TempoLife › Features › Food compounds: acid load, purines, oxalate and histamine
Food compounds
16 compound families that never appear on a nutrition label: PRAL acid load, purines, oxalate, histamine, tyramine, salicylates, nickel, FODMAPs, food pH, phytate, lectins, glycoalkaloids, goitrogens, cyanogenic glycosides, acrylamide and coumarin — what each one is, who it matters for, and how to read the tables.
This is reference material and not a diagnosis. Every page here describes a compound and the group of people it genuinely matters to; none of them can tell you what is wrong with you, and none of them is a reason to change or stop a prescribed medicine.
What these tables are, and what a nutrition label is not
A nutrition label answers one question: how much energy and how many macronutrients are in this. It is a legal minimum, and it is silent about everything a person actually looks up when something has gone wrong — the purines behind a gout attack, the oxalate behind a kidney stone, the fermentable carbohydrates behind a bad week with IBS, the histamine behind a flush after a tuna steak.
The compounds on this surface have one thing in common: each has a population it matters to and a much larger population it does not. That asymmetry is the reason they get looked up, and it is also the reason the internet handles them so badly, because a list written for someone with a confirmed diagnosis reads, to everyone else, like a list of foods to be afraid of.
The other reason they are handled badly is that they are not all the same kind of number. Four different things get printed in the same style of table:
- Measured on the food. Food pH, purine content, oxalate content. Real analytical values, but they differ between cultivars, seasons, laboratories and national tables — so the band is trustworthy and the decimal usually is not.
- Calculated from other numbers. PRAL is arithmetic on five nutrients, not an assay. Two sites can publish different PRAL values for the same food because they used different composition tables.
- A property of the handling, not the food. Histamine and tyramine are made by microbes over time. Two pieces of the same cheese, ripened differently, genuinely differ — which is why no table of them can be right.
- Created during cooking. Acrylamide does not exist in the raw ingredient. It is made in your pan, and how much depends on you.
Acid, base and pH
| Compound | Where the number comes from | Who looks it up |
|---|---|---|
| Acid load (PRAL) | Calculated from protein, phosphorus, potassium, calcium and magnesium | Kidney stone formers, chronic kidney disease, and anyone who has met the “alkaline diet” |
| Food pH | Measured directly with a meter, on the food itself | Home canners and picklers, anyone with dental erosion, anyone confused by “alkaline foods” |
Stones, gout and the gut
| Compound | Where the number comes from | Who looks it up |
|---|---|---|
| Purines | Present in the cells of the food, highest where cell density is highest | People with gout or hyperuricaemia, and people with uric-acid kidney stones |
| Oxalate | Made by the plant; also produced by the body’s own metabolism | People who have had a calcium-oxalate kidney stone |
| FODMAPs | Naturally present carbohydrates: fructans, galacto-oligosaccharides, lactose, fructose and polyols | People with diagnosed irritable bowel syndrome |
Amines and elimination diets
| Compound | Where the number comes from | Who looks it up |
|---|---|---|
| Histamine | Formed by bacteria during storage, ageing and fermentation | People investigating flushing and headache after meals; anyone who has had a reaction to fish |
| Tyramine | Formed by bacteria during ageing, curing and fermentation | People prescribed a monoamine oxidase inhibitor; people told tyramine triggers their migraine |
| Salicylates | Made by the plant itself, as part of its defence signalling | People considering an elimination diet; people told salicylates cause their asthma or hives |
Plant defence compounds
| Compound | Where the number comes from | Who looks it up |
|---|---|---|
| Phytate | The seed’s own phosphorus store, in bran, hulls and germ | People with low iron or zinc, and anyone eating mostly unleavened wholegrain food |
| Lectins | Plant proteins, concentrated in raw legume seeds | Anyone who cooks dried beans; anyone who has met a “lectin-free” diet |
| Glycoalkaloids | Made by the plant, and made faster by light, damage and sprouting | Everyone who stores potatoes; anyone who has heard nightshades are dangerous |
| Goitrogens | Plant defence compounds: glucosinolates, cyanogenic glycosides and isoflavones | People with thyroid disease, and anyone in a region with marginal iodine intake |
| Cyanogenic glycosides | Stored in the plant as an inert glycoside, released by the plant’s own enzyme | Anyone offered apricot kernels as a supplement; anyone cooking cassava, bamboo or elderberry |
Contact allergy and cooking chemistry
| Compound | Where the number comes from | Who looks it up |
|---|---|---|
| Nickel | Taken up from the soil by plants; also leached from cookware and cans | People with confirmed nickel contact allergy and unexplained dermatitis |
| Acrylamide | Formed during cooking above about 120 °C from asparagine and sugars | Everyone who fries, roasts or toasts starchy food |
| Coumarin | Natural constituent of cassia bark, tonka bean and sweet woodruff | Heavy cinnamon users, people giving cinnamon to children, cinnamon supplement takers |
Foods that carry three or more of these labels
This table is not from a source — it falls out of the sixteen band lists when you turn them inside out, counting only the raised bands and ignoring every reassuring one. It is the most useful thing on this page, because of what sits at the top of it: soy, legumes, wholegrains and nuts, followed by aged cheese and oily fish. Those are not the most dangerous foods in the shop. They are the most chemically interesting ones, and they are also among the foods with the best evidence behind them.
That is the argument against stacking these lists. Each one was written for a different person with a different problem, and each removes a different slice of the same small group of nutrient-dense foods. Follow one under supervision and you have a diagnostic tool. Follow four at once and you have removed legumes, wholegrains, nuts, fermented foods and most of the vegetable aisle to solve a problem only one of them was about.
How to read any of these tables without being misled
Check the serving, not the hundred grams. Almost every compound table is per 100 g, and almost nothing is eaten in 100 g units. Dried herbs top the salicylate table and are used a teaspoon at a time; vegetables sit low on most tables and are eaten by the plateful. A ranking by 100 g is not a ranking by exposure.
Ask what cooking does. Boiling removes a large share of soluble oxalate and much of the goitrogenic activity in brassicas, and does nothing at all to glycoalkaloids or histamine. Frying creates acrylamide from nothing. A table of raw values can be the wrong table entirely.
Ask whether the list was written for you. Purine tables were written for people with gout, oxalate tables for calcium-oxalate stone formers, tyramine sheets for people on a specific class of antidepressant. Stacking several of them together produces a diet nobody designed and nobody has tested.
Expect published tables to disagree. Different laboratories measure different purine bases; oxalate content varies with cultivar and soil; nickel content depends on where the crop grew. Disagreement between two reputable tables is usually real variation, not an error in one of them.
Where this sits next to the rest of the site
The per-food pages under food data carry the nutrient values — energy, macronutrients, and the vitamins and minerals where they are known — and every food named on this surface links back to its own page there. Can I eat that? answers a specific food-and-situation question with a verdict; this surface explains the compound behind the verdict. Foods by diet and allergen handles allergen and diet facets without quantities, and the E-number encyclopedia covers deliberate additives with their acceptable daily intakes. What is here is the chemistry a food arrived with, or acquired on the way to the plate.
Nothing on this surface is personal medical advice. If a food genuinely makes you ill, if you have had a kidney stone or a gout attack, or if you are considering removing a food group from your diet, the person to talk to is your doctor, pharmacist or a registered dietitian — they can test for the things that can be tested for, which a table cannot.
Sources are listed on each compound page and name the specific document. Food names and their links come from the site food database; no per-food quantity for any compound on this surface is asserted from that database, because the mineral fields a PRAL calculation needs are not in it. Checked 2026-09-06.
Frequently asked questions
Why are these compounds not on the nutrition label?
Because a label carries what the law requires — energy, fat, saturates, carbohydrate, sugars, protein and salt — and these are none of those. Some are contaminants, some are plant defence chemistry, some are made by bacteria during storage, and one of them (PRAL) is not a substance at all but a calculation. They matter to specific groups of people rather than to everyone, which is exactly why they are looked up rather than printed.
Are the numbers in these tables reliable?
They vary in reliability, and each page says which kind it is dealing with. Food pH is measured directly and is fairly stable. Purine and oxalate content is measured but differs between laboratories and cultivars. Histamine and tyramine are not properties of the food at all but of how it was handled. PRAL is calculated from five nutrients. Acrylamide is created in your own pan. Reading the number without knowing which kind it is is how people go wrong here.
Which page should I start with?
Start from the problem, not the compound. Gout and high uric acid lead to purines; a calcium-oxalate kidney stone leads to oxalate; IBS leads to FODMAPs; flushing after fish or aged cheese leads to histamine; a prescribed MAOI leads to tyramine; confirmed nickel contact allergy leads to nickel. If you arrived from an “alkaline diet” claim, the acid-load page is the one that answers it.
Is this the same as the nutrient pages?
No. The nutrient hubs and the per-food /calories pages carry the USDA nutrient data — energy, macronutrients, and the vitamins and minerals where they are known. This surface covers the compounds that sit outside that dataset, and it never invents a per-food quantity for them: where a value is not in the repository it is described as a band, not printed as a number.
Do I need to avoid all of these?
Almost certainly not. Most people need none of these lists, and every page here says who it is actually for. Elimination diets built from stacked online lists remove a great deal of food, and the nutritional cost of that is real — which is why each page names the small group it applies to and points everyone else back to the ordinary business of eating.
All 16 compound pages
Acid load (PRAL)
milliequivalents (mEq) per 100 g
Food pH
pH units (each step is a tenfold change in acidity)
Histamine
mg per kg of food (regulatory limits are set in these units)
Tyramine
mg per serving (the clinically relevant unit, not per 100 g)
Salicylates
mg per 100 g (published tables differ by more than tenfold)
Nickel
micrograms per 100 g (µg/100 g)
Purines
mg of purine bases per 100 g
Oxalate
mg per 100 g or per serving
FODMAPs
grams per serving, by category — measured values are licensed, not reproduced here
Phytate
mg per 100 g, and as a phytate-to-mineral molar ratio
Lectins
haemagglutinating units (hau) — a functional assay, not a weight
Glycoalkaloids
mg of total glycoalkaloids per kg of tuber
Goitrogens
no single unit — several unrelated mechanisms
Cyanogenic glycosides
mg of releasable hydrogen cyanide per kg
Acrylamide
micrograms per kg (µg/kg) of food
Coumarin
mg per kg of spice; intake assessed in mg per kg of body weight per day
The compound is one line; the diet is the rest
Whatever brought you here, the thing that decides the outcome is the pattern across weeks, not one table. TempoLife logs food, symptoms and weight in one place so the pattern is visible.