In the midst of the heartbreak & devastation that's now going on in Japan, I can't help but see the cognitive dissonance in posting about vitamin absorption, of all things.
This is the third time in the three years that I've been writing this blog that I'm reminded of the words that Shiraz Janjua wrote after a hurricane crushed Haiti three years ago. At that time, he was an associate producer for "Speaking of Faith"--he now works for the Canadian Film Board. Click here for that earlier post. This time, my thoughts are on Japan.
Shiraz asks, "How do we live our lives when part of us is so grateful for all our blessings, and the other is so guilty about all we have in the midst of all the brokenness in this world?"
"How do we watch the news or read the newspaper and see something so horrible happening to someone else, and then just go on with our day?"
"You are not obliged to finish the task, neither are you free to neglect it.”
Squash & Leafy Greens
How much dietary fat do we need to absorb vitamin A from carotene-rich yellow and green leafy vegetables?
"In summary, only a small amount of dietary fat (just 2.4 grams/meal--or 21 grams eaten throughout the day) is needed for optimal utilization of plant provitamin A carotenoids.
Data from the present study indicate that is is possible to improve the total-body vitamin A pool size and restore low liver vitamin A concentrations to normal concentrations by eating sufficient amounts of carotene-rich yellow and green leafy vegetables and minimal amounts of fat."
--Judy D. Ribaya-Mercado, Jeffrey B. Blumberg et al, "Carotene-rich plant foods ingested with minimal dietary fat enhance the total-body vitamin A pool size in Filipino schoolchildren as assessed by stable-isotope-dilution methodology," American Journal of Clinical Nutrition 2007;85:1041-9
If you received this post via email, click here to get to the web version.
If you're eating Esselstyn/Engine 2/McDougall/Fuhrman-style to prevent or reverse chronic diseases--or just low-fat plant-based--you aren't adding any fats or oils to your meals or to your cooking.
And I'm sure your friends, family, and everyone else are probably asking you a lot of questions about the way you eat!
- "How are you going to absorb the fat soluble vitamins (A,E,D) if you don't add any oil?"
- "Don't we need to add fats or oils to our food to be healthy?"
- My comment: Just to be clear--this isn't a no-fat diet--it's a no-added fat diet.
Which brings me to this past Sunday afternoon, when my husband and I went to see a play with our friends, Barb & Howard.
Before the play got started, Barbara & Howard asked me my opinion about absorbing the fat soluble vitamin A on a no-added fat diet.
Fair question. Their daughter, who has a master degree in nutrition from Tufts University, had recently said to them, "You know, you need to have enough fat in your diet in order to absorb vitamin A". But, how much?
OK--this question is always coming up. And my answer is usually, "Fat exists in almost everything we eat already--without adding a drop more of oil. And guess what? When I keep track of what I'm eating on this high-nutrient no-added fat diet, it turns out that I'm getting ridiculously high amounts of the best kind of vitamin A (the alpha & beta-carotene kind). And no worries--you can't "overdose" on too much of the vitamin A you get from plants. So, even if I'm only absorbing just a quarter of of what I'm eating, I'm still getting more than enough."
Here's what my food tracker said for a typical day for me:
- You consumed 68,639 IU of vitamin A. This is 2,288% of the recommended daily value for women.
- You consumed 25.2 grams of fat--13% of your total calories for the day. According to Dr. Neal Barnard, the diabetes expert--this is just perfect. He recommends getting 20-30 grams of fat per day.
- The Tufts Filipino Study I've quoted above found that children aged 9-12 only needed 2.4 grams of dietary fat to absorb vitamin A. The vitamin A absorption didn't increase a bit when the fat was increased to 5 grams or 10 grams per meal.
At every single meal I eat--I'm getting anywhere from 2.5 to 10.5 grams of fat--and I'm not adding a drop of oil to my meals. My fat comes from oatmeal, beans, chia or flax seed, grains, vegetables, berries, walnuts, and the natural fat that's in most every food out there. You don't have to go out of your way to add any extra. If you're in that enviable position that you need to gain weight--then sure, go ahead and add some avocado, seeds & walnuts--but not oil.
The Back Story - Why Some Experts Thought We Needed Lots of Oil to Absorb Vitamin A
Turns out, when it comes to answering the question, "How much fat do we need to eat to optimally absorb Vitamin A?" everyone looks to a 2004 Iowa State/Ohio State University study that fed college students plain lettuce & tomato salads with full-fat salad dressing, low-fat salad dressing, and fat-free salad dressing.
The Vitamins and Salad Dressing Story. Back in 2004 researchers at Iowa State University hooked up grad students with IV lines and had them eat bowls of salad made with greens, carrot shreds, and tomatoes, and topped them with either fat-free, reduced-fat, or full-fat salad dressings. Then they analyzed the blood of the salad eaters to determine how much vitamin A they were absorbing. Click here to access the Iowa State study.
Bottom Line: The salads with the full-fat dressing (a whopping 28 grams of fat) provided the best absorption of beta-carotene. The reduced-fat dressing (6 grams of fat) eaters had substantially less absorption of beta-carotene. And the fat-free dressing salad eaters had no absorption of the beta-carotenes.
There are big problems with this study.
- The participants were eating plain raw vegetable salads that weren't a part of a meal that contains fat--not how we usually eat our salads.
- Beta-carotene is harder to absorb from raw "intact" vegetables, than from cooked or even "Vita-mixed" vegetables, because the vitamin A is "trapped" within the tough cell walls of the vegetables. Cooking & Vita-mixing releases the carotene from the cell walls of vegetables.
Even the authors of the Iowa State salad study say, "Disruption of the plant [cell walls through homogenization (blending) or cooking] promotes the release and absorption of carotenoids. Fat is just the agent that can help "release" the beta-carotene from the cell walls of raw vegetables.
Except for maybe a lunch or dinner salad, most of my vitamn A comes from cooked vegetables or soups, or in Vita-mixed Green Smoothies.
- The Iowa State researchers didn't consider that there can be a delayed release & absorption of vitamin A when dietary fat is eaten at a later meal. That's right. Vitamin A is able to just hang out a bit--waiting for a tiny later "hit" of fat.
- The sponsor of the study was Procter & Gamble--a large producer of salad oils. I'm just saying....
The recent New York Times article pitching the imporatance of higher-fat salad dressings.
Tarah Parker-Pope recently cited the Iowa State/Procter Gamble study when she wrote "Dress Up Your Salad" in her New York Times "Well" blog on February 11, 2011. She wanted to give some scientific support to the higher-fat salad dressings developed by Martha Rose Shulman that she was highlighting.
Here's how Parker-Pope pitched her story:
"If you’re using low-fat dressing on your salad, you’re cutting more than calories from the dish. That’s because many of the nutrients in leafy green vegetables are fat-soluble, which means they need to be eaten with some fat so that the body can adequately absorb the nutrients."
Here's the comment I wrote to her article:
The study touting the “full-fat” salad dressing was conducted at Iowa State and it was sponsored by Procter & Gamble who wants to sell salad oil!
They were single plain vegetable salads-–not eaten as part of a meal that would naturally have some fat in it. Look at the article. That’s not how we usually eat foods.
You don’t need to add oil to absorb beta-carotene or other fat-soluble vitamins–you just need some fat–-and most foods have some fat within them. What about olives? Nuts? Avocados? Even tofu?
Cooking also aids the absorption of beta-carotene & lutein-–as does blending vegetables in a smoothie–breaking down their tough cell walls.
The DRI for vitamin A is 3000 IU a day. On an average day, I’m getting 68,638 IU a day from fruit & vegetables.
Probably don’t have to worry so much about missing out on every scrap of beta carotene if I skip the full-fat salad dressing!
The article citation: http://www.ajcn.org/content/80/2/396.full— The Healthy Librarian
Here's what JM, a Registered Dietititan, a Certified Diabetes Educator, and a Licensed Dietitian/Nutritionist later wrote to me in response to my NYT comment:
"I applaud your intelligent comments in reference to the article, "Dress Up your Salad" in the NY Times. Good job!
I am amazed at the high calorie counts--before dressing is added--of salads offered in restaurants because of the fatty ingredients. This has become more apparent since calorie levels began to appear on menus in Philadelphia. I am sure many diners have no clue that the calories in salads may be equivalent to a large meal, 800-1000 or more.
Of course small amounts of fat from other foods in the meal will aid absorption of fat-soluble vitamins.
Thanks for your post."
What the Tufts/USDA Filipino Study Discovered Three Years After the Iowa State Study
Who was in the study group?
The study followed 106 children, aged 9-12 who had subclinical vitamin A deficiencies--most likely from eating diets too low in plant-based beta-carotene.
How was the study conducted?
Baseline measurements of their vitamin A levels were taken at the start of the study
For 9 weeks the children were fed 3 meals a day, for five days a week. These meals included foods high in beta and alpha carotene: carrots, bok choy, squash, and swamp cabbage.
The children were divided into three different groups, based on how much dietary fat was added to each meal. Refined coconut oil--the most common source of dietary fat in rural Filipino communuties--was used.
One group received 2.4 grams (21.6 calories) of fat/per meal
One group received 5 grams (45 calories) of fat/per meal
One group received 10 grams (90 calories) or fat/per meal.
Records were also kept of any "after hours" or "weekend" snack or meals the children ate--and the fat contained within them.
Lowest added fat group: Ate 21 grams of fat a day/ 189 fat calories. 12% of their daily calories were from fat
- Medium added fat group: Ate 29.3 grams of fat a day/ 264 fat calories. 17% of their daily calories were from fat
- Highest added fat group: Ate 44.6 grams of fat a day/ 446 fat calories. 27% of their daily calories were from fat
How were the vitamin A levels measured?
The researchers used a state-of-the-art technique to measure the vitamin status of the children--deuterated-retinol-dilution (DRD) which uses deuterium-labeled vitamin A .
And the envelope, please. What did the study discover?
All three groups increased their vitamin A levels exactly the same amount--regardless of how much added fat they ate! It didn't matter a bit if they were in the 2.4 grams of fat group, the 5 grams of fat group, or the 10 grams of fat per meal group!
What Does This Study Means To Us?
1. We need much less fat than previously thought in order to absorb vitamin A from vegetables & fruits.
2. The body will absorb exactly what it needs when you get your vitamin A from plant sources (the alpha & beta carotenes)--adding extra fat will not increaste your vitamin A levels--it will just increase the calories you eat.
3. Cooking foods that are high in vitamin A help in the absorption of vitamin A because it helps to release the vitamin A from the plant's cell walls. Blending them raw in a Vita-Mix will likely have a similar effect.
4. The problem of vitamin A levels that are too low is often more one of not eating enough foods that are high in alpha & beta-carotene--than a problem of not eating enough added fat.
5. Only a small amount of dietary fat 2.4 grams/meal or 21 grams/day is needed for optimal utilization of plant provitamin A carotenoids.
6. It's possible to improve & restore vitamin A levels by eating sufficient amounts of carotene-rich yellow & green leafy vegetables & just a minimal amount of fat.
7. The Filipino children were absorbing all the fat they needed with only 12% of their diet coming from fat. Compare this to US children who consume an average of 34% of their calories as fat.
8. Would this research apply to adults? Probably. These children were eating about 1600 calories a day and the DRI's for older children & adults aren't that different.
The DRI for vitamin A in ages 9-12 is 600 ug/d
The DRI for vitamin A in women ages 14 and older is 700 ug/d
The DRI for vitamin A in men ages 14 and older is 900 ug/d
Roodenburg, A.J.C. reports that as little as 3 grams of fat is all that is needed to absorb vitamin A (alpha & beta-caroten) & vitamin E in adults. Almost the same amount of vitamin A was absorbed by subjects in his study, whether they were eating 3 grams of fat or 36 grams of fat. Too bad he didn't test for an even lower level of fat!
Note: In the Roodenburg study,the carotenoid Lutein--found in leafy greens--did require more fat for optimal absorption.
The simple non-fat solution to that one: Eat kale--it has the highest amount of lutein of any vegetable. Click here for lutein sources. Why load up on endothelial-damaging-high-calorie oil when you can just eat more kale?
Problem with the study: The authors used a lutein supplement--they didn't have their subjects eat real vegetables--and even the authors think that less fat would be needed to absorb the lutein when it's eaten as "real" vegetables!
9. Want the "whole enchilada" explanation from THE expert McDougall registered dietitian, Jeff Novick, about why we don't need to add extra fat to absorb fat soluble vitamins? Click here. He presents a compelling argument.
What Would 2.4 Grams of Fat Look Like?
Every meal that I eat already has at least 2.4 grams of fat in it.
But, say you want some extra insurance when you were eating a raw salad, or a vegetable dish.
What would 2.4 grams of fat look like?
- 1.5 teaspoons of walnuts
- 3/4 tablespoon of flax meal
- 1/2 tablespoon of chia seed
- 2 1/2 pitted kalamata olives
- 1/2 tsp. of olive oil
- 1 heaping tablespoon of avocado, which is a little over 1/2 ounce
Appetite for Reduction's Favorite Balsamic Vinaigrette--Get Your 2.4 grams of Salad Fat (almost)
My friend Mary discovered this easy delcious salad dressing in Isa Chandra Moskowitz's latest cookbook. Right now this is my go-to fave cookbook--and I could happily use it daily. Every week I find a new easy amazing recipe in Appetite for Reduction.
Isa has moved to the "no-to-low-fat camp". But, she's found that a mere 1/4 cup of cashews works as a perfect emulsifier for salad dressings. No oil, no eggs, no sugar, no mayo needed!
OK--I'm no cashew-advocate. I don't cook with or snack on cashews--but Isa is 100% right about how they improved the consistency & mouth-feel of salad dressings. And without adding much fat at all!
You could easily use this recipe as a template for many dressings--just switching up the balsamic for a citrus juice or other vinegar--and adding different spices or flavorings. The cashews and water sub for oil or mayo.
Balsamic Vinaigrette recipe on one page, click here
8 servings--1 1/2 tablespoons each
Prep Time: 10 minutes
1/4 cup raw cashew pieces (To make blending a breeze--if you have time--soak the cashews for 1 hour or overnight--then drain the water & proceed with the recipe--I DID NOT bother with the soaking)
2 TBS chopped shallots (I bet 2 cloves of garlic would taste fine)
1/4 cup good quality balsamic vinegar (oops--left this out of the original post!!)
1/2 cup water
2 teaspoons Dijon mustard
1 tsp. agave nectar (ya, I know, it now has a bad-reputation--but it's just 1 tsp.)
1/4 tsp of salt
A few shakes of freshly ground pepper
First place the cashews in the blender, or your Vita-Mix. Then add everything else. Isa says to blend for a least 5 minutes, using a rubber spatula to scrape down the sides often. Note: With a Vita-Mix I mixed this for less than 2 minutes--and never needed to scrape it down.
The key is to blend it until it's smooth--and not grainy.
Transfer the dressing into a covered container. It may seem thin at first, but it really thickens as it chills.
I haven't tried it yet--but I think substituting garlic for shallots might work just fine.
Nutrition info based on a 1 1/2 tablespoon serving.
Serving Size: 1 serving
|Amount Per Serving|
Wondering about how much protein you need to eat on a plant-based diet?
Be sure to read Ginny Kisch Messina's recent post on the subject:
Ginny's a vegan, a registered dietitian, and has twice co-authored the American Dietetic Association’s Position on Vegetarian Diets.
New book alert!
Yesterday, my friend Marlene lent me her autographed copy of Dr. Neal Barnard's latest book, now featured on PBS (public television): 21-Day Weight Loss Kickstart - Boost Metabolism, Lower Cholesterol, and Dramatically Improve Your Health. click here for more info.
Now, I'm not much interested in diet books--but this one is not your usual pop-culture fad diet--it's research-based & study-tested. Really.
This book has it all! Easy-to-understand scientific research to explain why this way of eating really works. I couldn't put it down! Enough said.