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Dietary walnuts inhibit colorectal cancer growth in mice by suppressing angiogenesis
Jutta M Nagel1, Mary Brinkoetter, Faidon Magkos
1Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
Objective:
Animal studies have demonstrated that dietary supplementation with flaxseed oil inhibits colorectal cancer growth. Recent data indicate that walnuts have strong antiproliferative properties against colon cancer cells in vitro but no previous study has assessed the effects of walnuts in vivo or performed a joint evaluation of flaxseed oil and walnuts. The aim of the present study was to examine the effect of dietary walnuts on colorectal cancer in vivo and to comparatively evaluate their efficacy in relation to flaxseed oil.
Methods:
HT-29 human colon cancer cells were injected in 6-wk-old female nude mice. After a 1-wk acclimation period, mice (n = 48) were randomized to diets containing ∼19% of total energy from walnuts, flaxseed oil, or corn oil (control) and were subsequently studied for 25 d.
Results:
Tumor growth rate was significantly slower in walnut-fed and flaxseed-fed mice compared with corn oil-fed animals (P < 0.05) by 27% and 43%, respectively. Accordingly, final tumor weight was reduced by 33% and 44%, respectively (P < 0.05 versus control); the differences between walnut and flaxseed diets did not reach significance. We found no differences among groups in metabolic and hormonal profile, serum antioxidant capacity, or inflammation (P > 0.05). However, walnuts and flaxseed oil significantly reduced serum expression levels of angiogenesis factors, including vascular endothelial growth factor (by 30% and 80%, respectively), and approximately doubled total necrotic areas despite smaller tumor sizes (P < 0.05 versus control). Dietary walnuts significantly decreased angiogenesis (CD34 staining; P = 0.017 versus control), whereas this effect did not reach significance in the flaxseed oil group (P = 0.454 versus control).
Conclusion:
We conclude that walnuts in the diet inhibit colorectal cancer growth by suppressing angiogenesis. Further studies are needed to confirm our findings in humans and explore underlying mechanisms.
Insights
Dietary walnuts and flaxseed oil significantly inhibit colorectal cancer growth in mice by reducing tumor size and suppressing angiogenesis. Walnuts demonstrated a notable decrease in blood vessel formation within tumors.
Area of Science:
- Oncology
- Nutrition Science
- Cancer Research
Background:
- Animal studies suggest flaxseed oil inhibits colorectal cancer growth.
- Walnuts show in vitro antiproliferative effects on colon cancer cells.
- Previous research has not evaluated walnuts in vivo for colorectal cancer or combined them with flaxseed oil.
Purpose of the Study:
- To investigate the in vivo effect of dietary walnuts on colorectal cancer growth.
- To compare the efficacy of walnuts against flaxseed oil in inhibiting colorectal cancer.
Main Methods:
- HT-29 human colon cancer cells were xenografted into female nude mice.
- Mice were randomized into three dietary groups: walnuts, flaxseed oil, or corn oil (control).
- Tumor growth and various biomarkers were monitored over 25 days.
Main Results:
- Both walnut and flaxseed oil diets significantly reduced tumor growth rate and final tumor weight compared to the control group.
- Walnuts and flaxseed oil decreased serum levels of vascular endothelial growth factor, a key angiogenesis factor.
- Dietary walnuts significantly reduced tumor angiogenesis, indicated by CD34 staining.
Conclusions:
- Dietary walnuts inhibit colorectal cancer growth, primarily by suppressing angiogenesis.
- Both walnuts and flaxseed oil show potential in cancer prevention and treatment.
- Further human studies are warranted to confirm these findings and elucidate mechanisms.
