Nightshade and salicylate sensitivity

What are salicylates?

Salicylates are the salts or esters of salicylic acid. They are converted into salicylic acid in the body, which is toxic, and even deadly, in high enough doses. It should be noted, however, that while a small minority of people are sensitive to salicylates, for most people salicylic acid brings health benefits. It calms inflammation, and may prevent heart disease and cancer.

We are exposed to salicylates orally, for example from ingesting plant foods that naturally contain salicylates in different concentrations, as well as medications (salicylic acid is the main ingredient in aspirin) and some foods such as breath mints and chewing gums; but we also absorb salicylates through the skin and lungs, and as such are exposed through use of cosmetics like acne products, perfumes, shampoo, sun cream, toothpaste and mouthwash, lotions and lipsticks; plus household products such as air fresheners and cleaning detergents.

Reaction to salicylates can occur through contact with commonly encountered foods and cosmetics. This is known as salicylate sensitivity, with typical reactions including:

• Wheezing or breathing difficulties
• Nasal congestion
• Alterations to skin colour
• Hives or itching skin
• Sore or swollen eyes
• Headache
• Fatigue
• Altered mood, such as depression
• Nausea or stomach pain
• Swelling of mouth, face, hands, feet or eyes

It is thought that salicylate sensitivity could, in part, be caused by a deficiency in zinc and omega 3 fatty acids, with research studies showing a reduction in symptoms in those sensitive to salicylates when taking high doses of one or both.

What are nightshades?

Nightshade foods are part of the Solanaceae family, which includes over 2000 species, some of which are quite deadly, such as belladonna. While perfectly healthy for most people, they can promote a reaction in those sensitive to their glycoalkaloids – a type of saponin also found in legumes and pseudo cereals like quinoa. These saponins have detergent-like qualities designed to inhibit ingestion by microbes and pests. Examples of glycoalkaloids in nightshades include solanine in potatoes and aubergines, capsaicin in peppers, and tomatine in tomatoes.

Foods within the nightshade family include:

• Potatoes
• Tomatoes
• Tamarillos and tomatillos
• Peppers (including chillies)
• Sorrel
• Aubergine
• Goji berries
• Cape gooseberries
• Huckleberries
• Cayenne pepper, chilli powder and paprika

Reactions to nightshade vegetables may include IBS, heartburn, joint pain, skin reactions and altered nerve sensation. While evidence is limited, there is a possible link between nightshade vegetables and the pain and inflammation associated with arthritis.

Like salicylates, saponins do bring beneficial properties including increased mineral absorption into the bloodstream by the creation of small pores, or holes, in the cells that line the gut. While some saponins only create these small holes that appear to do no harm, others bind more tightly to the cholesterol molecules within the cell membrane, creating larger pores and contributing to epithelial permeability, or leaky gut. Such pores may also impact on the cell’s ability to transport nutrients and carbohydrates into the bloodstream, slowing down the process. This may leave more food for pathogenic bacteria to feed on, which when combined with the possibility that saponins inhibit growth of beneficial bacterial strains, could contribute to dysbiosis, or imbalance of bacteria, within the gut. Additionally, glycoalkaloids can suppress the enzyme acetyl cholinesterase, which may negatively impact on nerve impulses and neurotransmitters.

While our day-to-day intake of nightshade vegetables shouldn’t be high enough for poisoning to occur, of more concern is moderate exposure over time and the possible resultant damage to the intestines in susceptible individuals, which could contribute to inflammation and risk of autoimmune disease. If you think you may be reacting to nightshade foods, consider keeping a food diary to monitor symptoms, or consult a professional for help with an elimination diet.

Written by Emma Rushe