Blackberry Jam. Full of goodness or a ‘devil’s food’?
Five years ago I turned up at a nutrition conference with hands died purple from blackberry picking. When asked what I had been doing, I innocently said making jam, not realising the commotion this would cause. For many people jam = refined sugar and anything with a large proportion of refined sugar is seen as BAD. But I would argue this shouldn’t include jam (and actually I don’t like the idea of classing food as good or bad anyway). Good quality Jam is full of vitamins, minerals, phytonutrients and fibre and can be linked with may health benefits including improved cognition and is a good source of energy for sport.
Blackberries are incredibly nutritious. One cup of fresh blackberries provides 30.2 mg of vitamin C, 50% of your daily requirement as well as good quantities of B Vitamins (with the exception of B12), Vitamin E, Vitamin K, Vitamin A and Choline (important for brain structure and function). Blackberries are also high fibre, (a cup of blackberries contains 7.6 grams) and are packed full of minerals, with good quantities of Calcium, Iron, Magnesium, Phosphorus, Potassium, Zinc, Copper, Manganese and Selenium.
Blackberries are also a great source of phytonutrients, being one of the best known sources of anthrocyanins (better than blueberries or blackcurrants) as well as containing other polyphenol flavanols, flavonols and hydroxybenzoic acids with well researched health or performance benefits. Blueberries and blackcurrants have been classed as superfoods and blackcurrants linked with enhanced performance in sport (see here).
The complete nutrient composition of raw blackberries can be found (here).
But are these nutrients still there in blackberry jam?
Obviously this slightly depends on the jam. Research looking at nutrient content of home made jams shows that although a proportion of the vitamins and phytonutrients in the fresh fruit is lost due to heating / smashing / sieving, as the juice and pulp is then concentrated down, the nutrient composition of fresh jam is still very good – greater than 70% of the original nutrient value remains. This does deteriorate the longer a jam is stored, with only around 50% remaining after six months but even then jam is nutritious. It is likely that more nutrients remain in jam than in jelly (the difference being that jelly is sieved and clear with no bits), many nutrients are found in greater quantities in the skin or around pips and jelly also has a lower fibre content. And contrary to what you would expect, there is some evidence that the polyphenol anthocyanin content of low-sugar jams ages better than similar high sugar jams. If you are interested in seeing this research, please do contact me for references.
And what about the sugar?
It is well understood that free / refined sugar has a greater impact on blood sugar than the same amount of sugar tied up in a whole food, fruit, vegetable or grain. There are a number of different reasons for this, including the fibre content but increasingly evidence points to a role for phytonutrients and in particular anthrocyanins. A number of good studies have shown that jam does not have the impact on the blood sugar curve that the ingredients would imply. Research looking at possible mechanisms has shown that polyphenols may inhibit the activity of digestive enzymes for glucose production and block the transporters responsible for glucose absorption.
The earliest cookbook, called Of Culinary Matters, which dates back to 1st century Rome, contained recipes for making jam. Through history jam and other preserves have been an important way of storing nutrients rich foods over winter. Crusaders returning to Britain are reported to have brought jam and jam recipes back with them and once it became known that Vitamin C prevented scurvy, jam became a valuable part of the sailors diet on merchant ships.
We now have access to fresh fruit and vegetables all the year round and the need to preserve has pretty much gone but as more and more research backs the idea that we need to increase the amount of phytonutrients we eat, preserves could have an important role again.
In February 2014, I wrote a post titled ‘What should we eat?” which introduced The Harvard Healthy Eating Plate, a healthy eating plan devised by scientists at Harvard University using all the latest available research. The Harvard Healthy Eating Plate advises that half of everything we eat should be fruit and vegetables. The latest UK data suggests that the majority of people still fail to get the recommended five fruit and vegetables a day even though this is a minimum recommended amount and would almost certainly not make up half of the food we eat.
The evidence for eating lots of fruit and vegetables is extensive. There are a number of well argued and researched health reasons why we should increase the amount in our diets. Jam wouldn’t qualify as one of your five a day for some of these benefits (though nor would Appletiser, tomato ketchup or fruit strings which are all marketed a such) but jam can have high concentrations of minerals, vitamins, antioxidants and phytonutrients and could help as part of a well structured varied diet. Perhaps Ikea has got it right…… meatballs and jam?.
Jam in sport
What you eat and drink around training and competition is known to affect performance, reduce injury risk and support recovery. Many sports nutritionists recommend bread and jam as a good snack food to eat in the hour before exercise or during tournaments. A brown or granary bread sandwich with jam contains sugar, starch and fibre – both quick release and slower release ‘energy’ and a wide variety of vitamins and minerals. A tablespoon (20g) of jam contains ~15g of carbohydrate, mostly sugar and two slices of wholewheat bread around 25g mixed carbohydrate. Commercially available sports gels contain between 18-51g carbohydrate per serving and sports drinks around 14g per 100ml of fluid (usually 250ml so 35g). In both these the main source of carbohydrate is sugar or a long chain glucose molecule such as maltodextrin. The brain and muscles use glucose for energy but to get the best performance that glucose needs to be supplied in a slow steady stream. Large ‘dumps’ of simple sugars can have a dramatic effect on insulin levels and lead to poor performance, energy slumps and anxiety. The energy release profile of a jam sandwich is likely to be better than most commercially available sports foods and although many drinks / gels / bars contain added vitamins and minerals, its likely that a jam sandwich has a better nutrient value as well.
In a balanced diet it is possible for all foods to have their place. Jam is a high sugar food, but providing it is good quality and fresh, it may also be nutritious and a good source of vitamins, minerals, phytonutrients and even fibre. You can read more about sport drinks here and about tournament nutrition – what to eat when here.