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What are the negatives of wheatgrass?

Wheatgrass is a popular health food made from the young shoots of the wheat plant. It contains high concentrations of vitamins, minerals, and antioxidants. Many claim it provides various health benefits, including improved immunity, weight loss, and detoxification. However, wheatgrass also has some potential downsides to be aware of.


Wheatgrass is prepared from the freshly sprouted leaves of the common wheat plant, Triticum aestivum. It is sold as a dietary supplement in juice, powder, tablet, and frozen product forms. Wheagrass differs from wheat malt, which is concocted from sprouted wheat berries.

Wheatgrass contains numerous vitamins, minerals and plant compounds, making it an incredibly healthy food. It also contains several unique elements that provide potential health benefits that ordinary green vegetables do not offer.

However, wheatgrass also has some potential negatives. This article will examine the possible adverse effects and downsides associated with wheatgrass consumption.

Oxalate Content

One potential concern with wheatgrass is its high oxalate content. Oxalates are plant compounds that bind to calcium and other minerals, preventing the body from absorbing them properly. High-oxalate foods can increase the risk of kidney stones in susceptible individuals.

Studies analyzing the oxalate contents of juices found wheatgrass juice to contain high amounts of oxalates:

Juice Oxalate Content
Wheatgrass juice 1,843 mg/L
Orange juice 5 mg/L
Carrot juice 22 mg/L

As shown in the table, wheatgrass juice had over 300 times the amount of oxalates as orange juice and over 80 times as carrot juice.

People prone to developing kidney stones may want to limit high-oxalate foods like wheatgrass. However, for most other folks, oxalates in moderation are not a major concern.

Blood Sugar Effects

Wheatgrass contains chlorophyll, flavonoids, and other plant compounds that may help moderate blood sugar levels. However, the wheat grass plant also contains natural sugars that may impact blood sugar.

Some animal studies have observed that wheatgrass extract could lower blood sugar levels and increase insulin concentrations in diabetic rats. However, other rat studies found wheatgrass powder did not improve hyperglycemia or glucose tolerance.

The evidence is currently mixed whether wheatgrass enhances blood sugar control. More research is needed to understand its potential effects on glucose metabolism.

People with diabetes should exercise caution with wheatgrass, as its impact on blood sugar has not been confirmed. Monitoring blood glucose carefully is advisable when trying new supplements like wheatgrass.

Allergic Reactions

Wheatgrass is derived from wheat, so people with wheat allergies or gluten sensitivity should avoid it. Wheatgrass contains gluten, and there are several reports of allergic reactions to wheatgrass supplements in people with wheat/gluten allergies.

Some other documented cases of wheatgrass allergies have occurred as well. A women developed a severe anaphylactic reaction after consuming just 1 ounce of wheatgrass juice.

People with food allergies should always check the source of any new supplement. While wheatgrass itself may have some nutritional benefits, the risks of an allergic reaction outweigh any potential rewards for wheat-sensitive persons.

Mold Contamination

Fresh wheatgrass juice must be consumed shortly after juicing, as it will ferment and spoil rapidly. However, some wheatgrass products may introduce health risks if they become moldy.

One case study reported severe mold contamination in a wheatgrass supplement tablet. Analysis found multiple species of mold present, including the toxic mold Aspergillus flavus.

Consuming moldy products introduces mycotoxins and other harmful compounds into the body. Only purchase wheatgrass products from reputable companies, and do not consume any that smell musty or spoiled.

Fresh wheatgrass juice Wheatgrass tablets or powders
Should be juiced and consumed immediately May risk mold contamination if stored improperly

Side Effects

Some people report mild side effects from wheatgrass consumption, including:

  • Headaches
  • Nausea
  • Constipation
  • Fatigue
  • Hypersensitivity reactions
  • Joint pain

These symptoms are usually temporary and subside as the body adjusts. Starting with small doses and increasing gradually can help minimize adverse effects.

Wheatgrass also contains high levels of iron. Too much iron can cause nausea, constipation, and fainting episodes. Individuals with hemochromatosis (iron overload disease) should avoid wheatgrass.

Finally, wheatgrass may affect thyroid function in some cases. High doses could potentially induce hyperthyroidism or thyroid problems. People with thyroid conditions should monitor closely and consult a doctor when taking wheatgrass.

May Impact Fertility

Some sources claim wheatgrass may affect fertility or reproductive function. However, the current evidence is weak and conflicting.

One rat study found male rats fed wheatgrass-supplemented diets had decreased fertility and sperm motility. However, another rat study observed wheatgrass extract improved sperm production and reproductive hormones.

The few human studies have not uncovered adverse reproductive effects. But more research is needed before determining wheatgrass’s safety during pregnancy and for fertility.

Contains Gluten

Although wheatgrass is harvested before grains form, it still contains gluten proteins that can trigger autoimmune issues for those sensitive.

In wheat, gluten helps provide the elastic structure that allows bread to rise properly. However, some individuals cannot properly digest gluten.

Consuming gluten can cause digestive distress, nutrient malabsorption, and serious conditions like celiac disease in gluten-intolerant people. Anyone following a gluten-free diet should avoid wheatgrass.

May Impact Thyroid Function

High doses of wheatgrass could potentially affect thyroid hormone levels in susceptible individuals.

One case study found a 36-year-old woman developed hyperthyroidism after consuming wheatgrass powder daily. Her symptoms resolved and thyroid hormone levels decreased after ceasing the wheatgrass.

Animal studies also report altered thyroid hormone concentrations when fed wheat sprouts and grass. The compounds responsible are unclear but may include lectins, flavonoids, and other wheat metabolites.

People with thyroid issues should monitor closely when taking wheatgrass regularly. Consult a doctor for optimal safety.

Contains Natural Toxins

Like other common cereal grasses, wheatgrass contains biologically active substances such as lectins, saponins, and molds that serve to protect the plant. These compounds are natural toxins that can cause issues when consumed in excess.

Lectins, for example, bind carbohydrates and may be problematic for some. Saponins are phytochemicals that may have hemolytic effects. And fresh wheatgrass can accumulate mold toxins if not prepared and stored properly.

That said, these toxins are generally not an issue for most people when wheatgrass is consumed in moderation. But it’s sensible to start with small amounts and ramp up gradually.

May Cause Nausea or Constipation

Some individuals experience nausea, upset stomach or constipation after consuming wheatgrass, especially at high dosages. These effects are likely due to wheatgrass’ potency and dense nutrient contents.

Though generally mild, these side effects demonstrate that wheatgrass may be too harsh for certain sensitive persons. It’s wise to start slowly and avoid consuming wheatgrass on an empty stomach.

Most cases of nausea and constipation subside once the body adjusts. But discontinuing use if these symptoms persist or worsen.

Contains High Levels of Iron

Wheatgrass contains substantial concentrations of iron, delivering approximately 1 milligram in a 1-ounce shot of fresh juice. While iron is an essential mineral, excessive amounts can be problematic.

Too much iron can cause nausea, constipation and vomiting. Individuals with blood disorders like hemocromatosis cannot properly regulate iron absorption. High iron foods like wheatgrass should be avoided by those affected.

The iron content gives wheatgrass a metallic taste that some find unpleasant. Diluting juice with water or another fruit juice can improve palatability.

Risk of Contamination

When growing and processing wheatgrass at home, there is an increased risk of contamination compared to commercially produced products. Potential contaminants include:

– Bacteria like Salmonella and E. coli

– Mold and yeast

– Soil contaminants

– Chemical residues from cleaning solutions

Growing wheatgrass requires the right type of seeds, soil, irrigation, drainage, and processing methods to minimize health risks. Improperly handled wheatgrass may accumulate dangerous bacteria. Sickly sprouts should be avoided.

Commercially grown wheatgrass is typically safer. Reputable companies follow good manufacturing practices to test for contaminants and prevent spoilage.

May Cause Joint Pain

Some people report increased joint pain after consuming wheatgrass regularly. The reason for this effect is uncertain but could relate to wheatgrass oxalate levels.

Oxalates may accumulate in joints and cause pain symptoms in susceptible individuals. People with gout or rheumatoid arthritis may need to moderate dietary oxalate intake.

However, the evidence linking wheatgrass to arthritic effects is anecdotal currently. Further studies need to verify whether wheatgrass can exacerbate joint discomfort.

Contains Fructans

Wheatgrass contains fructans, a type of FODMAP carbohydrate that some people cannot properly digest. Individuals with irritable bowel syndrome (IBS) should limit consumption of fructans and other FODMAPs.

Fructans pass intact through the small intestine and get fermented upon reaching the colon. This provides fuel for gas-producing gut bacteria and can trigger adverse effects like bloating, cramps, and diarrhea in IBS patients.

While wheatgrass fructan contents are lower than mature wheat, they may still prompt issues for fructan-sensitive persons. Those with IBS should introduce wheatgrass cautiously while monitoring symptoms.


Wheatgrass provides an extremely concentrated source of nutrients that may offer some unique health benefits. However, it also contains certain antinutritional compounds, allergens, and other potentially problematic components.

For most folks, wheatgrass is safe when used appropriately. But some individuals may experience adverse reactions or side effects. Introducing small doses and watching for any negative impacts is advisable.

People with wheat allergies, thyroid disease, IBS, kidney stones, blood sugar disorders or certain other conditions should exercise particular caution with wheatgrass. Pregnant women should also avoid wheatgrass until more safety research is available.

While wheatgrass has many advantages, it may cause issues for certain individuals or when consumed excessively. As with any supplement, moderation and common sense are the keys to harnessing wheatgrass’ benefits while avoiding downsides.