If you’ve ever looked at a vitamin label and noticed that the amount of a vitamin or mineral, such as vitamin C, appears in amounts higher than the recommended daily intake (RDI), you might be wondering why.

There’s an important distinction between the amount of a nutrient required to prevent deficiency, and the amount needed to achieve a therapeutic health benefit.

In Australia, the RDI for vitamin C is 45mg per day for most adults. This is amount recommended by the NHMRC to prevent deficiency-related conditions such as scurvy. Symptoms of scurvy can include fatigue, weakness, irritability, body aches (especially in the joints and legs), easy bruising, swollen or bleeding gums, poor wound healing, and dry rough skin. But preventing deficiency is not always the main goal of taking a supplement.

Many people take vitamin C for other purposes – such as to support immune health, reduce the duration of cold symptoms, or assist with wound healing. In these cases, the amount used in a product may be higher than the RDI. This is because it reflects the amount shown as effective in scientific research.

In Australia, complementary medicines (including vitamins and supplements) are regulated by the Therapeutic Goods Administration (TGA). The TGA requires that the dose of an active ingredient is backed by scientific evidence for the product’s claims.

For example, if clinical research shows that 500 mg of vitamin C a day is needed to achieve the particular health benefit, then that is the amount the product must contain. Complementary medicine products must be supported by evidence and are not allowed to make unsubstantiated claims.

While the RDI reflects basic nutritional needs for healthy people, there is also the concept of the Upper Level of Intake (UL). This is highest average daily amount that is unlikely to cause harmful effects for nearly everyone. Exceeding this level does not necessarily mean harmful effects will occur.

It’s important to note that therapeutic doses of vitamins and minerals used in complementary medicines are generally well within the UL, and where they exceed it, they are still within acceptable safety limits that are determined by the TGA for therapeutic uses. Some complementary medicines are also intended for shorter-term use depending on the product claim.

Supplements are also required to include specific warnings and directions on how to use the product safely, including when certain groups may need to exercise caution.

In Australia, vitamins, minerals and dietary supplements must meet strict standards for safety, quality, and efficacy. These standards are enforced by the TGA on all companies, manufacturers and laboratories, including product testing where required. Supplements for sale in Australia must carry an AUST L, AUST LA or AUST R number on the label. This sets them apart from unregulated or imported supplements, which may not meet the same safety and quality benchmarks.

More information is available on the TGA website.

Used correctly, vitamins, minerals and supplements can play an effective role in supporting health. If you’re using multiple products, or if you’re unsure whether a product is right for you, speak to a qualified healthcare professional, particularly one that has specialised training in nutrition. And always read the label and follow the directions for use.

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