Plant-based diets are supposed to be healthy, right? Unfortunately, there are many inflammatory substances in these foods. Learn the chemicals to watch for.
When I was 20, I read “The China Study”, which listed the miracles of a plant-based diet. In my experiments, I’ve found that the fewer plants I eat, the healthier I am.
I’ve listed 19 chemicals found mostly in ‘plant-based’ foods that can cause chronic inflammation and autoimmunity. Each person has a different immune system and can react differently to these substances. I’ve tried to list them in the order of importance for most people.
The foods mainly fall under the category of plant-based foods and secondarily cured meats.
Inflammatory Substances Naturally Found in Plant-Based Foods
1) Lectins
Do not confuse lectins with leptin, lactose or pectin.
Lectins are proteins that are found in every living organism, including viruses, bacteria, and pretty much all foods, to one degree or another – but most of them are harmless. Scientists have known about lectins since 1884.
The more nefarious of these proteins have the potential damage and destroy the cells in our intestines causing discomfort, poor digestion, and “leaky gut.”
Cell membranes in our body contain sugar molecules attached to fat and protein called glycolipids and glycoproteins (glyco=sugar). The lectins that harm our cells are chemically attracted to these sugar molecules and disrupt the cell wall.
Lectins can also spike inflammation in the gut, skin, joints and the hypothalamus in susceptible people.
Lectins are part of the defense mechanism of plants to protect them from being consumed [1].
Over time, our immune system has evolved to create antibodies that compete with lectins [2]. Unfortunately, not all of us have the genetics that creates antibodies that protect us from every harmful lectin. This is why some of us are sensitive to the lectins in nightshades, and others are not.
Some dietary sources of lectins such as wheat can directly break tight junctions in gut cells [3, 4].
On average, fifteen percent of a bean’s proteins are composed of lectins.
Studies show that bean lectins aren’t completely destroyed after soaking for 2 hours and cooking. In common beans, the lectin content declines from 820 to 3.2 (Hemagglutinating Activity), while in fava beans it declines from 51.3 to 6.4 [5].
Lectins can cause GI upset similar to classical food poisoning and immune responses like joint pain and rashes. Improperly prepared raw grains, dairy, and legumes like peanuts, and soybeans have especially high lectin levels.
A study was done on 800 people with autoimmune conditions who ate a diet that consisted of avoidance of grains, sprouted grains, pseudo-grains, beans and legumes, soy, peanuts, cashews, nightshades, melons and squashes, and non-Southern European cow milk products (Casein A1), and grain and/or bean fed animals.
Most of these people had elevated TNF-alpha. The result after 6 months was a normalization of TNF-alpha in all patients who complied with the diet.
The study concluded that elevated Adiponectin is a marker for lectin and gluten sensitivity, while TNF-alpha can be used as a marker for gluten/lectin exposure in sensitive individuals [6].
Dr. Gundry frowns upon foods that originated from America.
See my podcast with the author of the study: Dr. Steven Gundry.
2) Amines
Biogenic/vasoactive amines
Biogenic or vasoactive amines are produced by bacteria during fermentation, storage or decay [7].
They include beta-phenylethylamine, tyramine, tryptamine, putrescine, cadaverine, spermine, and spermidine, but histamine is the one most frequently linked to food-related symptoms [7].
When plasma histamine levels are raised above the normal range (0.3-1.0 ng/mL) this produces certain effects. For example a level of 1-2 ng/mL causes increased gastric acid secretion and heart rate, with, flushing, headache, urticaria, pruritus, and tachycardia occurring at a level of 3-5 ng/mL), bronchospasm at a level of 7-12 ng/mL and cardiac arrest occurring at levels of 100 ng/mL [7].
Thus large amounts of ingested histamine can cause significant symptoms in otherwise well individuals. For example symptoms of flushing, sweating, urticaria, GI symptoms, palpitations and in severe cases bronchospasm may occur following the consumption of spoiled fish [8].
This condition, known as scombroid poisoning, occurs due to the high level of histidine in certain fish species being converted into histamine by marine bacteria [9].
Due to the nature of the symptoms caused, reactions involving vasoactive amines may, therefore, be incorrectly diagnosed as a food allergy.
Although 75 mg of liquid histamine can provoke symptoms in healthy volunteers [10], defining a safe threshold level for sensitive individuals is difficult [11].
According to one study, mean levels of histamine were 3.63 mg/L for French wines, 2.19 mg/L for Italian wines and 5.02 mg/L for Spanish wines [12].
In a placebo-controlled study, one study found no correlation between wine histamine content and wine intolerance and concluded that other vaso-active amines or sulphites may be more relevant in intolerance to wine [13].
It has been proposed that other foods may be able to cause histamine release directly from tissue mast cells although evidence for this is lacking [7].
One study found that a diet low in vasoactive amines alleviated chronic headache in 73% of patients [7].
Another study reported that 27/44 (61%) of subjects had a significant improvement in idiopathic urticaria, angioedema, and pruritus on a diet low in dietary amines, although foods containing additives or high in natural salicylate were also restricted [11].
Subjects with chronic hives or angioedema had a marginally significant reduction in their use of antihistamines on a histamine-reducing diet compared to a control group who eliminated artificial sweeteners from their diet [14].
58% of adult patients with irritable bowel syndrome (IBS) considered foods rich in vasoactive amines, such as wine, beer, salami, and cheese, to be a cause of their symptoms [15].
The diagnosis of sensitivity to vasoactive amines is usually made through history and dietary exclusion; however, some studies have suggested that the measurement of diamine oxidase (DAO) levels may be helpful. One study found a DAO level <3 kU/mL was associated with reported symptoms to high histamine foods, whereas a level of >10 kU/mL indicated histamine intolerance was unlikely [16].
Patients with chronic idiopathic hives/urticaria and GI symptoms have been shown to have reduced DAO activity [17, 18].
Another study reported that the size of the skin prick test wheal to histamine after 50 min, the ‘histamine 50-skin-prick test’, was a useful diagnostic indicator; 82% of subjects with histamine intolerance maintained a wheal size greater than 3 mm compared with 18 % of controls [19].
Foods more likely to contain high levels of vaso-active amines and salicylate
| Vaso-active amines [16, 20, 21–22] | Salicylate [23, 24–25, 26] | |
|---|---|---|
| Meat, poultry, and seafood | All cured meat especially pork products e.g. ham, salami, pepperoni, game, bacon, sausages, fresh pork, fresh or canned tuna, canned sardines, anchovies, mackerel, salmon, herring, processed fish products (fish pastes, smoked, dried or pickled fish), fish sauce | |
| Milk and eggs | Blue cheese, parmesan, brie, camembert, Emmental, old gouda, cheddar cheese, and other hard cheeses | |
| Fruits | Oranges, bananas, tangerines, pineapple, grapes, strawberries | Granny Smith apples, cherries, strawberries, currants, raisins, kiwi, Gala melon, peaches and nectarines, raspberries |
| Vegetables, nuts, seeds, and savory snacks | Tomatoes, pickled cabbage, aubergine, spinach, broad beans, peanuts, tree nuts | Asparagus, sweet corn, raw tomatoes, tomato puree |
| Condiments and miscellaneous | Fermented soy products including miso and tempeh | Ginger, mixed herbs, mustard, oregano, curry powder, black pepper, cardamom pods, cinnamon, cumin, fenugreek, mint, nutmeg, paprika, rosemary, thyme, turmeric, licorice, peppermint, Worcestershire sauce, honey, tomato ketchup |
| Drinks | Green tea, champagne, coffee, cocoa, chocolate, wine, beer, fresh fruit juices, smoothies | Coffee, pineapple juice, cider, Benedictine liqueur, lemon tea, black tea, apple juice, cranberry juice, orange juice, tomato juice, fizzy drinks, Drambuie liqueur, wine, rum |
3) Tannins
I don’t believe all tannins are bad, but many of them stimulate the immune system too much.
Tannins are found in many plant foods and are considered anti-nutritional because they can cause problems with digestion and absorption of nutrients [27].
Tannins are a type of enzyme inhibitor that prevents adequate digestion and can cause protein deficiency and gastrointestinal problems.
Tannins give plants their color. Some are healthy and some are harmful (to people with an overactive immune system).
Human dietary sources of tannins are tea and coffee [28], wine (contributes to its bitterness) [29], cranberries [30], strawberries and blueberries [31]. Apple juice, grape juices, and berry juices are all high in tannins. Nuts such as hazelnuts, walnuts, and pecans also contain high amounts of tannins.
4) Trypsin Inhibitors
It’s important to remember that plant foods have tens of thousands of chemicals and any of them can stimulate the immune system too much for your biology.
In wheat, amylase trypsin inhibitors cause a Th1 driven immune response, activation of TLR4, and cause intestinal inflammation [32].
5) FODMAPS
FODMAPs are short-chain carbohydrates (oligosaccharides), disaccharides, monosaccharides and related alcohols that are poorly absorbed in the small intestine. These include short chain (oligo-) saccharide polymers of fructose (fructans) and galactose (galactans), disaccharides (lactose), monosaccharides (fructose), and sugar alcohols (polyols) such as sorbitol, mannitol, xylitol, and maltitol.
The term FODMAP is an acronym, deriving from “Fermentable Oligo-, Di-, Monosaccharides, And Polyols.”
FODMAPs caused fatigue and gut problems in people who thought they’re sensitive to gluten (33).
FODMAP avoidance should be the first-line therapy for the majority of patients with functional bowel symptoms [34, 35].
It can help with IBS and other gut problems [36].
6) Salicylates
Salicylate intolerance has been defined as a hypersensitivity reaction to salicylic acid, its derivatives or other related organic or inorganic acids of similar chemical structure [37].
Salicylic acid is widely distributed in plant foods (especially spices) and, like its synthetic counterpart (Aspirin), has anti-inflammatory activity. Namely, it inhibits COX-2 gene expression [38, 39].
It’s proposed that 2.5 % of Europeans may have salicylate sensitivity [40], but the evidence on which this assertion is based is sparse.
One study proposed that 2-7 % of all patients with inflammatory bowel syndrome and food allergies could be affected by salicylate intolerance [37]. Gibson and Barrett suggest that since there are no published studies demonstrating
7) Oxalates
Oxalates (oxalic acid) are considered anti-nutrients.
Foods with oxalates include leafy greens, vegetables, fruits, cocoa, nuts and seeds [41].
Oxalates are found in the highest quantities in sesame seeds, soybeans, and black and brown varieties of millet.
Your body can produce oxalate on its own or obtain it from food. Vitamin C can also be converted into oxalate when it’s metabolized [42].
Oxalates can bind to minerals to form calcium oxalate and iron oxalate. This mostly occurs in the colon, but can also take place in the kidneys and other parts of the urinary tract.
In sensitive individuals, high-oxalate diets have been linked to an increased risk of kidney stones and other health problems.
About 80% are made up of calcium oxalate [43].
However, most of the oxalate found in urine is produced by the body, rather than absorbed from food [44].
When 59 women with vulvodynia or chronic vaginal pain were treated with a low-oxalate diet and calcium supplements, nearly a quarter experienced improvements in symptoms [45].
Some gut bacteria, such as Oxalobacter formigenes, use oxalate as an energy source, which significantly reduces the amount your body absorbs [46]. Antibiotics decrease the number of these bacteria [47].
People with inflammatory bowel disease or gastric bypass surgery have an increased risk of developing kidney stones [48, 49, 50], partly because they are unable to regulate the amount of oxalate they absorb.
Foods High in Oxalate
Oxalates are found in almost all plants, but some plants contain very high amounts while others have very little.
Foods high in oxalate (100-900 mg per serving) include:
- Spinach
- Beets
- Swiss chard
- Cocoa powder
- Kale
- Sweet potatoes
- Peanuts
Drink a lot of water can help with kidney stones.
Boiling vegetables can reduce their oxalate content by anywhere from 30% up to 90%, depending on the vegetable [51].
Calcium binds to oxalate in the gut and reduces the amount your body absorbs [41, 52].
8-10) Sulphites, Benzoates, and MSG
I personally don’t have an issue with Sulphites, Benzoates or MSG.
Sulphites
Foods usually containing significant levels of added sulphite include cider, white wine, and dried fruit.
A plethora of reports in the 1980s demonstrated that sulphites in foods were provoking adverse reactions; by 1984 the US Food and Drug Administration had received more than 250 reports of suspected sulphite reactions including six deaths [53].
Foods containing a high level of free-form sulphites are more likely to provoke a reaction [54].
Sensitivity to sulphites mainly affects patients with asthma, especially those with severe steroid-dependant asthma. Sensitivity to sulphites has a reported prevalence of 3.9-4.6% in asthmatic patients, with those who were steroid dependent being most at risk [55].
A review suggested that 3–10 % of asthmatics experience symptoms on exposure to ingested sulphites [56].
An analysis of sulphite-sensitive cases in Korea found that two types of sulphite sensitivity existed, those with sulphite sensitive asthma was the most common, affecting two-thirds of their cohort, with the remainder having sulphite-sensitive hives (urticaria) [57].
Sulphites can also cause edema (swelling, especially of the lips or face), anaphylaxis, and rhinitis [7].
One study found 16% of wine sensitive asthmatics responded to sulphite additives in wine [58].
Benzoates
Benzoic acid is produced by many plants and is present in many foods, including berries and milk products, usually in relatively low concentrations of up to 40 mg/kg [59, 60].
Benzoate can also be a product of digestion, e.g. cinnamic acid from cinnamon is oxidized to a benzoate salt in the liver [61].
Benzoates are also added in much higher concentrations to soft drinks, jams, sweets, chocolates, ice creams, pickles, baked goods due to their antimicrobial properties [62, 63].
Benzoates have been linked to chronic hives (urticaria), asthma, atopic dermatitis, rhinitis, and anaphylaxis although there is limited good quality evidence to support these findings [7].
Glutamate (MSG)
Monosodium glutamate (MSG-E621) is a commonly added ingredient to savory foods. Glutamate also occurs naturally in other foods, with the ripening of fruits such as tomatoes and the curing of meat such as ham being associated with an increase in the free amino acids such as glutamate.
Results from studies have been mixed, but overall seem to show that some individuals could experience symptoms from the ingestion of MSG, although only in quantities greater than the normal dietary intake [7].
This additive has been linked to asthma, headache, hives (urticaria) and angioedema, rhinitis, psychiatric disorders and convulsions [7].
A headache has been the most commonly reported symptom in relation to MSG [64].
In one blinded placebo-controlled trial, 61 subjects with self-reported sensitivity to MSG were tested. 18/61 had no response, 21/61 had a placebo response and 22/61 a positive response to the active challenge only. On re-challenge, a threshold dose of 2.5 g MSG was established [65].
In another small blinded placebo-controlled trial, 14 healthy individuals reported a significant increase in reported headache and pericranial muscle tenderness after taking a large dose of MSG (150 mg/kg – about 10g MSG for the average weight man) [66].
Foods more likely to contain high levels of natural or added sulphites, benzoates, and monosodium glutamate:
| Sulphites (E220–E227) [67, 68, 69, 70] | Benzoates (E210–E219) [59, 71, 61, 70, 72] | Monosodium glutamate (E621–E623, E627, E635) [73, 74] | |
|---|---|---|---|
| Meat, poultry, and seafood | Prawns, lobster, dried salt cod, crab sticks, squid, meat burger, sausages | Dishes with a spicy sauce, ready to eat meals containing benzoates | Fish sauce |
| Milk and eggs | Yogurt, cheese | Parmesan cheese | |
| Fruits | Dried apricots, sultanas, figs, prunes, dates, dried banana, candied or glace fruit desiccated coconut, currants | Cranberries, bilberries, prunes, papaya, dried fruit, avocado | |
| Vegetables, nuts, seeds, and savory snacks | Dried mushrooms and other fungi, frozen, tinned or vacuum packed potatoes, French fries, instant mash, gnocchi, potato cakes, potato croquettes, vegetarian burgers and sausages, tinned asparagus, broad beans, French beans, chestnuts, walnuts | Pumpkin, kidney beans, soybeans, soy flour, broccoli, spinach, baked beans in tomato/spicy sauce, dry roasted and spicy nuts, Bombay mix, crisps (except ready salted), potato or corn snacks, | Mushrooms, spinach, savory snacks, crisps |
| Condiments and miscellaneous | Horseradish sauce, caramel coloring (E150) | Curry powder, allspice, mixed spice, nutmeg, clove, cinnamon, chocolate, cocoa, ketchup, soy sauce, Worcestershire sauce, salad dressing, salad cream, mayonnaise, jam, pickles | Soups, stock, gravy, rubs, coatings, ready-meals, soy sauce, black bean sauce, oyster sauce, tomato sauce, miso, marmite, instant rice, and noodle dishes |
| Drinks | Cider, wine, beer, fruit squash and cordials, soft drinks, grape juice, fruit juice drinks, cola drinks | Tea, squash, cordial, carbonated drinks, milkshake syrup, beer, ready-to-drink alcohol and mixers, spirits with added spices |
Foods likely to be high in added and/or natural ‘food chemicals’
| Food | Amine | Glutamate | Salicylate | Sulphite | Benzoate |
|---|---|---|---|---|---|
| Cheese | ✓ | ✓ | ✓ | ||
| Wine | ✓ | ✓ | ✓ | ||
| Soy | ✓ | ✓ | ✓ | ||
| Tea | ✓ | ✓ | |||
| Tomatoes | ✓ | ✓ | ✓ | ✓ | |
| Herbs and spices | ✓ | ✓ | |||
| Strawberries and pineapple | ✓ | ✓ | |||
| Spinach | ✓ | ✓ | ✓ | ||
| Worcestershire sauce | ✓ | ✓ | ✓ | ||
| Dried fruit | ✓ | ✓ | ✓ |
11-19) Other Anti-Nutrients in Plant Foods:
- Non-protein amino acids
- Glycosides
- Alkaloids (includes solanine, chaconine)
- Triterpenes
- Lignins
Saponins
High saponin foods include quinoa.
Phytic Acid (Also Called Phytate)
Phytate interferes with the absorption of minerals.
Phytic acid can block the absorption of phosphorus, calcium, copper, iron, magnesium, and zinc, and increase the absorption of copper.
Phytic acid also inhibits certain essential digestive enzymes (amylase, trypsin, and pepsin).
Read more about phytates.
Gluten
Gluten is one of the most difficult-to-digest plant proteins. It’s an enzyme inhibitor that has become notorious for causing gastrointestinal distress.
Isoflavones
Isoflavones are highest in soybeans. It can have estrogenic effects and cause hormonal changes and contribute to digestive issues. These are considered endocrine disruptors.
If You Have Food Sensitivities
I recommend following my lectin avoidance diet, which is really an elimination diet that helps you figure out which foods you are sensitive to. Beyond lectins, this diet helps you figure out issues from all the food substances mentioned below.
It doesn’t suit EVERYONE’s needs, but it’s a good template from which to build a personalized diet. You can download the initial food list for free below:
Lectin Avoidance Diet Cookbook
I have released the lectin avoidance cookbook. The cookbook includes a protocol to figure out which foods or substances cause inflammatory reactions for each individual person. It also includes 91 low lectin recipes (and growing) that are clearly labeled whether they are dairy-free, low tannin, low FODMAPs and/or low oxalate.
SelfHacked Elimination Diet Course
This is a video course (with PDF handouts) that provides:
- The most updated science behind food sensitivities and inflammation from foods put in a format that is accessible to the lay people
- Step-by-step instructions to carry out an elimination diet so you can be 100% sure whether you have food sensitivities, and accurately identify the culprits
- Facebook group support where you can ask food-related questions to other members and our consultants
