This guest post by Registered Nutritionist Phoebe Wharton answers an extremely common question which seems to cause confusion – is it healthy to eat fruit or not?

The Sugar Content of Fruit

The idea of fruit being bad for us seems to be related to sensationalist media reports of its high sugar content.

Fruit is high in a natural occurring sugar called fructose. Some studies have found that fructose may have some negative effects on the body such as: increasing blood pressure, impairing liver function or hindering insulin response (1-2). However, these effects were only seen to occur with excess fructose consumption. It’s also worth noting that the majority of studies used industrial fructose in the form of sugar syrup, processed foods, and sugar-sweetened beverages. Therefore these studies don’t apply to eating fruit (1-4).

If you drink a glass of water containing 3 tablespoons of sugar (the equivalent to a can of soda) your body would have a spike in blood glucose levels. This can lead to a subsequent drop in blood glucose levels, whereas studies have shown this does not occur when consuming fruit (4-5).

The cellular structure of the fruit is important for in terms of its impact on blood glucose levels (6 – 7). Let’s use an apple as an example – sugars are effectively stored within its cell wall, which our digestive track has to break down before the sugars are released (8). This takes time, so sugar is absorbed into the bloodstream slowly, which gives the liver more time to metabolise it and blood glucose levels remain more stable (2 – 6).

And because this naturally occurring fructose found in fruit is bound up with other nutrients in the cell wall of fruit it doesn’t count towards the recommended daily limit of ‘free sugars’.

Free sugars are found in: table sugar, sugary drinks, cakes, biscuits, chocolate, sugary breakfast cereals, syrups and honey.

Is Fruit a Satisfying Food?

Whether a food is satisfying depends on a number of factors including how hungry you are, what you fancy at that moment, as well as when and how you eat.

But there is some interesting research into the impact of different foods on our fullness and appetite. For example, some studies found that sugar effects the hormones that tell our brains that we are full, which can result in over-consumption of sugary foods. Whereas consuming a fibre-rich fruit (such as an apple) takes a longer time to chew and is digested more slowly (9). As it takes the apple traveling longer to travel through the digestive tract, this triggers satiety hormones in small intestine (1,2).

The result is that you feel satisfied for a longer period of time when you eat a piece of fruit as compared to a low fibre, high sugar food like fruit juice or jelly babies (6,7).  

A study in 2009 looked into the impact of consuming apples in different forms – whole apple, applesauce, and apple juice with and without added fibre. These were consumed prior to a meal to compare how they influenced feelings of fullness (satiety) and energy intake at meal. Results showed that individuals consuming the whole apple had an increase in satiety compared to the applesauce or apple juice. The researches also added naturally occurring levels of fibre to the juice, however this did not improve the feeling of fullness. Overall the results suggest that consuming whole fruit makes us feel fuller compared to pureed fruit or juice, and that eating fruit at the start of a meal may reduce energy intake. (8)

Food high in fibre, fat and protein are satisfying and keep us fuller for longer. So fruit can be a great way of adding fibre to a balanced meal to make it more filling. A great idea for a satisfying snack is to combine a piece of fruit with a high protein food such as a handful of nuts, a yoghurt or a piece of cheese.

Why is Fruit Juice Different?

Although juice still contains the vitamins which are found in whole fruit, the fibre content is much lower (4,8). As explained above, this means that fruit juice is less filling than whole fruit.

The juicing process also  breaks down the cell wall and releases the sugar which will be dissolved in the juice. This sugar is absorbed in the small intestine and enters the bloodstream quickly (6, 7). As stated previously this causes a more rapid rise in your blood glucose levels which may be followed by a dip in blood glucose levels, whereas blood sugars tend to be more stable after consuming a piece of whole fruit (3,6,8).

However, fruit juice is still very nutritious, and can be an affordable and convenient way of consuming a portion of fruit.

It’s important to bear in mind that the recommended portion size is 150ml of pure fruit juice per day (and this only counts as a portion of fruit once per day).

The Nutritional Benefits of Fruit

Fruit has many proven health benefits.

Regular fruit consumption has been associated with a lower risk of strokes, certain types of cancer and a lower risk of heart disease (3,5, 9,10).

Fruits are packed with essential nutrients such as:

• Vitamin A
• Vitamin C
• Vitamin E
• Folate
• Potassium

These nutrients are important for maintaining a number of body functions including blood pressure, vision, gut health and normal functioning of the nervous system and the immune system.

Fruits like berries are packed with antioxidants which help fight free radicals and reduce oxidative stress on the body (4).

As stated previously, whole fruit is full of fibre, the daily reference value for dietary fibre is 30g/day. However research has shown the average UK adult consumes half that at 15g/day.

Fibre is essential for the health of our digestive system. Research has also shown a reduced risk in developing, bowel cancer, heart disease, stroke and even type-2 diabetes with an increase in fibre consumption (10)

So fruit is an extremely healthy food, and most people would benefit from consuming more fruit and vegetables each day.

References:

1. Stanhope, K. L., Schwarz, J. M., & Havel, P. J. (2013). Adverse metabolic effects of dietary fructose: results from the recent epidemiological, clinical, and mechanistic studies. Current opinion in lipidology, 24(3), 198–206.
2. Johnson, R.J., Segal, M.S., Sautin, Y., Nakagawa, T., Feig, D.I., Kang, D.H., Gersch, M.S., Benner, S. and Sánchez-Lozada, L.G. (2007) Potential role of sugar (fructose) in the epidemic of hypertension, obesity and the metabolic syndrome, diabetes, kidney disease, and cardiovascular disease. 86(4) 899-906. Am J Clin Nutr.
3. Brown, L.., Rosner, B., Willett, W.W. and Sacks, F.M. (1999) Cholesterol-lowering effects of dietary fiber: a meta-analysis. 69(1):30-42. Am J Clin Nutr.
4. Dauchet, L.., Amouyel, P., Hercberg, S. and Dallongeville, J. (2006) Fruit and vegetable consumption and risk of coronary heart disease: a meta-analysis of cohort studies. 136(10):2588-93. J Nutr.
5. He, F.J., Nowson, C.A., Lucas, M. and MacGregor, G.A. (2007) Increased consumption of fruit and vegetables is related to a reduced risk of coronary heart disease: meta-analysis of cohort studies. 21(9):717-28. J Hum Hypertens.
6. Stanhope, K. L., Schwarz, J. M., Keim, N. L., Griffen, S. C., Bremer, A. A., Graham, J. L., … Havel, P. J. (2009). Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans. The Journal of clinical investigation, 119(5), 1322–1334.
7. White J. S. (2013). Challenging the fructose hypothesis: new perspectives on fructose consumption and metabolism. Advances in nutrition (Bethesda, Md.), 4(2), 246–256.
8. Flood-Obbagy, J. E., & Rolls, B. J. (2008). The effect of fruit in different forms on energy intake and satiety at a meal. Appetite, 52(2), 416–422. doi:10.1016/j.appet.2008.12.001
9. Aune, D., Giovannucci, E., Boffetta, P., Fadnes, L.T., Keum, N., Norat, T., Greenwood, D.C., Riboli, E., Vatten, L.J. and Tonstad, S. (2017)  Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality—a systematic review and dose-response meta-analysis of prospective studies, International Journal of Epidemiology, 46(3) Pages 1029–1056,
10. SACN- Carbohydrate and Health Report  https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/445503/SACN_Carbohydrates_and_Health.pdf