What foods are rich in iron and calcium? What do you need to know about calcium and iron? Around 99% of our body’s calcium is stored in our skeleton and teeth. Iron is one of the most common micronutrient deficiencies in the world and makes up 50% of all anaemias.
With the food we eat there are macronutrients and micronutrients. Macronutrients are what we require in large amounts each day as they provide us with energy. Macronutrients include fat, protein, and carbohydrate (also alcohol as it technically provides a lot of energy but no nutritional value). Micronutrients are our vitamins and minerals. Vitamins are organic compounds and include the B vitamins, A, D, E, K, and C to name a few. Minerals can be divided into macrominerals and microminerals. Macrominerals are the minerals we require in larger quantities, for example calcium and magnesium, whilst microminerals are those we only require in trace amounts. However, those trace amounts are often essential to our health. Iron is a micromineral, as are other minerals such as copper and zinc.
Over 60% of the iron found in our body is within our red blood cells. It is part of the haemoglobin structure which helps to transport oxygen around the body. Iron is also found in a compound called myoglobin which is found in our muscles and stores oxygen. Iron plays a fundamental part in our immune function and also in metabolic reactions throughout the body which are important for the production of energy.
The signs and symptoms of iron deficiency basically reflect its roles in energy production and oxygen distribution. Common signs and symptoms include, but are not limited to:
Shortness of breath
Sensitivity to the cold
Pica – more often seen in end stage iron deficiency anaemia. This is craving non-food items such as ice and soil.
What are the best sources of iron?
Iron as a whole is not absorbed that effectively by our body, however, the biggest influence on how much we absorb is actually our current body iron status. That is, if an individual is low in iron their body will respond and absorb more iron from the food consumed. Someone who has higher levels of iron will absorb less. Another important consideration with iron in foods is the form it is in. There are two forms of iron, haem and non-haem. Haem sources of iron are those that come from animal products and is better absorbed and less affected by dietary factors. Some good sources of haem iron include:
100g pork liver 21mg
½ cup cooked mussels 4.4mg
130g beef steak 3mg
100g Hoki fish 2.9mg
100g chicken breast 1.9mg
Non-haem iron is sourced form plant-based products and is less well absorbed and often affected by dietary factors. Sources of non-haem iron include:
Dietary factors that can reduce the absorption of iron include:
Polyphenols: tea, coffee, red wine, herbal tea
Phytates: legumes. Cereals, nuts
Oxalic acid: spinach, rhubarb, silver beet
Calcium: dairy foods, supplements
There is also a dietary compound that helps us absorb iron – Vitamin C. This is often why you may see iron supplements with vitamin C added. When eating meals that contain iron, pair them with fruit and vegetables (as you should be doing anyway!) as this will help the absorption of iron. Examples of good Vitamin C sources include:
Orange capsicum 137mg/100g
Younger children, boys, men and older adults: 8 – 10 mg/day.
Girls aged 14 to 18 years: 15mg/day.
Menstruating women: 18mg per/day.
Pregnant women: 27mg/day. Pregnant women need more to support the increased blood volume and iron needs of the developing foetus, while lactating women aged 19 – 30 years require 9mg/day.
Who is at risk of iron deficiency?
People on energy restricted diets
People with eating disorders
People with gastrointestinal disorders (e.g. IBD, coeliac)
People with alcohol dependence
Pregnant or breastfeeding women
People taking specific types of medication (antacids, proton pump inhibitors)
Vegetarians or vegans
Endurance athletes, especially runners
Those who donate blood regularly
Athletes who are altitude training
Top three Iron tips
Do not start taking iron supplements without knowing what’s going on. Although iron deficiency can lead to anaemia, so can other nutrient deficiencies and health conditions. Go and see your relevant health professional, that is your GP or a dietitian if you have concerns. Iron deficiency may be due to inadequate intake but can also be a marker for other conditions, e.g. undiagnosed coeliac, RED-S, and eating disorders.
If you are trying to increase your iron levels, drink coffee and tea between main meals.
Eat your vegetables, they not only enhance your health but will enhance your iron absorption too!
Calcium – more than just bone health.
We all know we need calcium for strong bones. Around 99% of our body’s calcium is stored in our skeleton and teeth. However, the remaining 1% in our bloodstream plays a critical role in a number of functions. These functions include aiding the electrical system of the heart, blood coagulation, muscle contractions, and functioning of the nervous system. It also acts like a ‘co-pilot’ in different metabolic reactions around the body helping them to run effectively.
The recommended daily requirements of calcium are 1,000mg for healthy adult males aged 19 – 70 years and females aged 19 – 50 years. As bone loss accelerates after menopause in women and men over 70 years, calcium requirements increase to 1,300mg daily. Children aged 12 – 18 years also require more calcium (1,300mg). Think of consuming calcium like saving for your retirement, although you may not see the benefits now, consuming calcium each day will mean you have good calcium savings for retirement (aka good bone health). Lack of savings in the bone bank now can lead to frail and porous bones later in life, otherwise known as osteoporosis.
Dairy products are without a doubt some of the richest food sources of calcium, but not the only sources. As an example, ¾ cup (180g) of the ‘Anchor Protein +’ unsweetened yoghurt will provide you with 357 mg of calcium, or 1 cup (250mL) of calci-trim/yellow top milk will provide you with 457mg of calcium. If you were to include these two foods with your breakfast you have already met 81% of your calcium requirements for the day – easy!
Where it can become more difficult is for people who do not consume dairy due to intolerance, allergies, or personal beliefs. For people consuming a dairy-free diet it is important to be really ‘smart’ about consuming calcium from non-dairy sources. Additionally, like other minerals such as iron, the bioavailability of the mineral needs to be considered, which basically means how much of that mineral can be absorbed from the food consumed. For example, you can consider spinach as a dairy-free calcium source with half a cup of cooked spinach containing around 130mg of calcium, but only 5% of this is absorbed as it has low bioavailability.
Calcium food source inspiration:
40g Edam cheese 396mg
2 poached eggs 50mg
1 cup blackberries 77mg
Regular latte 275mg
2 dried figs 64mg
2 slices grainy bread 40mg
125g cottage cheese 95mg
250mL fortified soy milk 400mg*
30g almond 75mg
90g canned sardines 300mg
*When choosing dairy-free milks ensure they are fortified with calcium at levels of 120mg/100mL or more.
Myth busting on dairy
Dairy products are high in sugar. FALSE. Unsweetened yoghurts and milk alongside cheese do not have added sugar. The only sugar in these products is natural sugar from the cow called lactose. Lactose sugar in unsweetened milk naturally occurs in quantities of 4.8g/100mL.
Dairy causes weight gain. FALSE. Research has shown people who included three servings of dairy on calorie-controlled diets lost more weight than people who consumed less dairy.
Lactose intolerance is the same as dairy intolerance. FALSE. People with lactose intolerance can typically consume a certain amount of lactose without symptoms. Some dairy products such as hard cheeses have very little to no lactose in them and are tolerated very well.
Cushla is a Registered Dietitian based in beautiful Canterbury, New Zealand, and works with clients all over the country and abroad. Having been a passionate runner for over a decade, Cushla has a special interest in sports and performance nutrition, which was a key motivator to studying dietetics. Cushla has experience working with athletes from all walks of life, from beginners right up to elite across a range of disciplines. When she isn’t helping her clients achieve awesome goals through the power of nutrition, you will find her exploring the great outdoors … most likely trail running! Outside of her private practice, Cushla specialises in diabetes and lipid disorders at one of New Zealand's largest health centres in Christchurch.
The approach Cushla takes with nutrition is unique, focussing on simplistic, realistic, and practical advice tailored to each individual. Being a foodie herself, Cushla is regularly making delicious and nutritious food to inspire others. Cushla translates science into practical terms whilst ensuring all advice, plans, and nutrition strategies are the right fit for YOU.