Buying Diet Supplements in Japan: Navigating Drugstores, Labels, and Regulatory Standards

Japan's pharmacy and drugstore chains are well-stocked with health supplements, and many visitors leave with bags full of health products. Understanding what distinguishes evidence-based Japanese supplements from marketing-driven products requires knowing the regulatory framework — which differs substantially from UK/EU or US systems.

Japan's Supplement Regulatory Categories

Japan operates a tiered health food system under the Food Labelling Act:

FOSHU (Foods for Specified Health Uses) — 特定保健用食品

The highest-evidence category. FOSHU products must:

• Submit clinical trial data to the Consumer Affairs Agency (CAA)
• Demonstrate efficacy through human studies
• Receive individual government approval before making health claims

FOSHU products display a specific blue-and-green government logo (a figure in motion within a checkmark). This mark is a genuine indicator of reviewed clinical evidence by Japanese standards — broadly comparable in rigour to EFSA-authorised health claims in the UK.

Examples of FOSHU-approved categories: Specific cholesterol-lowering plant sterols, blood pressure-modulating peptides, specific probiotic strains (Lactobacillus gasseri SBT2055), blood glucose management ingredients (banaba leaf at specific doses, resistant dextrin), and glucomannan for blood glucose modulation.

FFC (Food with Function Claims) — 機能性表示食品

Industry self-certification. Companies file a dossier with the CAA and wait 60 days — there is no pre-market government review. The FFC mark (a stylised leaf) indicates a self-certified claim, not government-approved efficacy. Evidence quality varies substantially.

Key distinction: FOSHU mark = government-reviewed evidence. FFC mark = company self-certification. Both are legal to sell; only FOSHU has external evidence review.

General Health Foods and Supplements

No specific claim marks. These products cannot make health claims but are sold as food supplements. Dose and ingredient quality vary widely.

Navigating the Japanese Pharmacy: Practical Guide

Major Japanese pharmacy chains (松本清/Matsumoto Kiyoshi, ツルハ/Tsuruha, サンドラッグ/Sundrug) typically stock supplements in a dedicated health food section separate from OTC medicines.

Reading Japanese supplement labels:

The key label elements to locate:

• 栄養成分表示 (Nutritional content declaration): Mandatory on all foods/supplements — lists energy, protein, fat, carbohydrate, sodium
• 原材料名 (Ingredients list): Descending order by weight — same as UK
• 内容量 (Content amount): Total product volume/weight
• 一日当たりの摂取目安量 (Daily intake guideline): The manufacturer's suggested daily serving
• FOSHU mark (特保): Look for the blue-green government logo if you want the highest-evidence category

Useful category terms:

• 体脂肪 (taishibo) = body fat
• 血糖値 (kettochi) = blood glucose
• コレステロール (koresterooru) = cholesterol
• 代謝 (taisha) = metabolism
• 腸内環境 (chonaikankyou) = intestinal environment/gut health

Ingredients with Genuine Evidence in Japanese Products

Resistant Dextrin (Fibresol-2 / 難消化性デキストリン)

A FOSHU-approved soluble fibre derived from corn starch. Multiple RCTs demonstrate:

• Reduction in postprandial blood glucose rise (~20% reduction vs control)
• Modest reduction in triglyceride response
• Gut microbiome prebiotic effect

Evidence grade: A for postprandial glucose moderation; B for gut health. Widely available in FOSHU-marked fibre supplements and functional drinks (Pepsi Special, Kirin Plus beverages contain it).

Dose: 5g resistant dextrin before or with a meal is the typical FOSHU-approved dose.

Specific Probiotic Strains (L. gasseri SBT2055)

FOSHU-approved at this specific strain. A 2010 RCT (European Journal of Clinical Nutrition, n=87 obese adults) found 200g/day of L. gasseri SBT2055-fermented milk reduced visceral fat area by 4.6% and BMI by 1.4% after 12 weeks. This is a specific strain-specific effect.

Available in yoghurt products (specific Snow Brand and Megmilk products) more than supplement capsules in Japanese retail.

Nattokinase (ナットウキナーゼ)

Enzyme from natto with FOSHU approval for cardiovascular health. B-grade evidence for mild blood pressure reduction and platelet aggregation inhibition.

Interaction warning: Anticoagulant activity — do not use with warfarin, apixaban, rivaroxaban, clopidogrel, or aspirin without medical guidance.

What to Be Cautious About

High-Dose EGCG Products

Concentrated green tea extract capsules are common in Japanese pharmacies. EFSA (2018) concluded concentrated EGCG extracts above 800mg/day carry hepatotoxicity risk. Some Japanese products exceed this threshold — check the EGCG content per serving and stay below 400mg/day from supplements.

Slimming Products Marketed Without FOSHU Marks

Products marketed with body fat or weight claims that lack the FOSHU mark are relying on FFC self-certification or no certified evidence at all. Ingredient adulteration has been documented in Japanese slimming supplements — the MHRA database of adulterated supplements includes Japanese-origin products containing undisclosed sibutramine (a withdrawn appetite suppressant) and undisclosed pharmaceutical laxatives.

"Diet Tea" Products (ダイエットティー)

Many herbal tea blends marketed for weight loss contain senna (センナ) as an undisclosed ingredient — a stimulant laxative. Long-term laxative use causes electrolyte imbalance and, with chronic use, laxative dependence. Check ingredient lists for センナ, センノシド, アロエ, or ダイオウ (rhubarb root) if concerned.

Bringing Supplements Home to the UK

UK customs rules for personal importation:

• Personal-use quantities (not for resale) of food supplements are permitted for import
• Products must not be listed as controlled substances in the UK
• Certain traditional medicines may contain restricted ingredients — check MHRA yellow card database if bringing traditional Kampo products

Practical recommendation: Japanese-origin ingredients with genuine evidence (glucomannan, EGCG at safe doses, resistant dextrin, nattokinase) are all available from UK-based manufacturers with UK regulatory compliance, English-language labelling, and allergen information — reducing the risk associated with imported products whose labelling you may not be able to fully verify.

For individuals on anticoagulant medications, cardiovascular medications, or diabetes medications, any Japanese supplement with metabolic or cardiovascular activity should be reviewed with a GP or pharmacist before use.