Red meat consumption increases ischemic stroke risk

Stroke is the leading cause of disability in the U.S., and the third leading cause of death, killing 137,000 Americans each year.[1]

There are two types of stroke – ischemic and hemorrhagic. Most strokes (about 85%) are ischemic strokes, in which blood flow to the brain becomes blocked either by a clot or a ruptured atherosclerotic plaque. The minority of strokes are hemorrhagic strokes, caused by the rupture of a blood vessel leading to bleeding in the brain. Ischemic stroke, similar to a heart attack, is caused by atherosclerosis, whereas hemorrhagic stroke is primarily caused by vessel damage due to years of elevated blood pressure.

A recent study has found that the consumption of red meat, at quantities similar to the average American’s intake, is associated with a large increase in risk of ischemic stroke. Processed meats were also associated with ischemic stroke risk. [2]

In this study, dietary patterns of 34,670 Swedish women were recorded, and the incidence of stroke was recorded over the following 10 years. The women had no cancer or cardiovascular disease at the start of the study. Women who ate at least 3.6 ounces of red meat daily were 42% more likely to suffer an ischemic stroke, compared to those who ate less than one ounce per day. The average American eats 3 ounces of red meat daily, which in this study was associated with a 22% increase in risk. Also, women who ate 1.5 ounces or more of processed meat per day had a 24% increase in risk for ischemic stroke compared to those who ate less than 0.5 ounces per day.[3, 4]

Raw meat. Flickr: Virtual Ern

In contrast, there is new evidence that dietary antioxidants, as measured by total antioxidant capacity (TAC) of the diet are protective against ischemic stroke.

Participants in the European Prospective Investigation into Cancer and Nutrition (EPIC), with the highest vs. lowest TAC had a 59% reduction in risk. Of course the foods with the highest antioxidant capacity are the nutrient-dense plant foods like green vegetables and berries. [5]

What is the connection between red and processed meats and ischemic stroke?

Atherosclerosis. First, red meat is a calorie-dense, protein-concentrated, saturated fat-rich food with a low content of micronutrients – these characteristics promote inflammation, weight gain and increased cholesterol levels, leading to formation of atherosclerotic plaque. As such, red meat consumption is associated with increased risk of ischemic heart disease and all-cause mortality. [6-9] Since atherosclerotic heart disease and ischemic stroke are so similar, it makes sense that red meat consumption would also increase stroke risk.

Blood pressure is another potential connection. Processed meats are usually high in sodium, which contributes to elevated blood pressure, the most important risk factor for both types of stroke; elevated blood pressure accounts for 62% of strokes.[10] Although salt intake is the dietary factor most known for increasing blood pressure, red meat intake is also associated with high blood pressure. Women who consumed 3.5 servings of red meat per week were found to have a 24% increase in risk of hypertension over a ten-year follow-up period.[11] A 7-year study of middle-aged men similarly found that meat intake was associated with larger increases in blood pressure, while vegetable and fruit intake were associated with smaller increases in blood pressure over time.[12]

Heme iron present in red meat is another factor, which may raise blood pressure and increase oxidative stress. Positive associations were found between heme iron (found only in animal foods) and blood pressure, and negative associations were found between non-heme iron (found in plant foods) intake and blood pressure. [13] Also, the heme iron in red meat can accumulate and cause free radical damage, which is known to contribute to the atherosclerotic process. [14]

These studies paint a clear picture – high nutrient, high antioxidant foods like vegetables and fruit are protective against stroke, and red and processed meats – low nutrient, low antioxidant foods - increase the risk of stroke.

 

References:
1. U.S. Centers for Disease Control: Stroke. Available from: http://www.cdc.gov/stroke/.
2. Larsson, S.C., J. Virtamo, and A. Wolk, Red meat consumption and risk of stroke in Swedish women. Stroke; a journal of cerebral circulation, 2011. 42(2): p. 324-9.
3. Reuters: Red meat raises women's stroke risk: study. The Montreal Gazette.
4. U.S. Department of Agriculture. Loss-adjusted Food Availibility: Spreadsheets. Available from: http://www.ers.usda.gov/Data/FoodConsumption/FoodGuideSpreadsheets.htm#meat.
5. Del Rio, D., et al., Total antioxidant capacity of the diet is associated with lower risk of ischemic stroke in a large Italian cohort. The Journal of nutrition, 2011. 141(1): p. 118-23.
6. Preis, S.R., et al., Dietary protein and risk of ischemic heart disease in middle-aged men. Am J Clin Nutr, 2010. 92(5): p. 1265-72.
7. Sinha, R., et al., Meat intake and mortality: a prospective study of over half a million people. Arch Intern Med, 2009. 169(6): p. 562-71.
8. Jakobsen, M.U., et al., Major types of dietary fat and risk of coronary heart disease: a pooled analysis of 11 cohort studies. Am J Clin Nutr, 2009. 89(5): p. 1425-32.
9. Fraser, G.E., Vegetarian diets: what do we know of their effects on common chronic diseases? The American journal of clinical nutrition, 2009. 89(5): p. 1607S-1612S.
10. He, F.J. and G.A. MacGregor, A comprehensive review on salt and health and current experience of worldwide salt reduction programmes. J Hum Hypertens, 2009. 23(6): p. 363-84.
11. Wang, L., et al., Meat intake and the risk of hypertension in middle-aged and older women. Journal of hypertension, 2008. 26(2): p. 215-22.
12. Miura, K., et al., Relation of vegetable, fruit, and meat intake to 7-year blood pressure change in middle-aged men: the Chicago Western Electric Study. American Journal of Epidemiology, 2004. 159(6): p. 572-80.
13. Tzoulaki, I., et al., Relation of iron and red meat intake to blood pressure: cross sectional epidemiological study. Bmj, 2008. 337: p. a258.
14. Brewer, G.J., Iron and copper toxicity in diseases of aging, particularly atherosclerosis and Alzheimer's disease. Experimental Biology and Medicine, 2007. 232(2): p. 323-35.

 

Trackbacks (0) Links to blogs that reference this article Trackback URL
http://www.diseaseproof.com/admin/trackback/242051
Comments (4) Read through and enter the discussion with the form at the end
MIke Rubino - March 8, 2011 6:37 PM

Great article. Yet red meat consumption remains great despite the overwhelming evidence over the years that it is a killer.

John Kuzora - March 16, 2011 3:58 PM

Just curious, but did you actually read the study? Straight from the conclusions:

"Fresh (unprocessed) meat was not associated with total stroke or any stroke subtype."

Even processed meats were NOT associated with total stroke!

John Kuzora - April 8, 2011 10:19 PM

Really? Did anyone actually read this study? This is such a GROSS MISREPRESENTATION of the DETAILS of the study! Maybe reduced meat consumption decreases reading comprehension skills.

SMH - January 26, 2012 8:39 AM

Wrong. Meat offers great nutrients in quantities that many plant sources do not offer. Iron, Zinc, B vitamins,and Protein. It is true that plant sources offer antioxidants and other vitamins. That is why we eat a balance of all food varieties!

Post A Comment / Question Use this form to add a comment to this entry.







Remember personal info?