VEGGIES + FAT = BETTER TOGETHER…a lesson in how to absorb the most nutrients from your vegetables

Did you know that when you eat raw carrots you only absorb 1-3% of the beta-carotene they contain?1

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That’s right, eating vegetables, raw—with no dressing, no dip, or no oil—is the surest way to miss-out on some of the most important nutrients nature has to offer.

The best evidence of this comes from a study published in the American Journal of Clinical Nutrition in 2004. In the experiment, they fed subjects three different salads and measured the amount of carotenoids (a specific class of nutrients, explained below) they absorbed.

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The catch is…the first salad contained fat-free dressing, the second contained reduced-fat dressing, and the third contained full-fat dressing.

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What did they find?

When people ate salad with full-fat dressing they absorbed FORTY-TIMES more beta-carotene compared to when they ate salad with fat-free dressing!

The morale of the story is, without fat, you simply can’t absorb certain nutrients!

So what are carotenoids anyway?

Carotenoids are antioxidant superstars that can improve cognition in older adults,2 stave off age-related macular degeneration,3 help prevent heart disease,4 and reduce risk for lung, stomach, colorectal, prostate and liver cancer.5

Chemically, they look like this…

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…and they’re what give plants their colour. Hence, they can be found in vegetables that are red, orange or yellow…

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…and they’re also abundant in dark leafy greens.

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But fat is not the only way to maximize absorption…

Lycopene, a type of carotenoid found in tomatoes, is the perfect example of this. Lycopene came into the limelight in the early 2000s when it was linked with decreased risk for cancer. But the catch is you can’t reap the benefits of lycopene by simply eating raw tomatoes.

This is precisely why Bolognese sauce—a meat-based tomato sauce that originated in Bologna, Italy, and is the Sunday dinner staple in my home…no bias here—is a masterpiece of both culinary and nutritional merit.

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Bolognese sauce exploits the tomato and maximizes your ability to absorb the lycopene it contains. Consider this:

  • By crushing tomato, lycopene absorption is increased6
  • By cooking tomato, lycopene absorption is increased even more(note: cooking usually produces a three-fold increase in absorbability)8
  • And by adding meat, you’re also adding fat; hence lycopene absorption is increased even more

Thus, everything about Bolognese sauce maximizes our absorption of the lycopene it contains, making it a delicious vehicle for maximum nutrient absorption.

Speaking of dishes that are both culinary and nutritional masterpieces, the Cobb salad is another perfect example…

In case anyone’s not familiar, the classic Cobb salad combines leafy greens with tomato, chives, avocado, cheese, chicken breast and its star ingredient…a boiled egg!

A study published in 2015 in the American Journal of Clinical Nutrition showcased the genius of the Cobb salad by demonstrating that co-consuming cooked eggs with salad increases carotenoid absorption three to eight fold.

But let’s back up for a second to talk about eggs, because they’re one of those foods that makes a nutrition geek like me sit back in awe of the amazing synergistic nutrient combinations found in nature.

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Remember how I said earlier that carotenoids are what give vegetables their colour? Well, carotenoids are also what make egg yolks orange/yellowish. As a result, egg yolk is one of the most easily absorbable sources of carotenoids because they contain carotenoids in combination with the fat necessary for absorption. And it doesn’t end there; yolks don’t contain just any-old kind of fat. In fact, they contain a special type of phospholipid that has been shown to specifically enhance carotenoid absorption.9, 10 Therefore, this is an example of how some nutrients are just meant to be together and how nature can be the best clue to finding these synergistic combinations.

And then there’s avocado…

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Avocado is another food that contains carotenoids in combination with the ideal kind of fat to aid absorption. Furthermore, one study showed that adding a cup of avocado to salsa resulted in 4.4 times greater lycopene absorption and 2.4 times greater beta-carotene absorption.11 Hence, avocado with salsa—a staple of Mexican cuisine—is not just a flavor match made in heaven, but also a nutritionally wise pairing. Not to mention, the avocado in Cobb salad is another nod to that genius combination of ingredients.

But how much fat is needed to maximize absorption?

Presently, there’s no definitive answer. But after browsing the literature, it seems a 1:2 ratio…

ONE tablespoon of oil (or any kind of fat such as salad dressing, butter, etc.) for every TWO cups of vegetables

…is a good rule of thumb.

Keep in mind, we don’t always eat vegetables in isolation, and in the context of a meal, there’s probably going to be fat coming from elsewhere, in which case, you could potentially add less without compromising absorption.

Meanwhile, in the “egg study” they compared the effect of 3 eggs versus 1.5 eggs on absorption of carotenoids from approximately 3 cups of salad. They found with more eggs, more nutrients were absorbed. But in the context of a cobb salad, when you factor in the fat coming from the bacon, avocado and chicken, the standard one egg-per-salad is probably good enough.

In Conclusion…

I have to admit, I wrote this blog, because I was formerly guilty of eating raw vegetables solo…who among us has not eaten a salad, sans dressing, in an effort to lose weight?

Hopefully, this post will help you dip that carrot guiltlessly, and add a little more olive oil to your salad, because at the end of the day, health is about balance, and vegetables were meant to be consumed with fat!

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References:

  1. Hedren E, Diaz V, and Svanberg U. Estimation of carotenoid accessibility from carrots determined by an in vitro digestion method. Eur J Clin Nutr, 2002. 56(5):425-30.
  2. Johnson EV, R; Mohn, E; Haddock, J; Rasmussen, H; Scott, T;. Avocado consumption increases neural lutein and improves cognitive function. The FASED Journal, 2015. 29(1 Supp. 3.28).
  3. Piermarocchi S, Saviano S, Parisi V, Tedeschi M, Panozzo G, Scarpa G, et al. Carotenoids in Age-related Maculopathy Italian Study (CARMIS): two-year results of a randomized study. Eur J Ophthalmol, 2012. 22(2):216-25.
  4. Liu S, Lee IM, Ajani U, Cole SR, Buring JE, and Manson JE. Intake of vegetables rich in carotenoids and risk of coronary heart disease in men: The Physicians’ Health Study. Int J Epidemiol, 2001. 30(1):130-5.
  5. Ito Y, Suzuki K, Ishii J, Hishida H, Tamakoshi A, Hamajima N, et al. A population-based follow-up study on mortality from cancer or cardiovascular disease and serum carotenoids, retinol and tocopherols in Japanese inhabitants. Asian Pac J Cancer Prev, 2006. 7(4):533-46.
  6. Brown MJ, Ferruzzi MG, Nguyen ML, Cooper DA, Eldridge AL, Schwartz SJ, et al. Carotenoid bioavailability is higher from salads ingested with full-fat than with fat-reduced salad dressings as measured with electrochemical detection. Am J Clin Nutr, 2004. 80(2):396-403.
  7. Dewanto V, Wu X, Adom KK, and Liu RH. Thermal processing enhances the nutritional value of tomatoes by increasing total antioxidant activity. J Agric Food Chem, 2002. 50(10):3010-4.
  8. Priyadarshani AM. A Review on Factors Influencing Bioaccessibility and Bioefficacy of Carotenoids. Crit Rev Food Sci Nutr, 2015:0.
  9. Baskaran V, Sugawara T, and Nagao A. Phospholipids affect the intestinal absorption of carotenoids in mice. Lipids, 2003. 38(7):705-11.
  10. Lakshminarayana R, Raju M, Keshava Prakash MN, and Baskaran V. Phospholipid, oleic acid micelles and dietary olive oil influence the lutein absorption and activity of antioxidant enzymes in rats. Lipids, 2009. 44(9):799-806.
  11. Unlu NZ, Bohn T, Clinton SK, and Schwartz SJ. Carotenoid absorption from salad and salsa by humans is enhanced by the addition of avocado or avocado oil. J Nutr, 2005. 135(3):431-6.
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RFF#117 – Eating fruits and vegetables with high levels of pesticides is linked with poor semen quality

A study by Harvard researchers showed that men with the highest intakes of pesticide-laden fruits and vegetables (2.1 servings/day) had a 49% lower total sperm count and a 32% lower percentage of morphologically normal sperm, when compared to men with lower intakes (<0.5 servings/day).

I learned about this fact from: http://humrep.oxfordjournals.org/content/early/2015/03/27/humrep.dev064.full

 

 

RFF#23 – During his presidency, George Bush Senior refused to eat broccoli

Supposedly he even banned it from Air Force One, stating:

“I do not like broccoli. I haven’t liked it since I was a little kid and my mother made me eat it, and I’m president of the United States, and I’m not going to eat any more broccoli.”

I learned about this fact from: http://www.nytimes.com/1990/03/23/us/i-m-president-so-no-more-broccoli.html and http://latimesblogs.latimes.com/washington/2010/08/michelle-obama-beets-george-bush-broccoli.html

RFF#20 – Visitors to the grave of Frederick the Great often bring potatoes

It has to do with the Russian famine of 1774. At the time, King Frederick began cultivating potatoes, and tried to convince the people to start eating them. However, to Frederick’s surprise, people refused them, on the basis that they were not accustomed to this vegetable. Nevertheless, clever King Frederick managed to coax the Russian people into eating potatoes by establishing a heavily guarded royal potato field. The crop eventually attracted the interest and envy of the local peasants who soon after began stealing the potatoes (as King Frederick hoped they would). Years later a French soldier who was captured by the Russians, Antoine-Augustin Parmentier, attributed his survival to the potato and went on to write a “Chemical Examination of the Potato”, in which he declared the potato “capable of reducing the calamities of famine”. There you have it…that’s why people still bring potatoes to the grave of King Frederick the Great.

—I learned about this fact from: Guttman J. Ask MHQ: King Frederick II of Prussia. Historynet.com. 2009. Accessed: 10 Dec 2012. Available from: http://www.historynet.com/ask-mhq-king-frederick-ii-of-prussia.htm

RFF#14 – Broccoli florets contain 7.7 times more antioxidants compared to the stem

For once, the better tasting part is actually better for you! But don’t forget, the stems have a lot of fiber, so they’re still worth eating.

—I learned about this fact from: Sissi Wachtel-Galor, Ka Wing Wong, Iris F.F. Benzie, The effect of cooking on Brassica vegetables, Food Chemistry, Volume 110, Issue 3, 1 October 2008, Pages 706-710.

RFF#12 – Popeye was right, spinach is amazing

Okay, okay, so maybe eating spinach won’t cause your muscles the spontaneously burst out of your shirt; nevertheless, there’s compelling evidence to show that spinach has some pretty powerful properties. In particular, research has demonstrated that nitrate containing vegetables, such as spinach or beets, enhance endurance. As a result, if you eat these foods prior to exercising, you may be able to exercise for a longer period of time, without feeling exhausted. How is that possible? Well, it has to do with the fact that the nitrates found in these vegetables, increase your muscle’s uptake of oxygen. In doing so, they enable your muscles to work for longer without becoming exhausted. Hence, the popularity of beet juice among pro-athletes.

—I learned about this fact from: Larsen FJ, Weitzberg E, Lundberg JO, Ekblom B. 2010. Dietary nitrate reduces maximal oxygen consumption while maintaining work performance in maximal exercise. Free Radical Biology & Medicine, 2010, 48:342-347. Bailey SJ, Winyard P, Vanhatalo A, Blackwell JR, DiMenna FJ, Wilkerson DP, Tarr J, Benjamin N, Jones MJ. Dietary nitrate supplementation reduces the O2 cost of low-intensity eBailey SJ, Winyard P, Vanhatalo A, Blackwell JR, DiMenna FJ, Wilkerson DP, Tarr J, Benjamin N, Jones MJ. Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise in humans. J Appl Physiol, 2009, 107:1144-1155. Larsen FJ, Weitzberg E, Lundberg JO, Ekblom B. Effects of dietary nitrate on oxygen cost during exercise. Acta Physiol, 2001, 191:59-66.

RFF#4 – Avocados have more potassium than bananas

You know how bananas are notorious for their potassium content? Well, the truth is, avocados actually have more potassium. As a matter of fact, one avocado has more than two times more potassium compared to a banana. Nevertheless, even though it’s high in potassium, an entire avocado still only satisfies 28% of the potassium you need everyday. Thus, you need five to ten servings of fruits and vegetables every day, because they’re the richest source of potassium, and each contains only a small amount. Finally, in case you’re wondering, potassium is desirable because it increases your body’s excretion of sodium. This is important because sodium consumption is the leading preventable risk factor for death worldwide.