It's August. And very much August in Europe, which is why I'm late this week. Here's your weekly installment of iron knowledge, and it's one I've really needed myself.
I'm battling iron deficiency again, for various reasons, and really, it's not helping in the heat, with the kids out of school and the general chaos that is summer with young kids.
So, here's what to understand about vitamin A and how it relates to iron.
It's one of those things that comes up when your iron won't budge and you start wondering what else might be going on. It's in most prenatals, and it really is involved in how your body uses iron.
The question is whether taking it actually does anything.
Vitamin A doesn’t help you absorb iron, but it does direct the iron you already have in three ways:
It tells your marrow to build red blood cells. The active form, retinoic acid, raises erythropoietin, the hormone that signals your bone marrow to make red blood cells.
It unlocks stored iron. Retinoic acid lowers hepcidin and raises lactoferrin, releasing iron from the liver back into your blood.
It helps you absorb plant iron. Vitamin A keeps non-heme iron absorbable by blocking phytates in grains, raising iron absorption from rice up to two-fold in people.
Take vitamin A away and the whole cycle stops. A low-vitamin-A person can develop an anemia that iron alone won’t fully fix until the vitamin A is replaced.
Vitamin A Primer
Vitamin A comes in two forms. Retinol is the ready-to-use form. It’s in animal foods (liver, dairy, eggs) and in supplements and skincare. Potent, and the one you can overdo.
Beta-carotene, in orange and dark green plants, is the one your body converts into retinol only as fast as it needs it, so it can’t build up in your body and it’s not easily overdosed.
Your cells actually use retinoic acid, made from retinol.
It only matters if you’re truly lacking vitamin A
In vitamin-A-deficient Moroccan children, vitamin A raised hemoglobin by 7 g/L and cut anemia from 54% to 38%, while ferritin fell, meaning it pulled iron out of storage rather than adding any. Total body iron didn't change.
Pooling the trials tells the same story. Vitamin A cut anemia risk by about 26% and raised hemoglobin ~3.5 g/L, but did not lower iron-deficiency rates at all. And every trial was in low-vitamin-A groups.
In deficient pregnant women, vitamin A plus iron beat either alone, but only about a third of the gain came from vitamin A, and two-thirds was the iron.
Vitamin A redistributes iron. It doesn't supply it. If you already have enough vitamin A, there's no traffic jam to clear.
And more than you need can be too much
In one trial, pregnant women who weren’t low in iron, adding vitamin A raised the risk of severe anemia by 41%. Keep in mind that this is a single study and we don’t know yet how to explain the mechanisms at play. One potential explanation is that vitamin A revved up red blood cell production faster than iron could keep up in some women. But it’s just a hypothesis at this stage.
What’s more conclusive: high-dose pre-formed vitamin A (i.e., retinol) is one of the few supplements proven to cause birth defects. Intakes above 15,000 IU a day roughly tripled the risk of certain malformations. Beta-carotene from food doesn’t carry that risk.
So who’s actually short on vitamin A?
In the US and other high-income countries, vitamin A deficiency is rare.
When it happens, it's usually not about eating too little. Because vitamin A is fat-soluble, it's mostly an absorption problem, seen in people who can't absorb fats well: celiac disease, Crohn's, cystic fibrosis, pancreatic problems, or after weight-loss surgery, and two other groups: people with chronic liver disease or heavy alcohol use (your liver stores most of your vitamin A), and premature babies, born with almost no stores.
Bottom line: If you eat a varied diet — animal-based foods + colorful plants — low vitamin A almost certainly isn’t why your iron is low. It’s not worth megadosing.
🚫 If your iron is low and you eat a varied diet, don't add a vitamin A supplement to fix it. Keep your effort on iron itself. Across the trials, vitamin A didn't lower iron-deficiency rates at all. It only redistributes iron you already have.
🥕 Get your vitamin A from food. That means, orange or dark-green veg with a little fat, a few times a week. Carrots, sweet potato and spinach give you beta-carotene, and the fat is what lets you absorb it. Food covers what you need without the risks.
🍊 If you want to help a meal's iron absorption, that's vitamin C's job. Eat your iron-rich foods with citrus, peppers or tomatoes, not a vitamin A pill. Vitamin C reliably boosts non-heme iron absorption. Vitamin A doesn't. The one study that found an effect saw it only for rice, not wheat, and a controlled trial found no absorption effect at all.
Here’s what caught my eye this week:
📄 Creatine added muscle even in people who weren't exercising: In 64 sedentary adults aged 45–65 (40 of them women), 10 g/day of creatine for 12 weeks increased lean tissue mass, strength and muscular endurance whether or not people also did an exercise and diet program. Those who did both also lost more body fat. The cognitive and blood-marker results are labelled exploratory by the authors, so more a lead rather than a finding.
📄 For bone density, three moderate resistance sessions a week ranked best: A network analysis of 34 trials and 1,746 people ranked moderate-intensity resistance training three times weekly highest for hip and spine bone density, and twice-weekly high-intensity training highest for whole-body density. Only some of those comparisons reached statistical significance, and the authors say the rankings should be read with caution.
🧴 WHOOP began bundling a year of Natural Cycles with its wearable: The band's temperature data feeds the app that Natural Cycles uses to identify fertile days.
Just sharing here what's new this week. No affiliates, no sponsorships, no freebies. A mention here isn't a recommendation.
How valuable was today's issue for you?
