Pigweed: Invasive Weed or Delicacy?

 

 Pigweed: Invasive Weed or Delicacy?

Written by Anne Ambs, Allergy and Asthma Center of NC, Cone Health Medical Group

As summer rapidly approaches, plants in the pigweed family begin to make an appearance across the United States. The American Academy of Allergy, Asthma & Immunology (AAAAI), the organization that oversees the National Allergy Bureau (NAB) pollen monitoring program, includes pigweed, goosefoot, lamb's quarters, amaranth, saltbush, and Russian thistle in a single group for pollen counting purposes. The pollen grains from these plants are so similar that it is not possible to distinguish them. 

Although pigweed is generally considered a nuisance weed, growing along the roadside and frequently fighting for space in lovingly cultivated gardens, it has long been utilized as a source of food, with nearly all parts of the pigweed being edible. Native American cultures grew pigweed as a staple crop, specifically Palmer amaranth (Amaranth palmeri),as its seeds can be popped or ground, and its leaves can be eaten raw or cooked into dishes as a vital ingredient in many regions across the world. Aztecs even considered red amaranth (Amaranth cruentus) as a critically important grain to be used in spiritual ceremonies. Other pigweed aliases include green amaranth, redroot amaranth, careless weed, tumbleweed, and callaloo.

Some people with pollen allergies can experience an uncomfortable, itchy feeling in their mouth or throat after eating fresh fruits or vegetables. This is called oral allergy syndrome or pollen allergy syndrome, which occurs when the immune system mistakenly identifies certain proteins in foods as similar proteins in pollens. It is estimated that about 1/4 to 1/3 of people with allergic rhinitis suffer from oral allergy syndrome. People with an allergy to pigweed pollen may experience symptoms of oral allergy syndrome when consuming citrus fruits, banana, pineapple, persimmon, zucchini, tomato, hazelnut, and peanut. Interestingly, peeling fresh fruit or vegetables can reduce symptoms and heating or cooking can further reduce symptoms.

Pigweed can be found throughout parts of Europe, like Germany, Hungary, and Spain, along with regions in Mexico, Brazil, Korea, Afghanistan, and Mozambique. Across the United States, pigweed is most prevalent in Arkansas, Missouri, Mississippi, Tennessee and Louisiana.

They begin to flower and shed pollen (anthesis) six weeks after emergence in the late summer and early fall. Pollen grains are spheroidal in shape, have between 30-65 pores, and measure 18-31 microns in diameter. The pollen is small enough to be carried by the wind, which is often how the problem starts for allergy sufferers. Symptoms can include runny nose, congestion, sneezing, postnasal drainage, and itchy red, watery eyes.

Image 1 (taken by Forsyth County staff on August 5, 2024): While the Forsyth County pollen team record weed pollen as either ‘ragweed’ or ‘non-ragweed,’ they were able to identify this non-ragweed pollen as a member of the pigweed family. The photo was taken at 40x magnification.

 

Many people who are affected by pigweed pollen allergies can find some temporary relief with over-the-counter allergy medications like antihistamines, nasal preparations, and allergy eye drops. Allergen avoidance measures for pollen can be followed; however, a certain amount of pollen exposure is inevitably unavoidable. If your symptoms are not well controlled with medication, then an allergy specialist may be in your future!

 An allergist can perform environmental allergy skin testing and sometimes blood testing to evaluate your allergies. With these specific results, an individual plan can be generated to provide the most effective relief from allergy symptoms.