Plant foods alter gene expression to curb inflammation

Inappropriately high levels of inflammation contribute to many of the chronic diseases of the modern world. Inflammation plays an important role in the development of atherosclerotic plaque, and inflammatory mediators have been shown to fuel tumor growth. [1] Certain characteristics of the Western diet are known to have pro-inflammatory effects – the high content of omega-6 fatty acids, for example, due to excessive oil and animal products, leads to overproduction of inflammatory molecules. Also, obesity is associated with chronic inflammation. Fat tissue produces a great number of both hormones and inflammatory molecules, and obesity-associated inflammation is said to be the link between excess body fat and chronic disease. [2]

 

Eating more plant foods and fewer animal products and oils is advisable to avoid these pro-inflammatory effects. Omega-3 fatty acids, in contrast to omega-6 fatty acids, are known to have anti-inflammatory effects. Fruits and vegetables are known to be protective against chronic disease due to their low calorie density and high quantity of micronutrients and antioxidants, and have been associated with reduced circulating inflammatory molecules. A study has shown that fruit and vegetable consumption alters circulating levels of inflammatory molecules by affecting gene expression in circulating white blood cells, limiting the production of inflammatory molecules by these cells.

Young adults reported their usual food intake, and the researchers correlated this to a number of inflammatory markers in blood, as well as expression of a number of pro-inflammatory genes in white blood cells. The subjects were divided into groups based on their quantity of fruit and vegetable consumption, and inflammatory markers (C-reactive protein, homocysteine, and TNFα) were 40% lower in the group with the highest (vs. lowest) fruit and vegetable consumption. Moreover, expression of four pro-inflammatory genes (ICAM1, ILR1, TNFα, and NF-κB1) were significantly lower in the circulating white blood cells of the high fruit and vegetable consumers. [3] C-reactive protein and plasma homocysteine are known risk factors for heart disease, and NF-κB is a key promoter of atherosclerosis development.[4]

This data suggests that plant foods have anti-inflammatory effects that have not yet been discovered.

We cannot underestimate the importance of high-nutrient foods. Our genes are inherited, but the expression of those genes is modified by our environment. Food components interact with our genes to affect the state of our health, and this study suggests that high-nutrient foods drive gene expression patterns that reduce inflammation and therefore risk of chronic disease.

 

References:

1. Sgambato, A. and A. Cittadini, Inflammation and cancer: a multifaceted link. Eur Rev Med Pharmacol Sci, 2010. 14(4): p. 263-8.
2. Hajer, G.R., T.W. van Haeften, and F.L. Visseren, Adipose tissue dysfunction in obesity, diabetes, and vascular diseases. Eur Heart J, 2008. 29(24): p. 2959-71.
3. Hermsdorff, H.H., et al., Fruit and vegetable consumption and proinflammatory gene expression from peripheral blood mononuclear cells in young adults: a translational study. Nutr Metab (Lond), 2010. 7: p. 42.
4. Kutuk, O. and H. Basaga, Inflammation meets oxidation: NF-kappaB as a mediator of initial lesion development in atherosclerosis. Trends Mol Med, 2003. 9(12): p. 549-57.

 

Tomatoes protect skin against sun damage

Skin cancer is the most common form of cancer in the U.S., affecting one out of every five Americans, and its incidence is rising. Ultraviolet (UV) radiation is responsible for the development of most skin cancers and also skin aging. [1]

Ultraviolet radiation from the sun exerts these aging and carcinogenic effects on the skin via oxidative stress, inflammation, and damage to DNA. As such, there has been much interest in the scientific community in using antioxidants from plant foods to protect against this damage. Photoprotection has been previously demonstrated in animal studies by multiple antioxidant supplements, including green tea catechins, proanthocyanadins, resveratrol, and silymarin. In addition to their antioxidant effects, these substances can also absorb UV radiation (when applied topically), enable DNA damage repair, and reduce inflammation. [2]

Lycopene, well-known for its prostate cancer-protective effects, is a carotenoid antioxidant present in red and pink fruits such as tomato, grapefruit, and papaya. It is especially concentrated in cooked tomato products like tomato paste. Lycopene is a powerful antioxidant that in vitro has been shown to prevent or repair damage to DNA that potentially leads to cancer development. Lycopene also stimulates production of antioxidant enzymes, inhibits signals that promote tumor progression, and promotes programmed death of cancerous cells. [3]

Researchers tested whether the antioxidant actions of lycopene in tomato paste could lessen the skin-damaging effects of UV radiation in human subjects. A group of healthy women consumed tomato paste daily for twelve weeks, and their skin’s reddening response to UV light was measured at the beginning and end of the study. After twelve weeks of tomato supplementation, the skin’s resistance to UV-induced reddening was enhanced. The tomato paste supplementation also resulted in reduced mitochondrial DNA damage and reduced activity of an enzyme that degrades the skin’s extracellular proteins, a process that contributes to skin aging. These results suggest that regular tomato consumption can help to reduce the skin-damaging effects of the sun. [4]

Tomatoes are rich not only in lycopene but in thousands of other protective compounds, both discovered and undiscovered, that likely have powerful heart disease- and cancer-preventive effects. Be sure to eat both fresh, raw tomatoes and cooked tomatoes to get the full spectrum of tomatoes’ phytochemicals.

 

References:

1. Skin Cancer Foundation: Skin Cancer Facts. October 14, 2010]; Available from: http://www.skincancer.org/Skin-Cancer-Facts/.
2. Nichols, J.A. and S.K. Katiyar, Skin photoprotection by natural polyphenols: anti-inflammatory, antioxidant and DNA repair mechanisms. Arch Dermatol Res, 2010. 302(2): p. 71-83.
3. van Breemen, R.B. and N. Pajkovic, Multitargeted therapy of cancer by lycopene. Cancer Lett, 2008. 269(2): p. 339-51.
4. Rizwan, M., et al., Tomato paste rich in lycopene protects against cutaneous photodamage in humans in vivo. Br J Dermatol, 2010.

 

Anti-cancer properties of watercress

Watercress is a super-duper food. Along with kale, collards, mustard greens, and turnip greens, watercress is one of the most nutrient-dense foods in the world. Most importantly, watercress is a specialist at preventing cancer.

Watercress belongs to the family of cruciferous vegetables, uniquely high in glucosinolates, which are precursors to cancer-fighting molecules called isothiocyanates (ITCs). Watercress is rich in a specific glucosinolate called gluconasturtiin, which is a precursor to the ITC phenethyl isothiocyanate (PEITC).[1] Epidemiologic associations between cruciferous vegetable intake and reduced cancer risk have sparked a surge in studies on the anti-cancer effects of specific cruciferous vegetables and their constituent isothiocyanates.

Anti-cancer properties of watercress had previously been established in cell culture experiments: In human breast cancer cells, watercress extract blocked the degradation of structural proteins, an early step in preparation for migration and subsequent invasion, which eventually leads to metastasis. [2] PEITC in watercress was also found to reduce tumor cell survival and decrease the action of hypoxia-inducible factor (HIF), which is a molecule that stimulates angiogenesis (blood vessel development), allowing a tumor to obtain a blood supply. [3]


A study investigated the effects of watercress on HIF activity in human subjects. Hypoxia (low oxygen levels) is a key stimulus for tumor growth – as a tumor grows, its oxygen and nutrient needs exceed those that it can receive by diffusion from adjacent healthy tissue. When tumor cells sense hypoxia, they send angiogenic signals to surrounding normal tissue in order to obtain a direct blood supply. HIF is an essential part of this process, activating the production of angiogenic proteins, consequently promoting tumor growth. [4]


Since the current study tested the effects of ingesting watercress on HIF activity in cells of human subjects, the data provided is more physiologically relevant, and strengthens the earlier cell culture results. Four breast cancer survivors ingested 80 grams of watercress (about 2 cups). Six and eight hours later, blood was drawn; PEITC levels were found to be elevated, and the effects of the watercress on white blood cells were measured. HIF activity was indeed reduced in these cells, confirming in humans the anti-cancer effects of watercress previously observed in cultured cells. [3, 5]

In short, PEITC from watercress prevents tumors from sending the signal to the body that requests a blood supply. Without a blood supply, the tumor cannot continue to grow. Watercress is a potent anti-cancer food!


For more information on the anti-cancer effects of cruciferous vegetables, read Newsletter #32.

 

References:
1. Higdon, J., et al., Cruciferous vegetables and human cancer risk: epidemiologic evidence and mechanistic basis. Pharmacological Research, 2007. 55(3): p. 224-236.
2. Rose, P., et al., Broccoli and watercress suppress matrix metalloproteinase-9 activity and invasiveness of human MDA-MB-231 breast cancer cells. Toxicol Appl Pharmacol, 2005. 209(2): p. 105-13.
3. Syed Alwi, S.S., et al., In vivo modulation of 4E binding protein 1 (4E-BP1) phosphorylation by watercress: a pilot study. Br J Nutr, 2010: p. 1-9.
4. Chen, L., A. Endler, and F. Shibasaki, Hypoxia and angiogenesis: regulation of hypoxia-inducible factors via novel binding factors. Exp Mol Med, 2009. 41(12): p. 849-57.
5. Watercress may 'turn off' breast cancer signal. 9/14/2010 9/30/2010]; Available from: http://www.soton.ac.uk/mediacentre/news/2010/sep/10_94.shtml.