The Nutrient Series – ENERGY

Although energy isn’t technically a nutrient, it is absolutely essential for our bodies. It is used by our cells to carry out all the processes needed to keep us alive. It comes from four components (macronutrients) of our diet; carbohydrate, protein, fat and alcohol (obviously, this isn’t an essential or recommended source of energy). Energy is measured in either kilojoules (kJ) or kilocalories (kcal). You may be most familiar with using kcals when talking about how much energy a foodstuff provides. The four macronutrients provide different amounts of energy;

  • Carbohydrate – 3.75 kcals per g of food (often rounded up to 4kcal/g)
  • Protein – 4 kcals per g of food
  • Fat – 9 kcals per g of food
  • Alcohol – 7 kcals per g of food

Throughout our lives, we have varying energy needs. Children’s and teenagers’ energy needs change as they grow, as growth and development requires energy. Adults doing a lot of exercise or those very unwell can often require more energy than the average adult. Each of our individual energy needs will be different, and can be estimated by a dietitian or other health care professional. They would take height, weight, age, gender and activity status into account. It is also worth mentioning that if you are trying to gain weight you need to eat more than this, and to lose weight you should eat less. The BDA recommends that for 1lb weight loss per week (which is the healthy guideline) you should cut your daily calorie intake by 500 kcals per day.

For a guideline, estimated average requirements (EAR) have been issued for use by the general population. The values below are for healthy adults aged between 19-59 years;

  EAR (kcal/day)
Men  
19-49 years 2,550
50-59 years 2,550
Women  
19-49 years 1,940
50-59 years 1,900

Based on DRVs, DoH

It can sometimes be useful to equate these guidelines to actual amounts of food, so I have given example days below for adult men and women. Obviously, this is just a sample day, to illustrate an average adult’s daily energy recommendation.

Male – roughly 2,550 kcals/day

Breakfast

45g Bran flakes

80g strawberries

1 sliced banana

125ml semi-skimmed milk

150ml orange juice

Total = 366 kcals

150

24

80

58

54

Mid-morning

30g mixed nuts

1 apple

Costa medium flat white coffee (semi-skimmed milk)

Total = 307 kcals

174

45

88

Lunch

Egg mayonnaise sandwich (white bread)

80g cherry tomatoes

3 or 4 dried apricots (40g)

Cereal bar

Total = 715 kcals

415

20

180

100

Mid-afternoon

Fruit yoghurt (roughly 125ml)

Cup of tea with semi-skimmed milk

Total = 110 kcals

100

10

Dinner

Spaghetti bolognaise (roughly 400g)

Side serving of 80g sweetcorn

& 80g broccoli

100g Apple crumble with 120ml custard

Total = 1047 kcals

604

63

30

350

Total 2545 kcals

 

Female – roughly 1,900 kcals/day

Breakfast

40g Bran flakes

80g strawberries

1 sliced banana

125ml semi-skimmed milk

150ml orange juice

Total = 351 kcals

135

24

80

58

54

Mid-morning

25g mixed nuts

1 apple

Costa medium flat white coffee (semi-skimmed milk)

Total = 278 kcals

145

45

88

Lunch

Egg mayonnaise sandwich (white bread)

80g cherry tomatoes

Cereal bar

Total = 535 kcals

415

20

100

Mid-afternoon

Cup of tea with semi-skimmed milk

Total = 10 kcals

10

Dinner

Spaghetti bolognaise (roughly 300g)

Side serving of 80g sweetcorn

& 80g broccoli

80g Apple crumble with 100ml custard

Total = 816 kcals

453

63

30

270

Total 1990 kcals

 

Sources

BDA Food Facts – Weight loss – https://www.bda.uk.com/foodfacts/Want2LoseWeight.pdf

Costa Coffee Nutritional Info – http://www.costa.co.uk/nutrition/nutrition-data-sept-2016.pdf

Dietary Reference Values for Food Energy and Nutrients for the United Kingdom, DoH, 1991

McCance and Widdowson’s Composition of Foods, 2015 – https://www.gov.uk/government/publications/composition-of-foods-integrated-dataset-cofid

 

The Nutrient Series – Iron

Over the next few months I will write some posts on the essential nutrients that we need to maintain good health, interspersed with posts on other subjects, maybe including a couple of recipes!

One nutrient that I often get asked about is iron, so I thought I would write the first post about that.

 

Why do we need iron?

Haemoglobin is the component found in red blood cells which carries oxygen around the body. Iron is an essential part of the haemoglobin structure, which is a key reason why iron deficiency can cause tiredness, as it means less oxygen is transported to the muscles when needed.

Iron is also contained in enzymes involved in muscle contraction (our muscles contract every time we use them).

Children would have fairly high requirements as iron is also needed for tissue growth and development.

 

How much should we be consuming?

Men and women need different amounts of iron in their diet due to the blood loss that females experience during menstruation.

 

The following requirements are for adults aged 19-50 years;

Males: 8.7 mg per day

Females: 14.8 mg per day

(Everyone over 50 years should consume 8.7 mg per day)

 

The requirements for teenagers (11-18 years);

Males: 11.3 mg per day

Females: 14.8 mg per day

(Dietary Reference Values)

 

Good sources of iron

There are two types of iron; haem and non-haem. Haem iron is present in animal products and is best absorbed. Non-haem iron comes from plant sources, and although it isn’t as well absorbed as haem iron, our bodies can still absorb it and vegetarian diets can provide enough iron.

 

The following foods are good sources of iron;

  • Meat, especially red meat such as beef
  • Fortified cereals and cereal products
  • Beans
  • Nuts
  • Green-leafy vegetables, such as kale or watercress
  • Wholegrains such as brown rice
  • Dried fruit, such as dried apricots

 

There are some foods which can help our bodies absorb the iron from our food;

  • Vitamin C – found in oranges and other fruits
  • Citric acid – present in oranges and other citrus fruits
  • Beta-carotene – present in brightly coloured fruit and veg such as carrots
  • Alcohol (only a small amount needed!)

And other foods can slightly inhibit the absorption of iron, such as caffeine.

So, drinking a glass of orange juice in the morning with your breakfast cereals, but avoiding the coffee until a bit later will optimise your iron absorption. And drinking a small glass of red wine with your steak in the evening will do the same!

 

How much do I need to eat to get my recommended daily intake?

A typical day may look like this;

Breakfast 30g Bran flakes, 125ml semi-skimmed milk & 150ml orange juice ≈5 mg
Mid-am snack 20g almonds & 30g dried apricots ≈1.85 mg
Lunch Tuna with raw spinach sandwich on brown bread

Banana

≈3 mg
Mid-pm snack 125 ml plain yoghurt with 80g blueberries and 15g sunflower seeds ≈1 mg
Dinner Beef mince spaghetti bolognaise with wholegrain pasta ≈4.4 mg
  TOTAL ≈15.25 mg

(McCance & Widdowson’s Composition of Foods)

The Department of Health says that any intake below 17 mg per day is safe for most people – but your daily intake of iron wouldn’t necessarily always be this high, it should just average out over the week.

 

Iron deficiency

If you are consistently not consuming enough iron, your body’s stores of it start getting empty and this could cause iron deficiency anaemia. This may make you feel tired, sluggish and run down and give you a pale complexion. If you are worried about being anaemic, you should go and speak to your doctor.

 

Can you have too much iron?

A high dose of iron is considered more than 20 mg per day (NHS Choices). You may experience constipation and nausea. Most people consume the right amount of iron in a normal healthy diet.

 

But please remember that everyone is slightly different, and these recommendations have been published for the general public. Some individuals may have different needs and should be advised accordingly by a dietitian or doctor.

 

 

Sources

Dietary Reference Values for Food Energy and Nutrients for the United Kingdom, DoH, 1991

Iron and Health, SACN, https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/339309/SACN_Iron_and_Health_Report.pdf

McCance and Widdowson’s Composition of Foods integrated dataset, PHE, https://www.gov.uk/government/publications/composition-of-foods-integrated-dataset-cofid

Molecular Basis of Human Nutrition, Tom Sanders and Peter Emery, 2003

NHS Choices, http://www.nhs.uk/Conditions/vitamins-minerals/Pages/Iron.aspx

Pexels: https://www.pexels.com

 

 

Is organic food worth the price?

Organic food is often more expensive than non-organic food, although the price difference can vary. For example Tesco Loose Braeburn Apples cost £2.00/kg compared to £2.94/kg for their Organic Braeburn Apples (price correct 08/11/16). There are many different factors as to why people may choose to buy organic food based on the nutritional, environmental and ethical impact. Although I will very briefly mention the other factors, I will focus on whether there is any nutritional basis for switching to organic products.

 

A meta-analysis (data combined from multiple studies) published in 2014 showed that organic crops contain higher levels of antioxidants, including vitamins C and E, which have been linked to reduced risk of diseases such as cardio vascular disease and certain cancers. The authors of the study found that consumption of organic crops provided an average of 20-40% higher antioxidant intakes than non-organic, equivalent to one or two portions of fruit or veg. However, they did recognise that there is still not much evidence showing that an increase in antioxidant intake actually improves health.

 

Another meta-analysis in the British Journal of Nutrition looked into the nutritional content of organic vs non-organic cow’s milk. They found that there was no significant difference in saturated and mono-unsaturated fat content. However, there was significantly more omega-3 fatty acid in organic milk.

Omega-3 may protect against heart disease as well as maintaining a good memory. Milk is not one of the richest sources of omega-3, though. Oily fish, such as mackerel and salmon, and nuts and seeds are good sources. So don’t feel that you have to change to organic milk to increase your omega-3 intake. It could be a change that complements other changes to your diet such as those mentioned above.

 

This interesting study found that people perceived organically labelled processed food such as cookies to be more nutritious than non-organically labelled food, even though the actual food was exactly the same. Participants also hugely underestimated the calorie content of the test food when it was labelled as organic, sometimes by as much as 24%! There is no strong evidence to suggest that the calorie content of organic food is different to its non-organic equivalent.

 

Regarding concerns about hormones used in dairy farming, hormone growth promotors have been banned for use in dairy farming in the UK, and other forms of hormones are only allowed to be given to cattle if specifically prescribed by a vetinary surgeon. Antibiotic use is also now restricted to reduce the risk of antibiotic resistance. For more information on cattle and dairy regulations in the UK visit: https://www.gov.uk/guidance/cattle-health

 

From an environmental point of view, organic farming reduces pesticide run-off and contamination of ground water. This reduces the chance of our drinking water being contaminated.

Organic also prohibits the use of genetic modification (GM) technology. However, there is still not a lot of strong evidence to suggest that GM has an effect on our health. It is a relatively new technology so the long term effects cannot really be tested yet.

 

There is emerging evidence that organic food may be more nutritious, but it is often a decision that people make based on environmental and ethical beliefs as well. Organic food can be a lot more expensive than non-organic so it may be more beneficial to increase your fruit and veg, fish and pulses intake, as part of a healthy diet. There needs to be more research done into whether eating organic food significantly improves your health.

*Please remember that I have written this article as a nutrition student so have focused on the nutritional effects of eating organic food.