Have you been feeling tired, grumpy and cold lately? This may apply to most of us this week, having to get back to work after a couple of long weekends.
But if it sticks around, it could be worth getting yourself checked to see how you're faring in an essential mineral: iron.
Iron is crucial for our health and wellbeing. It helps carry oxygen to our brains and muscles, keeping us physically and mentally strong, and helps us make energy and fight infections.
Every cell in our bodies needs iron.
But a fair chunk of us are low in it.
Women need twice as much as men, which means it's harder for us to get enough, and we're more likely to suffer from deficiencies.
The most recent data shows low iron levels affect one in 14 women, and more than a third of teenage girls don't achieve their daily requirements.
Young children are another at-risk group, because they're growing rapidly. Eight out of 10 toddlers are not meeting the recommended daily dietary intake and 14 per cent of children under 2 are deficient.
Other groups that could find their iron status low are athletes and people who exercise a lot, and people on restrictive diets.
It's difficult to get enough iron (along with other nutrients) when you're cutting calories; yet another good reason not to diet.
Vegetarians and vegans can also be at risk. It's entirely possible for them to get enough iron, but it needs careful attention.
Long term, iron deficiency can lead to anaemia, which is a serious issue.
So how can we keep our levels healthy?
It's a problem with a delicious solution, as it happens, and we're generally better off if we address it with food rather than supplements.
Iron is present in many foods and it comes in two forms: haem and non-haem.
Haem iron is in animal foods like meat and fish and is more easily absorbed than non-haem iron from plants.
Red meat is the most abundant source of iron, and eating beef, lamb and venison several times a week is a really good way to top up iron levels.
Mussels are another surprisingly good source, with similar levels to meat. It's also in chicken, pork and fish at lower levels.
When it comes to plants, we only absorb about 5 per cent of the iron present in the food, compared to 25 per cent of haem iron. But it'll all add up.
Beans, lentils, nuts and seeds all contain iron, so including these foods is a good idea, too.
Try adding them into your meat-based meals, combining the two types means you'll help your body absorb up to four times more of the non-haem iron.
And if you like a cuppa, have it after dinner rather than with your meal. The tannins in tea (and to a lesser extent in coffee) can interfere with iron absorption.
• It's World Iron Awareness Week this week. To find out more, go to: ironweek.co.nz.