Juicing has become an increasingly popular way to get more nutrients from fruits and vegetables. By extracting the juice from produce, you can consume a high concentration of vitamins, minerals, and other beneficial plant compounds. However, not all vegetables are well-suited for juicing. Some contain compounds that may become concentrated or bitter in juice form. Others have tough cell walls that don’t break down well in a juicer. This article will explore which vegetables are best avoided when making homemade juices.
Vegetables High in Oxalates
Some vegetables contain relatively high amounts of oxalic acid and oxalates. Oxalic acid can bind to calcium and other minerals, preventing absorption. In high amounts, it may also irritate the digestive tract. Vegetables highest in oxalates include:
| Vegetable | Oxalate Content |
|---|---|
| Spinach | 743 mg per 100 g cooked |
| Beet greens | 419 mg per 100 g cooked |
| Collard greens | 267 mg per 100 g cooked |
| Purslane | 135 mg per 100 g cooked |
| Rhubarb | 541 mg per 100 g cooked |
While these vegetables are very healthy and nutritious overall, it’s best to consume them in moderation and pair them with foods high in calcium, such as yogurt or cheese, to improve oxalate excretion and mineral absorption. Juicing concentrates the oxalic acid content, so spinach, beet greens, collard greens, purslane and rhubarb are not the best options for green juices.
High Mercury Vegetables
Some vegetables absorb and accumulate high levels of mercury from contaminated soils. Mercury is a heavy metal that can damage the kidneys and nervous system in high amounts. The EPA recommends limiting intake of high mercury vegetables, especially for pregnant women, infants, and young children. High mercury veggies include:
| Vegetable | Mercury Level |
|---|---|
| Carrots | 0.03 ppm |
| Parsnips | 0.03 ppm |
| Potatoes | 0.03 ppm |
| Cabbage | 0.06 ppm |
Mercury levels this high are still relatively low, but juicing carrots, parsnips, potatoes, and cabbage may concentrate the mercury content to excessive amounts. So these vegetables should be consumed in moderation for everyone and avoided in juice by sensitive populations.
High Glycemic Vegetables
Juices made purely with fruits and high glycemic vegetables can cause a rapid spike in blood sugar. For people with diabetes or pre-diabetes, it’s best to avoid juicing veggies that are high on the glycemic index. These include:
| Vegetable | Glycemic Index |
|---|---|
| Carrots | 71 |
| Beets | 64 |
| Parsnips | 97 |
| Pumpkin | 75 |
Combining these vegetables with healthy fats and proteins can help slow their absorption and reduce their impact on blood sugar. But for those monitoring glucose levels closely, the concentrated sugars in these juiced vegetables may cause unwanted spikes.
Goitrogenic Vegetables
Goitrogens are compounds found in some vegetables that may interfere with thyroid function by blocking iodine uptake. Those with thyroid issues may want to avoid juicing high goitrogen veggies like:
| Vegetable | Goitrogens |
|---|---|
| Broccoli | Glucosinolates, thiocyanate |
| Cauliflower | Glucosinolates, thiocyanate |
| Cabbage | Glucosinolates, thiocyanate |
| Kale | Glucosinolates, thiocyanate |
| Brussels sprouts | Glucosinolates, thiocyanate |
However, cooking helps inactivate goitrogenic compounds, so consuming these cruciferous vegetables in moderation should not negatively impact thyroid function for most people. Those with diagnosed thyroid disorders may still want to minimize consumption.
Nightshade Vegetables
The nightshade family of vegetables contains solanine, a compound that can exacerbate inflammation and arthritis pain in some individuals. Nightshades include:
| Vegetable | Solanine Content |
|---|---|
| Potatoes | Highest in green potatoes |
| Tomatoes | Low |
| Eggplant | Low |
| Peppers | Very low |
People with arthritis, joint pain, or autoimmune conditions may want to avoid juicing nightshades. Cooking or peeling potatoes can help reduce solanine content.
High Potassium Vegetables
Those with kidney disease or on dialysis need to limit potassium intake. Juicing vegetables high in potassium may result in excessive intake in one sitting. High potassium veggies include:
| Vegetable | Potassium per 100g |
|---|---|
| Potatoes | 500mg |
| Sweet potatoes | 337mg |
| Tomato juice | 370mg |
| Beet greens | 645mg |
| Spinach | 558mg |
Those with kidney issues should consult their doctor before consuming juices with these vegetables.
Gas-Causing Vegetables
Some people experience bloating, gas, and abdominal discomfort from vegetables that contain raffinose sugars. These compounds can ferment in the large intestine, releasing gas. Gas-promoting vegetables include:
| Vegetable | Raffinose Sugars |
|---|---|
| Cabbage | High |
| Brussels sprouts | High |
| Asparagus | Moderate |
| Leeks | Moderate |
| Onions | Moderate |
Those prone to intestinal gas may want to avoid juicing these vegetables.
Conclusion
While juicing can be a nutritious way to increase your fruit and vegetable intake, some vegetables are better suited for juicing than others. High oxalate, goitrogenic, and nightshade veggies, along with vegetables high in sugar, potassium or gas-promoting compounds may provide excessive amounts of certain substances, irritate the GI tract, or exacerbate existing health conditions when juiced. Always monitor your body’s response to determine which juices agree with you and your individual health needs. Focus on low glycemic veggies like leafy greens, celery, cucumber and herbs for vegetable-only juices.
