Penokok pemakanan atau penokok diet diniatkan untuk menyediakan nutrien yang mungkin kalau tidak dimakan dalam kuantiti secukupnya.
- Dietary Supplements: General Resources for Consumers (PDF|131 KB), Food and Nutrition Information Center, National Agricultural Library. List of resources that provides an overview of herbal and dietary supplements, including use, regulation, research, and cautionary information.
- Questions to Ask Before Taking Vitamin and Mineral Supplements, Nutrition.gov.
- Dietary Supplement Fact Sheets, NIH Office of Dietary Supplements.
- Dietary Supplements Labels Database, from the United States National Library of Medicine
- PubMed Dietary Supplement Subset from the U.S. National Institutes of Health Office of Dietary Supplements and United States National Library of Medicine
- Dietary Supplement Information from the U.S. Food and Drug Administration
- What's in the Bottle? An Introduction to Dietary Supplements, from the U.S. National Center for Complementary and Alternative Medicine
- Safety information on herbal supplements, from the U.S. National Institutes of Health
- Use of Complementary and Alternative Medicine (CAM) by the American Public: A report of the Institute of Medicine
- Marcus DM, Grollman AP (Disember 2002). "Botanical medicines--the need for new regulations". The New England Journal of Medicine. 347 (25): 2073–6. doi:10.1056/NEJMsb022858. PMID 12490692.
- EPC Evidence Reports on Dietary Supplements