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Most Supplements Now Made in Chinese Factories Using Genetically Engineered Microbes

ZOE Science & Nutrition · Most replayed moment: What The Science Says About Supplements | Prof Tim Spector & Prof Sarah Berry · June 23, 2026
Most Supplements Now Made in Chinese Factories Using Genetically Engineered Microbes
ZOE Science & Nutrition
ZOE Science & Nutrition
Most replayed moment: What The Science Says About Supplements | Prof Tim Spector & Prof Sarah Berry
"Most of them are now made in China. It's the biggest producer of these in vast factories. And I think the majority are now made from genetic engineering of microbes. They ferment them in these big tanks."
Professor Tim Spector revealed that the majority of vitamin and mineral supplements are now manufactured in China through genetically engineered microbe fermentation in industrial tanks, contradicting consumer perceptions of supplement production. He noted that surveys show some supplements don't even contain the chemicals they claim.

About this episode

On this episode of Zoe Recap, host Jonathan Wolf was joined by Professor Tim Spector and Professor Sarah Berry for a comprehensive examination of the supplement industry, its claims, and what the science actually supports. Spector opened with a controversial revelation that calcium supplements, which he previously prescribed to menopausal women, do not prevent fractures as intended and are instead associated with increased heart disease risk, possibly by hardening arteries. The conversation traced the historical origins of supplements back to industrialization and wartime deficiency crises, explaining why the modern supplement industry is built on outdated post-war science that no longer applies to well-nourished populations. Spector accused major food manufacturers of exploiting this legacy by adding trace minerals to sugar-laden processed foods and making unsubstantiated immune-boosting health claims. He further revealed that most supplements are now manufactured in Chinese factories using genetically engineered microbes, with surveys showing some products don't contain their labeled ingredients. Berry provided important nuance, identifying specific populations that genuinely benefit from supplementation including pregnant women taking folic acid, which reduces neural tube defects by 30-75%, elderly people with inadequate diets, vegans needing B12, and those with iron deficiency anemia. Both experts emphasized that for the majority of people eating reasonably balanced diets, vitamin and mineral deficiency is extremely rare, and the body tightly regulates nutrient levels within narrow ranges. Adding excess amounts through supplementation offers no benefit and can actually be harmful, forcing organs to work harder to eliminate toxins. The episode concluded with sharp criticism of premium supplements marketed at vulnerable consumers with inflated health promises.

Key takeaways

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