Diet high in omega-6 fats increases risk for ulcerative colitis

 

Ulcerative colitis falls under the category of inflammatory bowel diseases (IBD). It is an autoimmune disease in which excessive inflammation kills cells in the lining of the colon, leaving ulcers behind. Ulcerative colitis is a chronic condition that commonly causes abdominal pain and bloody diarrhea, and it carries with it an increased risk of colorectal cancer. In some severe cases, the colon must be surgically removed. Clearly, this condition also causes a great deal of emotional trauma.1

Recent studies have identified dietary patterns that may predispose individuals to ulcerative colitis. High intake of fats, refined sugars, and fried potato products were positively associated with ulcerative colitis, and fruit consumption was found to be protective.2

Most recently, omega-6 fatty acids have been investigated. Omega-6 fatty acids are essential fatty acids, meaning that we must obtain them from our diet for good health, but the typical American diet contains an excessive amount of omega-6, which can produce a pro-inflammatory environment in the body.

Linoleic acid is an omega-6 fat that is highly concentrated in red meat, cooking oils, and margarines. In the digestive system, linoleic acid is metabolized into arachidonic acid, which incorporates into cell membranes of the colon. When arachidonic acid is broken down further, its products are pro-inflammatory – these products are found in excess in the intestinal cells of patients with ulcerative colitis. For these reasons, scientists believed that excess linoleic acid might be linked to ulcerative colitis risk.

A prospective study of over 200,000 men and women in Europe found that the subjects who consumed the highest levels of omega-6 linoleic acid were 2.5 times more likely to be diagnosed with ulcerative colitis. The researchers also found a negative association between the omega-3 fatty acid DHA and ulcerative colitis – subjects in the highest level of DHA intake decreased their risk by 77%.3

Avoiding excess levels of linoleic acid is simply accomplished by eating a diet that is based on whole plant foods and limits animal products and added fats. A diet of natural whole foods provides us with omega-6 fatty acids in appropriate amounts - not in excess – producing an anti-inflammatory environment.

For those who already have ulcerative colitis, it is important to know that the condition can be improved and sometimes completely resolved with dietary changes – conventional treatment of IBD often includes immunosuppressive drugs with dangerous side effects. Specific dietary recommendations for sufferers of IBD are outlined in the Inflammatory Bowel Disease newsletter

References:

1. http://www.nlm.nih.gov/medlineplus/ulcerativecolitis.html#cat59

2. Shah S. Dietary Factors in the Modulation of Inflammatory Bowel Disease Activity. MedGenMed 2007; 9(1):60

3. Tjonneland A et al. Linoleic acid, a dietary n-6 polyunsaturated fatty acid, and the aetiology of ulcerative colitis: a nested case-control study within a European prospective cohort study. IBD in EPIC Study Investigators. Gut. 2009 Dec;58(12):1606-11. Epub 2009 Jul 23.

http://www.reuters.com/article/idUSTRE5B15S720091202

 

High fat intake - especially saturated fat - is associated with macular degeneration

 

Age-related macular degeneration (AMD) is the leading cause of vision loss in Americans over 60 years of age. This disease involves cell death in the macula of the eye, which has a high density of cone cells and is responsible for central vision.1 

A recent study published in the Archives of Ophthalmology2 investigated the relationship between fat intake and the presence of intermediate AMD 4-7 years later in over 1700 women, and found that some fats may benefit eye health while others may be damaging.

Total fat.Women aged 50-75 who consumed the highest proportion of calories from fat (43%) had the greatest risk of AMD – 70% higher odds than those with the lowest proportion of calories from fat (21%). As the authors stated,

"High-fat diets might be a marker for diets that are poor in many micronutrients that could protect against age-related macular degeneration.”3

They then looked further into the associations between specific types of dietary fat and AMD.

Saturated fats are detrimental when it comes to heart disease and cancer, so these results are no surprise - saturated fats showed the greatest association with AMD – 60% increased odds of AMD in women who consumed the greatest amounts. Monounsaturated fats, which are present in nuts, seeds, and avocados, were associated with a lower prevalence of the disease.

The associations between polyunsaturated fats and AMD are more difficult to interpret – the authors reported that both omega-3 and omega-6 polyunsaturated fatty acids were associated with a two-fold risk of AMD. But don’t overreact and throw away your walnuts and flaxseeds - the intakes of omega-3 and -6 in this study were highly correlated to one another, making it difficult to discern the effects of one from the other. Also, a 12-year study in the American Journal of Clinical Nutrition last month found that people at high risk for AMD were less likely to develop the disease if they had a greater intake of omega-3 fats.4 The authors of the current study hypothesized that excessive omega-6 fatty acid intake may influence AMD by promoting inflammation that can contribute to retinal damage. Vegetable oils, processed foods, and animal products contain high levels of omega-6 fats – with that in mind, the authors also stress that the associations that they found likely do not represent effects of only the types of fat, but the cumulative effects of the all the compounds in the foods that contain each type of fat.3

The evidence is overwhelming that a Nutritarian diet-style, with raw seeds and nuts as the major fat source, and the high exposure to phytochemicals and carotenoids is the healthiest way to eat. Can you imagine all the personal medical tragedies that could be prevented?   It would sure put a lot of drug companies and doctors out of business.

 

References:

1. http://www.nlm.nih.gov/medlineplus/maculardegeneration.html

2. Parekh N et al. Association Between Dietary Fat Intake and Age-Related Macular Degeneration in the Carotenoids in Age-Related Eye Disease Study (CAREDS). An Ancillary Study of the Women's Health Initiative. Arch Ophthalmol. 2009;127(11):1483-1493.

3. http://www.medpagetoday.com/Ophthalmology/GeneralOphthalmology/16950

4. Sangiovanni JP et al. {omega}-3 Long-chain polyunsaturated fatty acid intake and 12-y incidence of neovascular age-related macular degeneration and central geographic atrophy: a prospective cohort study from the Age-Related Eye Disease Study. Am J Clin Nutr. 2009 Oct 7. [Epub ahead of print]

 

Q & A: Balancing Your Omega Fats

We all know fat can be bad, like trans-fat. Trans-fat raises LDL or bad cholesterol and also lowers HDL or good cholesterol, but still, many fats are very healthy, like omega fats, found in stuff like avocados. Here’s a quick Q & A about balancing omega fats from Dr. Fuhrman’s member center:

Question: My dim understanding is that our diet and consequently our blood and our tissues should contain some ideal ratio of omega-6 fats and omega-3 fats, such as a 1 to 1 or 1 to 2 ratio of ecicosapentanoic acid (EPA) to arachidonic acid (AA). So the fact that a blood test would detect some AA is not necessarily bad, so long as the test detects a roughly equal amount of EPA, is this correct?

Dr. Fuhrman: Yes, you need some AA. Only in excess is it a problem. Some of fats are more pro-inflammatory, but it is a question of balance. When you eat a diet rich in greens with about half seeds and nuts in a 1 to 1 ratio, with some supplemental DHA if you do not eat fish regularly, then you get the right balance of fatty acids, obsessing to get a 1 to 1 or even a 2 to 1 ratio results in food paranoia.

Image credit: thegrocer*