Soy lecithin

Soy lecithin is a lecithin (a structural term for a triglyceride with one fatty acid replaced by phosphatic acid conjugates) which delivers a high level of phosphatidylserine (PS), phosphatidylcholine (PC), and phosphatidylinositol (PI).

This page features 26 unique references to scientific papers.

How to Take

Recommended dosage, active amounts, other details

Supplementation of soy lecithin seems to be in the range of 500-2,000mg. While it does not require to be taken with a meal, it is usually recommended to do so out of prudency.

Alternatively, soy lecithin can be dosed in accordance with phosphatidylcholine dosing.

Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects soy lecithin has on your body, and how strong these effects are.

Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
LDL-C Notable - See study
A decrease in LDL-C has been noted with soy lecithin ingestion to the degree of 42.05-56.15% in hypercholesterolemics, which is a remarkable decrease. Requires replication.
Total Cholesterol Notable - See study
A decrease in total cholesterol, mostly due to LDL-C, has been noted to the magnitude of 40.66-42.00% which is astounding; requires replication.
Cortisol Minor - See study
May reduce cortisol during a social stress test at 2g
Stress Minor - See study
May reduce perceived stress during stressful situations
HDL-C - - See study
No significant influence on HDL-C levels
Heart Rate - - See study
Despite the reduction in perceived stress, heart rate does not appear to be affected by supplemental soy lecithin
Triglycerides - - See study
No significant influence on triglycerides

1Sources and Composition

1.1. Sources

Lecithin is a term used to refer to a glycerol molecule with two fatty acids attached to it with the last open binding position being bound to a phosphatidic acid molecule, which can then be further bound to other molecules such as amino acids. The term 'soy lecithin' is used to described the lecithin from soy, and it is sometimes a vessel for phosphatidylserine (PS) due to it not requiring solvent extraction (Internal report[1]) and has a phosphatidylcholine,[2] phosphatidulethanolamine,[2] and phosphatidylinositol[3] content as well.[3]

Soy lecithin is lecithin (a category of molecules based on a certain structure) that is derived from soy, conferring a few phosphatidic acid related structures (the most common being phosphatidylserine and phosphatidylcholine, PS and PC respectively)

1.2. Composition

Soy lecithin contains:

  • Phosphatidylserine (PS; phosphatidic acid bound to serine) at around 3% total phospholipids[4]

  • Phosphatidylcholine (PC; phosphatidic acid bound to choline) at up to 29-31.7% of phospholipids[5][4]

  • Phosphatidylethanolamine (PE; phosphatidic acid bound to ethanolamine) at up to 20.8-23% of phospholipids[5][4]

  • Phosphatidylinositol (PI; phosphatidic acid bound to inositol) up to 15-17.5% of phospholipids[5][4]

  • Phosphatidic acid (PA; 7-17.5% of total phospholipids[5][4])

  • Phytosterols (most as glycosides) including β-sitosterol, sitostanol, and sitosteryl β-d-glucoside[6]

  • Phytoglycolipids (14.8% total phospholipids[4])

With the lipid composition of the above phospholipids accounting for:

  • Linoleic acid at 64%[4]

  • Palmitic acid at 14%[4]

  • Oleic acid at 10%[4]

  • Linolenic acid at 7%[4]

  • Stearic acid at 4%[4]

Relative to other sources of lecithin, soy appears to be comparatively high in PI with 15% of the phospholipids as PI[5] and 287mg/100g food product (soy overall, not just oil) being PI;[7] another popular lecithin, derived from egg yolk, is much lower in PI.[8]


2.1. Serum

Phosphatidylserine from soy lecithin appears to be absorbed by the body rapidly, reaching a Tmax at 90 minute after ingestion and reaching near baseline levels in serum at 180 minutes (Internal report, not peer reviewed[1])

Relative to 2.3g choline from choline chloride (3g), lecithin with an equal amount of choline has a lower value when measured at 30 minutes post ingestion (33% relative to 86%) but continues to rise over the course of 12 hours (265% of baseline).[9]


3.1. Aging

One study using a rat model of premature aging (SAMP8) noted that, relative to a group fed 5% lard for their lifetime, the active groups of soy lecithin (at 2% of the diet with 3% coming from soy oil) was associated with more survival than lard when measured at 12 months (although less than a diet with 2% fish oil instead of lecithin) although the lecithin outperformed all other groups in a cognitive test of aging (passive avoidance).[10]


4.1. Stress

A study using 400-800mg of phosphatidylserine and 450-900mg phosphatidic acid via soy lecithin (total oral dose of soy lecithin being 1,980-3,960mg) in 80 otherwise healthy adults subject to a stress test (Trier Social Stress Test) noted an anti-stress effect that peaked at the lowest dose as assessed by salivary ACTH and cortisol (both salivary and serum) as well as the STAI rating scale (particularly the subscale of distress); this study was funded by a producer of soy lecithin.[11]

2g soy lecithin appears to confer an anti-stress effect, with doubling the dose reducing the efficacy in otherwise healthy persons

5Cardiovascular Health

5.1. Lipids

In animals with hypercholesterolemia (high blood cholesterol), supplementation of the diet or isolated phosphatidylcholine appears to reduce circulating cholesterol secondary to stimulating bile acid secretion (a similar mechanism to most dietary fiber products that form gels).[12][13] This has been noted once with dietary soy lecithin in rats with normal cholesterol[14] although another study using 7 days supplementation of 2g/kg soy lecithin (31.7% PC, 20.8% PS, 17.5% PA; 14.8% phytoglycolipids) failed to find such an effect in rats with normal cholesterol.[4]

Administration of 500mg soy lecithin (68% phosphatidylcholine and 10% phosphatidylethanolamime) daily for 2 months, relative to the placebo treatment of 500mg soy oil, reduced total cholesterol (42.60%) and LDL-C (56.11%) without influencing HDL-C or triglycerides relative to baseline.[2]

May have cholesterol reducing properties, but limited human evidence and the mechanism does not appear to be unique (being common to soluble fiber in general)

6Inflammation and Immunology

6.1. Immune cells

7 days of dietary intake of soy lecithin at 2g/kg () has been noted to increase macrophage phagocytic activity in rats by aroud 29% without influencing alloxan-induced diabetic rats;[4] this is thought to be secondary to phosphatidylcholine, as macrophages cultured with PC in vitro have been shown to have altered function towards lymphocytes.[15]

In diabetic rats without effect on macrophages, lymphocyte count has been noted to preserved in diabetic rats given concavalin A (mitogen) relative to nondiabetic rats given concavalin A (and 92% greater than diabetic control); nondiabetic rats given soy lecithin has a suppression of lympchyte activity by approximately 35%.[4]

7Nutrient-Nutrient Interactions

7.1. Absorption enhancement

A brand name delivery system known as Phytosome®, which plays on the ability of soy lecithin (being phospholipids) to enhance delivery of hydrophobic/lipid soluble drugs or nutrients[16][17] with an overall stoichiometry in the range of 1:1–1:3 between the active and the phospholipid formulation aid.[18] The mechanisms underlying the absorption enhancement appear to be in part due improving their dispersion in the intestinal fluids and in part due to chaperoning molecules into enterocytes via forming complexes.[16] It seems that, relative to liposomes the reduced concentration of phospholipids allows a greater amount of phytochemicals to be integrated into the phytosome and as such phytosomes using soy lecithin can carry more substrate than an equal amount of liposomes.[18]

This has been used to enhance absorption of Boswellia Serrata,[19]Curcumin,[17] Silymarin (from Milk thistle),[17][20][21][22]Grape seed extract,[17] and green tea catechins.[17] Elsewhere, it has enhanced chemical resistant of resveratrol during simulated digestion (ex vivo).[23]

Some pharmaceuticals, such as Naproxen[24] also benefit from soy lecithin delivery.

Soy lecithin is used as an agent to increase intestinal bioavailability of some other agents (may not apply to all agents)

Soy lecithin phospholipids have also been used in immunological endeavours, as the nanoparticles formed from soy lecithin phospholipids can facilitate antigen uptake by antigen presenting cells (APC)[25] and thus lower the antigen payload required for a desired effect.[26]

Scientific Support & Reference Citations


  1. Kinetics and Safety of Soy Lecithin Phosphatidylserine (PS) Absorption.
  2. Mourad AM, et al. Influence of soy lecithin administration on hypercholesterolemia. Cholesterol. (2010)
  3. Honda K, et al. Toxicity studies of Asahi Kasei PI, purified phosphatidylinositol from soy lecithin. J Toxicol Sci. (2009)
  4. Miranda DT, et al. Soy lecithin supplementation alters macrophage phagocytosis and lymphocyte response to concanavalin A: a study in alloxan-induced diabetic rats. Cell Biochem Funct. (2008)
  5. Analysis of soybean lecithin by thin layer and analytical liquid chromatography.
  6. Lin X, et al. Phytosterol glycosides reduce cholesterol absorption in humans. Am J Physiol Gastrointest Liver Physiol. (2009)
  7. Phospholipid content of foods.
  8. The chemical composition of eggs.
  9. Hirsch MJ, Growdon JH, Wurtman RJ. Relations between dietary choline or lecithin intake, serum choline levels, and various metabolic indices. Metabolism. (1978)
  10. Ueda Y, et al. Effect of dietary lipids on longevity and memory in the SAMP8 mice. J Nutr Sci Vitaminol (Tokyo). (2011)
  11. Hellhammer J, et al. Effects of soy lecithin phosphatidic acid and phosphatidylserine complex (PAS) on the endocrine and psychological responses to mental stress. Stress. (2004)
  12. Polichetti E, et al. Dietary polyenylphosphatidylcholine decreases cholesterolemia in hypercholesterolemic rabbits: role of the hepato-biliary axis. Life Sci. (2000)
  13. Mastellone I, et al. Dietary soybean phosphatidylcholines lower lipidemia: mechanisms at the levels of intestine, endothelial cell, and hepato-biliary axis. J Nutr Biochem. (2000)
  14. Polichetti E, et al. Cholesterol-lowering effect of soyabean lecithin in normolipidaemic rats by stimulation of biliary lipid secretion. Br J Nutr. (1996)
  15. Nishiyama-Naruke A, Curi R. Phosphatidylcholine participates in the interaction between macrophages and lymphocytes. Am J Physiol Cell Physiol. (2000)
  16. Semalty A, et al. Supramolecular phospholipids-polyphenolics interactions: the PHYTOSOME strategy to improve the bioavailability of phytochemicals. Fitoterapia. (2010)
  17. Kidd PM. Bioavailability and activity of phytosome complexes from botanical polyphenols: the silymarin, curcumin, green tea, and grape seed extracts. Altern Med Rev. (2009)
  18. Hüsch J, et al. Structural properties of so-called NSAID-phospholipid-complexes. Eur J Pharm Sci. (2011)
  19. Hüsch J, et al. Enhanced absorption of boswellic acids by a lecithin delivery form (Phytosome(®)) of Boswellia extract. Fitoterapia. (2013)
  20. Hoh C, et al. Pilot study of oral silibinin, a putative chemopreventive agent, in colorectal cancer patients: silibinin levels in plasma, colorectum, and liver and their pharmacodynamic consequences. Clin Cancer Res. (2006)
  21. Kidd P, Head K. A review of the bioavailability and clinical efficacy of milk thistle phytosome: a silybin-phosphatidylcholine complex (Siliphos). Altern Med Rev. (2005)
  22. Filburn CR, Kettenacker R, Griffin DW. Bioavailability of a silybin-phosphatidylcholine complex in dogs. J Vet Pharmacol Ther. (2007)
  23. Sessa M, et al. Evaluation of the stability and antioxidant activity of nanoencapsulated resveratrol during in vitro digestion. J Agric Food Chem. (2011)
  24. Lichtenberger LM, et al. Naproxen-PC: a GI safe and highly effective anti-inflammatory. Inflammopharmacology. (2009)
  25. Sloat BR, et al. Strong antibody responses induced by protein antigens conjugated onto the surface of lecithin-based nanoparticles. J Control Release. (2010)
  26. Mansilla FC, et al. The immune enhancement of a novel soy lecithin/β-glucans based adjuvant on native Neospora caninum tachyzoite extract vaccine in mice. Vaccine. (2012)