Disclaimer: The following is for informational purposes only and should not be construed as individual nutrition or medical advice. Always consult a doctor or dietitian before taking any supplements.
I love researching vitamins! I know, I'm such a nutrition nerd. But, ever since 8th grade when I started researching foods for nutritional content, I've loved knowing what I'm getting from my food and how it's improving my health.
Ideally we are getting all the vitamins and minerals we need daily from food, but it doesn't always happen. That's were supplements may come in. The best way to know if you have a vitamin or mineral insufficiency or deficiency however is to talk with your doctor and test your levels. He or she can then recommend specific supplementation. For example, why take a multivitamin if you only need vitamin D?
That being said, I still often get the question about how to choose a multivitamin, so here we go.
First, though, what vitamins and minerals do we actually need each day? And can we get too much of a good thing?
The following amounts are recommended for women and men aged 19+ or 19-50:
The following amounts are recommended for pregnant and lactating women aged 19+. Vitamins or minerals not listed means recommendations do not differ from women aged 19+ who are not pregnant or lactating. For example, vitamin K recommendations are 90 mcg for women aged 19+ regardless of pregnancy or lactation.
Can we get too much? Yes! There are a handful of vitamins and minerals that have what's known as a tolerable upper intake level (UL) where supplemental intake (not from food sources) beyond this amount could have negative side affects.
The UL brings me to the first thing I look at in a multivitamin (MVI):
1. If the supplement contains 100% of daily needs for each vitamin and mineral, it must have more than one capsule.
A multivitamin is a supplement, so it supplements the diet, it doesn't replace it. Ideally we are getting all the nutrients we need from our food, however, without regular testing it is tough to know what we actually absorb. I like to think I'm getting most of what I need from food and use a multivitamin like an insurance policy. For this reason, I often only take half the dose of a MVI. Therefore, if there's 100% of everything in only one capsule, it's too much.
There are some vitamins and minerals that are pretty easy to get from the diet, one being vitamin B3, or niacin, which has a UL pf 35 mg/serving. Because it's easy to get from the diet, I definitely don't need a MVI that has 100% of the daily value. I also don't want one that is above the UL, which is pretty common!
Another is iron. Adult women need 18 mg/ day and pregnant women need 27 mg/day. I don't want a MVI that gives me 100% of iron needs as I know I will get some from my diet, and don't want to achieve the UL of 45 mg.
Vitamin A has a UL of 3000 mcg, so this is another one to be aware of when looking at a supplement.
2. The next thing I look at is the form of vitamin B12 and folate.
Most MVIs will contain vitamin B12 (also known as cobalamin) in the form "cyanocobalamin", however this is the synthetic form, whereas "methylcobalamin" is naturally occurring. Cyanocobalamin can be converted to methylcobalamin in the body. More research needs to be done, but methylcobalamin may be better retained than cyanocobalamin (2)
Most supplements will also contain "folic acid" (synthetic form), which takes time to convert in the body to the active form "5-methyltetrahydrofolate," and may be inefficient in some people (3)
For these reasons, and based on research I've done over the years, I tend to choose supplements containing the "methyl-" form.
3. Then I look for vitamin K2, typically in the form MK-7.
This is not a deal-breaker, but it's definitely a plus. Vitamin K2 is still being researched, but there has been evidence that it's important for bone health, cancer prevention (4), and improving insulin sensitivity (5).
It can be found in the diet, but food sources of vitamin K2 are limited. It is mainly found in grass-fed cheese (full fat), egg yolks, liver and other organ meat, and natto (fermented soy beans), which I know I'm definitely not eating a lot of!
4. Lastly, I look for a quality brand.
I look for brands that take pride in the quality in their products, perform third-party testing, and/or use the products themselves.
This doesn't seem like a big list of qualifications, but you'd be surprised how few supplements I've found that meet these needs!
Some of the brands that meet these requirements include:
Whole Earth & Sea Women's Multivitamin & Mineral --- UPDATE: A full dose contains over the vitamin A UL of 3000 mcg, can no longer recommend
Whole Earth & Sea Men's Multivitamin & Mineral --- UPDATE: A full dose contains over the vitamin A UL of 3000 mcg, can no longer recommend
Full Circle Prenatal (though it contains no iron)
I love Smarty Pants gummy vitamins for quality, however the only drawback is sugar content (6g/serving). Often times I'll separate the dose or take them after or before exercise. Ultimately though, I know I'm at least getting nutrients along with the sugar.
I've researched and looked at many vitamins over the years, but companies seem to be developing new supplements or improving their formulas. I will continue to update this list as I find supplements that qualify.
Sources
Vitamin and mineral requirements: https://ods.od.nih.gov/factsheets/list-all/
Link, Rachael. Methylcobalamin vs. Cyanocobalamin: What's the Difference? Healthline. May 12, 2020. https://www.healthline.com/nutrition/methylcobalamin-vs-cyanocobalamin
Arnarson, Atli. Folic Acid vs. Folate - What's the Difference? Healthline, August 19, 2019. https://www.healthline.com/nutrition/folic-acid-vs-folate.
Leech, Joe. Vitamin K2: Everything you need to know. Healthline. September 21, 2018. https://www.healthline.com/nutrition/vitamin-k2#_noHeaderPrefixedContent.
Choi, Huang Jin et al. Vitamin K2 Supplementation Improves Insulin Sensitivity via Osteocalcin Metabolism: A Placebo-Controlled Trial. Diabetes Care 2011 Sep; 34(9): e147-e147. https://care.diabetesjournals.org/content/34/9/e147.