This month, I’m working on a couple of responses to recently published criticisms of vegan diets. Among the issues that are frequently raised is one that focuses on fat-soluble vitamins. Some of the concerns are based on legitimate questions about active forms of these vitamins and their absorption from plant foods, and others aren’t. Regardless of those questions, though, plant foods can and do provide enough of the fat soluble vitamins A, D and K. (Vitamin E, which is also fat-soluble, is not involved in the controversy since it’s found in a very wide variety of foods.)
Vitamin A: It’s true that the preformed active type of this vitamin is found only in animal foods. But plants are abundant in vitamin A precursors like beta-carotene. In fact, these provitamin A compounds are important enough that the USDA measures vitamin A content of foods as “retinol activity equivalents (RAE),” which includes both preformed vitamin A and the compounds that the body turns into vitamin A. There is no separate RDA or recommendation for animal-derived pre-formed vitamin A.
You can meet your vitamin A requirement for the day by drinking just one-quarter cup of carrot juice or eating a cup of kale or spinach. Other foods that make significant contributions are sweet potatoes, cantaloupe, and dark orange winter squashes, including pumpkin. A word of caution though: Earlier assessments of retinol activity equivalents in plant foods over-estimated amounts. This is because more recent data show that conversion rates of the vitamin A precursors are lower than previously believed. As a result, vitamin A is a nutrient that deserves some attention in vegan diets. This doesn’t mean you can’t get enough; it does mean that it’s a good idea to make sure you eat vitamin A rich foods every day.
Vitamin D: This vitamin occurs naturally in only a few foods—fatty fish, eggs from chickens who were fed vitamin D, and mushrooms treated with ultraviolet light. With such limited dietary availability, humans wouldn’t have gotten very far if not for the fact that we can make all the vitamin D we need when skin is exposed to sunlight. As humans have moved farther from equatorial zones—and spend less time outdoors—it’s become harder to make enough, though, so vitamin D-fortified foods have become important.
Although people can get adequate vitamin D from fatty fish, most—omnivore or not—rely on fortified foods and sun exposure, two options that are as easily available to vegans as to omnivores.
The vegan form of vitamin D, which is called ergocalciferol or vitamin D2, has been shown to be as effective in raising blood levels of this nutrient as animal-derived vitamin D3 when it’s taken at a usual daily dose (1) (The RDA is 600 IUs; some experts recommend 1,000.) At megadoses, however, vitamin D2 may need to be taken more often.(2) But no one should be megadosing on vitamin D unless they are working with a doctor to correct a deficiency. And vitamin D2 has been used to effectively raise blood levels in people with deficiencies. (3, 4)
Vitamin K: Best sources of this nutrient are leafy green vegetables and canola, soy and olive oils. One form of vitamin K, called vitamin K2 or menaquinone, is found in animal products but in only one lone plant food—natto, a fermented soy product that isn’t a usual part of most western vegan diets. This isn’t a problem, though, because humans have no requirement for vitamin K2. We also have bacteria in our gut that produce this form of vitamin K—so we’re covered either way. Since vitamin K is essential for blood clotting we’d see some evidence of a deficiency if vegans weren’t getting enough. But a study that compared clotting rates between vegans and meat eaters found no difference. (5)
Getting Enough of the Fat Soluble Vitamins: The best way to make sure you’re getting adequate amounts of the fat soluble vitamins is to eat plenty of leafy green and dark orange vegetables and to take a vitamin D supplement if you don’t get adequate sun exposure. Gentle cooking improves the absorption of some vitamin A precursors, and cooking foods in small amounts of olive or canola oil can give you a vitamin boost while improving absorption of these vitamins.
1. Holick MF, Biancuzzo RM, Chen TC, et al. Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D. J Clin Endocrinol Metab 2008;93:677-81.
2. Romagnoli E, Mascia ML, Cipriani C, et al. Short and Long Term Variations in Serum Calciotrophic Hormones after a Single Very Large Dose of Ergocalciferol (Vitamin D2) or Cholecalciferol (Vitamin D3) in the Elderly. J Clin Endocrinol Metab 2008.
3. Thacher TD, Obadofin MO, O’Brien KO, Abrams SA. The effect of vitamin D2 and vitamin D3 on intestinal calcium absorption in Nigerian children with rickets. J Clin Endocrinol Metab 2009;94:3314-21.
4. Gordon CM, Williams AL, Feldman HA, et al. Treatment of Hypovitaminosis D in Infants and Toddlers. J Clin Endocrinol Metab 2008.
5. Sanders TA, Roshanai F. Platelet phospholipid fatty acid composition and function in vegans compared with age- and sex-matched omnivore controls. Eur J Clin Nutr 1992;46:823-31.
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A friend of mine recently got her vitamin D levels tested. It was low despite taking several thousand IUs of D-2 a day. She took that much because other vegan nutrition experts have told her that D-2 ( vegan vitamin D ) doesn't get absorbed as well as D-3. I am impressed that you have 4 citations that say D-2 works. Was my friend just taking too much or are some people anomalies, with special needs?
I don't know. I've heard anecdotal reports here and there from vegans who say that they have had trouble raising vitamin D levels with D2, but the research suggests it's not a problem. But yes, there's certainly a range of needs and some handful of people will need much more than the RDA. Was your friend deficient at some point? Because it can take a very long time to bring vitamin D levels back up, regardless of the type being used.
I don't know. Are there any figures for how long it takes Vitamin D levels to build up after a deficiency?
I'll have to look to see if any of the experts give a range for this. I only know that it can take many months before levels start to rise. There is also some evidence that it's important to be consistent in taking vitamin D supplements, so that could be a factor, too.
This past February, I had my blood tested and was slightly low vitamin D levels as I always wear sunscreen when I’m going to be in the sun for long as I burn easily and hadn’t been consistent about taking vitamins. I was instructed by my doctor to take 2,000 IU of vitamin D for the next two weeks and then have a retest of my blood. Rather than take just 2,000 IU D2 for the next two weeks, I took 4,000 IU at the start, 3,000 for the next few days, and 2,000 for the last week, and my blood level of vitamin D was back to normal on the retest. I now take 1,200 IU vitamin D2 each day from supplements. I’ll see what my blood levels are next year and will likely cut down to 800 IU per day (from supplements, I get more from fortified foods) if everything is still normal.
I have tried a few ways to cook kale, collards and Swiss chard, but can't say I'm a 'fan' of them. I do like spinach (prepared in any way) and beet greens, lightly sauteed with garlic. Question: what are your thoughts on 'green smoothies' with raw kale, etc? This seems like a painless, and possibly pleasant, way to get your greens first thing in the morning for a leg up on nutrition for the day. I've resisted the whole smoothie trend, since I prefer chewing my calories, instead of drinking them, but I'm flexible.
I think smoothies can be a good way to get more greens into your diet. Kale probably works the best in them. And be sure to add something with a higher fat content–some nuts or seeds or a little oil or tofu or avocado–to boost absorption.
Unfortunately, you have not addressed the claim that due to genetic variations, many people may not be able to convert pro-vitamin A carotenoids in sufficient amounts:
http://www.lmreview.com/articles/view/common-genetic-variants-and-other-host-related-factors-greatly-increase-susceptibility-to-vitamin-a-deficiency
And neither did the Institute of Medicine in specifying requirements for RAEs. Nutrient recommendations always have a safey factor built in to cover the variability in individual metabolism.
Hi,
As you're talking about kale; a few days ago, I attended a lecture by a dietitian (at the Oslo Vegetarfestival: http://www.oslovegetarfestival.no/program – the lecture was by Dr. Pernilla Karlsson (http://www.veganlife.se/)) and she said that children under 1 year old should not be given green leafy vegetables, as they don't have the enzymes to digest them. I had never heard of that before; so I'd like to know what you think about it.
Also, about B12, she said that one should take methylcobalamin, that it was more efficient than cyanocobalamin. She said that it was because cyanocobalamin never occurred in nature, that it was a synthetic form of B12; whereas methylcobalamin was a biological form; she also said that the cyanocobalamin ingested was converted into methylcobalamin in the organism anyway. I was a bit confused, as I've always read that cyanocobalamin was a better choice than methylcobalamin; and that the dosage requirements could be much higher for methylcobalamin than cyanocobalamin. What do you think?
Camille, the recommendation is to avoid giving infants leafy greens, carrots, turnips, or beets before the age of 4 months because these foods all contain nitrates which can cause a red blood cell disorder. But after the age of 4 months, it's fine to feed these foods to infants.
As for B12, I recommend cyanocobalamin because almost all of the research has used this form of the supplement. There is some evidence that methylcobalamin is less stable and therefore effective doses may be much, much higher. Without any good data on this, I'm reluctant to recommend it.
I have a question about D2 vs D3. I have been a vegetarian for 40 years. (I realize I'm a little out of place here) In winter I take a D3 supplement from Source Naturals (1000 I.U.) I understand that it is derived from the lanolin in sheeps wool. presumably derived from the wool of sheared sheep. It has a very good effect on my sleep and mental acuity. Do you know if the D3 is really derived from the lanolin of the sheared wool….as opposed to something less life supporting….?
It almost always comes from lanolin from sheep's wool or from fish oil. At any rate, vitamin D3 is always animal derived and usually the product of factory farming. And you're not out of place here; there are plenty of non-vegans who read this blog and all are welcome!
Now where’s that ‘Like’ button when you need it!
Interesting article. Why do you think the Endocrine Society recommends D(3) over D(2)?
"Vitamin D3 (cholecalciferol) is the form of the vitamin absorbed through the sun. It is superior to the synthetic Vitamin D2 (ergocalciferol). We highly recommend that anyone shopping for a Vitamin D supplement check the label in order to ensure it is D3 and not D2."
http://vitamind3blog.com/2011/06/endocrine-society-vitamin-d3-supplements/
Daisy, if you take a look at the recent (2011) statement from the Endocrine Society on their website, you'll see that they recommend either D2 or D3 for treating deficiency.
http://www.endo-society.org/media/press/2011/experts-recommend-screening-for-vitamin-d-deficiency-in-at-risk-populations.cfm
The blog you cited is a little confused about vitamin D metabolism!
That's interesting — I'd never thought to put tofu in a smoothie.
My doctor recommended 2000 IU of vitamin D but didn't specify between D2 or D3. I have read, in my travels, that D2 isn't as easily absorbed as D3 so if you take D2 you need to increase the dosage. If you're fortunate to have a nice strong sun shining down on you most of the year this isn't an issue. I live in Canada and supplementation is highly recommended.
Robert, I live in the Pacific Northwest so vitamin D is a concern for me, too. There is a lot of debate among the experts about how much vitamin D is really needed for people who don't get much sun exposure, and 2,000 IUs is not an unusual recommendation at all.
The issue about vitamin D2 isn't absorption, though. It really does seem to be absorbed as well as D3. However, in studies that use megadoses of it, blood levels start to drop more quickly after taking D2 compared to D3. For people taking moderate amounts–and 2,000 is a moderate amount–and taking it every day, this shouldn't be an issue.
I believe the safe upper limit to be around 4000 IU. Does that sound correct?
Yes, 4,000 IUs is the upper limit.
I’ve been hearing a few Doctors, like Dr. Weil, recommending eating more hard cheeses because they are rich in vitamin K2, which helps prevent cancer. This of course flies in the face of T. Colin Campbell’s research. I’m thinking of adding nato to my diet but I read it smells like, excuse my language…A#$ lol
Are you sure Dr. Weil says that? I couldn’t find anything in his vitamin K recommendations that refers to K2. I don’t think there is much research to support any relationship of cheese to cancer risk–either for or against.
And I agree with you about natto! It’s the texture that I can’t deal with. But that’s a cultural thing I guess since I believe it’s pretty popular in Japan.
I saw Dr. Li on Oz the other day talking about hard cheeses. Here is a link: http://healthybodydaily.com/dr-oz-cancer/dr-oz-gouda-cheese-can-reduce-cancer-risk-three-secret-weapons-to-prevent-cancer
I’m pretty sure it was Dr. Weil I saw on Martha Stewart a year or so ago recommending hard cheeses. I could be wrong.
That’s really interesting. I did a quick search of the medical research database for studies on “cheese vitamin K cancer” and only one study came up. It was an epidemiological study (which finds only associations, not cause and effect) and, although it found a link between vitamin K2 (as found in hard cheese) and decreased cancer risk, the results weren’t statistically significant. So I guess we don’t need to start eating hard cheeses! Thanks for the link to this info–I’m going to follow up on Dr. Weil to see what he says about all of this.
Dr. Mercola on Vitamin K2: http://www.youtube.com/watch?v=8ePU5NiRDSM
To me Dr. Mercola seems too eager to sell you supplements.
An interview with Cees Vermeer PhD. (top vitamin K2 resarcher of the world) conducted by Dr. Mercola. http://www.youtube.com/watch?v=WTm95J8SNGo&feature=related
There is the Rotterdam Study: http://jn.nutrition.org/content/134/11/3100.full
Lastly, Dr. Weil on K2: http://www.drweilblog.com/home/2010/4/25/vitamin-k-and-cancer-risk.html
In his blog he does not mention hard cheeses but on the show I saw him on, he did.
It seems that more and more research confirms that vegan diets are safe and beneficial. Eat a large and wide variety of plant based foods, take multivitamins and other specific vitamins when needed, and get outside and take in some sun and exercise. Why is everyone complicating this so much?
Hi Ginny!
The Company “Garden of Life” sells raw, vegan supplements called “the vitamin code”. And they have a D3 that is harvested from small organisms like yeast and certain forms of bacteria. Do you know them?
So we can ingest D3 and not needing animals. I really like their products
Michael
Thank you, Ginny for your excellent review of the fat-soluble vitamins.
I value your expert research-based “myth-busting reviews”–and I appreciate the time you put into replying with factual information to every comment. Thank you for all your work!
Perhaps this bit of advice, based on Dr. Angelo LIcata’s research at the Cleveland Clinic will be of interest. Take your vitamin D with your largest meal of the day–preferably one that has the most fat. It will make a big difference.
“In our practice, it is common to see patients treated with vitamin D supplements who do not achieve an appreciable rise in their serum 25OHD level after therapy despite large prescribed doses.
A consistent increase of 50% or greater was seen in the serum 25OHD concentration when patients consumed the vitamin with the largest daily meal.”
-Drs. Angelo Licata, MD, PhD. and Guy B. Mulligan, MD., Cleveland Clinic Foundation Metabolic Bone Clinic, “Taking vitamin D with the largest meal improves absorption and results in higher serum levels of 25-hydroxyvitamin D”, J Bone Miner Res 25(4):928-30, April 2010-
To read a detailed summary of the study: http://www.happyhealthylonglife.com/happy_healthy_long_life/2010/03/vitamin-d-at-dinner.html
There is virtually no reason to be talking about D2 vs D3 anymore. Natures Plus has a new vegan D3 supplement on the market called Source of Life Garden™ Vitamin D3.
“The first plant-source cholecalciferol, from a blend of eight different organic mushrooms”
You can contact them for more information on the process used with which they were able to isolate D3 from Mushrooms..
The Garden of Life D3, contrary to what the company used to claim, is not vegan.
It is made from feeding lanolin to yeast and you end up ingesting both.
The vegan community really needs to accelerate the pace of learning about what’s going on out there if we are to be taken seriously.
The vitamin D in mushrooms is ergocalciferol or vitamin D2. There is currently a process for making non-animal sourced vitamin D3 but it’s a semi-synthetic process using petrochemicals, according to an article on the Vegetarian Resource Group website. I believe it’s being used only in animal feed, and anyway, it doesn’t sound like what Nature’s Plus is using. There are some types of vitamin D3 that are grown in culture, but they always start out with cholesterol, which is a building block of vitamin D3. So I’m not convinced about the D3 in this product being vegan.
Only one way to know if it is legit. Contact Mr. Avila @ 631-293-0030 . I look forward to hearing how the conversation went!
That is really a bummer! I have been taking Source of Life D3 for the past month and a half. My D levels rose only about 10% over two months taking D2 and then rose over 50% over just a month taking the D3 (so finally not “deficient”).
There is no chance that Source of Life is actually Vitamin D3. I know for a fact Mushroom can only contain Vitamin D2.
However, exciting news from the vegan society……………………..
Vitashine is a new totally vegan vitamin D3: http://www.vitashine-d3.com.
Proven data, unlike the vague (fake) mushroom stories.
Jy
I’m still gray here. Some say that I literally cannot absorb fat soluble vitamins unles I take some oil with them. Is it true that if I eat up a bowl of salad, these vitamins simply go through my body unabsorbed? If I drink a glass of carrot juice, I don’t absorb any vitamin A or K?