Kelp
Laminaria digitata
About Kelp
Kelp (Laminaria digitata) is a herb used in the Western Herbalism tradition to help with Thyroid, Metabolism, Weight Loss, and Bone Health, among 1 other condition it addresses. The aerial parts and leaves are the parts traditionally used, taken internally.
Botanical background
Laminaria digitata is a large brown alga in the family Laminariaceae, also known by the common name Oarweed. It is found in the sublittoral zone of the northern Atlantic Ocean.
Source: Wikipedia, via iNaturalist
Parts used
Conditions addressed
Tea / Infusion
- Steep 1–2 tsp of dried Kelp in freshly boiled water for 5–10 minutes.
- Cover while steeping.
- Strain and drink.
Tincture
- Pack dried Kelp into a jar and cover with 40–60% alcohol.
- Seal and steep for 4–6 weeks, shaking daily.
- Strain and store in a dark dropper bottle.
Powder / Capsule
- Grind dried Kelp into a fine powder.
- Fill size 00 capsules or stir into smoothies or honey.
Pregnancy, Breastfeeding & Children
No herb-specific pregnancy/child safety research is documented for Kelp in our references — the guidance below is based on its general effect category, not research on Kelp itself. Always confirm with a midwife, doctor, or pediatrician.
Pregnancy
AvoidThis herb is associated with stimulant activity, which can raise heart rate and blood pressure — generally best avoided or strictly limited in pregnancy. This is a general, mechanism-based caution, not herb-specific research.
Breastfeeding
Use CautionStimulant compounds pass into breast milk and can cause infant irritability or poor sleep — generally used cautiously and in moderation.
Children
AvoidStimulant effects on the developing cardiovascular and nervous system mean these herbs are generally avoided in children.
Contraindications
- Thyroid disorders — may interfere with levothyroxine and other thyroid medications
- Active liver disease — monitor liver enzymes with long-term use
Warnings
⚠️ Liver Health
Some herbs used for liver conditions can be hepatotoxic at high doses. Have liver function monitored if using long-term.
⚠️ Allergic Reactions
Discontinue immediately if you experience rash, itching, swelling, or difficulty breathing.
⚠️ Not Medical Advice
This information is for educational purposes only. Always consult a qualified healthcare provider before using herbal remedies.
Drug & herb interactions
May have a stimulant effect
Watch for: Other caffeine-containing products, MAOIs, and stimulant medications (for ADHD or weight loss)
Additive stimulant effects can raise heart rate and blood pressure.
Processed by the liver
Watch for: Any medication that is also processed by liver enzymes (ask your pharmacist — this includes many common prescriptions)
Can alter how quickly the body clears certain medications, raising or lowering their effective dose.
May have a diuretic effect
Watch for: Diuretic medications and lithium
Additive fluid loss can affect electrolyte balance and change how the body clears lithium.
Where to find in nature
Native region
Europe, North America, Australia
Climate
Temperate
Habitat
Meadows, hedgerows, woodland edges, and cottage herb gardens
🌿 To see Kelp growing, visit botanical gardens, university plant collections, or specialist herb nurseries near you. If foraging in the wild, always work with an expert identifier — never consume a plant you are not 100% certain of.
Where to buy
In store
- Health food stores (Whole Foods, Natural Grocers, Holland & Barrett, GNC)
- Naturopathic clinics and integrative medicine practices
- Specialist herbal apothecaries and herbalist practices
- Farmers markets with herb vendors
Online
iHerb
Wide selection of standardised extracts, capsules, and powders with lab testing
Mountain Rose Herbs
Premium bulk dried herbs — certified organic, ethically sourced
Starwest Botanicals
Large selection of certified organic bulk herbs and powders
Herb Pharm
High-quality liquid extracts and tinctures, rigorous quality standards
Amazon
Convenient — verify brand certifications and check third-party testing
Etsy
Small-batch artisan herbalists, hand-harvested and wildcrafted herbs
Quality tips
When buying Kelp, look for: certified organic labelling, clearly stated country of origin, third-party lab testing for heavy metals and pesticides, and a batch expiry date. Standardised extracts offer consistent dosing; bulk dried herbs are more economical for regular use. Avoid very cheap, unlabelled products — quality varies enormously.