I want to be sure i get all my daily vitamins/minerals but i thought that only about 20% of vitamins from tablets are actually absorbed. So what else can i do? Should i just eat fortified foods like oatmeal and cereal, and if so how much of these vitamins are absorbed? should i take liquid vitamins, should i take large doses (5x the RDA) of each vitamin a day, or what exactly.
This is something I looked into a year or so ago on my own, so let’s dust of my brain cells and see what’s left.
I’ve heard some rumblings about multivitamins not being completely absorbed by the body, but I couldn’t find anything hard on exactly what proportion made it. I’d be interested in seeing a cite for the 20% figure, since it seems awfully low. Unfortunately, it’s the nature of, well, nature that nutirents are absorbed better from food than from supplements.
If you are concerned about absorption, you do have options.
- Take your vitamins with meals. They will absorb much better.
- Use chewables. Some people think that the Centrum-like pills don’t dissolve sufficiently, and they taste like crap anyway. Chewables have no such problems.
I guess that’s it. Liquid vitamins strike me as a rip-off, and as far as megadosing on vitamins, in the name of God, don’t do it with Vitamins A, D or Niacin. You could kill yourself. Other vitamins are pretty much harmless, but you’re probably wasting money. A decent, balanced diet has all the vitamins you need. You DO eat your vegetables, right?
Still, I’ve read from a couple of sources that taking a multivitamin a day seems to add a couple of years to your life expectancy, so they must be doing SOME good.
I don’t want to be a downer. but sometimes my first thought is “Primum non nocere” (Above all do no harm)
Though multivitamins (MVI) may be a good idea for many people, They are at at best an insurance policy. Most nutrition experts consider them unnecessary for most people with a healthy, varied, balanced diet-- which offers much superior nutrition to any pill, regardless, MVIs should never be seen as the primary, and especially not the sole, source of the RDA for vitamins
I’m not anti-supplements. There are a lot of people whose diets are not within shouting distance of balanced or healthy, and they’re not going to change easily. I happen to take a daily MVI myself “just in case”, but I discourage people from taking high doses of them.multivitamins are shotgun mixtures designed to be balanced at a specific dose, Taking too many (I’ve seen people take 3 at every meal) can cause problems, especially in the long term
The commonly recognized “vitamins” are the bare skeleton of good nutrition. They are chemicals that have lead to dramatic deficiency diseases in the past (i.e. is how they were originally found and classed as “vital”) Associated or related chemicals from the same dietary sources can also perform important functions, often assisting the “known” vitamin. Most of these other nutrients have not been characterized or studied well (there are 1000s of chemicals in a single plant), so the only realistic solution is to get them in the natural mix found in the plants and animals, on the assumption that we co-evolved with available nutrients, and to routinely vary our diets.
A varied diet also assists in the absorption of the nutrients in a supplement or the diet itself. Potassium, Magnesium and Calcium, for example, assist each other’s absorption, but simply taking extra supplements may not be a quick fix IIRC, chronic low dietary Mg decreases your ability to absorb Mg, and “Ca-hungry” bones can suck too much Ca from the blood, so supplement tablets can take months to achieve a balanced efficient absorption. Meanwhile, you’re taking several times the intended dose of Vitamin D, which tends to remove calcium from bones.
I think that the “20%” figure you heard is an exaggeration. The FDA is very familiar with bioavilability: it’s a crucial and tightly regulated property in the drugs they regulate. Many nutrition theories have been repeated so widely even some doctors believe them, but the advocates often just (mis)echo each others claims or reasoning, backed, at best, by a few old, weak, or outlier studies. To continue with Ca/Mg: since at least the 1970s, some vitamin makers have claimed that the common inexpensive Ca/Mg supplements aren’t well absorbed, and that only expensive natural dolomite, oyster shell, or coral tablets are worthwwhile. Actual testing proves that cheap inorganic Ca++/Mg++ absorbs as well or better than natural sources. but the pricier coral, dolomite, oyster shell, etc. have proven health risks: the FDA has issued warnings because appreciable levels of lead and other contaminants have been found in them, precisely because of their uncontrolled natural origin.
There are several vitamins where a sudden increase in supplementation can be painful or dangerous. Sudden high doses of Vitamin E can cause chest pains in some people, and sudden increases in Niacin can cause agitation, spasms, heart palpitations - or worse. A slow increase over a period of months is much better tolerated, but if you want high dises of a specific vitamin, take it separately. Also, I don’t believe the FDA currently regulates “higher than listed doses” for MVIs. That has been “on-again, off-again” since the 70s, and a multivitamin bottle I have in my desk only guarantees “at least” the listed amounts.
Vitamins A and D, can be toxic in high doses, and accumulate in fatty tissues. Vitamin A overdose is almost always due to excess oral supplements. There may also be skin absorption from overuse of “Vitamin A+D ointments”
You get these risky vitamins from other sources, aside from yourr MVI – often more than you may realize by reading the nutrition labels.
For example, even relatively brief sunlight exposure generates vitamins D in your subdermal fat; and essentially all US milk is supplemented with Vit D. In fact, supplementing milk is so cheap and easy process (shining UV on the milk creates Vit D in milk fats) that dairy packagers quite often overdo it. (“Testing of 42 milk samples found only 12% within the expected range of Vitamin D content. Testing of 10 samples of infant formula revealed seven with more that twice the Vitamin D content reported on the label, one of which had more than four times the label amount. Vitamin D is toxic in overdose.” New England Journal of Medicine, 1992, 326)
Taking the fat-soluble vitamins (A, D, E and sometimes K :)) with meals facilitates absorbing them, but not the water-soluble vitamins B and C. Niacin is a water-soluble vitamin (being a B vitamin) and as long as you increase the dosage slowly, there is no problem, except for possible skin-reddening at the beginning of the regimen.
Sweet, Christ KP, what an answer.
I’ve got two hijacks, if you’d be so kind:
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I’m thinking about those crazy herbal powders that have ingredient lists a mile long (examples here and here). Any suggestion on if those are worth the cash? Specifically the second one, I know some people who use this.
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This old thread that no one ever answered.
I didn’t look at the first one, but the second one makes me suspicious. He claims that every patient who ever came into his clinic was nutritionally deficient, he claims that said deficiencies can cause virtually any disease, he claims we live in a toxic environment with “less oxygen” than ever before. And he makes all sorts of claims about other sources of vitamins - that they’re dangerous and not bioavailable, and backs them up with assertions about where they come from. Maybe most vitamin B-12 comes from beef liver, but the fact that cows are treated with hormones doesn’t strike me as any reason to think the B-12 in their livers is somehow dangerous.
Not to say that his vitamin is bad; I couldn’t make any claims about that, and there’s no reason to think he produces a bad product. But he makes a lot of claims that send up red flags for quackery - everyone needs this, it can cure virtually any disease (implied by his statement that vitamin deficiencies can cause almost every disease), and the large-text warning on the front page that implies a government conspiracy to prevent good health. It’s the kind of thing that quack doctors say, so personally, I wouldn’t take any stock in what he says.
Re: Is it better to take a multivitamin in the morning or at night. This pdf from the Yale health center suggests taking you’re multivitamin with a meal.