Is soy protein effective in reducing cholesterol and improving bone health?

2020
Food & function 11(1)
- Kelli S George
- Joseph Muñoz
- Neda S Akhavan
- Elizabeth M Foley
- Shalom C Siebert
- Gershon Tenenbaum
- Dania A Khalil
- Sheau C Chai
- Bahram H Arjmandi

PubMed: 31848551
DOI: 10.1039/c9fo01081e

Study Design

Type: Randomized Controlled Trial (RCT)
Population: Ninety men and women (aged 27-87)
Methods: randomly assigned to consume 40 g of soy or casein protein daily for three months
Duration: three months

Rigorous Journal

Hyperlipidemia associated with cardiovascular health, and bone loss with regard to osteoporosis contribute to increased morbidity and mortality and are influenced by diet. Soy protein has been shown to reduce cholesterol levels, and its isoflavones may improve bone health. The objective of this study was to determine the effects of soy protein on lipid profiles and biomarkers of bone metabolism and inflammation. Ninety men and women (aged 27-87) were randomly assigned to consume 40 g of soy or casein protein daily for three months. Both soy and casein consumption significantly reduced bone alkaline phosphatase (P = 0.011) and body fat % (P < 0.001), tended to decrease tartrate-resistant acid phosphatase (P = 0.066), and significantly increased serum insulin-like growth factor-I (IGF-1) (P < 0.001), yet soy increased IGF-1 to a greater extent (P = 0.01) than casein. Neither treatment affected total cholesterol, HDL cholesterol, LDL cholesterol, or C-reactive protein. These results demonstrate that daily supplementation of soy and casein protein may have positive effects on indices of bone metabolism and body composition, with soy protein being more effective at increasing IGF-1, an anabolic factor, which may be due to soy isoflavones' role in upregulating Runx2 gene expression, while having little effect on lipid profiles and markers of inflammation.

Research Insights

Casein Protein→Increased High-Density Lipoprotein Cholesterol
Neither treatment affected total cholesterol, HDL cholesterol, LDL cholesterol, or C-reactive protein
Effect
Neutral
Effect size
Small
Dose
40 g/day
Casein Protein→Increased Insulin-Like Growth Factor I Level
significantly increased serum insulin-like growth factor-I (IGF-1) (P < 0.001), yet soy increased IGF-1 to a greater extent (P = 0.01) than casein
Effect
Beneficial
Effect size
Small
Dose
40 g/day
Casein Protein→Reduced Alkaline Phosphatase Level
Both soy and casein consumption significantly reduced bone alkaline phosphatase (P = 0.011)
Effect
Beneficial
Effect size
Small
Dose
40 g/day
Casein Protein→Reduced Blood Cholesterol
Neither treatment affected total cholesterol, HDL cholesterol, LDL cholesterol, or C-reactive protein
Effect
Neutral
Effect size
Small
Dose
40 g/day
Casein Protein→Reduced Body Fat Percentage
Both soy and casein consumption significantly reduced ... body fat % (P < 0.001)
Effect
Beneficial
Effect size
Small
Dose
40 g/day
Casein Protein→Reduced C-Reactive Protein Levels
Neither treatment affected total cholesterol, HDL cholesterol, LDL cholesterol, or C-reactive protein
Effect
Neutral
Effect size
Small
Dose
40 g/day
Casein Protein→Reduced LDL Cholesterol
Neither treatment affected total cholesterol, HDL cholesterol, LDL cholesterol, or C-reactive protein
Effect
Neutral
Effect size
Small
Dose
40 g/day
Casein Protein→Reduced Tartrate-Resistant Acid Phosphatase Level
tended to decrease tartrate-resistant acid phosphatase (P = 0.066)
Effect
Neutral
Effect size
Small
Dose
40 g/day
Soy Protein→Increased High-Density Lipoprotein Cholesterol
Neither treatment affected total cholesterol, HDL cholesterol, LDL cholesterol, or C-reactive protein
Effect
Neutral
Effect size
Small
Dose
40 g/day
Soy Protein→Increased Insulin-Like Growth Factor I Level
significantly increased serum insulin-like growth factor-I (IGF-1) (P < 0.001), yet soy increased IGF-1 to a greater extent (P = 0.01) than casein
Effect
Beneficial
Effect size
Small
Dose
40 g/day
Soy Protein→Reduced Alkaline Phosphatase Level
Both soy and casein consumption significantly reduced bone alkaline phosphatase (P = 0.011)
Effect
Beneficial
Effect size
Small
Dose
40 g/day
Soy Protein→Reduced Blood Cholesterol
Neither treatment affected total cholesterol, HDL cholesterol, LDL cholesterol, or C-reactive protein
Effect
Neutral
Effect size
Small
Dose
40 g/day
Soy Protein→Reduced Body Fat Percentage
Both soy and casein consumption significantly reduced ... body fat % (P < 0.001)
Effect
Beneficial
Effect size
Small
Dose
40 g/day
Soy Protein→Reduced C-Reactive Protein Levels
Neither treatment affected total cholesterol, HDL cholesterol, LDL cholesterol, or C-reactive protein
Effect
Neutral
Effect size
Small
Dose
40 g/day
Soy Protein→Reduced LDL Cholesterol
Neither treatment affected total cholesterol, HDL cholesterol, LDL cholesterol, or C-reactive protein
Effect
Neutral
Effect size
Small
Dose
40 g/day
Soy Protein→Reduced Tartrate-Resistant Acid Phosphatase Level
tended to decrease tartrate-resistant acid phosphatase (P = 0.066)
Effect
Neutral
Effect size
Small
Dose
40 g/day