Eat Nuts, Canola and Olive Oil to Boost Heart Health. Not So Fast!
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If you just heard about Dr. David Jenkins' hot-off-the-press study about how a low-cholesterol diet can be improved by adding monounsaturated fats (MUFA), which are commonly found in nuts, seeds, avocados, and oils such as olive oil, canola oil and sunflower oil, you may want to hear the full story.
According to the press release, patients with mild to moderate elevated cholesterol levels, who followed the cholesterol-lowering Portfolio Diet, that included the addition of monounsaturated fats, increased their HDLs by 12.5% and lowered their LDLs by 35%. As always--there's more to the story than meets the eye.
Number 1 point left out: Both study groups who followed the Portfolio Diet (a vegetarian diet high in beans, legumes, fruits, vegetables, and whole grains) experienced a whopping 35% decrease in their LDL levels--whether they were in the low or high monounsaturated fat (MUFA) group. Click here for the full article. Click here for the lay-language press release.
In a nutshell:
Researchers randomly assigned 17 men and seven postmenopausal women with mild to moderate elevated cholesterol levels to either a high-MUFA diet or a low-MUFA diet.
Both groups consumed a vegetarian diet that included oats, barley, psyllium, eggplant, okra, soy, almonds and a plant sterol-enriched margarine. In the high-MUFA group, the researchers substituted 13 percent of calories from carbohydrates with a high-MUFA sunflower oil, with the option of a partial exchange with avocado oil.
In the high-MUFA group, levels of "good" cholesterol (high-density lipoprotein cholesterol, or HDL) increased 12.5 percent while levels of "bad" cholesterol (low-density lipoprotein cholesterol or LDL) decreased 35 percent, according to the report in the Nov. 1 issue of CMAJ, the Canadian Medical Association Journal.
What the press release left out from the article:
"There were no treatment differences in terms of changes in triglycerides, LDL cholesterol or apolipoprotein B [between the two groups].
The prescriptive nature of the diet was another limitation, since adherence to a diet may be considerably less for a self-selected diet consumed under real-world conditions. The long-term effect on self-selected diets remains to be determined, in terms of compliance and in terms of the lipid response and, ultimately, cardiovascular outcomes.
Exercise and moderate alcohol consumptions may be regarded as pleasurable ways of raising HDL cholesterol. Weight loss and smoking cessation, although effective in raising HDL cholesterol, are more challenging for many people."
-Dr. David Jenkins, St. Michael's Hospital, Toronto, Ontario, lead author of "Adding monounsaturated fatty acids to a dietary portfolio of cholesterol-lowering food in hypercholesterolemia." CMAJ. 2010 Nov 1. [Epub ahead of print]- click here to read the full article.
There it is! Exactly what we've all longed to hear. Now we can safely enjoy nuts, olive oil, and avocados and get healthy at the same time. Raise our HDLs, increase our apolipoprotein A1 (the component of HDL that helps clear cholesterol from the blood), and lower our C-reactive protein scores (measure of inflammation).
But, hold on, before you load up on nuts and olive oil, consider this.
- Jenkins' dieters had all their meals provided for them for 2 months--measured out precisely. No estimates here.
- 13% of the carbohydrate calories were taken away from the high-monounsaturated group to make room for the sunflower oil. And they weren't given nuts or olive oil--it was sunflower oil! Not exactly the same as just adding 2 tablespoons of olive oil and 2 ounces of nuts to your diet. Both high and low monounsaturated fat groups in the study were eating about 2400 calories a day--so that meant they substituted 336 calories of the carbs for about 2 tablespoons of oil a day--almost a meal's worth of calories. Click here to see exactly what the dieters were eating.
- There was no change in weight loss between the two groups (high & low monounsaturated fats)
- There was no change in triglycerides between the two groups. And consider this about triglycerides:
"When triglycerides go up over 100 we start making abnormal forms of cholesterol--the small dense LDLs that are atherogenic and penetrate much more rapidly into the arteries than normal large LDLs.
When triglycerides start going up--and the changes start around 80-100--nearly everyone with triglycerides over 100 is making significant amounts of small dense atherogenic LDL--above 150 almost all LDL particles are small dense and atherogenic."
-Dr. Patrick E. McBride, Professor of Medicine and Family Medicine, University of Wisconsin, and a member of the Expert III NCEP Panel setting cholesterol guidelines-
To read more about the importance of keeping triglycerides low here.
- The large decreases seen in the C-reactive protein test is something very important to pay attention to--and certainly intrigues me--and it wasn't discussed much in the article or press release. Inflammation is one of the key drivers of heart disease.
- Olive oil may be considered a monounsaturated fat, but it's also high in omega-9, an oleic acid--and maybe not something beneficial to heart health.
"Contrary to our hypothesis, our study found that omega-9 (oleic acid)--rich in olive oil, impairs endothelial function after eating. If you've been using olive oil because you think it's healthy, it's time to think again. " Read more about the less healthy attributes of olive oil here.
"The beneficial components (of the Mediterranean Diet) appear to be anti-oxidant rich foods, including vegetables, fruits, and their derivatives. Dietary fruits, vegetables and their products appear to provide some protection against the direct impairment of endothelial functions produced by high-fat foods, including olive oil." (Vogel study: a meal containing olive oil impairs blood flow & vasodilation by 31%--and that was in healthy men)
-Dr. Robert Vogel-
- From Dr. Lawrence Rudel of Wake Forest University Baptist Medical Center: Rudel ran a five year study feeding olive oil and saturated fat to African Green monkeys. The monkeys metabolize fat in the same way as humans, so they're good stand-ins.. At the end of five years, their autopsies showed that the monkeys who were fed olive oil had higher HDLs (the good cholesterol) and lower LDLs (the bad cholesterol) than the ones fed the saturated fat diet. The big surprise here: Both groups had exactly the same amount of coronary artery disease. The higher HDLs & lower LDLs of the olive oil group were meaningless. Rudel later repeated the study on rodents, and got the same results.
- According to Dr. Caldwell Esselstyn, low HDLs in the presence of very low LDLs is of little concern--and commonly seen in many of his patients who have eliminated nuts & oils--as well as successfully prevented or reversed heart disease. When your LDLs are low (common when oils & animal products are eliminated) you just don't need high HDLs to remove them from the blood. Many of the Tarahumara Indians, who exhibited no heart disease, had low LDLs & low HDLs.
- Take a long hard look at the saturated fat content, and the high omega 6 content of most of the nuts--except for the humble English walnuts--which have a nice 4:1 omega-6 to omega-3 ratio.
When considering nuts, look to the English walnut--and be sure to swap out carb calories for the nuts eaten. 7 walnuts = 1 ounce = 185 calories. For me, since I eat about 1500 a day, that would mean eating about 7 walnuts, which would also mean eliminating a bowl of oatmeal or a whole grain hamburger bun.
I have to admit, when I cut out nuts & olive oil my HDLs did drop. But, I'm still sticking to the elimination of added oils--because I love the subsequest weight loss, and the loss of my belly fat--yet I still feel quite comfortable about eating a few walnuts, or a homemade cocoa-walnut-chia bar--especially after burning 400 calories with exercise. Click here for the recipe.
"The other issue is Omega 6s (and saturated fat) and making sure we do not get in too much of either. Ideally, saturated fat should be under 5% of our calories and the omega 6 to 3 ratio should be under 4:1 with under 2:1 even better.
Unfortunately, some nuts are very high in omega 6s and some are higher in saturated fat. So if you include any of these you would not want to over do them.
Most nuts have little if any omega 3s so they have very very poor ratios of omega 6 to omega 3s.
Black Walnuts are 16:1
English Walnuts 4:1
Pecans are 20:1
Pistachio is 37:1
Pine Nuts are 300:1
Macadamia is 6:1
Hazelnut is 88:1
Cashew is 117:1
Brazil Nut is 1000:1
Pumpkin Seeds 117:1
Sunflower Seeds 300:1
CA Avocados 15:1
FL Avocados 16.5:1
Flaxseed 3.9:1 ***
Chia Seed 3:1 ***
(***these is a reverse ratio as the omega 3 is higher than the omega 6)
In regard to Saturated fat
Black Walnuts are 5%
English Walnuts are 8%
Pecans are 8%
Pistachio is 8.5%
Pine Nuts are 6.6%
Macadamia is 15%
Hazelnut is 6.5%
Cashew is 12.5%
Brazil Nut is 21%
Almonds are 6%
Pumpkin Seeds 14%
Sunflower Seeds 6.5%
Chia Seed 6%
CA Avocados 11.5%
FL Avocados 15%
As you can see, most are not bad, but some are fairly high in saturated fat and some are really high in omega 6s. Some of these, like cashews may not be great choices. They are over 12% saturated fat and have a ratio of 117:1 Pumpkin seeds and brazil nuts are also not the best choices as they are also "higher" in saturated fat and have a "higher" ratio.
It looks like English Walnuts would be the best choice by far.
As always, go to the original research article--get the full story--and consider what impact other studies may have on the conclusions. For me, I'm comfortable with keeping out the added oils, eating walnuts, and an occasional slice of avocado. And I'm happy to increase my HDLs with exercise, and an occasional glass of Pinot Noir. Ultimately, we all make our own decisions.