Tomato paste is a staple in many cuisines across Africa. It offers flavor, color, and a tomato “kick” to stews, soups, sauces, and more. But how often do we ask: is it purely tomatoes? Are there hidden additives or contaminants? How does regular consumption affect health, especially in African settings? Below is an evidence-based look at what we know today.
What Is Tomato Paste — and What’s Often in It?
In its ideal form, tomato paste is simply tomatoes cooked down to concentrate the soluble solids (sugars, organic acids, pigments) after removing seeds and skin. In many regulatory standards, tomato paste must reach a minimum level of total soluble solids (TSS). For example, a quality assessment study notes that a tomato paste “should have not less than 24 % of TSS with no additives.”
In practice, especially in African markets, commercial tomato paste may include:
- Salt, sugar, or flavoring agents to improve taste.
- Acidity regulators (e.g. citric acid, ascorbic acid).
- Starches or diluents, used to bulk up the product or cut costs.
- Synthetic dyes or pigments, in rare but concerning cases.
One Ghanaian study from Kwame Nkrumah University of Science and Technology found traces of erythrosine (Red Dye No. 3) and starch in tomato paste samples — additives banned by the Ghana Food and Drugs Authority for such products. In a broader “tomato paste fraud” account involving Ghana and Lebanon, inclusion of starch or substitute ingredients is cited as a practice to deceive consumers or reduce costs.
In Nigeria, an older analysis of eight brands sold in Kano showed moisture content of 89–91 %, total solids far below recommended levels, and low nutrient densities — all signs of dilution or poor quality control. (ResearchGate)
These findings suggest that some commercial tomato pastes, particularly in parts of Africa, may not deliver the full benefit of a pure concentrate—but may instead carry risks tied to adulterants or low botanical content.
Nutritional and Phytochemical Profile
A pure, high-quality tomato paste can be a potent source of nutrients and bioactive compounds:
- Tomatoes are rich in vitamins (C, K, folate), potassium, and antioxidants like lycopene.
- Processing tomatoes into paste often reduces water and increases the concentration of lycopene. In fact, lycopene in tomato products tends to be more bioavailable (better absorbed) than in raw tomatoes.
- A 2025 study in Port-Harcourt (Nigeria) measured lycopene content of commercial pastes between 104.8 and 246.0 mg per kg.
- Tomato paste is low in fat, contains modest protein and fiber, and is a source of micronutrients when made properly.
Health Risks and Concerns
However, when dilution or adulteration occurs, these nutritional values decline. Also, heat processing inevitably reduces vitamin C and some labile compounds, though it may increase the extractability of lycopene.
Additives and Dyes
Erythrosine (Red Dye No. 3) is a synthetic dye with controversial safety. The U.S. Food and Drug Administration banned its use in foods in 2023 due to concerns about carcinogenicity in animal studies, particularly in male rats. places where regulatory enforcement is weak, residues of such dyes in tomato paste present a worrisome exposure route.
Starch or non-tomato fillers may be less harmful per se, but they dilute the benefit, reduce the expected dose of antioxidants, and may introduce allergenic grains (e.g. corn or wheat derivatives). In consumers with celiac disease or grain allergies, hidden starches pose a hidden hazard.
Heavy Metals and Packaging Leachates
A 2025 Scientific Reports study looked at canned tomato paste samples, finding that lead concentrations were above permissible limits in some instances, though many other metals were within acceptable ranges.
Heavy metal contamination may arise from:
- Residues in soil or water used for tomato cultivation.
- Contaminated processing water or equipment.
- Migration of metals (lead, tin) from can solder or linings.
Chronic exposure to lead is associated with neurological damage, kidney disease, hypertension, and interference with hematopoiesis. Cadmium exposure affects kidneys and bone. Arsenic and mercury carry cancer risks.
While the 2025 study suggested that most metals (apart from lead) were within regulatory limits, the presence of elevated lead in tomato pastes is alarming.
Metabolic Effects and Acidity
Tomato paste is acidic, which may provoke discomfort in individuals prone to gastroesophageal reflux or ulcer disease. Also, many commercial pastes include added salt or sugar, which may worsen hypertension or metabolic derangements if consumed heavily.
Because tomato paste is a concentrate, ingesting large quantities inadvertently ramps up salt or sugar intake.
Overconsumption of Lycopene
Lycopenemia (orange skin discoloration) can occur with excessive intake of lycopene-rich foods, though this is benign and reversible. Lycopene is not known to cause serious toxicity in normal consumption, though theoretical interactions exist (e.g. with anticoagulants).
Effects on Disease Conditions
Because tomato paste is a concentrated source of lycopene and other antioxidants, some studies associate it with:
- Improved endothelial function and reduced risk of cardiovascular disease (through oxidative stress reduction and nitric oxide effects).
- Possible cancer-protective effects, especially in prostate, lung, and gastrointestinal cancers (lycopene has been studied in this regard). However, effects are modest and more robust trials are needed.
- Anti-inflammatory benefits in chronic conditions, via suppression of oxidative damage.
On the flip side, contaminants (lead, dyes) may worsen outcomes in susceptible individuals: e.g. lead exposure may counter cardiovascular or renal benefit, or worsen hypertension.
If someone has kidney disease, impaired antioxidant defenses, or heavy-metal burden, repeated exposure to adulterated paste may add to cumulative toxic load.
Healthy Alternatives and Better Practices
Homemade or Local Pure Concentrates
Processing your own tomato concentrate—by cooking down fresh tomatoes to reduce water—ensures you know exactly what goes in (no dyes, starch). Even sun-dried or solar-evaporated concentrates may suit local conditions.
Use Whole Tomatoes More Often
Whenever possible, use fresh or canned whole tomatoes (without excessive processing). Blending or mashing fresh tomatoes preserves nutrients, fiber, and reduces risk of adulteration.
Certified, Transparent Brands
Choose brands that publish full ingredient labels, quality assurance certifications (e.g. ISO, HACCP), and independent third-party lab test results. Avoid brands with vague “color enhancers” or suspicious “thickening agents.”
Dilution Strategy
If using commercial paste, dilute it more heavily and use it as flavoring—not the bulk of a sauce. Combine with fresh tomato purée to reduce additive exposure per serving.
Nutrient-Boosted Alternatives
Some local innovators produce “tomato pomace” products — using leftover skins/seeds — which retain bioactive compounds like lycopene and fiber.
The Way Forward in African Contexts
To improve safety and health impact of tomato paste in Africa, key steps include:
- Stronger regulatory enforcement — Agencies must test commercial pastes for banned additives like erythrosine and contamination. The Ghana study underscores lax oversight.
- Routine heavy-metal monitoring, especially for lead and cadmium, in both raw produce and final products.
- Support for local, small-scale paste processing, with clean methods and quality control, as alternatives to mass industrial brands.
- Consumer education — teaching buyers to read ingredient lists, recognize adulteration (e.g. abnormally watery pastes, tinny flavor), and prefer pure-concentrate options.
- Research expansion — more regional studies in Nigeria, Kenya, South Africa, and elsewhere to map which brands or supply chains have unsafe practices.
Final Assessment
Tomato paste can be a potent nutritional ingredient when it’s truly just concentrated tomato. Its lycopene and antioxidant content may support vascular and general health. Yet in many African markets, adulteration with starches, dyes, or dilution is common. More worryingly, heavy-metal contamination (especially lead) has been documented in canned tomato pastes.
Health professionals should counsel patients—especially those with renal disease, hypertension, or heavy-metal vulnerability—to favor high-quality or home-made tomato products. Public health policy must push for stricter oversight of paste manufacturers, routine contaminant screening, and transparency.
Frequently Asked Questions (FAQ)
Q: Is all tomato paste risky?
No. Pure, well-manufactured tomato paste without additives or contamination is a nutritious food. The risk comes from adulteration, dyes, and metal contamination in less regulated products.
Q: Can I still get lycopene benefits if I use diluted paste?
Yes, but the dose per serving falls. To get equivalent lycopene, you may need more volume or supplement with fresh tomato or tomato juice.
Q: Should people with kidney disease avoid tomato paste?
They don’t need to avoid it entirely, but caution is prudent. Use versions low in added salt or contaminants, and avoid overuse, because potassium load and hidden additives may stress renal function.
Q: Are substitutes like tomato sauce or puree safer?
They can be—but similar risks of adulteration exist. The principle remains: inspect ingredient lists, prefer transparent brands, and minimize additive load.
Q: How often do adulteration studies occur in African countries?
Unfortunately, infrequently. The Ghana KNUST study is relatively recent (2025). More regular surveillance is needed.
