Hong Kong, February 2025 – The city’s Consumer Council has released a comprehensive analysis of six common sugars—slab sugar, red sugar, dark brown sugar, light brown sugar, white sugar, and rock candy—only to discover that none contain a single trace of iron. The findings, published in the latest issue of Choice magazine, debunk long-held beliefs about the “healthier” status of darker sugars while offering practical guidance for home cooks and health-conscious consumers.
Six Common Sugars: From Raw Slab to White Crystal
The six varieties differ mainly in production method and refinement level. Slab sugar, red sugar, dark brown sugar, and light brown sugar are traditionally made by extracting sugarcane juice, filtering out impurities, then boiling the liquid until it crystallizes. Because they skip a step called “purging”—which separates sugar crystals from molasses—these sugars retain more natural minerals. By contrast, white sugar and rock candy undergo full refining, stripping away all molasses and yielding a nearly pure sucrose product.
However, the council warns that many commercially available “traditional” sugars today are actually made by simply adding molasses and colouring to white sugar. Consumers can check the ingredient list: if molasses or artificial colour appears, the product is likely a modern blend rather than a genuinely traditional sugar.
Nutritional Breakdown: Darker Sugars Lead in Minerals, But All Miss Iron
Laboratory tests revealed that darker sugars contain notably higher levels of calcium and potassium. Dark brown sugar topped the calcium rankings with 18–127 mg per 100 g, followed by slab sugar at 8–122 mg. For potassium, slab sugar led with up to 944 mg per 100 g, while dark brown sugar ranged from 41–382 mg. White sugar and rock candy showed negligible or undetectable levels of both minerals.
Yet the council cautioned that one teaspoon (about 6 g) of even the most mineral-rich sugar provides only about 1% of the daily recommended calcium intake and 3% of potassium for adults aged 18–75. “These sugars cannot serve as a primary source of these nutrients,” the report states.
Even more striking: every single sample tested contained zero iron, contradicting popular claims that red or brown sugars help prevent anaemia.
TCM Perspectives: Each Sugar Has a Purpose
Dr. Lo Kwai-ching, a lecturer at the University of Hong Kong’s School of Chinese Medicine, offered traditional insights:
- Slab sugar: warms the spleen, nourishes the lungs, and suits those with weak digestion or dry cough.
- Red sugar and light brown sugar: traditionally used to invigorate blood circulation and relieve cold hands and feet.
- Dark brown sugar: believed to dispel cold and ease menstrual pain.
- White sugar: neutral in nature, seldom used in traditional remedies due to modern bleaching processes.
- Rock candy: moistens the throat and nourishes yin, ideal for dry skin and throat discomfort.
Dr. Lo noted that sugars produced from white sugar plus molasses may not carry the same therapeutic benefits as their traditionally made counterparts.
Calorie Check: One Teaspoon Requires a 7-Minute Walk
Each teaspoon of any tested sugar delivers 24 kilocalories. For a 60 kg adult, that means walking at 3 km/h for roughly seven minutes (about 350 metres) to burn off the energy. “Sugar is energy-dense, and even small amounts add up,” the council reminded.
Purity tests showed that white sugar and light brown sugar averaged nearly 100% total sugar content, while slab sugar had the lowest at around 92% due to higher moisture and molasses content.
How to Choose: Read Labels to Spot Real Traditional Sugars
The council’s key takeaway: don’t judge by colour alone. Dark sugars can still be highly refined if made from white sugar base. Always review the ingredient list—if “molasses” or “caramel colour” appears, the product is likely a modern composite. For those tracking mineral intake, nutrition labels should ideally list calcium and potassium amounts.
Bottom Line: Moderation Is Key
While darker sugars offer marginally more minerals, the differences are nutritionally insignificant in typical serving sizes. All sugars are high in calories and devoid of iron. The healthiest approach, experts agree, is to use sugar sparingly regardless of type. For those seeking traditional remedies, Dr. Lo recommends choosing sugars made by conventional methods and consulting a qualified Chinese medicine practitioner.
The Consumer Council’s full report appears in Choice issue 580. For related reading, the council also recently tested 50 cooking oils, finding 70% contained plasticisers and 60% tested positive for carcinogens—a reminder that even pantry staples deserve scrutiny.