Oxalates

As promised on Monday, I am going to give a quick overview of oxalates. I think it’s important for people to understand what they are, which foods they are in, and how they impact which nutrients you obtain from your foods.

What are they?

Oxalates are organic acids, and are made inside of plants, animals and humans on a regular basis. They are considered binders, because they combine chemically with nutrients to form certain substances that the body simply cannot absorb. Oxalates occur naturally due to the incomplete oxidation of carbohydrates. Oxalates or oxalic acid is found in many foods in high levels; however, they are found in certain household products in toxic levels. These include things like bleaches, anti-rust products, and metal cleaners.

Which foods contain high amounts of oxalates?

• Berries
• Currants
• Kiwi
• Purple grapes
• Figs
• Tangerines
• Plums
• Rhubarb
• Spinach
• Eggplant
• Endive
• Swiss chard
• Beet greens
• Collard greens
• Okra
• Parsley
• Kale (so sad!)
• Leeks
• Legumes
• Quinoa
• Celery
• Green beans
• Sweet potatoes
• Almonds
• Cashews
• Peanuts
• Soy products
• Wheat bran
• Wheat germ
• Cocoa
• Chocolate
• Black tea
• Coffee

What do oxalates do to the nutrients in our food?

The oxalates in food will bind with certain nutrients and carry them right through our digestive tract and out of our body through the urine, preventing absorption. And if the nutrients are not absorbed, we are not getting any of their health benefits. It’s as if the food never contained them in the first place. Nutrients that are affected by oxalates include calcium, iron, zinc, copper, magnesium, and vitamin B6. The main nutrient affected, though, is calcium.

People with kidney problems, gout or rheumatoid arthritis are advised to avoid foods containing high amounts of oxalates as much as possible. This is because the oxalates form crystals that are very sharp, and although they are small, they are still large enough to irritate the body. When these crystals are deposited into our tendons, joints, kidneys or organs, we experience pain and eventually more serious health problems like the ones listed above. If you are trying to increase your calcium or iron intake, it may also be a good idea to cut back on foods high in oxalates. However, I’m hesitant to give this advice because so many foods that contain oxalates also contain many other beneficial nutrients that our body needs. I think a varied diet will help ensure that you are receiving all essential nutrients, and not consuming too much of one food that contains high amounts of oxalates.

For most people who do not have serious health problems, including foods with oxalates in the diet is fine. Just make sure you eat a varied diet and don’t consume large amounts of oxalate-rich foods for extended periods of time (for example, don’t make spinach your one and only green vegetable).

When we cook our foods, the oxalates decrease by about 10% at best. There is really no easy way (so far) to reduce oxalates in the above foods. The farm that Ed and I do our CSA with, Grant Family Farms, is supposedly working on a spinach plant that is very low in oxalates. Some of the farmer’s assistants came to our classroom last week to talk to us about organic farming, and mentioned this. I got really excited – hopefully that spinach will show up in our CSA box at some point!

So now you know about oxalates. Hopefully it’s not too disheartening – just remember that there are still so many good things in vegetables and eating all the oxalates in the world is still better than eating processed foods!

How to Choose & Store Foods: Spinach, Oranges, Asparagus

A continuation of yesterday’s post…

Spinach

When selecting spinach, look for thick, strong, dark green leaves. The stems should also be green and strong, but not too thick. A thick stem indicates the spinach may have been overgrown. I prefer to buy the fresh spinach leaves, complete with the dirt from picking. They're easy to wash at home. The pre-washed spinach in a bag is convenient, but I don’t trust it. This is the type of spinach where bacteria, even E. coli, will creep up every once in a while. Last summer, my sister Madeline found a little “friend” in a brand new bag of pre-washed spinach from Whole Foods. I won’t give the details, but I will say I haven’t bought bagged spinach again since, and I’m sure she hasn’t either. Plus, the fresh leaves that aren’t already prepped and bagged are also less expensive.

Wash the spinach right before you use it to retain the most nutrients and keep it fresh longer. It will store in the fridge for 2-5 days depending on its quality. A slimy coating on the spinach leaves (or on most things in your fridge, for that matter, such as lunch meat or cheese), can indicate it has begun to go bad.

Oranges

Oranges are one of those fruits that are most likely to contain pesticides, so buying organic is preferable. Some oranges may seem so perfectly colored that it’s too good to be true. Well, you’re right, it is too good to be true. In many non-organic oranges, a dye is injected to create an evenly colored peel. This makes the oranges more appealing at the grocery store and hides any discoloration that may have resulted from harvesting, packaging, storing and traveling. My sister Alice was visiting last month and we had a bag of clementine tangerines, and she mentioned that they just must be dyed because even the white fleshy part right inside the skin was orange, not white. I did some research and (disappointingly), found that they are often dyed. Yet another reason to stick with the organic oranges. Artificial dyes in fresh fruit? No thank you!

Choose an orange that is round and smooth. Although discoloration is not necessarily bad, bruises and soft spots could be signs of rotting. Fully ripened oranges will have the most antioxidants. A heavy orange indicates it carries more juice, whereas a light orange may taste dry and flavorless. Like spinach, very large oranges may be overripe or overgrown and will not taste as good. In general, the smaller the orange, the more flavor and nutrients it will contain.

As for storage, the counter and the refrigerator are both good options. An orange will last a week or two if you’ve chosen a good orange, which is a huge benefit of these fruits. I eat more oranges in the summer months, so I like to store them in the fridge so they are cold and refreshing.

Asparagus

Asparagus reminds me of summer and BBQs. It’s one of our staple veggies because it’s easy to prepare and full of nutrients. A little lemon juice, olive oil, salt and pepper are all it needs. We used to wrap it in tinfoil and grill it alongside the meat or fish, but we discovered it tastes better and retains more juices if we do it in the oven.

When selecting asparagus, stalks should be very green, very straight, and round. Asparagus tips should be darker green (some are purple) and tightly closed, not flowering open. Also, don’t be afraid to touch the stalk – it should feel nice and firm. Thin asparagus will be much more tender and cook quickly, whereas a thick stalk could be more crunchy and hearty. I usually go for the thin or medium-thickness, to avoid buying asparagus that has been overgrown or chemically altered.

Asparagus should be stored in the refrigerator and will keep for a couple of days (or longer, but eating it sooner will ensure freshness and the most nutrients). Asparagus is very high in folate, which is an extremely important B-vitamin, especially for women of child-bearing age. You may remember from my post last week on water-soluble vitamins that folate is easily destroyed by light. For this reason, make sure you store asparagus somewhere in the fridge that is tucked away and not right underneath a light. A veggie drawer on the bottom usually works well. I also like to wrap it in a paper towel inside the bag, just to be sure.

This wraps up the choosing and storing for some of the more popular spring fruits and vegetables… look for a similar post in a couple of months when we are all moving on to the delicious summer foods!