Our food packaging in the UK is generally labelled with the quantity of sugar in the product. In 2015, the UK's Science Advisory Committee came up with a report recommending we reduce consumption to 5% of total dietary energy, which led to the figures of no more than 35g for a man and 25g for a woman. Now, it would only be sensible to make such a recommendation if, as I assumed, it matched the labelling - but it doesn't, making it practically meaningless. This is a recommendation for 'free sugar', where the labelling is the amount of total sugar. Free sugar is defined as 'all monosaccharides and disaccharides added to foods by the manufacturer, cook or consumer, plus sugars naturally present in honey, syrups and unsweetened fruit juices. Under this definition lactose (the sugar in milk) when naturally present in milk and milk products and the sugars contained within the cellular structure of foods (particularly fruits and vegetables) are excluded.' Got it?
There are two problems here. One (the one that confused me) is that it doesn't make any sense for your labelling legislation to require a different definition of sugar content to your recommendation for consumption. But the other is that limiting restrictions entirely to free sugars makes very little sense. For example, they treat all the sugar in orange juice as free sugar, but none of the sugar in an orange (say) as free sugar. However, when you eat an orange, you release a lot of the fruit juice in your mouth, assuming you don't swallow the segments whole. Why isn’t that free sugar? Clearly it is.
There is also a problem with lactose, the sugar in milk. Again, it’s not clear how much this should be counted, but it seems wildly illogical to simply ignore it. And downright weird to count it when it's added, but not when it's already there, as milk has no structural protection to prevent absorption, as there is in fruit.
As far as I can see from the document, there is not good evidence of the involvement of non-free sugars in diabetes, but equally there is not good evidence they are not involved (and nothing either way on heart conditions etc.) My suspicion is they didn't want to scare people off eating fruit and drinking milk because there are other nutrients in them that are good - but the result is a very confusing message.
I suspect the best thing is to cut down on all sugar, but of the sugar you do have, to make sure that it is accompanied by other beneficial nutrients. By all means drink milk (assuming no lactose intolerance) and eat fruit - they are good for you because of those nutrients - but don't consume too much. As mentioned in the book, it's sensible if more of your 5 (or 7 or 10) a day are vegetables rather than fruit. And I'd definitely stay away from smoothies and other very high sugar content drinks (Frappacinos, for instance) and foods mentioned in the book, except as occasional treats.