What vitamins should I take to strengthen my joints?

The first sorting: a joint's six tissues, and which vitamin the register attaches to each

What vitamins should I take to strengthen my joints is a question that the shelf answers with a joint formula, a capsule containing a dozen things with a picture of a knee on the label, and the honest page answers with two sortings that the formula skips, because a reader who does the sortings ends up with one tablet in winter and a shopping list, which is cheaper and better evidenced than the formula. The first sorting is by tissue, because a joint is not one thing. A joint is bone, the two ends that meet; cartilage, the glassy caps on the ends; ligament, the straps that hold the ends together; tendon, the cords that attach muscle to bone across the joint; the capsule and its synovial lining, which enclose the joint and make its fluid; and the muscle that crosses the joint, which holds it stable, moves it and absorbs the load of each step before it reaches the surface. Each tissue has its own biology and its own nutrient dependencies, and the register of authorised health claims, which lists every sentence a product may lawfully print about a nutrient's effect, attaches each vitamin to the tissues it has evidence for and to no others, which makes the register the honest map of the joint. Vitamin D contributes to the maintenance of normal bones and of normal muscle function, and to normal calcium absorption, so it is attached to the bone and to the muscle, which are the joint's hardest tissue and its strengthener. Vitamin C contributes to normal collagen formation for the normal function of cartilage and of bones, so it is attached to the cartilage and the bone through the collagen both are built on. Vitamin K contributes to the maintenance of normal bones. And that is the end of the vitamin list, because no vitamin is attached by the register to ligament, tendon or capsule, the register searched for those words returning no vitamin at all; the connective tissue sentences belong to two minerals, copper, which contributes to the maintenance of normal connective tissues, and manganese, which contributes to their normal formation, so that a reader who wants a lawful sentence about the straps and cords of a joint is reading about minerals, with the register's verb examined on the vitamins for strong bones and joints page. The first sorting leaves the reader with three vitamins and two minerals, each attached to a named tissue, and a joint formula that includes anything else, the B vitamins, vitamin E, biotin, is including passengers. It also leaves the reader with a verb, and the verb on every sentence is contributes to the maintenance of or to the normal formation of, never strengthens, because the register permits a claim when deficiency impairs the function and sufficiency restores it, which is a maintenance relationship and not a building one; the sentences say that a joint short of these nutrients does worse and a joint supplied with them does normally, and nothing about a joint supplied with more doing better.

The second sorting: take against eat, the one vitamin that is a take, the strengthener and the vitamin attached to it, and the worked example

The second sorting is take against eat, and it turns the list of three vitamins and two minerals into one tablet and a shopping list. A nutrient is a take when a reader cannot reliably get enough of it from food and the gap matters, and an eat when any varied diet supplies it to the point at which more does nothing, and for the joint's nutrients the sorting is clear. Vitamin C is an eat: it works as a cofactor for the enzymes that stabilise new collagen, those enzymes saturate at intakes around 100 to 200mg a day, a single satsuma supplies the 80mg reference intake and a pepper or a serving of broccoli supplies more, and no trial of vitamin C above sufficiency has improved any joint, so a reader eating fruit or vegetables most days is done and a 1000mg tablet changes the colour of their urine. Vitamin K is an eat, from green vegetables, with its bone sentence met by ordinary intake and a caution for anyone on warfarin that makes a supplement a conversation rather than a purchase. Copper and manganese are eats, from nuts, seeds, wholegrains, shellfish and pulses, each a cofactor for enzymes that saturate, with copper deficiency rare and manganese deficiency essentially unknown on a mixed diet. Vitamin D is the take, for a reason that is geography rather than biology: the skin makes vitamin D from sunlight, and the British sun from October to March is too low in the sky for the skin to make any at all, so that around one adult in five or six has a low blood level by late winter, more among people with dark skin, who cover their skin, who are housebound or who spend their days indoors, and the national guidance says that everyone should consider taking 10 micrograms a day through autumn and winter and that the higher-risk groups should take it all year. That is the one vitamin a reader should take for their joints, and it is attached to the two tissues that matter most, the bone and the muscle, with the decade-by-decade version on the vitamins for bones and joints in adults page. The thing that strengthens a joint, in the sense the reader means, is none of the vitamins and is the muscle around it: the injury prevention trials that assigned whole teams to strength and balance programmes cut knee and ankle injuries by a third to a half, strength training alone cut injuries by a third, and no prevention trial has ever used a vitamin, on the build stronger joints page; and vitamin D's muscle function sentence is the only vitamin the register attaches to the strengthener, with a low winter level associated with weaker muscle and more falls in older adults, which makes the one take the right one for a reader whose joint strength is their concern. So the honest answer has three parts: take vitamin D, 10 micrograms a day from October to March or all year if at risk; eat the C, the K and the minerals in a varied diet; and strengthen the joint with the muscle around it, two or three sessions a week of resistance and balance work, which is what the vitamins were being asked to do and cannot. Collagen's place is beside the strength work, as the tendon protocol's adjunct and the joint trials' small effect at 10g, and its labels carry vitamin C's cartilage sentence because 12mg clears the threshold, which is a borrowed eat rather than a take. The worked example is stated on its true terms: two capsules, 1200mg hydrolysed type 1 marine collagen with 12mg vitamin C at 15% of its reference value plus zinc, 120 for £16.99 at 28p a day, lab tested and UK made, carrying vitamin C's collagen formation sentence for cartilage and bones and zinc's, no vitamin D, and no joint claim of its own, since the register permits none for collagen. What vitamins should I take to strengthen my joints: one, vitamin D in winter, attached to the bone and the muscle; eat the rest; and strengthen the joint with the muscle, which no vitamin does.

What to check on the label