because this can minimize the loss of other nutrients compared with boiling. Also, soaking some of the high oxalate foods in water and a small amount of apple cider vinegar or lemon juice can potentially reduce the oxalate content. Also, avoid or minimize using raw kale, spinach, or Swiss chard in salads or smoothies. Instead, use greens with lower oxalate content such as green or red leaf or Romaine lettuce in salads and smoothies.

So, you certainly don’t need to give up spinach, especially since it has so many benefits. However, you may want to consider how you prepare it and consider using other greens, in addition to spinach.

However, there are exceptions for those with certain health conditions including: absorptive hypercalciuria and enteric hyperoxaluria. Individuals with these conditions should significantly restrict their consumption of high oxalate foods, such as spinach.

Other Important Factors

Research has shown that the intake of protein, calcium, and water influence the formation of calcium oxalate to a greater degree than the intake of oxalates from specific foods. High-protein intake can lead to kidney stone formation, while too much calcium in the body leads to calcification, crystallization, which can impact the risk for heart disease and kidney issues.

In addition, being properly hydrated is important for flushing the kidneys. This can also aid in removing other toxins from the body. In fact, I recently increased my water intake to about one gallon per day.

Bottomline

As far as the potential negative impact on health and running performance, oxalates are the least harmful of the antinutrients, with other antinutrients including lectins and phytic acid having a potentially greater negative effect. However, you should consider limiting the amount of raw vegetables, like spinach, kale and broccoli that you consume. Steaming can be a good option for these foods in order to lower oxalate content. Also, you may want to use other greens for your salads and smoothies, such as green/red leaf and romaine lettuce that have a significant lower oxalate content. Those individuals with certain conditions, including hyperoxolauria should restrict consumption of foods high in oxalates, especially in raw form. However, for most people there are significant benefits in consuming vegetables such as spinach. Just keep in mind which preparation is best and to include variety. Finally, avoid high-protein intake and consume a sufficient amount of water on a daily basis.

Please let me know if you have any questions, or if I can be of help in any way.

Your friend and coach,

Brian

References

Kim Wagner Jones, Lindsay K. Eller, Jill A. Parnell, Patricia K. Doyle-Baker, Alun L. Edwards, and Raylene A. Reimer. Effect of a dairy and calcium rich diet on weight loss and appetite during energy restriction in overweight and obese adults: a randomized trial. Eur J Clin Nutr. 2013 Apr; 67(4): 371–376.

Vadim A. Finkielstein and David S. Goldfarb. Strategies for preventing calcium oxalate stones. CMAJ. 2006 May 9; 174(10): 1407–1409.

Noonan SC, Savage GP. Oxalate content of foods and its effect on humans. Asia Pac J Clin Nutr. 1999 Mar;8(1):64-74.

Mathew D. Sorensen. Calcium intake and urinary stone disease. Transl Androl Urol. 2014 Sep; 3(3): 235–240.

Bendsen NT, Hother AL, Jensen SK, Lorenzen JK, Astrup A. Effect of dairy calcium on fecal fat excretion: a randomized crossover trial. Int J Obes (Lond). 2008 Dec;32(12):1816-24.

Dave Asprey. The Bulletproof Diet.

Yuri Elkaim Super Nutrition Academy. Module 6 Lesson 4 Antinutrients.

Joseph Pizzorno. The Toxin Solution.

Jayson Calton. Supplements Revealed.

https://draxe.com/nutrition/foods-high-in-calcium/

https://draxe.com/nutrition/foods-high-in-calcium/

https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/

https://draxe.com/nutrition/spinach-nutrition/

https://www.cancer.gov/about-cancer/causes-prevention/risk/diet/calcium-fact-sheet#q5

Share this: Share on FacebookShare on Google+Tweet about this on TwitterShare on LinkedIn

Leave a Reply

Your email address will not be published. Required fields are marked *