A beginner's guide to herbal supplements

People have used plants for as long as there have been people. Today, herbal supplements are one of the largest categories on the shelf, and also one of the hardest to read. A bottle might say "turmeric", "Curcuma longa", "95% curcuminoids" and "10:1 extract" all in one place. This guide translates those phrases, explains how herbal products are made, and sets out the sensible questions to ask before taking one.

What "herbal" means

A herbal (or botanical) supplement contains a plant or an extract of a plant. Despite the name, it is not limited to "herbs" in the kitchen sense: the part used can be a leaf, root, bark, flower, seed or fruit, and fungi and algae are sometimes grouped with them. The label should tell you which part of which plant is inside. That detail matters, because the same plant can contain different compounds in the root than in the leaf.

The Latin name

Common names are unreliable: "sage" can mean several different plants, and "ginseng" can refer to unrelated species. A botanical name has two parts, genus and species, such as Echinacea purpurea or Silybum marianum (milk thistle). When a label includes it, you can be sure which plant the manufacturer means. When it does not, you have less to go on.

Powder, extract or standardized extract?

• Whole herb powder: the dried plant ground up. It is the simplest form, and larger amounts are needed because the plant is not concentrated.
• Extract: the plant is soaked in a solvent such as water, alcohol or glycerin, and the liquid is concentrated. A ratio such as "4:1" suggests that four parts of raw plant were used to make one part of extract, so the product is more concentrated than a plain powder.
• Standardized extract: the manufacturer measures one or more marker compounds and adjusts the product to contain a stated percentage, for example "standardized to a given percentage of silymarin" in milk thistle. This makes batches more consistent and makes products easier to compare.

Neither route is automatically better. Whole herb products appeal to people who prefer less processing; standardized extracts appeal to people who want a defined amount of a particular compound. What matters is that the label states what you are getting.

Quality starts with the label, then the maker

Because herbs are agricultural products, their composition varies with species, soil, harvest time and drying. Reputable manufacturers follow the FDA's current good manufacturing practices, which cover identity, purity and labeling of supplements. Some also use voluntary independent testing programs, such as those run by USP or NSF, and display the seal on the label. A seal tells you that the product was submitted and met that program's criteria; the absence of a seal does not mean a product is poor, only that you have less to verify it with.

Natural does not mean risk-free

This is the most important point in this guide. A plant can contain strongly active compounds, and some are well documented to affect how medicines work. Some examples to illustrate the point:

• St. John's wort is a widely cited example of an herb that interacts with many prescription medicines, including some antidepressants, oral contraceptives and blood thinners.
• Ginkgo and garlic are among the herbs that clinicians commonly ask about before surgery or for anyone taking blood thinners.
• Echinacea belongs to the daisy family; people who are allergic to ragweed or related plants should read the label carefully and check with a clinician.
• Kava products have drawn warnings from regulators in several countries because of rare cases of liver injury.

These are illustrations, not a complete list, and they do not mean these herbs are unsafe for everyone. They mean that "herbal" is a category with real pharmacology, and that you should treat it with the same care as any other active ingredient.

Who should talk to a professional first

Anyone who is pregnant, nursing, planning surgery, taking prescription medicine, managing a medical condition, or giving a product to a child should speak to a clinician or pharmacist before starting a herbal product. A pharmacist can check your medicines against an ingredient in a few minutes and often at no charge.

Practical habits

1. Start with one product at a time. If you try three new herbs on the same day and something disagrees with you, you will not know which one.
2. Follow the directions. The "suggested use" is based on the form and strength of that specific product.
3. Keep the box or a photo of the label. You may need the ingredient list and lot number later.
4. Write it down. Our guide to keeping a simple supplement log shows how.
5. Check dates. Powders and extracts lose potency and aroma over time; see Storing supplements.

Single herbs and blends

You will meet two kinds of herbal products in the shop. Single-herb products contain one plant, which makes them easy to read. Blends combine several, which is convenient but less transparent, particularly when the label shows a proprietary blend. Our guide to blends and proprietary formulas explains how to read them.

Where to start in the shop

The Herbal & Natural Care category is organized by plant, so you can go straight to what you are looking for. Examples include Echinacea, Garlic, Milk Thistle, Olive Leaf and Saw Palmetto, with a broader Herbal Supplements section for the rest.